TY  - JOUR
A1  - Hermanns, Jolanda
A1  - Keller, David
T1  - The development, use, and evaluation of digital games and quizzes in an introductory course on organic chemistry for preservice chemistry teachers
JF  - Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society
N2  - Due to the COVID pandemic, the introductory course on organic chemistry was developed and conducted as anonline course. To ensure methodical variety in this course,educational games and quizzes have been developed, used, and evaluated. The attendance of the course, and therefore also the use of the quizzes and games, was voluntary. The quizzes'main goalwas to give the students the opportunity to check whether they had memorized the knowledge needed in the course. Another goal was to make transparent which knowledge the students shouldmemorize by rote. The evaluation shows that the students hadnot internalized all knowledge which they should apply in severaltasks on organic chemistry. They answered multiselect questions in general less well than single-select questions. The games shouldcombine fun with learning. The evaluation of the games shows that the students rated them very well. The students used thosegames again for their exam preparation, as the monitoring of accessing the games showed. Students'experiences with usingelectronic devices in general or for quizzes and games have also been evaluated, because their experience could influence thestudents'assessment of the quizzes and games used in our study. However, the students used electronic devices regularly and shouldtherefore be technically competent to use our quizzes and games. The evaluation showed that the use of digital games for learningpurposes is not very common, neither at school nor at university, although the students had worked with such tools before. Thestudents are also very interested in using and developing such digital games not only for their own study, but also for their future work at school
KW  - Organic Chemistry
KW  - Second-Year Undergraduate
KW  - Humor
KW  - Puzzles
KW  - Games;
KW  - Internet
KW  - Web-Based Learning
KW  - Distance Learning
KW  - Self Instruction
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jchemed.2c00058
SN  - 0021-9584
SN  - 1938-1328
VL  - 99
IS  - 4
SP  - 1715
EP  - 1724
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Raju, Rajarshi Roy
A1  - Koetz, Joachim
T1  - Pickering Janus emulsions stabilized with gold nanoparticles
JF  - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society
N2  - We report a modified approach to the batch scale preparation of completely engulfed core-shell emulsions or partially engulfed Janus emulsions with colorful optical properties, containing water, olive oil, and silicone oil. The in situ reduction of gold chloride, forming gold nanoparticles (AuNPs) at the olive oil interface in the absence or presence of chitosan, leads to the formation of compartmentalized olive-silicone oil emulsion droplets in water. In the absence of additional reducing components, time-dependent morphological transformations from partial engulfment to complete engulfment were observed. Similar experiments in the presence of chitosan or presynthesized AuNPs show an opposite time-dependent trend of transformation of core-shell structures into partially engulfed ones. This behavior can be understood by a time-dependent rearrangement of the AuNPs at the interface and changes of the interfacial tension. The Pickering effect of AuNPs at oil-water and oil-oil interfaces brings not only color effects to individual microdroplets, which are of special relevance for the preparation of new optical elements, but also a surprising self-assembly of droplets.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.langmuir.1c02256
SN  - 0743-7463
SN  - 1520-5827
VL  - 38
IS  - 1
SP  - 147
EP  - 155
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lood, Kajsa
A1  - Tikk, Triin
A1  - Krüger, Mandy
A1  - Schmidt, Bernd
T1  - Methylene capping facilitates cross-metathesis reactions of enals
BT  - a short synthesis of 7-methoxywutaifuranal from the xylochemical isoeugenol
JF  - The journal of organic chemistry
N2  - Four combinations of type-I olefins isoeugenol and 4-hydroxy-3-methoxystyrene with type-II olefins acrolein and crotonaldehyde were investigated in cross-metathesis (CM) reactions. While both type-I olefins are suitable CM partners for this transformation, we observed synthetically useful conversions only with type-II olefin crotonaldehyde. For economic reasons, isoeugenol, a cheap xylochemical available from renewable lignocellulose or from clove oil, is the preferred type-I CM partner. Nearly quantitative conversions to coniferyl aldehyde by the CM reaction of isoeugenol and crotonaldehyde can be obtained at ambient temperature without a solvent or at high substrate concentrations of 2 mol.L-1 with the second-generation Hoveyda-Grubbs catalyst. Under these conditions, the ratio of reactants can be reduced to 1:1.5 and catalyst loadings as low as 0.25 mol % are possible. The high reactivity of the isoeugenol/crotonaldehyde combination in olefin metathesis reactions was demonstrated by a short synthesis of the natural product 7-methoxywutaifuranal, which was obtained from isoeugenol in a 44% yield over five steps. We suggest that the superior performance of crotonaldehyde in the CM reactions investigated can be rationalized by "methylene capping", i.e., the steric stabilization of the propagating Ru-alkylidene species.
KW  - Aldehydes
KW  - Catalysts
KW  - Hydrocarbons
KW  - Metathesis
KW  - Mixtures
Y1  - 2022
U6  - https://doi.org/10.1021/acs.joc.1c02851
SN  - 0022-3263
SN  - 1520-6904
VL  - 87
IS  - 5
SP  - 3079
EP  - 3088
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Polley, Nabarun
A1  - Werner, Peter
A1  - Balderas-Valadez, Ruth Fabiola
A1  - Pacholski, Claudia
T1  - Bottom, top, or in between
BT  - combining plasmonic nanohole arrays and hydrogel microgels for optical fiber snsor applications
JF  - Advanced materials interfaces
N2  - Attractive label-free plasmonic optical fiber sensors can be developed by cleverly choosing the arrangement of plasmonic nanostructures and other building blocks. Here, the final response depends very much on the alignment and position (stacking) of the individual elements. In this work, three different types of fiber optic sensing geometries fabricated by simple layer-by-layer stacking are presented, consisting of stimulus-sensitive poly-N-isopropylacrylamide (polyNIPAM) microgel arrays and plasmonic nanohole arrays (NHAs), namely NHA/polyNIPAM, polyNIPAM/NHA, polyNIPAM/NHA/polyNIPAM. Their optical response to a representative stimulus, namely temperature, is investigated. NHA/polyNIPAM monitors the volume phase transition of polyNIPAM microgels through changes in the spectral position and the amplitude of the reflection minimum of plasmonic NHA. In contrast, polyNIPAM/NHA shows a more complex response to the swelling and collapse of polyNIPAM microgels in their reflectance spectra. The most pronounced changes in optical response are observed by monitoring the amplitude of the reflectance minimum of this sensor during heating/cooling cycles. Finally, the triple stack of polyNIPAM/NHA/polyNIPAM at the end of a optical fiber tip combines the advantages of the NHA/polyNIPAM, polyNIPAM/NHA double stacks for optical sensing. The unique layer-by-layer stacking of microgel and nanostructure is customizable and can be easily adopted for other applications.
KW  - bottom-up fabrication
KW  - layer-by-layer stacking
KW  - microgel arrays
KW  - optical
KW  - fiber sensors
KW  - plasmonic nanohole arrays
Y1  - 2022
U6  - https://doi.org/10.1002/admi.202102312
SN  - 2196-7350
VL  - 9
IS  - 15
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Pilar Yeste, Maria
A1  - Carlos Hernandez-Garrido, Juan
A1  - Kumke, Michael Uwe
A1  - Alvarado, Sarah
A1  - Cauqui, Miguel Angel
A1  - Juan Calvino, Jose
A1  - Primus, Philipp-Alexander
T1  - Low-temperature growth of reactive pyrochlore nanostructures on Zirconia-supported ceria
BT  - implications for improved catalytic behavior
JF  - ACS applied nano materials
N2  - The use of a catalyst support for the design of nanoscale heterogeneous catalysts based on cerium oxide offers vast possibilities for future catalyst development, particularly with regard to an increased focus on the use of renewable biogas and an emerging hydrogen economy. In this study, zirconia-supported ceria catalysts were synthesized, activated by using different thermochemical treatments, and characterized by way of temperature-programmed reduction (TPR), oxygen storage capacity, Xray diffraction, electron microscopy, and luminescence spectroscopy using Eu3+ as a spectroscopic probe. Through reduction-oxidation pretreatment routines, reactive pyrochlore structures were created at temperatures as low as 600 degrees C and identified through TPR and electron microscopy experiments. A structural relationship and alignment of the crystal planes is revealed in high-resolution scanning transmission electron microscopy experiments through the digital diffraction patterns. Low-temperature pretreatment induces the formation of reactive pyrochlore domains under retention of the surface area of the catalyst system, and no further morphological changes are detected. Furthermore, the formation of pyrochlore domains achieved through severe reduction and mild reoxidation (SRMO) treatments is reversible. Over multiple alternating SRMO and severe reduction and severe reoxidation (SRSO) treatments, europium spectroscopy and TPR results indicate that pyrochlore structures are recreated over consecutive treatments, whenever the mild oxidation step at 500 degrees C is the last treatment (SRMO, SRMO-SRSO-SRMO, etc.).
KW  - pyrochlore
KW  - nanocomposite
KW  - ceria
KW  - zirconia
KW  - supported catalyst
KW  - oxygen
KW  - storage capacity
Y1  - 2022
U6  - https://doi.org/10.1021/acsanm.2c00416
SN  - 2574-0970
VL  - 5
IS  - 5
SP  - 6316
EP  - 6326
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sperlich, Eric
A1  - Kelling, Alexandra
A1  - Kwesiga, George
A1  - Schmidt, Bernd
T1  - Intermolecular interactions in the solid-state structures of isoflavones
BT  - the relationship between supramolecular structure, torsion angle, and macroscopic properties
JF  - CrystEngComm / The Royal Society of Chemistry
N2  - The molecular structures of three closely related isoflavones have been determined by single crystal X-ray diffraction and have been analysed by geometry matching with the CSD, Hirshfeld surface analysis and analysis of stacking interactions with the Aromatic Analyser program (CSD). The formation of the supramolecular structure by non-covalent interactions was studied and substantial differences in the macroscopic properties e.g., the solubility, were correlated with hydrogen bonding and pi-stacking interactions. Moreover, a correlation between the supramolecular structure, the torsion angle (between benzopyran group and aryl group), and macroscopic properties was determined in the three compounds.
Y1  - 2022
U6  - https://doi.org/10.1039/d2ce00169a
SN  - 1466-8033
VL  - 24
IS  - 26
SP  - 4731
EP  - 4739
PB  - Royal Society of Chemistry
CY  - London
ER  - 
TY  - JOUR
A1  - Prüfert, Christian
A1  - Villatoro Leal, José Andrés
A1  - Zühlke, Martin
A1  - Beitz, Toralf
A1  - Löhmannsröben, Hans-Gerd
T1  - Liquid phase IR-MALDI and differential mobility analysis of nano- and sub-micron particles
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Infrared matrix-assisted desorption and ionization (IR-MALDI) enables the transfer of sub-micron particles (sMP) directly from suspensions into the gas phase and their characterization with differential mobility (DM) analysis. A nanosecond laser pulse at 2940 nm induces a phase explosion of the aqueous phase, dispersing the sample into nano- and microdroplets. The particles are ejected from the aqueous phase and become charged. Using IR-MALDI on sMP of up to 500 nm in diameter made it possible to surpass the 100 nm size barrier often encountered when using nano-electrospray for ionizing supramolecular structures. Thus, the charge distribution produced by IR-MALDI could be characterized systematically in the 50-500 nm size range. Well-resolved signals for up to octuply charged particles were obtained in both polarities for different particle sizes, materials, and surface modifications spanning over four orders of magnitude in concentrations. The physicochemical characterization of the IR-MALDI process was done via a detailed analysis of the charge distribution of the emerging particles, qualitatively as well as quantitatively. The Wiedensohler charge distribution, which describes the evolution of particle charging events in the gas phase, and a Poisson-derived charge distribution, which describes the evolution of charging events in the liquid phase, were compared with one another with respect to how well they describe the experimental data. Although deviations were found in both models, the IR-MALDI charging process seems to resemble a Poisson-like charge distribution mechanism, rather than a bipolar gas phase charging one.
Y1  - 2022
U6  - https://doi.org/10.1039/d1cp04196g
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 4
SP  - 2275
EP  - 2286
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - López de Guereñu Kurganova, Anna
A1  - Klier, Dennis Tobias
A1  - Haubitz, Toni
A1  - Kumke, Michael Uwe
T1  - Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4
BT  - Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10-50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.
KW  - Upconversion luminescence
KW  - Lanthanides
KW  - Near infra-red
KW  - Ultra-low
KW  - temperature
KW  - Time-resolved spectroscopy
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00161-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 235
EP  - 245
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - THES
A1  - Zhou, Shuo
T1  - Biological evaluation and sulfation of polymer networks from glycerol glycidyl ether
N2  - Cardiovascular diseases are the main cause of death worldwide, and their prevalence is expected to rise in the coming years. Polymer-based artificial replacements have been widely used for the treatment of cardiovascular diseases. Coagulation and thrombus formation on the interfaces between the materials and the human physiological environment are key issues leading to the failure of the medical device in clinical implantation. The surface properties of the materials have a strong influence on the protein adsorption and can direct the blood cell adhesion behavior on the interfaces. Furthermore, implant-associated infections will be induced by bacterial adhesion and subsequent biofilm formation at the implantation site. Thus, it is important to improve the hemocompatibility of an implant by altering the surface properties. One of the effective strategies is surface passivation to achieve protein/cell repelling ability to reduce the risk of thrombosis. 
This thesis consists of synthesis, functionalization, sterilization, and biological evaluation of bulk poly(glycerol glycidyl ether) (polyGGE), which is a highly crosslinked polyether-based polymer synthesized by cationic ring-opening polymerization. PolyGGE is hypothesized to be able to resist plasma protein adsorption and bacterial adhesion due to analogous chemical structure as polyethylene glycol and hyperbranched polyglycerol. Hydroxyl end groups of polyGGE provide possibilities to be functionalized with sulfates to mimic the anti-thrombogenic function of the endothelial glycocalyx. 
PolyGGE was synthesized by polymerization of the commercially available monomer glycerol glycidyl ether, which was characterized as a mixture of mono-, di- and tri-glycidyl ether. Cationic ring opening-polymerization of this monomer was carried out by ultraviolet (UV) initiation of the photo-initiator diphenyliodonium hexafluorophosphate. With the increased UV curing time, more epoxides in the side chains of the monomers participated in chemical crosslinking, resulting in an increase of Young’s modulus, while the value of elongation at break of polyGGE first increased due to the propagation of the polymer chains then decreased with the increase of crosslinking density. Eventually, the chain propagation can be effectively terminated by potassium hydroxide aqueous solution. PolyGGE exhibited different tensile properties in hydrated conditions at body temperature compared to the values in the dry state at room temperature. Both Young’s modulus and values of elongation at break were remarkably reduced when tested in water at 37 °C, which was above the glass transition temperature of polyGGE. At physiological conditions, entanglements of the ployGGE networks unfolded and the free volume of networks were replaced by water molecules as softener, which increased the mobility of the polymer chains, resulting in a lower Young’s modulus. 
Protein adsorption analysis was performed on polyGGE films with 30 min UV curing using an enzyme-linked immunosorbent assay. PolyGGE could effectively prevent the adsorption of human plasma fibrinogen, albumin, and fibronectin at the interface of human plasma and polyGGE films. The protein resistance of polyGGE was comparable to the negative controls: the hemocompatible polydimethylsiloxane (PDMS), showing its potential as a coating material for cardiovascular implants. Moreover, antimicrobial tests of bacterial activity using isothermal microcalorimetry and the microscopic image of direct bacteria culturing demonstrated that polyGGE could directly interfere biofilm formation and growth of both Gram-negative and antibiotic-resistant Gram-positive bacteria, indicating the potential application of polyGGE for combating the risk of hospital-acquired infections and preventing drug-resistant superbug spreading.
To investigate its cell compatibility, polyGGE films were extracted by different solvents (ethanol, chloroform, acetone) and cell culture medium. Indirect cytotoxicity tests showed extracted polyGGE films still had toxic effects on L929 fibroblast cells. High-performance liquid chromatography/electrospray ionization mass spectrometry revealed the occurrence of organochlorine-containing compounds released during the polymer-cell culture medium interaction. A constant level of those organochlorine-containing compounds was confirmed from GGE monomer by a specific peak of C-Cl stretching in infrared spectra of GGE. This is assumed to be the main reason causing the increased cell membrane permeability and decreased metabolic activity, leading to cell death. Attempts as changing solvents were made to remove toxic substances, however, the release of these small molecules seems to be sluggish. The densely crosslinked polyGGE networks can possibly contribute to the trapping of organochlorine-containing compounds. These results provide valuable information for exploring the potentially toxic substances, leaching from polyGGE networks, and propose a feasible strategy for minimizing the cytotoxicity via reducing their crosslinking density.

Sulfamic acid/ N-Methyl-2-pyrrolidone (NMP) were selected as the reagents for the sulfation of polyGGE surfaces. Fourier transform attenuated total reflection infrared spectroscopy (ATR-FT-IR) was used to monitor the functionalization kinetics and the results confirmed the successful sulfate grafting on the surface of polyGGE with the covalent bond -C-O-S-. X-ray photoelectron spectroscopy was used to determine the element composition on the surface and the cross-section of the functionalized polyGGE and sulfation within 15 min guarantees the sulfation only takes place on the surface while not occurring in the bulk of the polymer. The concentration of grafted sulfates increased with the increasing reaction time. The hydrophilicity of the surface of polyGGE was highly increased due to the increase of negatively charged end groups. Three sterilization techniques including autoclaving, gamma irradiation, and ethylene oxide (EtO) sterilization were used for polyGGE sulfates. Results from ATR-FT-IR and Toluidine Blue O quantitative assay demonstrated the total loss of the sulfates after autoclave sterilization, which was also confirmed by the increased water contact angle. Little influence on the concentration of sulfates was found for gamma-irradiated and autoclaving sterilized polyGGE sulfates. To investigate the thermal influence on polyGGE sulfates, one strategy was to use poly(hydroxyethyl acrylate) sulfates (PHEAS) for modeling. The thermogravimetric analysis profile of PHEAS demonstrated that sulfates are not thermally stable independent of the substrate materials and decomposition of sulfates occurs at around 100 °C. Although gamma irradiation also showed little negative effect on the sulfate content, the color change in the polyGGE sulfates indicates chemical or physical change might occur in the polymer. EtO sterilization was validated as the most suitable sterilization technique to maintain the chemical structure of polyGGE sulfates.
In conclusion, the conducted work proved that bulk polyGGE can be used as an antifouling coating material and shows its antimicrobial potential. Sulfates functionalization can be effectively realized using sulfamic acid/NMP. EtO sterilization is the most suitable sterilization technique for grafted sulfates. Besides, this thesis also offers a good strategy for the analysis of toxic leachable substances using suitable physicochemical characterization techniques. Future work will focus on minimizing/eliminating the release of toxic substances via reducing the crosslinking density. Another interesting aspect is to study whether grafted sulfates can meet the need for anti-thrombogenicity.
N2  - Herz-Kreislauf-Erkrankungen sind weltweit die Haupttodesursache, und es wird erwartet, dass ihre Prävalenz in den kommenden Jahren zunehmen wird. Künstlicher Ersatz auf Polymerbasis wird in großem Umfang für die Behandlung von Herz-Kreislauf-Erkrankungen eingesetzt. Gerinnung und Thrombenbildung an den Grenzflächen zwischen den Materialien und der menschlichen physiologischen Umgebung sind ein Hauptproblem, das zum Versagen des Medizinprodukts bei der klinischen Implantation führt. Die Oberflächeneigenschaften der Materialien haben einen starken Einfluss auf die Proteinadsorption und können das Adhäsionsverhalten von Blutzellen an den Grenzflächen steuern. Darüber hinaus werden Implantat-assoziierte Infektionen durch bakterielle Adhäsion und anschließende Biofilmbildung an der Implantationsstelle ausgelöst. Daher ist es wichtig, die Hämokompatibilität eines Implantats durch Veränderung der Oberflächeneigenschaften zu verbessern. Eine der wirksamen Strategien ist die Oberflächenpassivierung, um die Fähigkeit zur Protein-/Zellabweisung zu erreichen und so das Thromboserisiko zu verringern. 
Diese Arbeit befasst sich mit der Synthese, Funktionalisierung, Sterilisation und biologischen Bewertung von Poly(glycerin glycidyl ether) (polyGGE), einem stark vernetzten Polymer auf Polyetherbasis, das durch kationische Ringöffnungspolymerisation hergestellt wird. Es wird angenommen, dass PolyGGE aufgrund seiner ähnlichen chemischen Struktur wie Polyethylenglykol und hyperverzweigtes Polyglycerin der Adsorption von Plasmaproteinen und der Anhaftung von Bakterien widerstehen kann. Die Hydroxyl-Endgruppen von PolyGGE können mit Sulfaten funktionalisiert werden, um die antithrombogene Funktion der endothelialen Glykokalyx zu imitieren. 
PolyGGE wurde durch Polymerisation des kommerziell erhältlichen Monomers Glycerin Glycidyl ether synthetisiert, das als Mischung aus Mono-, Di- und Triglycidylether charakterisiert wurde. Die kationische Ringöffnungspolymerisation dieses Monomers wurde mit Hilfe des Photoinitiators Diphenyliodoniumhexafluorophosphat durch Ultraviolett (UV) ausgelöst. Mit zunehmender UV-Härtungszeit nahmen mehr Epoxide in den Seitenketten der Monomere an der chemischen Vernetzung teil, was zu einem Anstieg des Elastizitätsmoduls führte, während der Wert der Bruchdehnung von polyGGE zunächst aufgrund der Ausbreitung der Polymerketten anstieg und dann mit zunehmender Vernetzungsdichte abnahm. Schließlich kann die Kettenausbreitung durch wässrige Kaliumhydroxidlösung wirksam gestoppt werden. PolyGGE wies im hydratisierten Zustand bei Körpertemperatur andere Zugeigenschaften auf als im trockenen Zustand bei Raumtemperatur. Sowohl der Elastizitätsmodul als auch die Werte der Bruchdehnung waren deutlich reduziert, wenn sie in Wasser bei 37 °C getestet wurden, was oberhalb der Glasübergangstemperatur von PolyGGE lag. Unter physiologischen Bedingungen entfalteten sich die Verflechtungen der PolyGGE-Netzwerke und das freie Volumen der Netzwerke wurde durch Wassermoleküle als Weichmacher ersetzt, was die Mobilität der Polymerketten erhöhte und zu einem niedrigeren Elastizitätsmodul führte. 
Die Proteinadsorptionsanalyse wurde an PolyGGE-Filmen mit 30-minütiger UV-Härtung unter Verwendung eines Enzymimmunoassays durchgeführt. PolyGGE konnte die Adsorption von Fibrinogen, Albumin und Fibronektin aus menschlichem Plasma an der Grenzfläche zwischen menschlichem Plasma und PolyGGE-Filmen wirksam verhindern. Die Proteinresistenz von PolyGGE war vergleichbar mit den Negativkontrollen: dem hämokompatiblen Polydimethylsiloxan, was sein Potenzial als Beschichtungsmaterial für kardiovaskuläre Implantate zeigt. Darüber hinaus zeigten antimikrobielle Tests der bakteriellen Aktivität mittels isothermischer Mikrokalorimetrie und das mikroskopische Bild der direkten Bakterienkultur, dass PolyGGE die Biofilmbildung und das Wachstum sowohl von gramnegativen als auch von antibiotikaresistenten grampositiven Bakterien direkt stören kann, was auf die potenzielle Anwendung von PolyGGE zur Bekämpfung des Risikos von Krankenhausinfektionen und zur Verhinderung der Ausbreitung arzneimittelresistenter Superbugs hinweist.
Um die Zellkompatibilität zu untersuchen, wurden polyGGE-Folien mit verschiedenen Lösungsmitteln (Ethanol, Chloroform, Aceton) und Zellkulturmedium extrahiert. Indirekte Zytotoxizitätstests zeigten, dass die extrahierten polyGGE-Filme immer noch eine toxische Wirkung auf L929-Fibroblastenzellen hatten. Die Hochleistungsflüssigkeitschromatographie/Elektrospray-Ionisations-Massenspektrometrie zeigte das Auftreten von chlororganischen Derivaten, die während der Interaktion zwischen Polymer und Zellkulturmedium freigesetzt wurden. Ein konstantes Niveau dieser chlororganischen Derivate wurde vom GGE-Monomer durch einen spezifischen C-Cl-Streckungspeak im Infrarotspektrum von GGE bestätigt. Es wird angenommen, dass dies der Hauptgrund für die erhöhte Permeabilität der Zellmembran und die verringerte Stoffwechselaktivität ist, was zum Zelltod führt. Es wurden Versuche unternommen, die Lösungsmittel zu wechseln, um die toxischen Substanzen zu entfernen, aber die Freisetzung dieser kleinen Moleküle scheint nur langsam zu erfolgen. Die dicht vernetzten polyGGE-Netzwerke können möglicherweise zum Einschluss chloridhaltiger Verbindungen beitragen. Diese Ergebnisse liefern wertvolle Informationen für die Erforschung potenzieller toxischer Substanzen, die aus PolyGGE-Netzwerken ausgewaschen werden, und schlagen eine praktikable Strategie zur Minimierung der Zytotoxizität durch Verringerung der Vernetzungsdichte vor.
Als Reagenzien für die Sulfatierung von PolyGGE-Oberflächen wurden Sulfaminsäure und N-Methyl-2-Pyrrolidon (NMP) gewählt. Die Fourier-Transformations-Infrarotspektroskopie mit abgeschwächter Totalreflexion (ATR-FT-IR) wurde zur Überwachung der Funktionalisierungskinetik eingesetzt, und die Ergebnisse bestätigten die erfolgreiche Sulfatpfropfung auf der Oberfläche von PolyGGE mit der kovalenten Bindung -C-O-S-. Mit Hilfe der Röntgen-Photoelektronenspektroskopie wurde die Elementzusammensetzung auf der Oberfläche und der Querschnitt des funktionalisierten PolyGGE bestimmt, und die Sulfatierung innerhalb von 15 Minuten garantiert, dass die Sulfatierung nur auf der Oberfläche stattfindet, während sie in der Masse des Polymers nicht vorkommt. Die Konzentration der gepfropften Sulfate nahm mit zunehmender Reaktionszeit zu. Die Hydrophilie der Oberfläche von polyGGE wurde durch die Zunahme negativ geladener Endgruppen stark erhöht. Für die PolyGGE-Sulfate wurden drei Sterilisationstechniken verwendet: Autoklavieren, Gammastrahlenbestrahlung und Ethylenoxid (EtO)-Sterilisation. Die Ergebnisse der quantitativen ATR-FT-IR und Toluidinblau O-Untersuchung zeigten den vollständigen Verlust der Sulfate nach der Sterilisation im Autoklaven, was auch durch den erhöhten Wasserkontaktwinkel bestätigt wurde. Bei den mit Gammastrahlen und im Autoklaven sterilisierten PolyGGE-Sulfaten wurde nur ein geringer Einfluss auf die Sulfatkonzentration festgestellt. Um den thermischen Einfluss auf PolyGGE-Sulfate zu untersuchen, bestand eine Strategie darin, ein Poly(hydroxyethylacrylat)-Sulfat (PHEAS) für die Modellierung zu verwenden. Das Profil der thermogravimetrischen Analyse von PHEAS zeigte, dass Sulfate unabhängig von den Substratmaterialien thermisch nicht stabil sind und die Zersetzung der Sulfate bei etwa 100 °C stattfindet. Obwohl die Gammasterilisation ebenfalls kaum negative Auswirkungen auf den Sulfatgehalt hat, deutet die Farbveränderung der PolyGGE-Sulfate darauf hin, dass chemische oder physikalische Veränderungen im Polymer auftreten könnten. Die EtO-Sterilisation erwies sich als die am besten geeignete Sterilisationstechnik, um die chemische Struktur der PolyGGE-Sulfate zu erhalten.
Zusammenfassend lässt sich sagen, dass die durchgeführte Arbeit bewiesen hat, dass PolyGGE als Antifouling-Beschichtungsmaterial verwendet werden kann und sein antimikrobielles Potenzial zeigt. Die Funktionalisierung der Sulfate kann mit Sulfaminsäure/NMP effektiv durchgeführt werden. Die EtO-Sterilisation ist die am besten geeignete Sterilisationstechnik für gepfropfte Sulfate. Darüber hinaus bietet diese Arbeit auch eine gute Strategie für die Analyse toxischer auslaugbarer Substanzen mit Hilfe geeigneter physikalisch-chemischer Charakterisierungstechniken. Zukünftige Arbeiten werden sich darauf konzentrieren, die Freisetzung toxischer Substanzen durch Verringerung der Vernetzungsdichte zu minimieren bzw. zu eliminieren. Ein weiterer interessanter Aspekt ist die Untersuchung, ob gepfropfte Sulfate den Anforderungen an die Anti-Thrombogenität gerecht werden können.
KW  - Sulfation
KW  - Antifouling
KW  - antimicrobial
KW  - Polyether
Y1  - 2022
ER  - 
TY  - JOUR
A1  - Liu, Yue
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - On demand sequential release of (sub)micron particles controlled by size and temperature
JF  - Small : nano micro
N2  - Polymeric devices capable of releasing submicron particles (subMP) on demand are highly desirable for controlled release systems, sensors, and smart surfaces. Here, a temperature-memory polymer sheet with a programmable smooth surface served as matrix to embed and release polystyrene subMP controlled by particle size and temperature. subMPs embedding at 80 degrees C can be released sequentially according to their size (diameter D of 200 nm, 500 nm, 1 mu m) when heated. The differences in their embedding extent are determined by the various subMPs sizes and result in their distinct release temperatures. Microparticles of the same size (D approximate to 1 mu m) incorporated in films at different programming temperatures T-p (50, 65, and 80 degrees C) lead to a sequential release based on the temperature-memory effect. The change of apparent height over the film surface is quantified using atomic force microscopy and the realization of sequential release is proven by confocal laser scanning microscopy. The demonstration and quantification of on demand subMP release are of technological impact for assembly, particle sorting, and release technologies in microtechnology, catalysis, and controlled release.
KW  - on demand particle release
KW  - temperature-memory effect
KW  - thermosensitive
KW  - polymer surface
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202104621
SN  - 1613-6810
SN  - 1613-6829
VL  - 18
IS  - 5
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Moradian, Hanieh
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
T1  - Co-delivery of genes can be confounded by bicistronic vector design
JF  - MRS Communications
N2  - Maximizing the efficiency of nanocarrier-mediated co-delivery of genes for co-expression in the same cell is critical for many applications. Strategies to maximize co-delivery of nucleic acids (NA) focused largely on carrier systems, with little attention towards payload composition itself. Here, we investigated the effects of different payload designs: co-delivery of two individual "monocistronic" NAs versus a single bicistronic NA comprising two genes separated by a 2A self-cleavage site. Unexpectedly, co-delivery via the monocistronic design resulted in a higher percentage of co-expressing cells, while predictive co-expression via the bicistronic design remained elusive. Our results will aid the application-dependent selection of the optimal methodology for co-delivery of genes.
KW  - Molecular
KW  - Packaging
KW  - Protein
Y1  - 2022
U6  - https://doi.org/10.1557/s43579-021-00128-7
SN  - 2159-6859
SN  - 2159-6867
VL  - 12
IS  - 2
SP  - 145
EP  - 153
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Hartlieb, Matthias
T1  - Photo-iniferter RAFT polymerization
JF  - Macromolecular rapid communications : publishing the newsletters of the European Polymer Federation
N2  - Light-mediated polymerization techniques offer distinct advantages over polymerization reactions fueled by thermal energy, such as high spatial and temporal control as well as the possibility to work under mild reaction conditions. Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a highly versatile radical polymerization method that can be utilized to control a variety of monomers and produce a vast number of complex macromolecular structures. The use of light to drive a RAFT-polymerization is possible via multiple routes. Besides the use of photo-initiators, or photo-catalysts, the direct activation of the chain transfer agent controlling the RAFT process in a photo-iniferter (PI) process is an elegant way to initiate and control polymerization reactions. Within this review, PI-RAFT polymerization and its advantages over the conventional RAFT process are discussed in detail.
KW  - light
KW  - photo-iniferter reversible addition-fragmentation chain-transfer
KW  - photo-mediated polymerization
KW  - radical polymerization
KW  - reversible
KW  - addition-fragmentation chain-transfer polymerization
Y1  - 2021
U6  - https://doi.org/10.1002/marc.202100514
SN  - 1521-3927
VL  - 43
IS  - 1
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Badetko, Dominik
A1  - Czarnecki, Maciej
A1  - Wichterich, Lukas
A1  - Schmidt, Peter
A1  - Brudy, Cosima
A1  - Sperlich, Eric
A1  - Kelling, Alexandra
T1  - Studies toward the total synthesis of arylnaphthalene lignans via a Photo-Dehydro-Diels-Alder (PDDA) reaction
JF  - The journal of organic chemistry
N2  - An efficient method for the preparation of arylnaphthalene lignans (ANLs) was developed, which is based on thePhoto-Dehydro-DIELS-ALDER(PDDA) reaction. While intermolecular PDDA reactions turned out to be inefficient, theintramolecular variant using suberic acid as tether linking two aryl propiolic esters smoothly provided naphthalenophanes. Theirradiations were performed with a previously developed annular continuous-flow reactor and UVB lamps. In this way, the naturalproducts Alashinol D, Taiwanin C, and an unnamed ANL could be prepared.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.joc.2c00195
SN  - 0022-3263
SN  - 1520-6904
VL  - 87
IS  - 9
SP  - 5904
EP  - 5915
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - THES
A1  - Michaelis, Marcus
T1  - Molekulare Erkennung von Cellulose und Cellulose-Fragmenten durch Cellulose-Bindemodule & Interaktionsstudien zwischen den zytoplasmatischen Domänen von Integrin-β1/β3 und dem fokalen Adhäsionsprotein Paxillin
T1  - Molecular recognition of cellulose and cellulose fragments by cellulose binding modules & Interaction studies between the cytoplasmic domains of integrin-β1/β3 and the focal adhesion protein paxillin
N2  - Proteine erfüllen bei einer Vielzahl von Prozessen eine essenzielle Rolle. Um diese Funktionsweisen zu verstehen, bedarf es der Aufklärung derer Struktur und deren Bindungsverhaltens mit anderen Molekülen wie Proteinen, Peptiden, Kohlenhydraten oder kleinen Molekülen. Im ersten Teil dieser Arbeit wurden der Wildtyp und die Punktmutante N126W eines Kohlenhydrat-bindenden Proteins aus dem hitzestabilen Bakterium C. thermocellum untersucht, welches Teil eines Komplexes ist, der Kohlenhydrate wie Cellulose erkennen, binden und abbauen kann. Dazu wurde dieses Protein mit E.coli Bakterien hergestellt und durch Metallchelat- und Größenausschlusschromatographie gereinigt. Die Proteine konnten isotopenmarkiert mittels Kernspinresonanz-Spektroskopie (NMR) untersucht werden. H/D-Austauschexperimente zeigten leicht und schwer zugängliche Stellen im Protein für eine mögliche Ligandenwechselwirkung. Anschließend konnte eine Interaktion beider Proteine mit Cellulosefragmenten festgestellt werden. Diese interagieren über zwischenmolekulare Kräfte mit den Seitenketten von aromatischen Aminosäuren und über Wasserstoffbrückenbindungen mit anderen Resten. Weiterhin wurde die Calcium-Bindestelle analysiert und es konnte gezeigt werden, das diese nach der Proteinherstellung mit einem Calcium-Ion besetzt ist und dieses mit dem Komplexbildner EDTA entfernbar ist, jedoch wieder reversibel besetzt werden kann. Zum Schluss wurde mittels zweier Methoden versucht (grafting from und grafting to), das Protein mit einem temperatursensorischen Polymer (Poly-N-Isopropylacrylamid) zu koppeln, um so Eigenschaften wie Löslichkeit oder Stabilität zu beeinflussen. Es zeigte sich, das während die grafting from Methode (Polymer wächst direkt vom Protein) zu einer teilweisen Entfaltung und Destabilisierung des Proteins führte, bei der grafting to Methode (Polymer wird separat hergestellt und dann an das Protein gekoppelt) das Protein seine Stabilität behielt und nur wenige Polymerketten angebaut waren. Der zweite Teil dieser Arbeit beschäftigte sich mit der Interaktion von zwei LIM-Domänen des Proteins Paxillin und der zytoplasmatischen Domäne der Peptide Integrin-β1 und Integrin-β3. Diese spielen eine wichtige Rolle bei der Bewegung von Zellen. Dabei interagieren sie mit einer Vielzahl an anderen Proteinen, um fokale Adhäsionen (Multiproteinkomplexe) zu bilden. Bei der Herstellung des Peptids Integrin-β3 zeigte sich durch Größenausschlusschromatographie und Massenspektrometrie ein Abbau, bei dem verschiedene Aminosäuregruppen abgespalten werden. Dieser konnte durch eine Zugabe des Serinprotease-Inhibitors AEBSF verhindert werden. Anschließend wurde die direkte Interaktion der Proteine untereinander mittels NMR untersucht. Dabei zeigte sich, das Integrin-β1 und Integrin-β3 an die gleiche Position binden, nämlich an den flexiblen Loop der LIM3-Domäne von Paxillin. Die Dissoziationskonstanten zeigten, dass Integrin-β1 mit einer zirka zehnfach höheren Affinität im Vergleich zu Integrin-β3 an Paxillin bindet. Während Paxillins Bindestelle an Integrin-β1 in der Mitte des Peptids liegt, ist bei Integrin-β3 der C-Terminus essenziell. Daher wurden die drei C-terminalen Aminosäuren entfernt und erneut Bindungsstudien durchgeführt, welche gezeigt haben, das die Affinität dadurch fast vollständig unterbunden wurde. Final wurde der flexible Loop der LIM3-Domäne in zwei andere Aminosäuresequenzen mutiert, um die Bindung auf der Paxillin-Seite auszulöschen. Jedoch zeigten sowohl Zirkulardichroismus-Spektroskopie als auch NMR-Spektroskopie, dass die Mutationen zu einer teilweisen Entfaltung der Domäne geführt haben und somit nicht als geeignete Kandidaten für diese Studien identifiziert werden konnten.
N2  - Proteins play an essential role in a variety of processes. Understanding these functions requires elucidation of their structure and their binding behavior with other molecules such as proteins, peptides, carbohydrates, or small molecules. In the first part of this work, the wild type and the point mutant N126W of a carbohydrate-binding protein from the heat-stable bacterium C. thermocellum were studied, which is part of a complex that can recognize, bind and degrade carbohydrates such as cellulose. For this purpose, this protein was produced with E. coli bacteria and purified by metal chelation and size exclusion chromatography. The proteins could be isotopically labeled by nuclear magnetic resonance (NMR) spectroscopy. H/D exchange experiments revealed easy and difficult sites in the protein for possible ligand interaction. Subsequently, interaction of both proteins with cellulose fragments was detected. These interact with the side chains of aromatic amino acids via intermolecular forces and with other residues via hydrogen bonds. Furthermore, the calcium binding site was analyzed and it could be shown that it is occupied by a calcium ion after protein production and that this can be removed with the complexing agent EDTA, but that it can be reversibly occupied again. Finally, two methods (grafting from and grafting to) were used to couple the protein with a temperature-sensitive polymer (poly-N-isopropylacrylamide) in order to influence properties such as solubility or stability. It was found that while the grafting from method (polymer grows directly from the protein) resulted in partial unfolding and destabilization of the protein, in the grafting to method (polymer is prepared separately and then coupled to the protein) the protein retained its stability and only a few polymer chains were attached. The second part of this work dealt with the interaction of two LIM domains of the protein paxillin and the cytoplasmic domain of the peptides integrin-β1 and integrin-β3, which play an important role in cell movement. In doing so, they interact with a variety of other proteins to form focal adhesions (multiprotein complexes). In the preparation of the peptide integrin-β3, size exclusion chromatography and mass spectrometry revealed a degradation in which various amino acid groups are cleaved. This could be prevented by addition of the serine protease inhibitor AEBSF. Subsequently, the direct interaction of the proteins with each other was investigated by NMR. This showed that integrin-β1 and integrin-β3 bind to the same position, namely to the flexible loop of the LIM3 domain of paxillin. The dissociation constants showed that integrin-β1 binds to paxillin with an approximately tenfold higher affinity compared to integrin-β3. While Paxillin's binding site to integrin-β1 is in the middle of the peptide, the C-terminus is essential for integrin-β3. Therefore, the three C-terminal amino acids were removed and binding studies were performed again, which showed that this almost completely prevented affinity. Finally, the flexible loop of the LIM3 domain was mutated into two other amino acid sequences to extinguish binding on the paxillin side. However, both circular dichroism spectroscopy and NMR spectroscopy showed that the mutations resulted in partial unfolding of the domain and thus could not be identified as suitable candidates for these studies.
KW  - CBM
KW  - cellulose-binding
KW  - Cellulose-Bindung
KW  - protein polymer conjugate
KW  - Protein-Polymer-Konjugat
KW  - focal adhesion
KW  - fokale Adhäsionen
KW  - Integrin
KW  - Paxillin
KW  - cell migration
KW  - Zellmigration
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-555162
ER  - 
TY  - THES
A1  - Michalik-Onichimowska, Aleksandra
T1  - Real-time monitoring of (photo)chemical reactions in micro flow reactors and levitated droplets by IR-MALDI ion mobility and mass spectrometry
N2  - Eine nachhaltigere chemische Industrie erfordert eine Minimierung der Lösungsmittel und Chemikalien. Daher werden Optimierung und Entwicklung chemischer Prozesse vor einer Produktion in großem Maßstab in kleinen Chargen durchgeführt. Der entscheidende Schritt bei diesem Ansatz ist die Skalierbarkeit von kleinen Reaktionssystemen auf große, kosteneffiziente Reaktoren. Die Vergrößerung des Volumens des Reaktionsmediums geht immer mit der Vergrößerung der Oberfläche einher, die mit dem begrenzenden Gefäß in Kontakt steht. Da das Volumen kubisch, während die Oberfläche quadratisch mit zunehmendem Radius skaliert, nimmt ihr Verhältnis nicht linear zu. Viele an der Grenzfläche zwischen Oberfläche und Flüssigkeit auftretende Phänomene können die Reaktionsgeschwindigkeiten und Ausbeuten beeinflussen, was zu falschen Prognosen aufgrund der kleinskaligen Optimierung führt. Die Anwendung von schwebenden Tropfen als behälterlose Reaktionsgefäße bietet eine vielversprechende Möglichkeit, die oben genannten Probleme zu vermeiden.
In der vorgestellten Arbeit wurde eine effiziente Kopplung von akustisch schwebenden Tropfen und IM Spektrometer für die Echtzeitüberwachung chemischer Reaktionen entwickelt, bei denen akustisch schwebende Tropfen als Reaktionsgefäße fungieren. Das Design des Systems umfasst die berührungslose Probenahme und Ionisierung, die durch Laserdesorption und -ionisation bei 2,94 µm realisiert wird. Der Umfang der Arbeit umfasst grundlegende Studien zum Verständnis der Laserbestrahlung von Tropfen im akustischen Feld. Das Verständnis dieses Phänomens ist entscheidend, um den Effekt der zeitlichen und räumlichen Auflösung der erzeugten Ionenwolke zu verstehen, die die Auflösung des Systems beeinflusst.
Der Aufbau umfasst eine akustische Falle, Laserbestrahlung und elektrostatische Linsen, die bei hoher Spannung unter Umgebungsdruck arbeiten. Ein effektiver Ionentransfer im Grenzflächenbereich zwischen dem schwebenden Tropfen und dem IMS muss daher elektrostatische und akustische Felder vollständig berücksichtigen. Für die Probenahme und Ionisation wurden zwei unterschiedliche Laserpulslängen untersucht, nämlich im ns- und µs-Bereich. Die Bestrahlung über µs-Laserpulse bietet gegenüber ns-Pulse mehrere Vorteile: i) das Tropfenvolumen wird nicht stark beeinflusst, was es ermöglichet, nur ein kleines Volumen des Tropfens abzutasten; ii) die geringere Fluenz führt zu weniger ausgeprägten Schwingungen des im akustischen Feld eingeschlossenen Tropfens und der Tropfen wird nicht aus dem akustischen Feld rückgeschlagen, was zum Verlust der Probe führen würde; iii) die milde Laserbestrahlung führt zu einer besseren räumlichen und zeitlichen Begrenzung der Ionenwolken, was zu einer besseren Auflösung der detektierten Ionenpakete führt. Schließlich ermöglicht dieses Wissen die Anwendung der Ionenoptik, die erforderlich ist, um den Ionenfluss zwischen dem im akustischen Feld suspendierten Tropfen und dem IM Spektrometer zu induzieren. Die Ionenoptik aus 2 elektrostatischen Linsen in der Nähe des Tropfens ermöglicht es, die Ionenwolke effektiv zu fokussieren und direkt zum IM Spektrometer-Eingang zu führen. Diese neuartige Kopplung hat sich beim Nachweis einiger basischer Moleküle als erfolgreich erwiesen. Um die Anwendbarkeit des Systems zu belegen, wurde die Reaktion zwischen N-Boc Cysteine Methylester und Allylalkohol in einem Chargenreaktor durchgeführt und online überwacht. Für eine Kalibrierung wurde der Reaktionsfortschritt parallel mittels 1H-NMR verfolgt. Der beobachtete Reaktionsumsatz von mehr als 50% innerhalb der ersten 20 Minuten demonstrierte die Eignung der Reaktion, um die Einsatzpotentiale des entwickelten Systems zu bewerten.
N2  - One aspect of achieving a more sustainable chemical industry is the minimization of the usage of solvents and chemicals. Thus, optimization and development of chemical processes for large-scale production is favourably performed in small batches. The critical step in this approach is upscaling the batches from the small reaction systems to the large reactors mandatory for cost efficient production in an industrial environment. Scaling up the bulk volume always goes along with increasing the surface where the reaction medium is in contact with the confining vessel. Since volume scales proportional with the cubic dimension while the surface scales quadratic, their ratio is size-dependent. The influence of reaction vessel walls can change the reaction performance. A number of phenomena occurring at the surface-liquid interface can affect reaction rates and yields, resulting in possible difficulties in predicting and extrapolating from small size production scale to large industrial processes. The application of levitated droplets as a containerless reaction vessels provides a promising possibility to avoid the above-mentioned issues. 
In the presented work, an efficient coupling of acoustically levitated droplets to an ion mobility (IM) spectrometer, operating at ambient conditions, was designed for real-time monitoring of chemical reactions. The design of the system comprises noncontact sampling and ionization of the droplet realised by laser desorption/ionization at 2,94 µm. The scope of the work includes fundamental studies covering understanding of laser irradiation of droplets enclosed in an acoustical field. Understanding of this phenomenon is crucial to comprehending the effects of temporal and spatial resolution of the generated ion plume that influence the resolution of the system.
The set-up includes an acoustic trap, laser irradiation and ion manipulation electrostatic lenses operating at high voltage at ambient pressure. The complexity of the design needs to fully be considered for an effective ion transfer at the interface region between the levitated droplet and IM spectrometer. For sampling and ionization, two distinct laser pulse lengths were evaluated, ns and µs. Irradiation via µs laser pulses provides several advantages: i) the droplet volume is not extensively impinged, as in case of ns laser pulses, allowing the sampling of only the small volume of the droplet; ii) the lower fluence results in less pronounced oscillations of the droplet confined in the acoustic field. The droplet will not be dissipated out of the acoustic field leading to loss of the sample; iii) the mild laser irradiation results in better spatial and temporal ion plume confinement, leading to better resolution of the detected ion packets. Finally, this knowledge allows the application of ion optics necessary to induce ion flow between the droplet suspended in the acoustic field and the IM spectrometer. The ion optics, composed of 2 electrostatic lenses placed in the near vicinity of the droplet, allow effective focusing of the ion plume and its redirection directly to the IM spectrometer entrance. This novel coupling has proved to be successful for detection of some simple molecules ionizable at the 2.94 µm wavelength. To further demonstrate the applicability of the system, a proof-of-principle reaction was selected, fulfilling the requirements of the system, and was subjected to comprehensive investigation of its performance. Herein, the reaction between N-Boc cysteine methyl ester and allyl alcohol has been performed in a batch reactor and on-line monitored via 1H NMR to establish reaction propagation. With the additional assessment, it was confirmed that the thiol-ene coupling can be performed within first 20 minutes of the irradiation with a reaction yield above 50%, proving that the reaction can be applied as a study case to assess the possibilities of the developed system.
T2  - Echtzeit-Überwachung von (Photo)chemischen Reaktionen in Mikroströmungsreaktoren und schwebenden Tropfen durch IR-MALDI Ionenmoblität- und Massenspektrometrie
KW  - ion mobility spectrometry
KW  - mass spectrometry
KW  - acoustically levitated droplets
KW  - photochemical reactions
KW  - akustisch schwebende Tropfen
KW  - Ionenmobilitätspektrometrie
KW  - Massenspektrometrie
KW  - Photochemische Reaktionen
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-557298
ER  - 
TY  - JOUR
A1  - Kossmann, Janina
A1  - Sanchez-Manjavacas, Maria Luz Ortiz
A1  - Brandt, Jessica
A1  - Heil, Tobias
A1  - López-Salas, Nieves
A1  - Albero, Josep
T1  - Mn(ii) sub-nanometric site stabilization in noble, N-doped carbonaceous materials for electrochemical CO2 reduction
JF  - Chemical communications : ChemComm / The Royal Society of Chemistry
N2  - The preparation of stable and efficient electrocatalysts comprising abundant and non-critical row-materials is of paramount importance for their industrial implementation. Herein, we present a simple synthetic route to prepare Mn(ii) sub-nanometric active sites over a highly N-doped noble carbonaceous support. This support not only promotes a strong stabilization of the Mn(ii) sites, improving its stability against oxidation, but also provides a convenient coordination environment in the Mn(ii) sites able to produce CO, HCOOH and CH3COOH from electrochemical CO2 reduction.
Y1  - 2022
U6  - https://doi.org/10.1039/d2cc00585a
SN  - 1359-7345
SN  - 1364-548X
VL  - 58
IS  - 31
SP  - 4841
EP  - 4844
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - THES
A1  - Kwesiga, George
T1  - Synthesis of isoflavonoids from African medicinal plants with activity against tropical infectious diseases
T1  - Synthese von Isoflavonoiden aus afrikanischen Heilpflanzen mit Wirkung gegen tropische Infektionskrankheiten
N2  - Two approaches for the synthesis of prenylated isoflavones were explored: the 2,3-oxidative rearrangement/cross metathesis approach, using hypervalent iodine reagents as oxidants and the Suzuki-Miyaura cross-coupling/cross metathesis approach. Three natural prenylated isoflavones: 5-deoxy-3′-prenylbiochanin A (59), erysubin F (61) and 7-methoxyebenosin (64), and non-natural analogues: 7,4′-dimethoxy-8,3′-diprenylisoflavone (126j) and 4′-hydroxy-7-methoxy-8,3′-diprenylisoflavone (128) were synthesized for the first time via the 2,3-oxidative rearrangement/cross metathesis approach, using mono- or diallylated flavanones as key intermediates. The reaction of flavanones with hypervalent iodine reagents afforded isoflavones via a 2,3-oxidative rearrangement and the corresponding flavone isomers via a 2,3-dehydrogenation. This afforded the synthesis of 7,4′-dimethoxy-8-prenylflavone (127g), 7,4′-dimethoxy-8,3′-diprenylflavone (127j), 7,4′-dihydroxy-8,3′-diprenylflavone (129) and 4′-hydroxy-7-methoxy-8,3′-diprenylflavone (130), the non-natural regioisomers of 7-methoxyebenosin, 126j, erysubin F and 128 respectively. Three natural prenylated isoflavones: 3′-prenylbiochanin A (58), neobavaisoflavone (66) and 7-methoxyneobavaisoflavone (137) were synthesized for the first time using the Suzuki-Miyaura cross-coupling/cross metathesis approach. The structures of 3′-prenylbiochanin A (58) and 5-deoxy-3′-prenylbiochanin A (59) were confirmed by single crystal X-ray diffraction analysis. The 2,3-oxidative rearrangement approach appears to be limited to the substitution pattern on both rings A and B of the flavanone while the Suzuki-Miyaura cross-coupling approach appears to be the most suitable for the synthesis of simple isoflavones or prenylated isoflavones whose prenyl substituents or allyl groups, the substituents that are essential precursors for the prenyl side chains, can be regioselectively introduced after the construction of the isoflavone core.
The chalcone-flavanone hybrids 146, 147 and 148, hybrids of the naturally occurring bioactive flavanones liquiritigenin-7-methyl ether, liquiritigenin and liquiritigenin-4′-methyl ether respectively were also synthesized for the first time, using Matsuda-Heck arylation and allylic/benzylic oxidation as key steps.
The intermolecular interactions of 5-deoxy-3′-prenylbiochanin A (59) and its two closely related precursors 106a and 106b was investigated by single crystal and Hirshfeld surface analyses to comprehend their different physicochemical properties. The results indicate that the presence of strong intermolecular O-H···O hydrogen bonds and an increase in the number of π-stacking interactions increases the melting point and lowers the solubility of isoflavone derivatives. However, the strong intermolecular O-H···O hydrogen bonds have a greater effect than the π-stacking interactions.
5-Deoxy-3′-prenylbiochanin A (59), erysubin F (61) and 7,4′-dihydroxy-8,3′-diprenylflavone (129), were tested against three bacterial strains and one fungal pathogen. All the three compounds were inactive against Salmonella enterica subsp. enterica (NCTC 13349), Escherichia coli (ATCC 25922), and Candida albicans (ATCC 90028), with MIC values greater than 80.0 μM. The diprenylated isoflavone erysubin F (61) and its flavone isomer 129 showed in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300) at MIC values of 15.4 and 20.5 μM, respectively. 5-Deoxy-3′-prenylbiochanin A (59) was inactive against this MRSA strain. Erysubin F (61) and its flavone isomer 129 could serve as lead compounds for the development of new alternative drugs for the treatment of MRSA infections.
N2  - Ziel dieser Studie war es, aus afrikanischen Heilpflanzen isolierte Naturstoffe künstlich herzustellen, die zur Behandlung tropischer Infektionskrankheiten wie Malaria und bakterieller Infektionen eingesetzt werden, um Schlüsselsubstanzen für die Entwicklung neuer Medikamente zu identifizieren. Sechs Naturstoffe aus afrikanischen Heilpflanzen wie dem Korallenbaum (Erythrina-species) wurden erstmals künstlich hergestellt. Bei der Herstellung dieser Naturstoffe wurden auch sechs weitere verwandte nicht-natürliche Analoga hergestellt.
Zwei Naturstoffe (5-Deoxy-3′-prenylbiochanin A und Erysubin F) aus dem Korallenbaum (Erythrina sacleuxii) und eine verwandte nicht-natürliche Substanz wurden auf ihre antimikrobielle Aktivität gegen drei Bakterienstämme und einen Pilzstamm getestet. Alle drei Substanzen waren nicht wirksam gegen Escherichia coli, ein Bakterium, das Harnwegsinfektionen und Durchfall verursacht; Salmonella entrica, das Typhus verursacht, und Candida albicans, das Candidiasis verursacht. Erysubin F und sein nicht-natürliches Analogon waren sehr aktiv gegen Methicillin-resistente Staphylococcus aureus (MRSA), ein Bakterium, das hauptsächlich in sehr geringen Konzentrationen Hautinfektionen verursacht. 5-Deoxy-3'-prenylbiochanin A war gegen diesen MRSA-Stamm nicht aktiv. Erysubin F und sein nicht-natürliches Analogon könnten als Schlüsselsubstanzen für die Entwicklung eines neuen Medikaments gegen Infektionen durch MRSA dienen.
KW  - synthesis
KW  - isoflavonoids
KW  - African medicinal plants
KW  - tropical infectious diseases
KW  - Afrikanische Heilpflanzen
KW  - Isoflavonoide
KW  - Synthese
KW  - tropische Infektionskrankheiten
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-559069
ER  - 
TY  - THES
A1  - Bäckemo, Johan Dag Valentin
T1  - Digital tools and bioinspiration for the implementation in science and medicine
T1  - Digitale Werkzeuge und Bioinspiration für die Umsetzung in der Wissenschaft und der Medizin
N2  - Diese Doktorarbeit untersucht anhand dreier Beispiele, wie digitale Werkzeuge wie Programmierung, Modellierung, 3D-Konstruktions-Werkzeuge und additive Fertigung in Verbindung mit einer auf Biomimetik basierenden Design\-strategie zu neuen Analysemethoden und Produkten führen können, die in Wissenschaft und Medizin Anwendung finden.

Das Verfahren der Funkenerosion (EDM) wird häufig angewandt, um harte Metalle zu verformen oder zu formen, die mit normalen Maschinen nur schwer zu bearbeiten sind. In dieser Arbeit wird eine neuartige Krümmungsanalysemethode als Alternative zur Rauheitsanalyse vorgestellt. Um besser zu verstehen, wie sich die Oberfläche während der Bearbeitungszeit des EDM-Prozesses verändert, wurde außerdem ein digitales Schlagmodell erstellt, das auf einem ursprünglich flachen Substrat Krater auf Erhebungen erzeugte. Es wurde festgestellt, dass ein Substrat bei etwa 10.000 Stößen ein Gleichgewicht erreicht. Die vorgeschlagene Krümmungsanalysemethode hat das Potenzial, bei der Entwicklung neuer Zellkultursubstrate für die Stammzellenforschung eingesetzt zu werden. Zwei Arten, die in dieser Arbeit aufgrund ihrer interessanten Mechanismen analysiert wurden, sind die Venusfliegenfalle und der Bandwurm. Die Venusfliegenfalle kann ihr Maul mit einer erstaunlichen Geschwindigkeit schließen. Der Schließmechanismus kann für die Wissenschaft interessant sein und ist ein Beispiel für ein so genanntes mechanisch bi-stabiles System - es gibt zwei stabile Zustände. Der Bandwurm ist bei Säugetieren meist im unteren Darm zu finden und heftet sich mit seinen Saugnäpfen an die Darmwände. Wenn der Bandwurm eine geeignete Stelle gefunden hat, stößt er seine Haken aus und heftet sich dauerhaft an die Wand. Diese Funktion könnte in der minimalinvasiven Medizin genutzt werden, um eine bessere Kontrolle der Implantate während des Implantationsprozesses zu ermöglichen. Für beide Projekte wurde ein mathematisches Modell, das so genannte Chained Beam Constraint Model (CBCM), verwendet, um das nichtlineare Biegeverhalten zu modellieren und somit vorherzusagen, welche Strukturen ein mechanisch bi-stabiles Verhalten aufweisen könnten. Daraufhin konnten zwei Prototypen mit einem 3D-Drucker gedruckt und durch Experimente veranschaulicht werden, dass sie beide ein bi-stabiles Verhalten aufweisen. Diese Arbeit verdeutlicht das hohe Anwendungspotenzial für neue Analysenmethoden in der Wissenschaft und für neue Medizinprodukte in der minimalinvasiven Medizin.
N2  - Biomimicry is the art of mimicking nature to overcome a particular technical or scientific challenge. The approach studies how evolution has found solutions to the most complex problems in nature. This makes it a powerful method for science. In combination with the rapid development of manufacturing and information technologies into the digital age, structures and material that were before thought to be unrealizable can now be created with simple sketch and the touch of a button. This doctoral thesis had as its primary goal to investigate how digital tools, such as programming, modelling, 3D-Design tools and 3D-Printing, with the help from biomimicry, could lead to new analysis methods in science and new medical devices in medicine.

The Electrical Discharge Machining (EDM) process is applied commonly to deform or mold hard metals that are difficult to work using normal machinery. A workpiece submerged in an electrolyte is deformed while being in close vicinity to an electrode. When high voltage is put between the workpiece and the electrode it will cause sparks that create cavitations on the substrate which in turn removes material and is flushed away by the electrolyte. Usually, such surfaces are analysed based on roughness, in this work another method using a novel curvature analysis method is presented as an alternative. In addition, to better understand how the surface changes during process time of the EDM process, a digital impact model was created which created craters on ridges on an originally flat substrate. These substrates were then analysed using the curvature analysis method at different processing times of the modelling. It was found that a substrate reaches an equilibrium at around 10000 impacts. The proposed curvature analysis method has potential to be used in the design of new cell culture substrates for stem cell.

The Venus flytrap can shut its jaws at an amazing speed. The shutting mechanism may be interesting to use in science and is an example of a so-called mechanical bi-stable system – there are two stable states. In this work two truncated pyramid structures were modelled using a non-linear mechanical model called the Chained Beam Constraint Model (CBCM). The structure with a slope angle of 30 degrees is not bi-stable and the structure with a slope angle of 45 degrees is bi-stable. Developing this idea further by using PEVA, which has a shape-memory effect, the structure which is not bi-stable could be programmed to be bi-stable and then turned off again. This could be used as an energy storage system. Another species which has interesting mechanism is the tapeworm. Some species of this animal has a crown of hooks and suckers located on its side. The parasite commonly is found in mammals in the lower intestine and attaches to the walls by using its suckers. When the tapeworm has found a suitable spot, it ejects its hooks and permanently attaches to the wall. This function could be used in minimally invasive medicine to have better control of implants during the implantation process. By using the CBCM model and a 3D-printer capable of tuning how hard or soft a printed part is, a design strategy was developed to investigate how one could create a device that mimics the tapeworm. In the end a prototype was created which was able attach to a pork loin at an under pressure of 20 kPa and to ejects its hooks at an under pressure of 50 kPa or above.

These three projects is an exhibit of how digital tools and biomimicry can be used together to come up with applicable solutions in science and in medicine.
KW  - bioinspiration
KW  - non-linear mechanics
KW  - modelling
KW  - shape-memory
KW  - additive manufacturing
KW  - Bioinspiration
KW  - nichtlineare Mechanik
KW  - Modellierung
KW  - Formgedächtnis
KW  - additive Fertigung
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-571458
ER  - 
TY  - THES
A1  - Freyse, Daniel
T1  - Thioacetal-Bausteine für Fluoreszenzfarbstoffe und molekulare Stäbe
T1  - Thioacetal building blocks for fluorescent dyes and molecular rods
N2  - Im Rahmen dieser Dissertation wurde der Sauerstoff im Grundgerüst der [1,3]-Dioxolo[4.5-f]benzodioxol-Fluoreszenzfarbstoffe (DBD-Fluoreszenzfarbstoffe) vollständig mit Schwefel ausgetauscht und daraus eine neue Klasse von Fluoreszenzfarbstoffen entwickelt, die Benzo[1,2-d:4,5-d']bis([1,3]dithiol)-Fluorophore (S4-DBD-Fluorophore). Insgesamt neun der besonders interessanten, difunktionalisierten Vertreter konnten synthetisiert werden, die sich in ihren elektronenziehenden Gruppen und in ihrer Anordnung unterschieden.

Durch den Austausch von Sauerstoff mit Schwefel kam es zu teilweise auffälligen Veränderungen in den Fluoreszenzparametern, wie eine Abnahme der Fluoreszenzquantenausbeuten und -lebenszeiten aber auch eine deutliche Rotverschiebung in den Absorptions- und Emissionswellenlängen mit großen STOKES-Verschiebungen. Damit sind die S4-DBD-Fluorophore eine wertvolle Ergänzung für die DBD-Farbstoffe.

Die Ursachen für die Abnahme der Lebenszeiten und Quantenausbeuten konnte auf eine hohe Besetzung des Triplett-Zustandes zurückgeführt werden, welcher durch die verstärkten Spin-Bahn-Kopplungen des Schwefels hervorgerufen wird. Zusammen mit dem Arbeitskreis physikalische Chemie der Universität Potsdam konnten auch die photophysikalischen Prozesse über die Transienten-Absorptionsspektroskopie (TAS) aufgeklärt werden.

Eine Strategie zur Funktionalisierung der S4-DBD-Farbstoffe am Thioacetalgerüst konnte entwickelt werden. So gelang es Alkohol-, Propargyl-, Azid-, NHS-Ester-, Carbonsäure-, Maleimid- und Tosyl-Gruppen an S4-DBD-Dialdehyden anzubringen.

Erweiternd wurden molekulare Stäbe auf Basis von Schwefel-Oligo-Spiro-Ketalen (SOSKs) untersucht, bei denen Sauerstoff durch Schwefel ersetzt wurde. Hier konnten die Synthesen der löslichkeitsvermittelnden TER-Muffe und auch des Tetrathiapentaerythritols als Grundbaustein deutlich verbessert werden. Aus diesen konnte ein einfaches SOSK-Polymer hergestellt werden. Weitere Versuche zum Aufbau eines Stabes müssen aber noch untersucht werden. Um einen S-OSK-Stab aufzubauen hat sich dabei die Dithiocarbonat-Gruppe in ersten Versuchen als potenzielle geeignete Schutzgruppe für das Tetrathiapentaerythritol herausgestellt.
N2  - In this Thesis, the oxygen in the structure of the [1,3]-dioxolo[4.5-f]benzodioxole fluorescent dyes (DBD) was completely exchanged with sulfur and from this a new class of fluorescent dyes were developed, the S4-DBD fluorophores. A total of nine of the particularly interesting bifunctional representatives could be synthesized, which differ in their electron-withdrawing groups and their arrangements.

The exchange of the oxygen with sulfur causes striking changes in the fluorescence parameters, such as a decrease in the fluorescence quantum yields and lifetimes and a distinct red shifting of the absorption and emission wavelengths with large STOKESShifts. This makes the S4-DBD fluorophores a valuable addition to the DBD dyes.

The causes for the decrease in lifetimes and quantum yields could be traced back to a high triplet state occupancy, which is caused by the increased spin-orbit coupling of the sulfur atoms. The photophysical processes after absorption could also be revealed via the transient absorption spectroscopy (TAS) during a cooperation with the Department of Physical Chemistry of the University of Potsdam.

In order to influence the photophysical properties as little as possible, a strategy for functionalizing the S4-DBD dyes on the thioacetal structure could be developed. Using the example of S4-DBD dialdehyde, alcohol, propargyl, azide, NHS ester, carboxylic acid, maleimide and tosyl groups could be succesfuly obtained.

Another area in this thesis, where the exchange of oxygen with sulfur was investigated, are molecular rods based on sulfur-oligo-spiro-ketals (S-OSK). Here, the syntheses of the solubilizing TER-Sleeves and also of tetrathiapentaerythritol as a basic building block could be significantly improved. A simple S-OSK polymer could be produced from these, but further attempts to build a rod have yet to be investigated. In order to build up an S-OSK rod, the dithiocarbonate group turned out to be a potentially suitable protective group for the tetrathiapentaerythritol.
KW  - organische Chemie
KW  - organic chemistry
KW  - Fluoreszenzfarbstoffe
KW  - Fluorescent Dyes
KW  - Fluorophore
KW  - Fluorophores
KW  - Thioacetale
KW  - Thioacetals
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549252
ER  - 
TY  - THES
A1  - Lüdecke, Nils
T1  - Bio-sourced adsorbing poly(2-oxazoline)s mimicking mussel glue proteins  for antifouling applications
T1  - Biobasierende, adsorbeirende, Muschelklebeproteine nachahmende Poly(2-oxazoline) für Antifouling-Anwendungen
N2  - Nature developed countless systems for many applications. In maritime environments, several organisms established extra-ordinary mechanisms to attach to surfaces. Over the past years, the scientific interest to employ those mechanisms for coatings and long-lasting adhering materials gained significant attention. 
This work describes the synthesis of bio-inspired adsorbing copoly(2-oxazoline)s for surface coatings with protein repelling effects, mimicking mussel glue proteins. From a set of methoxy substituted phenyl, benzyl, and cinnamyl acids, 2-oxazoline monomers were synthesized. All synthesized 2-oxazolines were analyzed by FT-IR spectroscopy, NMR spectroscopy, and EI mass spectrometry. With those newly synthesized 2-oxazoline monomers and 2-ethyl-2-oxazoline, kinetic studies concerning homo- and copolymerization in a microwave reactor were conducted. The success of the polymerization reactions was demonstrated by FT-IR spectroscopy, NMR spectroscopy, MALDI-TOF mass spectrometry, and size exclusion chromatography (SEC). The copolymerization of 2-ethyl-2-oxazoline with a selection of methoxy-substituted 2-oxazolines resulted in water-soluble copolymers. To release the adsorbing catechol and cationic units, the copoly(2-oxazoline)s were modified. The catechol units were (partially) released by a methyl aryl ether cleavage reaction. A subsequent partial acidic hydrolysis of the ethyl unit resulted in mussel glue protein-inspired catechol and cation-containing copolymers. The modified copolymers were analyzed by NMR spectroscopy, UV-VIS spectroscopy, and SEC. The catechol- and cation-containing copolymers and their precursors were examined by a Quartz Crystal Microbalance with Dissipation (QCM-D), so study the adsorption performance on gold, borosilicate, iron, and polystyrene surfaces. An exemplary study revealed that a catechol and cation-containing copoly(2-oxazoline)-coated gold surface exhibits strong protein repelling properties.
N2  - In der Natur entwickelten sich unzählige Anpassungen für ebenso viele Lebensbereiche. In maritimen Umgebungen haben sich beispiels-weise bei verschiedenen Organis-men außergewöhnliche Strategien entwickelt, um sich an Oberflächen an-zuheften. In den letzten Jahren hat das wissenschaftliche Interesse an der Nutzung dieser Mechanismen für an Oberflächen haftende Materialien stark zugenommen. 
Diese Arbeit beschreibt die Synthese von Muschelklebeprotein nachahmenden, bioinspirierten Copoly(2-oxazolinen) für Oberflächen-beschichtungen mit protein-abweisender Wirkung. Aus einer Gruppe von methoxysubstituierten Phenyl-, Benzyl , und Zimtsäuren wurden 2-Oxazolin-Monomere synthetisiert. Alle synthetisierten 2-Oxazoline wurden mittels FT-IR-Spektroskopie, NMR Spektroskopie und EI-Massenspektrometrie analysiert. Mit diesen neu synthetisierten 2-Oxazolin-Monomeren und 2-Ethyl-2-oxazolin (wasserlösliche Komponente) wurden kinetische Studien zur Homo- und Copolymerisation in einem Mikrowellenreaktor durchgeführt. Der Nachweis der Polymerisationsreaktionen erfolgte durch FT-IR Spektroskopie, NMR Spektroskopie, MALDI-TOF Massenspektrometrie und Gel-Permeations-Chromatographie (GPC). Die Copolymerisation von 2-Ethyl-2-Oxazolin mit Methoxyaryl-substituierten 2-Oxazolinen führte zu wasserlöslichen Copolymeren. Um die adsorbierenden Catechol- und kationischen-Einheiten freizusetzen, wurden die Copolymere modifiziert. Die Catechol-Einheiten wurden durch eine (partielle) Methylaryletherspaltung freigesetzt. Eine anschließende partielle saure Hydrolyse der Ethyleinheit führte zu, von Muschelklebeproteinen inspirierten, catechol- und kationen-haltigen Copolymeren. Die modifizierten Copolymere wurde mittels NMR Spektroskopie, UV-VIS Spektroskopie und SEC analysiert. Die catechol- und kationenhaltigen Copolymere und deren Vorläufercopolymere wurden mittels einer Quarzkristallmikrowaage mit Dissipation (QCM-D) hinsichtlich ihrer Adsorptionsfähigkeit an den Oberflächen Gold, Borosilicat, Eisen und Polystyrol untersucht. Exemplarisch wurde gezeigt, dass eine mit catechol und kationenhaltigem Copoly(2-oxazoline) beschichtete Goldoberfläche, stark proteinabweisende Eigenschaften aufweist.
KW  - poly(2-oxazoline)s
KW  - adhesive
KW  - anti-fouling
KW  - mussel-mimicking
KW  - klebend
KW  - Antifouling
KW  - Muschelnachahmend
KW  - Poly(2-oxazoline)
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549836
ER  - 
TY  - THES
A1  - Gäbert, Chris
T1  - Light-responsive polymer systems aiming towards programmable friction
T1  - Lichtschaltbare Polymersysteme mit dem Ziel programmierbarer Reibung
BT  - the application driven development of 9-anthracene ester-terminated silicone oils and spiropyran graft copolymers as novel functional materials
BT  - die anwendungsorientierte Entwicklung von 9-Anthracenester-terminierten Silikonölen und Spiropyran-Pfropfcopolymeren als neuartige Funktionsmaterialien
N2  - The development of novel programmable materials aiming to control friction in real-time holds potential to facilitate innovative lubrication solutions for reducing wear and energy losses. This work describes the integration of light-responsiveness into two lubricating materials, silicon oils and polymer brush surfaces.
The first part focusses on the assessment on 9-anthracene ester-terminated polydimethylsiloxanes (PDMS-A) and, in particular, on the variability of rheological properties and the implications that arise with UV-light as external trigger. The applied rheometer setup contains an UV-transparent quartz-plate, which enables radiation and simultaneous measurement of the dynamic moduli. UV-A radiation (354 nm) triggers the cycloaddition reaction between the terminal functionalities of linear PDMS, resulting in chain extension. The newly-formed anthracene dimers cleave by UV-C radiation (254 nm) or at elevated temperatures (T > 130 °C). The sequential UV-A radiation and thermal reprogramming over three cycles demonstrate high conversions and reproducible programming of rheological properties. In contrast, the photochemical back reaction by UV-C is incomplete and can only partially restore the initial rheological properties. The dynamic moduli increase with each cycle in photochemical programming, presumably resulting from a chain segment re-arrangement as a result of the repeated partial photocleavage and subsequent chain length-dependent dimerization. In addition, long periods of radiation cause photooxidative degradation, which damages photo-responsive functions and consequently reduces the programming range. The absence of oxygen, however, reduces undesired side reactions. Anthracene-functionalized PDMS and native PDMS mix depending on the anthracene ester content and chain length, respectively, and allow fine-tuning of programmable rheological properties. The work shows the influence of mixing conditions during the photoprogramming step on the rheological properties, indicating that material property gradients induced by light attenuation along the beam have to be considered. Accordingly, thin lubricant films are suggested as potential application for light-programmable silicon fluids.
The second part compares strategies for the grafting of spiropyran (SP) containing copolymer brushes from Si wafers and evaluates the light-responsiveness of the surfaces. Pre-experiments on the kinetics of the thermally initiated RAFT copolymerization of 2-hydroxyethyl acrylate (HEA) and spiropyran acrylate (SPA) in solution show, first, a strong retardation by SP and, second, the dependence of SPA polymerization on light. Surprisingly, the copolymerization of SPA is inhibited in the dark. These findings contribute to improve the synthesis of polar, spiropyran-containing copolymers. The comparison between initiator systems for the grafting-from approach indicates PET-RAFT superior to thermally initiated RAFT, suggesting a more efficient initiation of surface-bound CTA by light. Surface-initiated polymerization via PET-RAFT with an initiator system of EosinY (EoY) and ascorbic acid (AscA) facilitates copolymer synthesis from HEA and 5-25 mol% SPA. The resulting polymer film with a thickness of a few nanometers was detected by atomic force microscopy (AFM) and ellipsometry. Water contact angle (CA) measurements demonstrate photo-switchable surface polarity, which is attributed to the photoisomerization between non-polar spiropyran and zwitterionic merocyanine isomer. Furthermore, the obtained spiropyran brushes show potential for further studies on light-programmable properties. In this context, it would be interesting to investigate whether swollen spiropyran-containing polymers change their configuration and thus their film thickness under the influence of light. In addition, further experiments using an AFM or microtribometer should evaluate whether light-programmable solvation enables a change in frictional properties between polymer brush surfaces.
N2  - Die Entwicklung neuartiger programmierbarer Materialien zur Anpassung von Reibung in Echtzeit birgt Potenzial, innovative Schmierungslösungen zu ermöglichen, um Verschleiß und Energieverluste zu reduzieren. Die vorliegende Arbeit beschreibt die Integration von Lichtlichtschaltbarkeit in zwei schmierende Materialien, Silikonöle und Oberflächen mit Polymerbürsten.
Der erste Teil konzentriert sich auf die Bewertung von 9-Anthracenester-terminierten Polydimethylsiloxanen (PDMS-As) und insbesondere auf die Veränderbarkeit der rheologischen Eigenschaften sowie Implikationen, die sich bei der Verwendung von UV-Licht als externe Trigger ergeben. Der verwendete Rheometeraufbau enthält eine UV-transparente Quarzplatte, welche somit die Bestrahlung bei gleichzeitiger Messung der dynamischen Moduli ermöglicht. UV-A-Strahlung (354 nm) löst die Cycloadditionsreaktion zwischen den endständigen Funktionalitäten des linearen PDMS aus und führt so zu einer Kettenverlängerung. Die dabei gebildeten Anthracen-Dimere werden durch UV-C-Strahlung (254 nm) oder bei erhöhten Temperaturen (T > 130 °C) gespalten. Die sequentielle UV-A-Bestrahlung und thermische Reprogrammierung in drei Schaltzyklen führen zu hohen Umsätzen und zeigen reproduzierbar einstellbare Materialeigenschaften. Im Gegensatz dazu ist die photochemische Rückreaktion durch UV-C unvollständig und kann die ursprünglichen rheologischen Eigenschaften nur teilweise wiederherstellen. Die dynamischen Module nehmen mit jedem Zyklus der photochemischen Programmierung zu, was vermutlich auf eine Neuanordnung der Kettensegmente infolge der wiederholten partiellen Photospaltung und der anschließenden kettenlängenabhängigen Dimerisierung zurückzuführen ist. Darüber hinaus kommt es bei langer Bestrahlungsdauer zu einem photooxidativen Abbau, der die photoschaltbaren Funktionen des Silikons beeinträchtigt und folglich den Programmierbereich verringert. Der Ausschluss von Sauerstoff reduziert jedoch unerwünschte Nebenreaktionen. Anthracenfunktionalisiertes PDMS und unfunktionalisiertes PDMS mischen sich in Abhängigkeit vom Anthracenestergehalt beziehungsweise der Kettenlänge und ermöglichen die Feinabstimmung programmierbarer rheologischer Eigenschaften. Die Arbeit zeigt den Einfluss der Mischungsbedingungen während des Photoprogrammierungsschritts auf die rheologischen Eigenschaften, was darauf hindeutet, dass Materialeigenschaftsgradienten, die durch Lichtabschwächung entlang des Lichtstrahls entstehen, berücksichtigt werden müssen. Entsprechend werden dünne Schmiermittelfilme als mögliche Anwendung für lichtprogrammierbare Silikonöle vorgeschlagen.
Der zweite Teil vergleicht ‚grafting-from‘-Methoden zur Synthese Spiropyran(SP)-haltiger Copolyme auf Si-Wafern und bewertet die Lichtschaltbarkeit der Oberflächeneigenschaften. Vorversuche zur Kinetik der thermisch initiierten RAFT-Copolymerisation von 2-Hydroxyethylacrylat (HEA) und Spiropyranacrylat (SPA) in Lösung zeigen erstens, eine starke Retardierung durch SP, und zweitens, die Lichtabhängigkeit der SPA-Polymerisation. Überraschenderweise ist die Copolymerisation von SPA im Dunkeln gehemmt. Diese Ergebnisse tragen dazu bei, die Synthese von polaren, spiropyranhaltigen Copolymeren zu verbessern. Der Vergleich zwischen Initiatorsystemen für den ‚grafting-from‘-Ansatz zeigt, dass PET-RAFT der thermisch initiierten RAFT überlegen ist, was auf eine effizientere Initiierung von oberflächengebundenem CTA durch Licht hindeutet. Die oberflächeninitierte Polymerisation via PET-RAFT mit einem Initiatorsystem aus EosinY (EoY) und Ascorbinsäure (AscA) ermöglicht die Copolymersynthese aus HEA und 5-25 mol% SPA. Der entstandene Polymerfilm mit einer Dicke von einigen Nanometern wurde mittels Rasterkraftmikroskopie (AFM) und Ellipsometrie nachgewiesen. Die Messungen des Wasserkontaktwinkels (CA) zeigt eine photoschaltbare Oberflächenpolarität, welche der Photoisomerisierung zwischen unpolaren Spiropyran und zwitterionischen Merocyanin-Isomer zugeschrieben wird. Darüber hinaus zeigen die erhaltenen Spiropyranbürsten Potenzial für weitere Untersuchungen zu lichtprogrammierbaren Eigenschaften. In diesem Zusammenhang wäre es interessant weiterführend zu untersuchen, ob gequollene spiropyranhaltige Polymere unter Lichteinfluss tatsächlich ihre Konfiguration und damit ihre Filmdicke ändern. Darüber hinaus wäre es sinnvoll, mit Hilfe eines AFM oder Mikrotribometers zu evaluieren, ob diese lichtprogrammierbare Solvatisierung eine Veränderung der Reibungseigenschaften zwischen Polymerbürstenoberflächen ermöglicht.
KW  - programmable friction
KW  - lubricant
KW  - light-programmable viscosity
KW  - spiropyran copolymer
KW  - grafting-from
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-553380
ER  - 
TY  - THES
A1  - Neumann, Christian
T1  - Development of functionalized waterborne coatings for the production of multifunctional microapsules
Y1  - 2022
ER  - 
TY  - JOUR
A1  - Ebel, Kenny
A1  - Bald, Ilko
T1  - Low-energy (5-20 eV) electron-induced single and double strand breaks in well-defined DNA sequences
JF  - The journal of physical chemistry letters / American Chemical Society
N2  - Ionizing radiation is used in cancer radiation therapy to effectively damage the DNA of tumors. The main damage is due to generation of highly reactive secondary species such as low-energy electrons (LEEs). The accurate quantification of DNA radiation damage of well-defined DNA target sequences in terms of absolute cross sections for LEE-induced DNA strand breaks is possible by the DNA origami technique; however, to date, it is possible only for DNA single strands. In the present work DNA double strand breaks in the DNA sequence 5'-d(CAC)(4)/5'd(GTG)(4) are compared with DNA single strand breaks in the oligonucleotides 5'-d(CAC)(4) and 5'-d(GTG)(4) upon irradiation with LEEs in the energy range from 5 to 20 eV. A maximum of strand break cross section was found around 7 and 10 eV independent of the DNA sequence, indicating that dissociative electron attachment is the underlying mechanism of strand breakage and confirming previous studies using plasmid DNA.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpclett.2c00684
SN  - 1948-7185
VL  - 13
IS  - 22
SP  - 4871
EP  - 4876
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - THES
A1  - Brandi, Francesco
T1  - Integrated biorefinery in continuous flow systems using sustainable heterogeneous catalysts
T1  - Integrierte Bioraffinerie in kontinuierlichen Fließsystemen unter Verwendung nachhaltiger heterogener Katalysatoren
N2  - The negative impact of crude oil on the environment has led to a necessary transition toward alternative, renewable, and sustainable resources. In this regard, lignocellulosic biomass (LCB) is a promising renewable and sustainable alternative to crude oil for the production of fine chemicals and fuels in a so-called biorefinery process. LCB is composed of polysaccharides (cellulose and hemicellulose), as well as aromatics (lignin). The development of a sustainable and economically advantageous biorefinery depends on the complete and efficient valorization of all components. Therefore, in the new generation of biorefinery, the so-called biorefinery of type III, the LCB feedstocks are selectively deconstructed and catalytically transformed into platform chemicals. For this purpose, the development of highly stable and efficient catalysts is crucial for progress toward viability in biorefinery. Furthermore, a modern and integrated biorefinery relies on process and reactor design, toward more efficient and cost-effective methodologies that minimize waste. In this context, the usage of continuous flow systems has the potential to provide safe, sustainable, and innovative transformations with simple process integration and scalability for biorefinery schemes.
   This thesis addresses three main challenges for future biorefinery: catalyst synthesis, waste feedstock valorization, and usage of continuous flow technology. Firstly, a cheap, scalable, and sustainable approach is presented for the synthesis of an efficient and stable 35 wt.-% Ni catalyst on highly porous nitrogen-doped carbon support (35Ni/NDC) in pellet shape. Initially, the performance of this catalyst was evaluated for the aqueous phase hydrogenation of LCB-derived compounds such as glucose, xylose, and vanillin in continuous flow systems. The 35Ni/NDC catalyst exhibited high catalytic performances in three tested hydrogenation reactions, i.e., sorbitol, xylitol, and 2-methoxy-4-methylphenol with yields of 82 mol%, 62 mol%, and 100 mol% respectively. In addition, the 35Ni/NDC catalyst exhibited remarkable stability over a long time on stream in continuous flow (40 h). Furthermore, the 35Ni/NDC catalyst was combined with commercially available Beta zeolite in a dual–column integrated process for isosorbide production from glucose (yield 83 mol%). 
   Finally, 35Ni/NDC was applied for the valorization of industrial waste products, namely sodium lignosulfonate (LS) and beech wood sawdust (BWS) in continuous flow systems. The LS depolymerization was conducted combining solvothermal fragmentation of water/alcohol mixtures (i.e.,methanol/water and ethanol/water) with catalytic hydrogenolysis/hydrogenation (SHF). The depolymerization was found to occur thermally in absence of catalyst with a tunable molecular weight according to temperature. Furthermore, the SHF generated an optimized cumulative yield of lignin-derived phenolic monomers of 42 mg gLS-1. Similarly, a solvothermal and reductive catalytic fragmentation (SF-RCF) of BWS was conducted using MeOH and MeTHF as a solvent. In this case, the optimized total lignin-derived phenolic monomers yield was found of 247 mg gKL-1.
N2  - Die negativen Auswirkungen von Rohöl auf die Umwelt haben zu einem notwendigen Übergang zu alternativen, erneuerbaren und nachhaltigen Ressourcen geführt. In dieser Hinsicht ist lignozellulosehaltige Biomasse (LCB) eine vielversprechende erneuerbare und nachhaltige Alternative zu Erdöl für die Herstellung von Feinchemikalien und Kraftstoffen in einem sogenannten Bioraffinerie-Prozess. LCB setzt sich aus Polysacchariden (Cellulose und Hemicellulose) sowie Aromaten (Lignin) zusammen. Die Entwicklung einer nachhaltigen und wirtschaftlich vorteilhaften Bioraffinerie hängt von der vollständigen und effizienten Verwertung aller Komponenten ab. Zu diesem Zweck ist die Entwicklung hochstabiler und effizienter Katalysatoren entscheidend für den Fortschritt in Richtung Bioraffinerie-Wirtschaftlichkeit. Darüber hinaus ist eine moderne und integrierte Bioraffinerie auf ein Prozess- und Reaktordesign angewiesen, das auf effizientere und kostengünstigere Methoden abzielt, die den Abfall minimieren. In diesem Zusammenhang hat die Verwendung von kontinuierlichen Durchflusssystemen das Potenzial, sichere, nachhaltige und innovative Transformationen mit einfacher Prozessintegration und Skalierbarkeit für Bioraffineriesysteme zu bieten.
   Diese Arbeit befasst sich mit drei wesentlichen Herausforderungen für die zukünftige Bioraffinerie: Katalysatorsynthese, Valorisierung von Abfallstoffen und Einsatz von kontinuierlicher Durchflusstechnik. Zuerst wird ein kostengünstiger, skalierbarer und nachhaltiger Ansatz für die Synthese eines effizienten und stabilen 35-Gew.-%-Ni-Katalysators auf einem hochporösen, stickstoffdotierten Kohlenstoffträger (35Ni/NDC) in Pelletform vorgestellt. Zunächst wurde die Leistung dieses Katalysators für die Hydrierung von LCB-abgeleiteten Verbindungen wie Glucose, Xylose und Vanillin in kontinuierlichen Durchflusssystemen in wässriger Phase bewertet. Der 35Ni/NDC-Katalysator zeigte hohe katalytische Leistungen in drei getesteten Hydrierungsreaktionen, d. h. Sorbit, Xylit und 2-Methoxy-4-methylphenol mit Ausbeuten von 82 mol%, 62 mol% bzw. 100 mol%. Darüber hinaus zeigte der 35Ni/NDC-Katalysator eine bemerkenswerte Stabilität über eine lange Zeit im kontinuierlichen Fluss (40 h). Auβerrdem wurde der 35Ni/NDC-Katalysator mit handelsüblichem Beta-Zeolith in einem integrierten Zweisäulenprozess für die Isosorbid-Produktion aus Glukose kombiniert (Ausbeute 83 mol%). 
   Schließlich wurde 35Ni/NDC für die Valorisierung von industriellen Abfallprodukten, nämlich Natriumlignosulfonat (LS) und Buchenholzsägemehl (BWS) in kontinuierlichen Durchflusssystemen eingesetzt. Die Depolymerisation von LS wurde durch eine Kombination von solvothermischer Fragmentierung von Wasser/Alkohol-Gemischen (d.h. MeOH/Wasser und Ethanol/Wasser) mit katalytischer Hydrogenolyse/Hydrierung (SHF) durchgeführt. Es wurde festgestellt, dass die Depolymerisation thermisch in Abwesenheit des Katalysators mit einem abstimmbaren Molekulargewicht in Abhängigkeit von der Temperatur erfolgt. Außerdem wurde mit der SHF eine optimierte kumulative Monomerausbeute von 42 mg gLS-1 erzielt. In ähnlicher Weise wurde eine solvothermale und reduktiv-katalytische Fragmentierung (SF-RCF) von BWS mit MeOH und MeTHF als Lösungsmittel durchgeführt. In diesem Fall wurde eine optimierte Gesamtmonomerausbeute von 247 mg gKL-1 gefunden.
KW  - sustainable chemistry
KW  - green chemistry
KW  - biorefinery
KW  - flow chemistry
KW  - heterogeneous catalysis
KW  - Bioraffinerie
KW  - grüne Chemie
KW  - heterogene Katalyse
KW  - Strömungschemie
KW  - nachhaltige Chemie
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-537660
ER  - 
TY  - THES
A1  - Youk, Sol
T1  - Molecular design of heteroatom-doped nanoporous carbons with controlled porosity and surface polarity for gas physisorption and energy storage
N2  - The world energy consumption has constantly increased every year due to economic development and population growth. This inevitably caused vast amount of CO2 emission, and the CO2 concentration in the atmosphere keeps increasing with economic growth. To reduce CO2 emission, various methods have been developed but there are still many bottlenecks to be solved. Solvents easily absorbing CO2 such as monoethanol-amine (MEA) and diethanolamine, for example, have limitations of solvent loss, amine degradation, vulnerability to heat and toxicity, and the high cost of regeneration which is especially caused due to chemisorption process. Though some of these drawbacks can be compensated through physisorption with zeolites and metal-organic frameworks (MOFs) by displaying significant adsorption selectivity and capacity even in ambient conditions, limitations for these materials still exist. Zeolites demand relatively high regeneration energy and have limited adsorption kinetics due to the exceptionally narrow pore structure. MOFs have low stability against heat and moisture and high manufacturing cost.
Nanoporous carbons have recently received attention as an attractive functional porous material due to their unique properties. These materials are crucial in many applications of modern science and industry such as water and air purification, catalysis, gas separation, and energy storage/conversion due to their high chemical and thermal stability, and in particular electronic conductivity in combination with high specific surface areas. Nanoporous carbons can be used to adsorb environmental pollutants or small gas molecules such as CO2 and to power electrochemical energy storage devices such as batteries and fuel cells. In all fields, their pore structure or electrical properties can be modified depending on their purposes.
This thesis provides an in-depth look at novel nanoporous carbons from the synthetic and the application point of view. The interplay between pore structure, atomic construction, and the adsorption properties of nanoporous carbon materials are investigated. Novel nanoporous carbon materials are synthesized by using simple precursor molecules containing heteroatoms through a facile
templating method. The affinity, and in turn the adsorption capacity, of carbon materials toward polar gas molecules (CO2 and H2O) is enhanced by the modification of their chemical construction. It is also shown that these properties are important in electrochemical energy storage, here especially for supercapacitors with aqueous electrolytes which are basically based on the physisorption of ions on carbon surfaces. This shows that nanoporous carbons can be a “functional” material with specific physical or chemical interactions with guest species just like zeolites and MOFs.
The synthesis of sp2-conjugated materials with high heteroatom content from a mixture of citrazinic acid and melamine in which heteroatoms are already bonded in specific motives is illustrated. By controlling the removal procedure of the salt-template and the condensation temperature, the role of salts in the formation of porosity and as coordination sites for the stabilization of heteroatoms is proven. A high amount of nitrogen of up to 20 wt. %, oxygen contents of up to 19 wt.%, and a high CO2/N2 selectivity with maximum CO2 uptake at 273 K of 5.31 mmol g–1 are achieved. Besides, the further controlled thermal condensation of precursor molecules and advanced functional properties on applications of the synthesized porous carbons are described. The materials have different porosity and atomic construction exhibiting a high nitrogen content up to 25 wt. % as well as a high porosity with a specific surface area of more than 1800 m2 g−1, and a high performance in selective CO2 gas adsorption of 62.7. These pore structure as well as properties of surface affect to water adsorption with a remarkably high Qst of over 100 kJ mol−1 even higher than that of zeolites or CaCl2 well known as adsorbents. In addition to that, the pore structure of HAT-CN-derived carbon materials during condensation in vacuum is fundamentally understood which is essential to maximize the utilization of porous system in materials showing significant difference in their pore volume of 0.5 cm3 g−1 and 0.25 cm3 g−1 without and with vacuum, respectively.
The molecular designs of heteroatom containing porous carbon derived from abundant and simple molecules are introduced in the presented thesis. Abundant precursors that already containing high amount of nitrogen or oxygen are beneficial to achieve enhanced interaction with adsorptives. The physical and chemical properties of these heteroatom-doped porous carbons are affected by mainly two parameters, that is, the porosity from the pore structure and the polarity from the atomic composition on the surface. In other words, controlling the porosity as well as the polarity of the carbon materials is studied to understand interactions with different guest species which is a fundamental knowledge for the utilization on various applications.
N2  - Nanoporöse Kohlenstoffe haben in letzter Zeit aufgrund ihrer einzigartigen Eigenschaften als ein attraktives funktionelles poröses Material Aufmerksamkeit erregt. Diese Materialien sind aufgrund ihrer hohen chemischen und thermischen Stabilität und insbesondere aufgrund ihrer elektronischen Leitfähigkeit in Kombination mit hohen spezifischen Oberflächen von entscheidender Bedeutung für viele Anwendungen der modernen Wissenschaft und Industrie wie Wasser- und Luftreinigung, Katalyse, Gastrennung und Energiespeicherung/-umwandlung. Nanoporöse Kohlenstoffe können verwendet werden, um Umweltschadstoffe oder kleine Gasmoleküle wie CO2 zu adsorbieren und elektrochemische Energiespeicher wie Batterien und Brennstoffzellen anzutreiben. Ihre Porenstruktur oder ihre elektrischen Eigenschaften je nach Einsatzzweck modifiziert werden.
Diese Arbeit bietet einen eingehenden Blick auf neuartige nanoporöse Kohlenstoffe aus synthetischer und anwendungstechnischer Sicht. Das Zusammenspiel zwischen Porenstruktur, atomarem Aufbau und den Adsorptionseigenschaften von nanoporösen Kohlenstoffmaterialien wird untersucht. Neuartige nanoporöse Kohlenstoffmaterialien werden unter Verwendung einfacher Vorläufermoleküle, die Heteroatome enthalten, durch ein einfaches Templatverfahren synthetisiert. Die Affinität und damit die Adsorptionskapazität von Kohlenstoffmaterialien gegenüber polaren Gasmolekülen (CO2 und H2O) wird durch die Modifikation ihres chemischen Aufbaus erhöht. Es wird auch gezeigt, dass diese Eigenschaften bei der elektrochemischen Energiespeicherung wichtig sind. Hier insbesondere für Superkondensatoren mit wässrigen Elektrolyten, die grundsätzlich auf der Physisorption von Ionen an Kohlenstoffoberflächen beruhen. Dies zeigt, dass nanoporöse Kohlenstoffe, genauso wie Zeolithen und MOFs, ein „funktionelles“ Material mit spezifischen physikalischen oder chemischen Wechselwirkungen mit Gastspezien sein können. Mit den Vorteilen einer hohen elektrischen Leitfähigkeit, einer gut entwickelten Porenstruktur und einer stark hydrophilen Oberflächenstruktur sind nanoporöse Kohlenstoffe vielversprechende Materialien, die weitreichende Auswirkungen auf verschiedene Bereiche des zukünftigen Energiebedarfs haben.
KW  - porous carbon
KW  - gas adsorption
KW  - energy storage
KW  - N-doped carbon
KW  - poröser Kohlenstoff
KW  - Gasadsorption
KW  - Energiespeicher
KW  - N-dotierter Kohlenstoff
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-539098
ER  - 
TY  - JOUR
A1  - Mazurek-Budzyńska, Magdalena
A1  - Behl, Marc
A1  - Neumann, Richard
A1  - Lendlein, Andreas
T1  - 4D-actuators by 3D-printing combined with water-based curing
JF  - Materials today. Communications
N2  - The shape and the actuation capability of state of the art robotic devices typically relies on multimaterial systems from a combination of geometry determining materials and actuation components. Here, we present multifunctional 4D-actuators processable by 3D-printing, in which the actuator functionality is integrated into the shaped body. The materials are based on crosslinked poly(carbonate-urea-urethane) networks (PCUU), synthesized in an integrated process, applying reactive extrusion and subsequent water-based curing. Actuation capability could be added to the PCUU, prepared from aliphatic oligocarbonate diol, isophorone diisocyanate (IPDI) and water, in a thermomechanical programming process. When programmed with a strain of epsilon(prog) = 1400% the PCUU networks exhibited actuation apparent by reversible elongation epsilon'(rev) of up to 22%. In a gripper a reversible bending epsilon'(rev)((be)(nd)()) in the range of 37-60% was achieved when the actuation temperature (T-high) was varied between 45 degrees C and 49 degrees C. The integration of actuation and shape formation could be impressively demonstrated in two PCUU-based reversible fastening systems, which were able to hold weights of up to 1.1 kg. In this way, the multifunctional materials are interesting candidate materials for robotic applications where a freedom in shape design and actuation is required as well as for sustainable fastening systems.
KW  - 4D-actuation
KW  - 3D-printing
KW  - Ink
KW  - Gripper
KW  - Fastener
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtcomm.2021.102966
SN  - 2352-4928
VL  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - THES
A1  - Brinkmann, Pia
T1  - Laserinduzierte Breakdownspektroskopie zur qualitativen und quantitativen Bestimmung von Elementgehalten in geologischen Proben mittels multivariater Analysemethoden am Beispiel von Kupfer und ausgewählten Seltenen Erden
N2  - Ein schonender Umgang mit den Ressourcen und der Umwelt ist wesentlicher Bestandteil des modernen Bergbaus sowie der zukünftigen Versorgung unserer Gesellschaft mit essentiellen Rohstoffen. Die vorliegende Arbeit beschäftigt sich mit der Entwicklung analytischer Strategien, die durch eine exakte und schnelle Vor-Ort-Analyse den technisch-praktischen Anforderungen des Bergbauprozesses gerecht werden und somit zu einer gezielten und nachhaltigen Nutzung von Rohstofflagerstätten beitragen. Die Analysen basieren auf den spektroskopischen Daten, die mittels der laserinduzierten Breakdownspektroskopie (LIBS) erhalten und mittels multivariater Datenanalyse ausgewertet werden. Die LIB-Spektroskopie ist eine vielversprechende Technik für diese Aufgabe. Ihre Attraktivität machen insbesondere die Möglichkeiten aus, Feldproben vor Ort ohne Probennahme oder ‑vorbereitung messen zu können, aber auch die Detektierbarkeit sämtlicher Elemente des Periodensystems und die Unabhängigkeit vom Aggregatzustand. In Kombination mit multivariater Datenanalyse kann eine schnelle Datenverarbeitung erfolgen, die Aussagen zur qualitativen Elementzusammensetzung der untersuchten Proben erlaubt. Mit dem Ziel die Verteilung der Elementgehalte in einer Lagerstätte zu ermitteln, werden in dieser Arbeit Kalibrierungs- und Quantifizierungsstrategien evaluiert. Für die Charakterisierung von Matrixeffekten und zur Klassifizierung von Mineralen werden explorative Datenanalysemethoden angewendet. Die spektroskopischen Untersuchungen erfolgen an Böden und Gesteinen sowie an Mineralen, die Kupfer oder Seltene Erdelemente beinhalten und aus verschiedenen Lagerstätten bzw. von unterschiedlichen Agrarflächen stammen.
Für die Entwicklung einer Kalibrierungsstrategie wurden sowohl synthetische als auch Feldproben von zwei verschiedenen Agrarflächen mittels LIBS analysiert. Anhand der Beispielanalyten Calcium, Eisen und Magnesium erfolgte die auf uni- und multivariaten Methoden beruhende Evaluierung verschiedener Kalibrierungsmethoden. Grundlagen der Quantifizierungsstrategien sind die multivariaten Analysemethoden der partiellen Regression der kleinsten Quadrate (PLSR, von engl.: partial least squares regression) und der Intervall PLSR (iPLSR, von engl.: interval PLSR), die das gesamte detektierte Spektrum oder Teilspektren in der Analyse berücksichtigen. Der Untersuchung liegen synthetische sowie Feldproben von Kupfermineralen zugrunde als auch solche die Seltene Erdelemente beinhalten. Die Proben stammen aus verschiedenen Lagerstätten und weisen unterschiedliche Begleitmatrices auf. Mittels der explorativen Datenanalyse erfolgte die Charakterisierung dieser Begleitmatrices. Die dafür angewendete Hauptkomponentenanalyse gruppiert Daten anhand von Unterschieden und Regelmäßigkeiten. Dies erlaubt Aussagen über Gemeinsamkeiten und Unterschiede der untersuchten Proben im Bezug auf ihre Herkunft, chemische Zusammensetzung oder lokal bedingte Ausprägungen. Abschließend erfolgte die Klassifizierung kupferhaltiger Minerale auf Basis der nicht-negativen Tensorfaktorisierung. Diese Methode wurde mit dem Ziel verwendet, unbekannte Proben aufgrund ihrer Eigenschaften in Klassen einzuteilen.
Die Verknüpfung von LIBS und multivariater Datenanalyse bietet die Möglichkeit durch eine Analyse vor Ort auf eine Probennahme und die entsprechende Laboranalytik weitestgehend zu verzichten und kann somit zum Umweltschutz sowie einer Schonung der natürlichen Ressourcen bei der Prospektion und Exploration von neuen Erzgängen und Lagerstätten beitragen. Die Verteilung von Elementgehalten der untersuchten Gebiete ermöglicht zudem einen gezielten Abbau und damit eine effiziente Nutzung der mineralischen Rohstoffe.
N2  - The sustainable use of resources and the environment is an important part of modern mining and the  supply of our society with essential raw materials in the future. The present work focuses on the development of analytical strategies that address the technical-practical requirements of the mining process through accurate and rapid on-site analysis, thus contributing to the targeted and sustainable use of raw material deposits. The analyses are based on spectroscopic data obtained by laser-induced breakdown spectroscopy (LIBS) and evaluated by multivariate data analysis. LIB spectroscopy is a promising technique for this task. Its advantages are in particular the possibility to measure field samples on site without sample collection or preparation, but also the detectability of all elements of the periodic table and the independence of the state of matter. In combination with multivariate data analysis, rapid data processing can be performed, allowing statements to be made on the qualitative elemental composition of the samples investigated. With the goal of determining the distribution of elemental contents in a deposit, calibration and quantification strategies are evaluated in this work. Exploratory data analysis methods are used to characterize matrix effects and to classify minerals. Spectroscopic studies are performed on soils and rocks as well as on minerals containing copper or rare earth elements originating from different deposits or from different agricultural sites.

To develop a calibration strategy, both synthetic and field samples from two different agricultural sites were analyzed using LIBS. Using calcium, iron and magnesium as example analytes, the evaluation of different calibration methods based on univariate and multivariate methods was performed.

Basics of the quantification strategies are the multivariate analysis methods of partial least squares regression (PLSR) and interval PLSR (iPLSR), which consider the whole detected spectrum or partial spectra in the analysis. The investigation is based on synthetic and field samples of copper minerals as well as those containing rare earth elements. The samples are from different deposits and have varying accompanying matrices.

Exploratory data analysis was used to characterize these accompanying matrices. The principal component analysis used for this purpose groups data on the basis of differences and regularities. This allows conclusions to be drawn about similarities and differences between the samples examined in terms of their origin, chemical composition or locally determined characteristics. Finally, the classification of copper-bearing minerals was based on non-negative tensor factorization. This method was used with the aim of classifying unknown samples based on their properties.

The combination method of LIBS and multivariate data analysis offers the possibility to avoid sampling and the corresponding laboratory analysis as far as possible by an on-site analysis and can thus contribute to environmental protection as well as to a conservation of natural resources during the prospection and exploration of new ore veins and deposits. The distribution of element contents of the investigated areas also enables a precise mining and thus an efficient utilization of the mineral raw materials.
KW  - LIBS
KW  - laserinduzierte Breakdownspektroskopie
KW  - Seltene Erdelemente
KW  - Kupfer
KW  - PCA
KW  - PLSR
KW  - NTF
KW  - copper
KW  - LIBS
KW  - NTF
KW  - PCA
KW  - PLSR
KW  - rare earth elements
KW  - laser induced breakdown spectroscopy
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-572128
ER  - 
TY  - JOUR
A1  - Lindic, Tilen
A1  - Sinha, Shreya
A1  - Mattsson, Stefan
A1  - Paulus, Beate
T1  - Prediction of a model crystal structure for Ni2F5 by first-principles calculations
JF  - Zeitschrift für Naturforschung : B, Chemical sciences
N2  - Electrochemical fluorination in anhydrous HF, also known as the Simons process, is a widely used industrial method for fluorination of organic compounds. Its mechanism, being not so well understood, has long been debated and is believed to involve higher valent nickel fluorides formed on the nickel-plated anode during the process. One of these is speculated to be Ni2F5, which was previously reported in the literature and assigned via infrared spectroscopy, but its crystal structure is not yet known. We have identified known crystal structures of compounds with similar stoichiometries as Ni2F5 and utilized them as a starting point for our periodic DFT investigations, applying the PBE+U method. Ni2F5 as the most stable polymorph was found to be of the same crystal structure as another mixed valent fluoride, Cr2F5. The calculated lattice parameters are a = 7.24 angstrom, b = 7.40 angstrom, c = 7.08 angstrom and beta = 118.9 degrees with an antiferromagnetic ordering of the nickel magnetic moments.
KW  - crystal structure prediction
KW  - DFT
KW  - Ni2F5
Y1  - 2022
U6  - https://doi.org/10.1515/znb-2022-0072
SN  - 0932-0776
SN  - 1865-7117
VL  - 77
IS  - 6
SP  - 469
EP  - 473
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - THES
A1  - Prüfert, Christian
T1  - Laser ablation and matter sizing
BT  - a focused view on molecules, sub-micron particles, and aerosols
N2  - The doctoral thesis presented provides a comprehensive view of laser-based ablation techniques promoted to new fields of operation, including, but not limited to, size, composition, and concentration analyses. It covers various applications of laser ablation techniques over a wide range of sizes, from single molecules all the way to aerosol particles. The research for this thesis started with broadening and deepening the field of application and the fundamental understanding of liquid-phase IR-MALDI. Here, the hybridization of ion mobility spectrometry and microfluidics was realized by using IR-MALDI as the coupling technique for the first time. The setup was used for monitoring the photocatalytic performance of the E-Z isomerization of olefins. Using this hybrid, measurement times were so drastically reduced that such photocatalyst screenings became a matter of minutes rather than hours. With this on hand, triple measurements screenings could not only be performed within ten minutes, but also with a minimum amount of resources highlighting its potential as a green chemistry alternative to batch-sized reactions. Along the optimizing process of the IR-MALDI source for microfluidics came its application for another liquid sample supply method, the hanging drop. This demarcated one of the first applications of IR-MALDI for the charging of sub-micron particles directly from suspensions via their gas-phase transfer, followed by their characterization with differential mobility analysis. Given the high spectral quality of the data up to octuply charged particles became experimentally accessible, this laid the foundation for deriving a new charge distribution model for IR-MALDI in that size regime. Moving on to even larger analyte sizes, LIBS and LII were employed as ablation techniques for the solid phase, namely the aerosol particles themselves. Both techniques produce light-emitting events and were used to quantify and classify different aerosols. The unique configuration of stroboscopic imaging, photoacoustics, LII, and LIBS measurements opened new realms for analytical synergies and their potential application in industry. The concept of using low fluences, below 100 J/cm2, and high repetition rates of up to 500 Hz for LIBS makes for an excellent phase-selective LIBS setup. This concept was combined with a new approach to the photoacoustic normalization of LIBS. Also, it was possible to acquire statistically relevant amounts of data in a matter of seconds, showing its potential as a real-time optimization technique. On the same time axis, but at much lower fluences, LII was used with a similar methodology to quickly quantify and classify airborne particles of different compositions. For the first time, aerosol particles were evaluated on their LII susceptibility by using a fluence screening approach.
N2  - Die vorliegende kumulative Dissertation hat die lasergestützte Flüssig- und Festphasen-Ablation (Ab-
tragung) zur Molekül- und Partikelanalyse zur Grundlage. Mittels Infrarotstrahlung wurden die Analyten, vom molekularen bis zum Mikrometergröÿenbereich, in die Gasphase überführt, ionisiert oder geladen und anschließend durch spektrometrische beziehungsweise spektroskopische Analysemethoden identifiziert und quantifiziert. Eingangs wurden IR-MALDIs (infrared laser-assisted matrix dispersion ionization) Anwendungsbereiche als Kopplungsmethode etabliert sowie fundamentale Aspekte des Ionisationsprozesses innerhalb der IR-MALDI beleuchtet. Die als Kopplungsmethode eingesetzte IR-MALDI ermöglichte die erstmalige Zusammenführung eines Mikrochip-Reaktors mit einem Niederdruck-Ionenmobilitätsspektrometer. Dies geschah über die IR-MALDI eines vom Mikrochip ejektierten Flüssigkeitsmikrostrahls und wurde für die Verlaufsbeoachtung photokatalysierter Isomerisierungsreaktionen verwendet. Dieses hybride Konzept aus Mikrochip-Reaktor und Niederdruck-Ionenmobilitätsspektrometer hatte eine erhebliche Reduktion der benötigten Messzeit zur Folge. Die Messzeit konnte, im Vergleich zur mehrstündigen Verlaufsbeobachtung von Reaktionen im Kolben, auf nur wenige Minuten verringert werden. Hiermit war es nun also nicht nur möglich Dreifachmessungen innerhalb von nur zehn Minuten auszuführen, sondern es wurde auch nur ein kleinster Bruchteil der sonst üblichen Rohstoffe benötigt, was wiederum zeigt, welches Potential diese systemische Miniaturisierung für nachhaltige Chemie hat. Entlang der Entwicklung dieser Flüssigkeitsstrahlkopplung konnte IR-MALDI auch auf einen Aufbau mit hängendem Tropfen übertragen werden. Hierdurch kam es zu einer der ersten Gasphasenanalysen von Submikron-Partikeln direkt aus einer Suspension heraus. Nachdem diese durch IR-MALDI mit entsprechender Ladung versehen wurden, konnten sie mittels differentieller Mobilitätsanalyse charakterisiert werden. Durch die hohe spektrale Auflösung der Methode war eine eindeutige Zuordnung von bis zu acht Ladungen auf einem Partikel möglich. Folglich lieferte dies die Grundlage zur Evaluierung bestehender IR-MALDI-Ladungsverteilungsmodelle und schlussendlich zur Entwicklung eines neuen Ladungsverteilungsmodels. Anschließend wurde die Ablation auf noch größere Partikel, auf denen die Ablation direkt und damit in der festen Phase stattfinden konnte, übertragen. Hierbei fanden LIBS (laser-induced break-down spectroscopy) und LII (laser-induced incandescence) ihre Anwendung in der Aerosolquantifizierung sowie in deren Identifizierung beziehungsweise Klassierung. Die vielschichtige Methodenkonfiguration bestehend aus Stroboskopie, Photoakustik, LII und LIBS eröffnete neue Dimensionen für analytische Synergien. In diesem Zusammenhang wurde ein neuer Ansatz zur photoakustischen Normierung von Einzelsignalen in der LIBS entwickelt. Als weiteres Alleinstellungsmerkmal wurde LIBS mit niedrigen Fluenzen (Energie pro Fläche) von unter 100 J/cm2, somit also phasenselektiv, und hohen Wiederholungsraten von bis zu 500 Hz verwendet. Somit konnte innerhalb von Sekunden eine statistisch relevante Menge an Daten erhoben werden, nahezu in Echtzeit, was wiederum Anwendungspotentiale in Industrieprozessen aufzeigt. Auf derselben Zeitskala, jedoch bei deutlich geringeren Fluenzen (<1.5 J/cm2), wurde auch die LII für Partikelzählung verwendet. Hierbei wurde erstmals das Potential der LII zur Klassierung von Partikeln im Rahmen eines Fluenz-Screenings gezeigt.
KW  - Ion mobility spectrometry (IMS)
KW  - Infrared matrix-assisted laser desorption ionization (IR-MALDI)
KW  - Differential mobility analysis (DMA)
KW  - laser-induced breakdown spectroscopy (LIBS)
KW  - laser-induced incandescence (LII)
KW  - Differentielle Mobilitätsanalyse (DMA)
KW  - Matrix-unterstützte Laser-Desorption/Ionisation (IR-MALDI)
KW  - Ionenmobilitätsspektrometry (IMS)
KW  - Laserinduzierte Plasmaspektroskopie (LIBS)
KW  - Laserinduzierte Inkandeszenz (LII)
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-559745
ER  - 
TY  - JOUR
A1  - Titov, Evgenii
A1  - Kopp, Tristan
A1  - Hoche, Joscha
A1  - Humeniuk, Alexander
A1  - Mitrić, Roland
T1  - (De)localization dynamics of molecular excitons
BT  - comparison of mixed quantum-classical and fully quantum treatments
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2  - Molecular excitons play a central role in processes of solar energy conversion, both natural and artificial. It is therefore no wonder that numerous experimental and theoretical investigations in the last decade, employing state-of-the-art spectroscopic techniques and computational methods, have been driven by the common aim to unravel exciton dynamics in multichromophoric systems. Theoretically, exciton (de)localization and transfer dynamics are most often modelled using either mixed quantum-classical approaches (e.g., trajectory surface hopping) or fully quantum mechanical treatments (either using model diabatic Hamiltonians or direct dynamics). Yet, the terms such as "exciton localization" or "exciton transfer" may bear different meanings in different works depending on the method in use (quantum-classical vs. fully quantum). Here, we relate different views on exciton (de)localization. For this purpose, we perform molecular surface hopping simulations on several tetracene dimers differing by a magnitude of exciton coupling and carry out quantum dynamical as well as surface hopping calculations on a relevant model system. The molecular surface hopping simulations are done using efficient long-range corrected time-dependent density functional tight binding electronic structure method, allowing us to gain insight into different regimes of exciton dynamics in the studied systems.
Y1  - 2022
U6  - https://doi.org/10.1039/d2cp00586g
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 20
SP  - 12136
EP  - 12148
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Fischer, Eric Wolfgang
A1  - Anders, Janet
A1  - Saalfrank, Peter
T1  - Cavity-altered thermal isomerization rates and dynamical resonant localization in vibro-polaritonic chemistry
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - It has been experimentally demonstrated that reaction rates for molecules embedded in microfluidic optical cavities are altered when compared to rates observed under "ordinary" reaction conditions. However, precise mechanisms of how strong coupling of an optical cavity mode to molecular vibrations affects the reactivity and how resonance behavior emerges are still under dispute. In the present work, we approach these mechanistic issues from the perspective of a thermal model reaction, the inversion of ammonia along the umbrella mode, in the presence of a single-cavity mode of varying frequency and coupling strength. A topological analysis of the related cavity Born-Oppenheimer potential energy surface in combination with quantum mechanical and transition state theory rate calculations reveals two quantum effects, leading to decelerated reaction rates in qualitative agreement with experiments: the stiffening of quantized modes perpendicular to the reaction path at the transition state, which reduces the number of thermally accessible reaction channels, and the broadening of the barrier region, which attenuates tunneling. We find these two effects to be very robust in a fluctuating environment, causing statistical variations of potential parameters, such as the barrier height. Furthermore, by solving the time-dependent Schrodinger equation in the vibrational strong coupling regime, we identify a resonance behavior, in qualitative agreement with experimental and earlier theoretical work. The latter manifests as reduced reaction probability when the cavity frequency omega(c) is tuned resonant to a molecular reactant frequency. We find this effect to be based on the dynamical localization of the vibro-polaritonic wavepacket in the reactant well.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0076434
SN  - 0021-9606
SN  - 1089-7690
VL  - 156
IS  - 15
PB  - American Institute of Physics
CY  - Melville, NY
ER  - 
TY  - JOUR
A1  - Sperlich, Eric
A1  - Köckerling, Martin
T1  - [Nb6Cl14(pyrazine)(4)], a versatile precursor for ligand-supported hexanuclear niobium cluster compounds: synthesis, characterization, follow-up reactions, and intermolecular interactions
JF  - Inorganic chemistry
N2  - The compound [Nb6Cl14(pyrazine)(4)]center dot 2CH(2)Cl(2) (1) was investigated for its suitability as a starting compound for new ligand-supported hexanuclear niobium cluster compounds. The synthesis, stability to air and increased temperature, solubility and usability for subsequent reactions of 1, and purification and separation of the reaction products are discussed. The compounds with cluster units [Nb6Cl14L4], where L = iso-quinoline N-oxides (2), 1,1-dimethylethylenediamines (3), or thiazoles (4), and [Nb6Cl14(PEt3)(3.76)(Et3PO)(0.24)]-[Nb6Cl14(MeCN)(4)]center dot 4MeCN (5) are presented as follow-up products. The crystal structures of compounds 1-5 are analyzed, and the structures are discussed with respect to their intraand intermolecular bonding situations and crystal packing. In addition to hydrogen bonds and pi-pi interactions, the appearance of chalcogen and halogen bonds and lone pair-pi interactions between Nb-6 cluster units was observed for the first time.
KW  - Cluster chemistry
KW  - crystals
KW  - ligands
KW  - molecules
KW  - transition metals
Y1  - 2022
U6  - https://doi.org/10.1021/acs.inorgchem.1c03109
SN  - 0020-1669
SN  - 1520-510X
VL  - 61
IS  - 5
SP  - 2409
EP  - 2420
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Schürmann, Robin
A1  - Nagel, Alessandro
A1  - Juergensen, Sabrina
A1  - Pathak, Anisha
A1  - Reich, Stephanie
A1  - Pacholski, Claudia
A1  - Bald, Ilko
T1  - Microscopic understanding of reaction rates observed in plasmon chemistry of nanoparticle-ligand systems
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - Surface-enhanced Raman scattering (SERS) is an effective and widely used technique to study chemical reactions induced or catalyzed by plasmonic substrates, since the experimental setup allows us to trigger and track the reaction simultaneously and identify the products. However, on substrates with plasmonic hotspots, the total signal mainly originates from these nanoscopic volumes with high reactivity and the information about the overall consumption remains obscure in SERS measurements. This has important implications; for example, the apparent reaction order in SERS measurements does not correlate with the real reaction order, whereas the apparent reaction rates are proportional to the real reaction rates as demonstrated by finite-difference time-domain (FDTD) simulations. We determined the electric field enhancement distribution of a gold nanoparticle (AuNP) monolayer and calculated the SERS intensities in light-driven reactions in an adsorbed self-assembled molecular monolayer on the AuNP surface. Accordingly, even if a high conversion is observed in SERS due to the high reactivity in the hotspots, most of the adsorbed molecules on the AuNP surface remain unreacted. The theoretical findings are compared with the hot-electron-induced dehalogenation of 4-bromothiophenol, indicating a time dependency of the hot-carrier concentration in plasmon-mediated reactions. To fit the kinetics of plasmon-mediated reactions in plasmonic hotspots, fractal-like kinetics are well suited to account for the inhomogeneity of reactive sites on the substrates, whereas also modified standard kinetics model allows equally well fits. The outcomes of this study are on the one hand essential to derive a mechanistic understanding of reactions on plasmonic substrates by SERS measurements and on the other hand to drive plasmonic reactions with high local precision and facilitate the engineering of chemistry on a nanoscale.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.2c00278
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 11
SP  - 5333
EP  - 5342
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - THES
A1  - Mazzanti, Stefano
T1  - Novel photocatalytic processes mediated by carbon nitride photocatalysis
T1  - Neuartige photokatalytische Prozesse vermittelt durch Kohlenstoffnitrid-Photokatalyse
N2  - The key to reduce the energy required for specific transformations in a selective manner is the employment of a catalyst, a very small molecular platform that decides which type of energy to use. The field of photocatalysis exploits light energy to shape one type of molecules into others, more valuable and useful. 
However, many challenges arise in this field, for example, catalysts employed usually are based on metal derivatives, which abundance is limited, they cannot be recycled and are expensive. Therefore, carbon nitrides materials are used in this work to expand horizons in the field of photocatalysis.
Carbon nitrides are organic materials, which can act as recyclable, cheap, non-toxic, heterogeneous photocatalysts. In this thesis, they have been exploited for the development of new catalytic methods, and shaped to develop new types of processes. 
Indeed, they enabled the creation of a new photocatalytic synthetic strategy, the dichloromethylation of enones by dichloromethyl radical generated in situ from chloroform, a novel route for the making of building blocks to be used for the productions of active pharmaceutical compounds. 
Then, the ductility of these materials allowed to shape carbon nitride into coating for lab vials, EPR capillaries, and a cell of a flow reactor showing the great potential of such flexible technology in photocatalysis. 
Afterwards, their ability to store charges has been exploited in the reduction of organic substrates under dark conditions, gaining new insights regarding multisite proton coupled electron transfer processes. 
Furthermore, the combination of carbon nitrides with flavins allowed the development of composite materials with improved photocatalytic activity in the CO2 photoreduction.
Concluding, carbon nitrides are a versatile class of photoactive materials, which may help to unveil further scientific discoveries and to develop a more sustainable future.
N2  - Der Schlüssel zur selektiven Reduzierung des Energieverbrauchs für bestimmte Reaktionen ist der Einsatz eines Katalysators, der entscheidet, welche Art von Energie verwendet werden soll. Bei der Photokatalyse wird Lichtenergie verwendet, um eine Art von Molekülen in andere umzuwandeln, die wertvoller und nützlicher sind.
Im Gebiet der Photokatalyse gibt es jedoch viele Herausforderungen. Beispielsweise besitzen die verwendeten Katalysatoren üblicherweise eine Basis aus seltenen Erden, deren Verfügbarkeit begrenzt ist, die teuer sind und die nicht recycelt werden können. Daher werden in dieser Arbeit Kohlenstoffnitridmaterialien verwendet, um den Horizont der Photokatalyse zu erweitern.
Kohlenstoffnitride sind organische Materialien, die als recycelbare, billige, ungiftige, heterogene Photokatalysatoren fungieren können. In dieser Arbeit wurden sie für die Entwicklung neuer katalytischer Methoden und in neuen Prozesstypen eingesetzt.
Es konnte gezeigt werden, dass Kohlenstoffnitride für die Dichlormethylierung von Enonen, durch in-situ aus Chloroform erzeugte Dichlormethylradikale, benutzt werden können. Dies stellt eine neue photokatalytische Synthesestrategie dar und kann zur Herstellung von Bausteinen für pharmazeutische Wirkstoffe verwendet werden.
Die Eigenschaften von Kohlenstoffnitriden ermöglichten es, Laborfläschchen, EPR-Kapillaren und die Zelle eines Durchflussreaktors damit zu beschichten, was ein großes Potenzial in der Photokatalyse darstellt.
Im Weiteren wurde die Fähigkeit der Kohlenstoffnitride, Ladungen zu speichern, bei der Reduktion organischer Substrate unter lichtfreien Bedingungen genutzt, um neue Erkenntnisse über protonengekoppelte Elektronentransferprozesse an mehreren katalytischen Zentren zu gewinnen.
Zusätzlich konnte gezeigt werden, dass aus Kohlenstoffnitriden und Flavinen Verbundwerkstoffen mit verbesserter photokatalytischer Aktivität bei der CO2-Photoreduktion hergestellt werden können.
Zusammenfassend lässt sich sagen, dass Kohlenstoffnitride eine vielversprechende Klasse photoaktiver Materialien sind, die dazu beitragen können eine nachhaltigere Zukunft zu gestalten.
KW  - heterogeneous photocatalysis
KW  - carbon nitrides
KW  - organic synthesis
KW  - heterogene Photokatalyse
KW  - Kohlenstoffnitriden
KW  - organische Synthese
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-542099
ER  - 
TY  - JOUR
A1  - Fischer, Eric Wolfgang
A1  - Werther, Michael
A1  - Bouakline, Foudhil
A1  - Grossmann, Frank
A1  - Saalfrank, Peter
T1  - Non-Markovian vibrational relaxation dynamics at surfaces
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - Vibrational dynamics of adsorbates near surfaces plays both an important role for applied surface science and as a model lab for studying fundamental problems of open quantum systems. We employ a previously developed model for the relaxation of a D-Si-Si bending mode at a D:Si(100)-(2 x 1) surface, induced by a "bath " of more than 2000 phonon modes [Lorenz and P. Saalfrank, Chem. Phys. 482, 69 (2017)], to extend previous work along various directions. First, we use a Hierarchical Effective Mode (HEM) model [Fischer et al., J. Chem. Phys. 153, 064704 (2020)] to study relaxation of higher excited vibrational states than hitherto done by solving a high-dimensional system-bath time-dependent Schrodinger equation (TDSE). In the HEM approach, (many) real bath modes are replaced by (much less) effective bath modes. Accordingly, we are able to examine scaling laws for vibrational relaxation lifetimes for a realistic surface science problem. Second, we compare the performance of the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) approach with that of the recently developed coherent-state-based multi-Davydov-D2 Ansatz [Zhou et al., J. Chem. Phys. 143, 014113 (2015)]. Both approaches work well, with some computational advantages for the latter in the presented context. Third, we apply open-system density matrix theory in comparison with basically "exact " solutions of the multi-mode TDSEs. Specifically, we use an open-system Liouville-von Neumann (LvN) equation treating vibration-phonon coupling as Markovian dissipation in Lindblad form to quantify effects beyond the Born-Markov approximation. Published under an exclusive license by AIP Publishing.
KW  - phonons
KW  - Vibrational states
KW  - Chemical dynamics
KW  - Adsorption
KW  - Surface science
KW  - Open quantum systems
KW  - Density-matrix
KW  - Coherent states
KW  - Markov processes
Y1  - 2022
U6  - https://doi.org/10.1063/5.0092836
SN  - 0021-9606
SN  - 1089-7690
SN  - 1520-9032
VL  - 156
IS  - 21
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - THES
A1  - Tang, Jo Sing Julia
T1  - Biofunctional polymers for medical applications
T1  - Biofunktionale Polymere für medizinische Anwendungen
N2  - Carbohydrates are found in every living organism, where they are responsible for numerous, essential biological functions and processes. Synthetic polymers with pendant saccharides, called glycopolymers, mimic natural glycoconjugates in their special properties and functions. Employing such biomimetics furthers the understanding and controlling of biological processes. Hence, glycopolymers are valuable and interesting for applications in the medical and biological field. However, the synthesis of carbohydrate-based materials can be very challenging. In this thesis, the synthesis of biofunctional glycopolymers is presented, with the focus on aqueous-based, protecting group free and short synthesis routes to further advance in the field of glycopolymer synthesis. 
A practical and versatile precursor for glycopolymers are glycosylamines. To maintain biofunctionality of the saccharides after their amination, regioselective functionalization was performed. This frequently performed synthesis was optimized for different sugars. The optimization was facilitated using a design of experiment (DoE) approach to enable a reduced number of necessary experiments and efficient procedure. Here, the utility of using DoE for optimizing the synthesis of glycosylamines is discussed. 
The glycosylamines were converted to glycomonomers which were then polymerized to yield biofunctional glycopolymers. Here, the glycopolymers were aimed to be applicable as layer-by-layer (LbL) thin film coatings for drug delivery systems. To enable the LbL technique, complimentary glycopolymer electrolytes were synthesized by polymerization of the glycomonomers and subsequent modification or by post-polymerization modification. For drug delivery, liposomes were embedded into the glycopolymer coating as potential cargo carriers. The stability as well as the integrity of the glycopolymer layers and liposomes were investigated at physiological pH range. 
Different glycopolymers were also synthesized to be applicable as anti-adhesion therapeutics by providing advanced architectures with multivalent presentations of saccharides, which can inhibit the binding of pathogene lectins. Here, the synthesis of glycopolymer hydrogel particles based on biocompatible poly(N-isopropylacrylamide) (NiPAm) was established using the free-radical precipitation polymerization technique. The influence of synthesis parameters on the sugar content in the gels and on the hydrogel morphology is discussed. The accessibility of the saccharides to model lectins and their enhanced, multivalent interaction were investigated.  
At the end of this work, the synthesis strategies for the glycopolymers are generally discussed as well as their potential application in medicine.
N2  - Kohlenhydrate sind in jedem Lebewesen zu finden, wo sie für zahlreiche, essenzielle biologische Funktionen und Prozesse verantwortlich sind. Synthetische Polymere, die Saccharide tragen, werden Glykopolymere genannt und können natürliche Glykokonjugate in ihren besonderen Eigenschaften und Funktionen nachahmen. Der Einsatz solcher Biomimetika fördert das Verständnis und die Kontrolle biologischer Prozesse. Daher sind Glykopolymere besonders interessant für Anwendungen im medizinischen und biologischen Bereich. Die Synthese von Materialien auf Kohlenhydratbasis kann jedoch eine große Herausforderung darstellen. In dieser Arbeit wird die Synthese biofunktioneller Glykopolymere vorgestellt, wobei der Schwerpunkt auf wässrigen, schutzgruppenfreien und kurzen Synthesewegen liegt, um weitere Fortschritte auf dem Gebiet der Glykopolymersynthese zu erzielen. 
Ein praktisches und vielseitiges Ausgangsmaterial für Glykopolymere sind Glykosylamine. Um die Biofunktionalität der Saccharide nach deren Aminierung zu erhalten, wurde eine regioselektive Funktionalisierung durchgeführt. Diese häufig durchgeführte Synthese wurde für verschiedene Zucker optimiert. Die Optimierung wurde durch die Anwendung von statistischer Versuchsplanung (Design of Experiments, DoE) vereinfacht, um die Anzahl der erforderlichen Experimente zu reduzieren und ein effizientes Verfahren zu ermöglichen. Hier wird der Nutzen des DoE-Ansatzes für die Optimierung der Synthese von Glykosylaminen diskutiert. 
Die Glykosylamine wurden in Glykomonomere umgewandelt, die daraufhin polymerisiert wurden, um biofunktionelle Glykopolymere zu erhalten. Die Glykopolymere sollten als Layer-by-Layer (LbL)-Beschichtungen für Drug-Delivery-Systeme anwendbar sein. Um die LbL-Technik zu ermöglichen, wurden komplementäre Glykopolymerelektrolyte durch Polymerisation der Glykomonomere mit anschließender Modifkation oder durch Postpolymerisationsglykosylierung hergestellt. Für die Verabreichung von Arzneimitteln wurden Liposomen als potenzielle Wirkstoffcarrier in die Glykopolymerbeschichtung eingebettet. Die Stabilität sowie die Unversehrtheit der Glykopolymerschichten und Liposomen wurden im physiologischen pH-Bereich nachgewiesen. 
Abschließend wurden verschiedene Glykopolymere synthetisiert, die als Anti-Adhäsions-Therapeutika anwendbar sein könnten, indem sie komplexe Architekturen mit multivalenter Präsentation von Sacchariden bereitstellen, welche die Bindung von Pathogenenlektinen hemmen können. Hier wurde die Synthese von Glykopolymer-Hydrogelpartikeln auf der Basis von biokompatiblem Poly(N-isopropylacrylamid) (NiPAm) mit Hilfe einer radikalischen Fällungspolymerisation etabliert. Der Einfluss der Syntheseparameter auf den Zuckergehalt in den Gelen und auf die Hydrogelmorphologie wurde diskutiert. Die Zugänglichkeit der Saccharide für Modell-Lektine und ihre verstärkte, multivalente Interaktion wurden untersucht.  
Zum Abschluss dieser Arbeit werden die Synthesestrategien für die Glykopolymere sowie deren mögliche Anwendung in der Medizin allgemein diskutiert.
KW  - glycopolymers
KW  - Glykopolymere
KW  - glycoconjugates
KW  - Glykokonjugate
KW  - glycogels
KW  - Glykogele
KW  - layer-by-layer glycopolymer coating
KW  - Layer-by-Layer Glykopolymerbeschichtung
KW  - design of experiments
KW  - statistische Versuchsplanung (Design of Experiments)
KW  - glycopolymer electrolytes
KW  - Glykopolymer-Elektrolyt
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-563639
ER  - 
TY  - JOUR
A1  - Chea, Sany
A1  - Nguyen, Khac Toan
A1  - Rosencrantz, Ruben R.
T1  - Microwave-Assisted Synthesis of 5 '-O-methacryloylcytidine Using the Immobilized Lipase Novozym 435
JF  - Molecules
N2  - Nucleobase building blocks have been demonstrated to be strong candidates when it comes to DNA/RNA-like materials by benefiting from hydrogen bond interactions as physical properties. Modifying at the 5 ' position is the simplest way to develop nucleobase-based structures by transesterification using the lipase Novozym 435. Herein, we describe the optimization of the lipase-catalyzed synthesis of the monomer 5 '-O-methacryloylcytidine with the assistance of microwave irradiation. Variable reaction parameters, such as enzyme concentration, molar ratio of the substrate, reaction temperature and reaction time, were investigated to find the optimum reaction condition in terms of obtaining the highest yield.
KW  - microwave irradiation
KW  - Novozym 435
KW  - cytidine
KW  - monomer
KW  - smart materials
Y1  - 2022
U6  - https://doi.org/10.3390/molecules27134112
SN  - 1420-3049
VL  - 27
IS  - 13
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Chea, Sany
A1  - Schade, Kristin
A1  - Reinicke, Stefan
A1  - Bleul, Regina
A1  - Rosencrantz, Ruben R.
T1  - Synthesis and self-assembly of cytidine- and guanosine-based copolymers
JF  - Polymer Chemistry
N2  - The base pairing property and the "melting" behavior of oligonucleotides can take advantage to develop new smart thermoresponsive and programmable materials. Complementary cytidine- (C) and guanosine- (G) based monomers were blockcopolymerized using RAFT polymerization technique with poly-(N-(2-hydroxypropyl) methacrylamide) (pHPMA) as the hydrophilic macro chain transfer agent (macro-CTA). C-C, G-G and C-G hydrogen bond interactions of blockcopolymers with respectively C and G moieties have been investigated using SEM, DLS and UV-Vis. Mixing and heating both complementary copolymers resulted in reforming new aggregates. Due to the ribose moiety of the isolated nucleoside-bearing blockcopolymers, the polarity is increased for better solubility. Self-assembly investigations of these bioinspired compounds are the crucial basis for the development of potential future drug delivery systems.
Y1  - 2022
U6  - https://doi.org/10.1039/d2py00615d
SN  - 1759-9954
SN  - 1759-9962
VL  - 13
IS  - 35
SP  - 5058
EP  - 5067
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Li, Zhen
A1  - Spangenberg, Erik
A1  - Schicks, Judith Maria
A1  - Kempka, Thomas
T1  - Numerical simulation of hydrate formation in the LArge-Scale Reservoir Simulator (LARS)
JF  - Energies : open-access journal of related scientific research, technology development and studies in policy and management
N2  - The LArge-scale Reservoir Simulator (LARS) has been previously developed to study hydrate dissociation in hydrate-bearing systems under in-situ conditions. In the present study, a numerical framework of equations of state describing hydrate formation at equilibrium conditions has been elaborated and integrated with a numerical flow and transport simulator to investigate a multi-stage hydrate formation experiment undertaken in LARS. A verification of the implemented modeling framework has been carried out by benchmarking it against another established numerical code. Three-dimensional (3D) model calibration has been performed based on laboratory data available from temperature sensors, fluid sampling, and electrical resistivity tomography. The simulation results demonstrate that temperature profiles, spatial hydrate distribution, and bulk hydrate saturation are consistent with the observations. Furthermore, our numerical framework can be applied to calibrate geophysical measurements, optimize post-processing workflows for monitoring data, improve the design of hydrate formation experiments, and investigate the temporal evolution of sub-permafrost methane hydrate reservoirs.
KW  - methane hydrate
KW  - temperature sensor
KW  - electrical resistivity tomography
KW  - hydrate formation
KW  - numerical simulation
Y1  - 2022
U6  - https://doi.org/10.3390/en15061974
SN  - 1996-1073
VL  - 15
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - THES
A1  - Doering, Ulrike
T1  - Preparation, characterization and modification of oil loaded protein microcapsules and composite protein-mineral microcapsules
N2  - Diese Doktorarbeit behandelt die Synthese von Protein- und kompositen Protein-Mineral-Mikrokapseln durch die Anwendung von hochintensivem Ultraschall an der Öl-Wasser-Grenzfläche. Während ein System durch BSA-Moleküle stabilisiert wird, wird das andere System durch verschiedene mit BSA modifizierten Nanopartikeln stabilisiert. Sowohl von allen Synthesestufen als auch von den resultierenden Kapseln wurden umfassende Untersuchungen durchgeführt und eine plausible Erklärung für den Mechanismus der Kapselbildung wurde vorgestellt. Während der Bildung der BSA-Mikrokapseln adsorbieren die Proteinmoleküle als Erstes an der O/W-Grenzfläche, entfalten sich dort und bilden ein Netzwerk, das durch hydrophobe Wechselwirkungen und Wasserstoffbrückenbindungen zwischen den benachbarten Molekülen stabilisiert wird. Gleichzeitig bewirkt die Ultraschallbehandlung die Quervernetzung der BSA-Moleküle über die Bildung von intermolekularen Disulfidbindungen. In dieser Doktorarbeit werden die experimentellen Nachweise für die durch Ultraschall induzierte Quervernetzung von BSA in den Schalen der proteinbasierten Mikrokapseln aufgezeigt. Deshalb wurde das Konzept, das vor vielen Jahren von Suslick und seinen Mitarbeitern vorgestellt wurde, zum ersten Mal durch experimentelle Nachweise bestätigt. Außerdem wurde ein konsistenter Mechanismus für die Bildung der intermolekularen Disulfidbindungen in der Kapselschale vorgestellt, der auf der Neuverteilung der Thiol- und Disulfidgruppen in BSA unter der Wirkung von hochenergetischem Ultraschall basiert. Auch die Bildung von kompositen Protein-Mineral-Mikrokapseln, die mit drei verschiedenen Ölen gefüllt wurden und deren Schalen aus Nanopartikeln bestehen, war erfolgreich. Die Beschaffenheit des Öls und die Art der Nanopartikel in der Schale hatten Einfluss auf die Größe und Form der Mikrokapseln. Die Untersuchung der kompositen Kapseln zeigte, dass die BSA-Moleküle, die an der Oberfläche der Nanopartikel in der Kapselschale adsorbiert sind, nicht durch intermolekulare Disulfidbindungen quervernetzt sind. Stattdessen findet die Bildung einer Pickering-Emulsion statt. Die Oberflächenmodifizierung der kompositen Mikrokapseln durch Vormodifizierung der Hauptbestandteile und auch durch Postmodifizierung der Oberfläche der fertigen kompositen Mikrokapseln wurde erfolgreich demonstriert. Zusätzlich wurden die mechanischen Eigenschaften beider Kapselarten verglichen. Dabei erwiesen sich die Protein-Mikrokapseln widerstandsfähiger gegenüber elastischer Deformation.
N2  - This thesis deals with the synthesis of protein and composite protein-mineral microcapsules by the application of high-intensity ultrasound at the oil-water interface. While one system is stabilized by BSA molecules, the other system is stabilized by different nanoparticles modified with BSA. A comprehensive study of all synthesis stages as well as of resulting capsules were carried out and a plausible explanation of the capsule formation mechanism was proposed. During the formation of BSA microcapsules, the protein molecules adsorb firstly at the O/W interface and unfold there forming an interfacial network stabilized by hydrophobic interactions and hydrogen bonds between neighboring molecules. Simultaneously, the ultrasonic treatment causes the cross-linking of the BSA molecules via the formation of intermolecular disulfide bonds. In this thesis, the experimental evidences of ultrasonically induced cross-linking of the BSA in the shells of protein-based microcapsules are demonstrated. Therefore, the concept proposed many years ago by Suslick and co-workers is confirmed by experimental evidences for the first time. Moreover, a consistent mechanism for the formation of intermolecular disulfide bonds in capsule shells is proposed that is based on the redistribution of thiol and disulfide groups in BSA under the action of high-energy ultrasound. The formation of composite protein-mineral microcapsules loaded with three different oils and shells composed of nanoparticles was also successful. The nature of the loaded oil and the type of nanoparticles in the shell, had influence on size and shape of the microcapsules. The examination of the composite capsule revealed that the BSA molecules adsorbed on the nanoparticles surface in the capsule shell are not cross-linked by intermolecular disulfide bonds. Instead, a Pickering emulsion formation takes place. The surface modification of composite microcapsules through both pre-modification of main components and also the post-modification of the surface of ready composite microcapsules was successfully demonstrated. Additionally, the mechanical properties of protein and composite protein-mineral microcapsules were compared. The results showed that the protein microcapsules are more resistant to elastic deformation.
T2  - Herstellung, Charakterisierung und Modifizierung von Öl-gefüllten Protein-Mikrokapseln und kompositen Protein-Mineral-Mikrokapseln
KW  - Protein Microcapsules
KW  - Proteinmikrokapseln
KW  - Sonication
KW  - Beschallung
KW  - Pickering Emulsion
KW  - Pickering Emulsion
KW  - Colloid Chemistry
KW  - Kolloidchemie
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-559589
ER  - 
TY  - JOUR
A1  - Doering, Ulrike
A1  - Grigoriev, Dmitry
A1  - Tapio, Kosti
A1  - Bald, Ilko
A1  - Böker, Alexander
T1  - Synthesis of nanostructured protein-mineral-microcapsules by sonication
JF  - Soft matter
N2  - We propose a simple and eco-friendly method for the formation of composite protein-mineral-microcapsules induced by ultrasound treatment. Protein- and nanoparticle-stabilized oil-in-water (O/W) emulsions loaded with different oils are prepared using high-intensity ultrasound. The formation of thin composite mineral proteinaceous shells is realized with various types of nanoparticles, which are pre-modified with Bovine Serum Albumin (BSA) and subsequently characterized by EDX, TGA, zeta potential measurements and Raman spectroscopy. Cryo-SEM and EDX mapping visualizations show the homogeneous distribution of the densely packed nanoparticles in the capsule shell. In contrast to the results reported in our previous paper,(1) the shell of those nanostructured composite microcapsules is not cross-linked by the intermolecular disulfide bonds between BSA molecules. Instead, a Pickering-Emulsion formation takes place because of the amphiphilicity-driven spontaneous attachment of the BSA-modified nanoparticles at the oil/water interface. Using colloidal particles for the formation of the shell of the microcapsules, in our case silica, hydroxyapatite and calcium carbonate nanoparticles, is promising for the creation of new functional materials. The nanoparticulate building blocks of the composite shell with different chemical, physical or morphological properties can contribute to additional, sometimes even multiple, features of the resulting capsules. Microcapsules with shells of densely packed nanoparticles could find interesting applications in pharmaceutical science, cosmetics or in food technology.
Y1  - 2022
U6  - https://doi.org/10.1039/d1sm01638e
SN  - 1744-6848
VL  - 18
IS  - 13
SP  - 2558
EP  - 2568
PB  - Royal Society of Chemistry
CY  - London
ER  - 
TY  - JOUR
A1  - Zhang, Shanshan
A1  - Liu, Yue
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Ultrathin collagen type I films formed at the air-water interface
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - Collagen-based biomaterials with oriented fibrils have shown great application potential in medicine. However, it is still challenging to control the type I collagen fibrillogenesis in ultrathin films. Here, we report an approach to produce cohesive and well-organized type I collagen ultrathin films of about 10 nm thickness using the Langmuir-Blodgett technique. Ellipsometry, rheology, and Brewster angle microscopy are applied to investigate in situ how the molecules behave at the air-water interface, both at room temperature and 37 degrees C. The interfacial storage modulus observed at room temperature vanishes upon heating, indicating the existence and disappearance of the network structure in the protein nanosheet. The films were spanning over holes as large as 1 mm diameter when transferred at room temperature, proving the strong cohesive interactions. A highly aligned and fibrillar structure was observed by atomic force microscopy (AFM) and optical microscopy.
Y1  - 2022
U6  - https://doi.org/10.1557/s43580-021-00160-8
SN  - 2059-8521
VL  - 7
IS  - 4
SP  - 56
EP  - 62
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Mazarei, Elham
A1  - Barker, John R.
T1  - CH2 + O-2
BT  - reaction mechanism, biradical and zwitterionic character, and formation of CH2OO, the simplest Criegee intermediate
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies
N2  - The singlet and triplet potential surfaces for the title reaction were investigated using the CBS-QB3 level of theory. The wave functions for some species exhibited multireference character and required the CASPT2/6-31+G(d,p) and CASPT2/aug-cc-pVTZ levels of theory to obtain accurate relative energies. A Natural Bond Orbital Analysis showed that triplet (CH2OO)-C-3 (the simplest Criegee intermediate) and (CH2O2)-C-3 (dioxirane) have mostly polar biradical character, while singlet (CH2OO)-C-1 has some zwitterionic character and a planar structure. Canonical variational transition state theory (CVTST) and master equation simulations were used to analyze the reaction system. CVTST predicts that the rate constant for reaction of (CH2)-C-1 + O-3(2) is more than ten times as fast as the reaction of (CH2)-C-3 ((XB1)-B-3) + O-3(2) and the ratio remains almost independent of temperature from 900 K to 3000 K. The master equation simulations predict that at low pressures the (CH2O)-C-1 + O-3 product set is dominant at all temperatures and the primary yield of OH radicals is negligible below 600 K, due to competition with other primary reactions in this complex system.
Y1  - 2021
U6  - https://doi.org/10.1039/d1cp04372b
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 2
SP  - 914
EP  - 927
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Hoffmann, Falk
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Analytical model and Monte Carlo simulations of polymer degradation with improved chain cut statistics
JF  - Journal of materials research : JMR
N2  - The degradation of polymers is described by mathematical models based on bond cleavage statistics including the decreasing probability of chain cuts with decreasing average chain length. We derive equations for the degradation of chains under a random chain cut and a chain end cut mechanism, which are compared to existing models. The results are used to predict the influence of internal molecular parameters. It is shown that both chain cut mechanisms lead to a similar shape of the mass or molecular mass loss curve. A characteristic time is derived, which can be used to extract the maximum length of soluble fragments l of the polymer. We show that the complete description is needed to extract the degradation rate constant k from the molecular mass loss curve and that l can be used to design polymers that lose less mechanical stability before entering the mass loss phase.
KW  - Modeling
KW  - Degradable
KW  - Polymer
KW  - Molecular weight
KW  - Simulation
Y1  - 2022
U6  - https://doi.org/10.1557/s43578-022-00495-4
SN  - 0884-2914
SN  - 2044-5326
VL  - 37
IS  - 5
SP  - 1093
EP  - 1101
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Tang, Jo Sing Julia
A1  - Smaczniak, Aline Debrassi
A1  - Tepper, Lucas
A1  - Rosencrantz, Sophia
A1  - Aleksanyan, Mina
A1  - Dähne, Lars
A1  - Rosencrantz, Ruben R.
T1  - Glycopolymer based LbL multilayer thin films with embedded liposomes
JF  - Macromolecular bioscience
N2  - Layer-by-layer (LbL) self-assembly emerged as an efficient technique for fabricating coating systems for, e.g., drug delivery systems with great versatility and control. In this work, protecting group free and aqueous-based syntheses of bioinspired glycopolymer electrolytes aredescribed. Thin films of the glycopolymers are fabricated by LbL self-assembly and function as scaffolds for liposomes, which potentially can encapsulate active substances. The adsorbed mass, pH stability, and integrity of glycopolymer coatings as well as the embedded liposomes are investigated via whispering gallery mode (WGM) technology and quartz crystal microbalance with dissipation (QCM-D) monitoring , which enable label-free characterization. Glycopolymer thin films, with and without liposomes, are stable in the physiological pH range. QCM-D measurements verify the integrity of lipid vesicles. Thus, the fabrication of glycopolymer-based surface coatings with embedded and intact liposomes is presented.
KW  - glycopolymers
KW  - layer-by-layer self-assembly
KW  - liposomes
KW  - polyelectrolyte
KW  - multilayer film
Y1  - 2022
U6  - https://doi.org/10.1002/mabi.202100461
SN  - 1616-5187
SN  - 1616-5195
VL  - 22
IS  - 4
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Madani, Amiera
A1  - Anghileri, Lucia
A1  - Heydenreich, Matthias
A1  - Möller, Heiko Michael
A1  - Pieber, Bartholomäus
T1  - Benzylic fluorination induced by a charge-transfer complex with a solvent-dependent selectivity switch
JF  - Organic letters / publ. by the American Chemical Society
N2  - We present a divergent strategy for the fluorination of phenylacetic acid derivatives that is induced by a charge-transfer complex between Selectfluor and 4-(dimethylamino)pyridine. A comprehensive investigation of the conditions revealed a critical role of the solvent on the reaction outcome. In the presence of water, decarboxylative fluorination through a single-electron oxidation is dominant. Non-aqueous conditions result in the clean formation of alpha-fluoro-alpha-arylcarboxylic acids.
KW  - Charge transfer
KW  - Halogenation
KW  - Oxidation
KW  - Reaction products
KW  - Reagents
Y1  - 2022
U6  - https://doi.org/10.1021/acs.orglett.2c02050
SN  - 1523-7060
SN  - 1523-7052
VL  - 24
IS  - 29
SP  - 5376
EP  - 5380
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Goswami, Koushik
T1  - Inertial particle under active fluctuations
BT  - diffusion and work distributions
JF  - Physical review E, Statistical, nonlinear, and soft matter physics
N2  - We study the underdamped motion of a passive particle in an active environment. Using the phase space path integral method we find the probability distribution function of position and velocity for a free and a harmonically bound particle. The environment is characterized by an active noise which is described as the Ornstein-Uhlenbeck process (OUP). Taking two similar, yet slightly different OUP models, it is shown how inertia along with other relevant parameters affect the dynamics of the particle. Further we investigate the work fluctuations of a harmonically trapped particle by considering the trap center being pulled at a constant speed. Finally, the fluctuation theorem of work is validated with an effective temperature in the steady-state limit.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevE.105.044123
SN  - 2470-0045
SN  - 2470-0053
VL  - 105
IS  - 4
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Roy, Parna
A1  - Mukherjee, Arpita
A1  - Mondal, Pritha
A1  - Bhattacharyya, Biswajit
A1  - Narayan, Awadhesh
A1  - Pandey, Anshu
T1  - Electronic structure and spectroscopy of I-III-VI2 nanocrystals
BT  - a perspective
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - I-III-VI2 semiconductor nanocrystals have been applied to a host of energy conversion devices with great success. Large scale implementation of device concepts based on these materials has, however, been somewhat stymied by the strong role of defects in determining the optoelectronic characteristics of these materials. Here we present a perspective view of the role of electronic structure and defects on the physical properties, particularly the spectroscopy, of this family of materials. Applications of these materials are further discussed in this context.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.1c10922
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 17
SP  - 7364
EP  - 7373
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - THES
A1  - Chea, Sany
T1  - Glycomaterials: From synthesis of glycoconjugates to potential biomedical applications
T1  - Glykomaterialien: Von der Synthese von Glykokonjugaten zu potenziellen biomedizinischen Anwendungen
N2  - The importance of carbohydrate structures is enormous due to their ubiquitousness in our lives. The development of so-called glycomaterials is the result of this tremendous significance. These are not exclusively used for research into fundamental biological processes, but also, among other things, as inhibitors of pathogens or as drug delivery systems. This work describes the development of glycomaterials involving the synthesis of glycoderivatives, -monomers and -polymers. Glycosylamines were synthesized as precursors in a single synthesis step under microwave irradiation to significantly shorten the usual reaction time. Derivatization at the anomeric position was carried out according to the methods developed by Kochetkov and Likhorshetov, which do not require the introduction of protecting groups. Aminated saccharide structures formed the basis for the synthesis of glycomonomers in β-configuration by methacrylation. In order to obtain α-Man-based monomers for interactions with certain α-Man-binding lectins, a monomer synthesis by Staudinger ligation was developed in this work, which also does not require protective groups. Modification of the primary hydroxyl group of a saccharide was accomplished by enzyme-catalyzed synthesis. Ribose-containing cytidine was transesterified using the lipase Novozym 435 and microwave irradiation. The resulting monomer synthesis was optimized by varying the reaction partners. To create an amide bond instead of an ester bond, protected cytidine was modified by oxidation followed by amide coupling to form the monomer. This synthetic route was also used to isolate the monomer from its counterpart guanosine. After obtaining the nucleoside-based monomers, they were block copolymerized using the RAFT method. Pre-synthesized pHPMA served as macroCTA to yield cytidine- or guanosine-containing block copolymer. These isolated block copolymers were then investigated for their self-assembly behavior using UV-Vis, DLS and SEM to serve as a potential thermoresponsive drug delivery system.
N2  - Die Bedeutung von Kohlenhydratstrukturen ist immens, da sie in unserem Leben allgegenwärtig sind. Die Entwicklung sogenannter Glykomaterialien ist das Ergebnis dieser großen Bedeutung. Diese werden nicht nur zur Erforschung grundlegender biologischer Prozesse eingesetzt, sondern unter anderem auch als Hemmstoffe für Krankheitserreger oder als Wirkstofftransportsysteme. Die vorliegende Arbeit beschreibt die Entwicklung von Glycomaterialien durch die Synthese von Glycoderivaten, -monomeren und -polymeren. Glycosylamine wurden als Vorstufen in einem einzigen Syntheseschritt unter Mikrowellenbestrahlung synthetisiert, um die übliche Reaktionszeit deutlich zu verkürzen. Die Derivatisierung an der anomeren Position wurde nach den von Kochetkov und Likhorshetov entwickelten Methoden durchgeführt, die keine Einführung von Schutzgruppen erfordern. Die aminierten Saccharidstrukturen bildeten die Grundlage für die Synthese von Glycomonomeren in β-Konfiguration durch Methacrylierung. Um α-Man-basierte Monomere für Interaktionen mit bestimmten α-Man-bindenden Lektinen zu erhalten, wurde in dieser Arbeit eine Monomersynthese durch Staudinger-Ligation entwickelt, die ebenfalls keine Schutzgruppen erfordert. Die Modifizierung der primären Hydroxylgruppe eines Saccharids wurde durch enzymkatalysierte Synthese erreicht. Ribosehaltiges Cytidin wurde mit Hilfe der Lipase Novozym 435 und Mikrowellenbestrahlung umgeestert. Die resultierende Monomersynthese wurde durch Variation der Reaktionspartner optimiert. Um eine Amidbindung anstelle einer Esterbindung zu erzeugen, wurde geschütztes Cytidin durch Oxidation und anschließende Amidkupplung modifiziert, um das Monomer zu bilden. Dieser Syntheseweg wurde auch zur Isolierung des Monomers aus seinem Gegenstück Guanosin verwendet. Nach der Gewinnung der nukleosidbasierten Monomere wurden diese mit Hilfe der RAFT-Methode blockcopolymerisiert. Vorsynthetisiertes pHPMA diente als MakroCTA, um Cytidin- oder Guanosin-haltige Blockcopolymere zu erhalten. Diese isolierten Blockcopolymere wurden dann mit UV-Vis, DLS und SEM auf ihr Selbstorganisationsverhalten untersucht, um als potenzielles thermoresponsives Drug-Delivery-System zu dienen.
KW  - polymer chemistry
KW  - glyco chemistry
KW  - glycomonomer
KW  - glycopolymer
KW  - lectin
KW  - drug delivery
KW  - thermoresponsive
KW  - glycoconjugate
KW  - Glykochemie
KW  - Glykokonjugat
KW  - Glykomonomer
KW  - Glykopolymer
KW  - Lektin
KW  - Polymerchemie
KW  - thermoresponsiv
KW  - Drug Delivery
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-574240
ER  - 
TY  - THES
A1  - Simsek, Ibrahim
T1  - Ink-based preparation of chalcogenide perovskites as thin films for PV applications
T1  - Präparation von Chalkogeniden Perowskiten auf Basis von molekularer Tinte als Dünnschichten für PV Anwendungen
N2  - The increasing demand for energy in the current technological era and the recent political decisions about giving up on nuclear energy diverted humanity to focus on alternative environmentally friendly energy sources like solar energy. Although silicon solar cells are the product of a matured technology, the search for highly efficient and easily applicable materials is still ongoing. These properties made the efficiency of halide perovskites comparable with silicon solar cells for single junctions within a decade of research. However, the downside of halide perovskites are poor stability and lead toxicity for the most stable ones.
On the other hand, chalcogenide perovskites are one of the most promising absorber materials for the photovoltaic market, due to their elemental abundance and chemical stability against moisture and oxygen. In the search of the ultimate solar absorber material, combining the good optoelectronic properties of halide perovskites with the stability of chalcogenides could be the promising candidate.
Thus, this work investigates new techniques for the synthesis and design of these novel chalcogenide perovskites, that contain transition metals as cations, e.g., BaZrS3, BaHfS3, EuZrS3, EuHfS3 and SrHfS3. There are two stages in the deposition techniques of this study: In the first stage, the binary compounds are deposited via a solution processing method. In the second stage, the deposited materials are annealed in a chalcogenide atmosphere to form the perovskite structure by using solid-state reactions.
The research also focuses on the optimization of a generalized recipe for a molecular ink to deposit precursors of chalcogenide perovskites with different binaries. The implementation of the precursor sulfurization resulted in either binaries without perovskite formation or distorted perovskite structures, whereas some of these materials are reported in the literature as they are more favorable in the needle-like non-perovskite configuration.
Lastly, there are two categories for the evaluation of the produced materials: The first category is about the determination of the physical properties of the deposited layer, e.g., crystal structure, secondary phase formation, impurities, etc. For the second category, optoelectronic properties are measured and compared to an ideal absorber layer, e.g., band gap, conductivity, surface photovoltage, etc.
N2  - Der stetig wachsende Energieverbrauch in der aktuellen technologischen Ära und die kürzliche Entscheidung der Politik auf Nuklearenergie zu verzichten hat die Menschheit dazu geleitet sich auf alternative umweltfreundliche Energiequellen wie Solare Energie zu fokussieren. Obwohl Silizium Solarzellen das Produkt einer ausgereiften Technologie sind geht die Suche nach hocheffizienten Materialien, die einfach umzusetzen sind weiter. Diese Eigenschaften führten zur Vergleichbarkeit von Halogeniden Perowskiten mit Silizium in Einfachsolarzellen innerhalb eines Jahrzehnts der Forschung. Allerdings mangelt es bei Halogeniden Perowskiten an Stabilität und jene stabile haben eine Blei-Toxizität.
Andererseits bieten Chalkogenide Perowskite aussichtsreiche Eigenschaften als Absorber Materialien für den Photovoltaik Markt auf Grund des hohen Vorkommens der Elemente auf dem Planeten und ihrer chemischen Stabilität in Luft. Auf der Suche nach dem ultimativen Absorber Material für Solarzellen könnte sich eine Kombination der guten optoelektronischen Eigenschaften von Halogeniden Perowskiten mit der Stabilität von Chalkogeniden als guter Kandidat herausstellen.
Infolgedessen untersucht diese Arbeit neue Methoden für die Synthese und das Design dieser neuartigen Chalkogeniden Perowskite, welche Übergangsmetalle als Kationen enthalten, z.B. BaZrS3, BaHfS3, EuZrS3, EuHfS3 and SrHfS3. Es gibt zwei Schritte in den Methoden der Deposition in dieser Untersuchung: Im ersten Schritt werden die binären Verbindungen durch eine Lösungsmittelprozessierung auf dem Substrat aufgebracht. Daraufhin wird im zweiten Schritt das aufgetragene Material in einer Chalkogeniden Atmosphäre getempert, um die Perowskit Struktur durch Festkörperreaktion zu bilden.
Die Untersuchung fokussiert sich außerdem auf die Optimierung eines generalisierten Rezeptes für molekulare Tinte zur Deposition eines Präkursors aus unterschiedlichen binären Verbindungen. Die Implementierung der Präkursor Schwefelung führt entweder zu einer Formation der binären Verbindungen ohne Perowskit Struktur oder in der verzerrten Perowskit Struktur, obwohl für manche dieser Materialien laut Literatur die nadelförmige nicht-Perowskit Struktur günstiger sein sollte.
Zuletzt gibt es zwei Kategorien für die Evaluierung der hergestellten Materialien: Die erste Kategorie behandelt die Determinierung der physikalischen Eigenschaften der deponierten Dünnschicht, z.B. Kristallstruktur, Sekundärphasen, Unreinheiten. In der zweiten Kategorie werden die optoelektronischen Eigenschaften gemessen und mit einem idealen Absorber verglichen, z.B. Bandlücke, Leitfähigkeit, Oberflächen Photospannung, etc.
KW  - chalcogenide
KW  - perovskite
KW  - Perowskite
KW  - Chalkogenide
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-572711
ER  - 
TY  - THES
A1  - Heyne, Benjamin
T1  - Design and Synthesis of Highly Efficient InPZnS/ZnSe/ZnS Multishell Quantum Dots and Phase Transfer via Ligand Exchange
Y1  - 2022
ER  - 
TY  - JOUR
A1  - Kim, Jiyong
A1  - Kim, Yohan
A1  - Park, Kyoungwon
A1  - Boeffel, Christine
A1  - Choi, Hyung-Seok
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Ligand Effect in 1-Octanethiol Passivation of InP/ZnSe/ZnS Quantum Dots-Evidence of Incomplete Surface Passivation during Synthesis
JF  - Small : nano micro
N2  - The lack of anionic carboxylate ligands on the surface of InP/ZnSe/ZnS quantum dots (QDs), where zinc carboxylate ligands can be converted to carboxylic acid or carboxylate ligands via proton transfer by 1-octanethiol, is demonstrated. The as-synthesized QDs initially have an under-coordinated vacancy surface, which is passivated by solvent ligands such as ethanol and acetone. Upon exposure of 1-octanethiol to the QD surface, 1-octanethiol effectively induces the surface binding of anionic carboxylate ligands (derived from zinc carboxylate ligands) by proton transfer, which consequently exchanges ethanol and acetone ligands that bind on the incomplete QD surface. These systematic chemical analyses, such as thermogravimetric analysis-mass spectrometry and proton nuclear magnetic resonance spectroscopy, directly show the interplay of surface ligands, and it associates with QD light-emitting diodes (QD-LEDs). It is believed that this better understanding can lead to industrially feasible QD-LEDs.
KW  - colloidal quantum dots
KW  - incomplete surface passivation
KW  - indium
KW  - phosphide
KW  - surface chemistry
KW  - thiol passivation
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202203093
SN  - 1613-6810
SN  - 1613-6829
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Behrens, Karsten
A1  - Balischewski, Christian
A1  - Sperlich, Eric
A1  - Menski, Antonia Isabell
A1  - Balderas-Valadez, Ruth Fabiola
A1  - Pacholski, Claudia
A1  - Günter, Christina
A1  - Lubahn, Susanne
A1  - Kelling, Alexandra
A1  - Taubert, Andreas
T1  - Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Eight d-metal-containing N-butylpyridinium ionic liquids (ILs) with the nominal composition (C4Py)2[Ni0.5M0.5Cl4] or (C4Py)2[Zn0.5M0.5Cl4] (M = Cu, Co, Mn, Ni, Zn; C4Py = N-butylpyridinium) were synthesized, characterized, and investigated for their optical properties. Single crystal and powder X-ray analysis shows that the compounds are isostructural to existing examples based on other d-metal ions. Inductively coupled plasma optical emission spectroscopy measurements confirm that the metal/metal ratio is around 50 : 50. UV-Vis spectroscopy shows that the optical absorption can be tuned by selection of the constituent metals. Moreover, the compounds can act as an optical sensor for the detection of gases such as ammonia as demonstrated via a simple prototype setup.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1316 
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-587512
SN  - 1866-8372
IS  - 1316
SP  - 35072
EP  - 35082
ER  - 
TY  - JOUR
A1  - Figueroa Campos, Gustavo Adolfo
A1  - G. K. T. Kruizenga, Johannes
A1  - Sagu Tchewonpi, Sorel
A1  - Schwarz, Steffen
A1  - Homann, Thomas
A1  - Taubert, Andreas
A1  - Rawel, Harshadrai Manilal
T1  - Effect of the post-harvest processing on protein modification in green coffee beans by phenolic compounds
JF  - Foods : open access journal
N2  - The protein fraction, important for coffee cup quality, is modified during post-harvest treatment prior to roasting. Proteins may interact with phenolic compounds, which constitute the major metabolites of coffee, where the processing affects these interactions. This allows the hypothesis that the proteins are denatured and modified via enzymatic and/or redox activation steps. The present study was initiated to encompass changes in the protein fraction. The investigations were limited to major storage protein of green coffee beans. Fourteen Coffea arabica samples from various processing methods and countries were used. Different extraction protocols were compared to maintain the status quo of the protein modification. The extracts contained about 4–8 µg of chlorogenic acid derivatives per mg of extracted protein. High-resolution chromatography with multiple reaction monitoring was used to detect lysine modifications in the coffee protein. Marker peptides were allocated for the storage protein of the coffee beans. Among these, the modified peptides K.FFLANGPQQGGK.E and R.LGGK.T of the α-chain and R.ITTVNSQK.I and K.VFDDEVK.Q of β-chain were detected. Results showed a significant increase (p < 0.05) of modified peptides from wet processed green beans as compared to the dry ones. The present study contributes to a better understanding of the influence of the different processing methods on protein quality and its role in the scope of coffee cup quality and aroma. View Full-Text
KW  - Arabica coffee
KW  - coffee processing
KW  - protein modification
KW  - bound phenolic compounds
KW  - peptide biomarkers
KW  - LC-MS/MS
Y1  - 2022
U6  - https://doi.org/10.3390/foods11020159
SN  - 2304-8158
VL  - 11
PB  - MDPI
CY  - Basel, Schweiz
ET  - 2
ER  - 
TY  - JOUR
A1  - Behrens, Karsten
A1  - Balischewski, Christian
A1  - Sperlich, Eric
A1  - Menski, Antonia Isabell
A1  - Balderas-Valadez, Ruth Fabiola
A1  - Pacholski, Claudia
A1  - Günter, Christina
A1  - Lubahn, Susanne
A1  - Kelling, Alexandra
A1  - Taubert, Andreas
T1  - Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors
JF  - RSC Advances
N2  - Eight d-metal-containing N-butylpyridinium ionic liquids (ILs) with the nominal composition (C4Py)2[Ni0.5M0.5Cl4] or (C4Py)2[Zn0.5M0.5Cl4] (M = Cu, Co, Mn, Ni, Zn; C4Py = N-butylpyridinium) were synthesized, characterized, and investigated for their optical properties. Single crystal and powder X-ray analysis shows that the compounds are isostructural to existing examples based on other d-metal ions. Inductively coupled plasma optical emission spectroscopy measurements confirm that the metal/metal ratio is around 50 : 50. UV-Vis spectroscopy shows that the optical absorption can be tuned by selection of the constituent metals. Moreover, the compounds can act as an optical sensor for the detection of gases such as ammonia as demonstrated via a simple prototype setup.
Y1  - 2022
U6  - https://doi.org/10.1039/d2ra05581c
SN  - 2046-2069
VL  - 12
SP  - 35072
EP  - 35082
PB  - RSC
CY  - London
ER  - 
TY  - JOUR
A1  - Kapernaum, Nadia
A1  - Lange, Alyna
A1  - Ebert, Max
A1  - Grunwald, Marco A.
A1  - Häge, Christian
A1  - Marino, Sebastian
A1  - Zens, Anna
A1  - Taubert, Andreas
A1  - Gießelmann, Frank
A1  - Laschat, Sabine
T1  - Current topics in ionic liquid crystals
JF  - ChemPlusChem
N2  - Ionic liquid crystals (ILCs), that is, ionic liquids exhibiting mesomorphism, liquid crystalline phases, and anisotropic properties, have received intense attention in the past years. Among others, this is due to their special properties arising from the combination of properties stemming from ionic liquids and from liquid crystalline arrangements. Besides interesting fundamental aspects, ILCs have been claimed to have tremendous application potential that again arises from the combination of properties and architectures that are not accessible otherwise, or at least not accessible easily by other strategies. The current review highlights recent developments in ILC research, starting with some key fundamental aspects. Further subjects covered include the synthesis and variations of modern ILCs, including the specific tuning of their mesomorphic behavior. The review concludes with reflections on some applications that may be within reach for ILCs and finally highlights a few key challenges that must be overcome prior and during true commercialization of ILCs.
KW  - electrochemistry
KW  - ionic liquid crystals
KW  - mesogen mesophases
KW  - self-assembly
KW  - X-ray diffraction
Y1  - 2021
U6  - https://doi.org/10.1002/cplu.202100397
SN  - 2192-6506
VL  - 87
IS  - 1
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Balischewski, Christian
A1  - Bhattacharyya, Biswajit
A1  - Sperlich, Eric
A1  - Günter, Christina
A1  - Beqiraj, Alkit
A1  - Klamroth, Tillmann
A1  - Behrens, Karsten
A1  - Mies, Stefan
A1  - Kelling, Alexandra
A1  - Lubahn, Susanne
A1  - Holtzheimer, Lea
A1  - Nitschke, Anne
A1  - Taubert, Andreas
T1  - Tetrahalidometallate(II) ionic liquids with more than one metal
BT  - the effect of bromide versus chloride
JF  - Chemistry - a European journal
N2  - Fifteen N-butylpyridinium salts - five monometallic [C4Py](2)[MBr4] and ten bimetallic [C4Py](2)[(M0.5M0.5Br4)-M-a-Br-b] (M=Co, Cu, Mn, Ni, Zn) - were synthesized, and their structures and thermal and electrochemical properties were studied. All the compounds are ionic liquids (ILs) with melting points between 64 and 101 degrees C. Powder and single-crystal X-ray diffraction show that all ILs are isostructural. The electrochemical stability windows of the ILs are between 2 and 3 V. The conductivities at room temperature are between 10(-5) and 10(-6) S cm(-1). At elevated temperatures, the conductivities reach up to 10(-4) S cm(-1) at 70 degrees C. The structures and properties of the current bromide-based ILs were also compared with those of previous examples using chloride ligands, which illustrated differences and similarities between the two groups of ILs.
KW  - electrochemistry
KW  - ionic liquids
KW  - metal-containing ionic liquids;
KW  - N-butylpyridinium bromide
KW  - tetrahalidometallates
Y1  - 2022
U6  - https://doi.org/10.1002/chem.202201068
SN  - 1521-3765
VL  - 28
IS  - 64
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tartivel, Lucile
A1  - Blocki, Anna M.
A1  - Braune, Steffen
A1  - Jung, Friedrich
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - An Inverse shape-memory hydrogel scaffold switching upon cooling in a tissue-tolerated temperature range
JF  - Advanced materials interfaces
N2  - Tissue reconstruction has an unmet need for soft active scaffolds that enable gentle loading with regeneration-directing bioactive components by soaking up but also provide macroscopic dimensional stability. Here microporous hydrogels capable of an inverse shape-memory effect (iSME) are described, which in contrast to classical shape-memory polymers (SMPs) recover their permanent shape upon cooling. These hydrogels are designed as covalently photo cross-linked polymer networks with oligo(ethylene glycol)-oligo(propylene glycol)-oligo(ethylene glycol) (OEG-OPG-OEG) segments. When heated after deformation, the OEG-OPG-OEG segments form micelles fixing the temporary shape. Upon cooling, the micelles dissociate again, the deformation is reversed and the permanent shape is obtained. Applicability of this iSME is demonstrated by the gentle loading of platelet-rich plasma (PRP) without causing any platelet activation during this process. PRP is highly bioactive and is widely acknowledged for its regenerative effects. Hence, the microporous inverse shape-memory hydrogel (iSMH) with a cooling induced pore-size effect represents a promising candidate scaffold for tissue regeneration for potential usage in minimally invasive surgery applications.
KW  - active scaffold
KW  - critical micellation temperature
KW  - hydrogel
KW  - inverse
KW  - shape-memory effect
KW  - platelet-rich plasma
Y1  - 2022
U6  - https://doi.org/10.1002/admi.202101588
SN  - 2196-7350
VL  - 9
IS  - 6
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Zhao, Yuhang
A1  - Sarhan, Radwan Mohamed
A1  - Eljarrat, Alberto
A1  - Kochovski, Zdravko
A1  - Koch, Christoph
A1  - Schmidt, Bernd
A1  - Koopman, Wouter-Willem Adriaan
A1  - Lu, Yan
T1  - Surface-functionalized Au-Pd nanorods with enhanced photothermal conversion and catalytic performance
JF  - ACS applied materials & interfaces
N2  - Bimetallic nanostructures comprising plasmonic and catalytic components have recently emerged as a promising approach to generate a new type of photo-enhanced nanoreactors. Most designs however concentrate on plasmon-induced charge separation, leaving photo-generated heat as a side product. 
This work presents a photoreactor based on Au-Pd nanorods with an optimized photothermal conversion, which aims to effectively utilize the photo-generated heat to increase the rate of Pd-catalyzed reactions. Dumbbell-shaped Au nanorods were fabricated via a seed-mediated growth method using binary surfactants. Pd clusters were selectively grown at the tips of the Au nanorods, using the zeta potential as a new synthetic parameter to indicate the surfactant remaining on the nanorod surface. 
The photothermal conversion of the Au-Pd nanorods was improved with a thin layer of polydopamine (PDA) or TiO2. 
As a result, a 60% higher temperature increment of the dispersion compared to that for bare Au rods at the same light intensity and particle density could be achieved. 
The catalytic performance of the coated particles was then tested using the reduction of 4-nitrophenol as the model reaction. Under light, the PDA-coated Au-Pd nanorods exhibited an improved catalytic activity, increasing the reaction rate by a factor 3. 
An analysis of the activation energy confirmed the photoheating effect to be the dominant mechanism accelerating the reaction. Thus, the increased photothermal heating is responsible for the reaction acceleration. 
Interestingly, the same analysis shows a roughly 10% higher reaction rate for particles under illumination compared to under dark heating, possibly implying a crucial role of localized heat gradients at the particle surface. 
Finally, the coating thickness was identified as an essential parameter determining the photothermal conversion efficiency and the reaction acceleration.
KW  - Au-Pd nanorods
KW  - PDA
KW  - photothermal conversion
KW  - surface plasmon
KW  - 4-nitrophenol
Y1  - 2022
U6  - https://doi.org/10.1021/acsami.2c00221
SN  - 1944-8244
SN  - 1944-8252
VL  - 14
IS  - 15
SP  - 17259
EP  - 17272
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Floyd, Thomas G.
A1  - Song, Ji-Inn
A1  - Hapeshi, Alexia
A1  - Laroque, Sophie
A1  - Hartlieb, Matthias
A1  - Perrier, Sebastien
T1  - Bottlebrush copolymers for gene delivery: influence of architecture, charge density, and backbone length on transfection efficiency
JF  - Journal of materials chemistry : B, materials for biology and medicine
N2  - The influence of polymer architecture of polycations on their ability to transfect mammalian cells is probed. Polymer bottle brushes with grafts made from partially hydrolysed poly(2-ethyl-2-oxazoline) are used while varying the length of the polymer backbone as well as the degree of hydrolysis (cationic charge content). Polyplex formation is investigated via gel electrophoresis, dye-displacement and dynamic light scattering. Bottle brushes show a superior ability to complex pDNA when compared to linear copolymers. Also, nucleic acid release was found to be improved by a graft architecture. Polyplexes based on bottle brush copolymers showed an elongated shape in transmission electron microscopy images. The cytotoxicity against mammalian cells is drastically reduced when a graft architecture is used instead of linear copolymers. Moreover, the best-performing bottle brush copolymer showed a transfection ability comparable with that of linear poly(ethylenimine), the gold standard of polymeric transfection agents, which is used as positive control. In combination with their markedly lowered cytotoxicity, cationic bottle brush copolymers are therefore shown to be a highly promising class of gene delivery vectors.
Y1  - 2022
U6  - https://doi.org/10.1039/d2tb00490a
SN  - 2050-750X
SN  - 2050-7518
VL  - 10
IS  - 19
SP  - 3696
EP  - 3704
PB  - Royal Society of Chemistry
CY  - London [u.a.]
ER  - 
TY  - JOUR
A1  - Pan, Xuefeng
A1  - Sarhan, Radwan Mohamed
A1  - Kochovski, Zdravko
A1  - Chen, Guosong
A1  - Taubert, Andreas
A1  - Mei, Shilin
A1  - Lu, Yan
T1  - Template synthesis of dual-functional porous MoS2 nanoparticles with photothermal conversion and catalytic properties
JF  - Nanoscale
N2  - Advanced catalysis triggered by photothermal conversion effects has aroused increasing interest due to its huge potential in environmental purification. 
In this work, we developed a novel approach to the fast degradation of 4-nitrophenol (4-Nip) using porous MoS2 nanoparticles as catalysts, which integrate the intrinsic catalytic property of MoS2 with its photothermal conversion capability. 
Using assembled polystyrene-b-poly(2-vinylpyridine) block copolymers as soft templates, various MoS 2 particles were prepared, which exhibited tailored morphologies (e.g., pomegranate-like, hollow, and open porous structures). 
The photothermal conversion performance of these featured particles was compared under near-infrared (NIR) light irradiation. 
Intriguingly, when these porous MoS2 particles were further employed as catalysts for the reduction of 4-Nip, the reaction rate constant was increased by a factor of 1.5 under NIR illumination. 
We attribute this catalytic enhancement to the open porous architecture and light-to-heat conversion performance of the MoS2 particles. This contribution offers new opportunities for efficient photothermal-assisted catalysis.
Y1  - 2022
U6  - https://doi.org/10.1039/d2nr01040b
SN  - 2040-3372
VL  - 14
IS  - 18
SP  - 6888
EP  - 6901
PB  - RSC Publ. (Royal Society of Chemistry)
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Xie, Dongjiu
A1  - Xu, Yaolin
A1  - Wang, Yonglei
A1  - Pan, Xuefeng
A1  - Härk, Eneli
A1  - Kochovski, Zdravko
A1  - Eljarrat, Alberto
A1  - Müller, Johannes
A1  - Koch, Christoph T.
A1  - Yuan, Jiayin
A1  - Lu, Yan
T1  - Poly(ionic liquid) nanovesicle-templated carbon nanocapsules functionalized with uniform iron nitride nanoparticles as catalytic sulfur host for Li-S batteries
JF  - ACS nano
N2  - Poly(ionic liquid)s (PIL) are common precursors for heteroatom-doped carbon materials. Despite a relatively higher carbonization yield, the PIL-to-carbon conversion process faces challenges in preserving morphological and structural motifs on the nanoscale. Assisted by a thin polydopamine coating route and ion exchange, imidazoliumbased PIL nanovesicles were successfully applied in morphology-maintaining carbonization to prepare carbon composite nanocapsules. Extending this strategy further to their composites, we demonstrate the synthesis of carbon composite nanocapsules functionalized with iron nitride nanoparticles of an ultrafine, uniform size of 3-5 nm (termed "FexN@C "). Due to its unique nanostructure, the sulfur-loaded FexN@C electrode was tested to efficiently mitigate the notorious shuttle effect of lithium polysulfides (LiPSs) in Li-S batteries. The cavity of the carbon nanocapsules was spotted to better the loading content of sulfur. The well-dispersed iron nitride nanoparticles effectively catalyze the conversion of LiPSs to Li2S, owing to their high electronic conductivity and strong binding power to LiPSs. Benefiting from this well-crafted composite nanostructure, the constructed FexN@C/S cathode demonstrated a fairly high discharge capacity of 1085 mAh g(-1) at 0.5 C initially, and a remaining value of 930 mAh g(-1 )after 200 cycles. In addition, it exhibits an excellent rate capability with a high initial discharge capacity of 889.8 mAh g(-1) at 2 C. This facile PIL-to-nanocarbon synthetic approach is applicable for the exquisite design of complex hybrid carbon nanostructures with potential use in electrochemical energy storage and conversion.
KW  - poly(ionic liquid)s
KW  - nanovesicles
KW  - sulfur host
KW  - iron nitride
KW  - Li-S
KW  - batteries
Y1  - 2022
U6  - https://doi.org/10.1021/acsnano.2c01992
SN  - 1936-0851
SN  - 1936-086X
VL  - 16
IS  - 7
SP  - 10554
EP  - 10565
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kuntze, Kim
A1  - Viljakka, Jani
A1  - Titov, Evgenii
A1  - Ahmed, Zafar
A1  - Kalenius, Elina
A1  - Saalfrank, Peter
A1  - Priimagi, Arri
T1  - Towards low-energy-light-driven bistable photoswitches
BT  - ortho-fluoroaminoazobenzenes
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days. <br /> [GRAPHICS] <br /> .
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00145-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 159
EP  - 173
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Abbasi, Ali
A1  - Xu, Yaolin
A1  - Khezri, Ramin
A1  - Etesami, Mohammad
A1  - Lin, C.
A1  - Kheawhom, Soorathep
A1  - Lu, Yan
T1  - Advances in characteristics improvement of polymeric membranes/separators for zinc-air batteries
JF  - Materials Today Sustainability
N2  - Zinc-air batteries (ZABs) are gaining popularity for a wide range of applications due to their high energy density, excellent safety, and environmental friendliness. A membrane/separator is a critical component of ZABs, with substantial implications for battery performance and stability, particularly in the case of a battery in solid state format, which has captured increased attention in recent years. In this review, recent advances as well as insight into the architecture of polymeric membrane/separators for ZABs including porous polymer separators (PPSs), gel polymer electrolytes (GPEs), solid polymer electrolytes (SPEs) and anion exchange membranes (AEMs) are discussed. The paper puts forward strategies to enhance stability, ionic conductivity, ionic selectivity, electrolyte storage capacity and mechanical properties for each type of polymeric membrane. In addition, the remaining major obstacles as well as the most potential avenues for future research are examined in detail.
KW  - Ionic selectivity
KW  - Ionic conductivity
KW  - Gel polymer
KW  - Ion exchange
KW  - Porous
KW  - polymer
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtsust.2022.100126
SN  - 2589-2347
VL  - 18
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Penschke, Christopher
A1  - Edler von Zander, Robert
A1  - Beqiraj, Alkit
A1  - Zehle, Anna
A1  - Jahn, Nicolas
A1  - Neumann, Rainer
A1  - Saalfrank, Peter
T1  - Water on porous, nitrogen-containing layered carbon materials
BT  - the performance of computational model chemistries
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies / RSC, Royal Society of Chemistry
N2  - Porous, layered materials containing sp(2)-hybridized carbon and nitrogen atoms, offer through their tunable properties, a versatile route towards tailormade catalysts for electrochemistry and photochemistry. A key molecule interacting with these quasi two-dimensional materials (2DM) is water, and a photo(electro)chemical key reaction catalyzed by them, is water splitting into H-2 and O-2, with the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) as half reactions. The complexity of some C/N-based 2DM in contact with water raises special needs for their theoretical modelling, which in turn is needed for rational design of C/N-based catalysts. In this work, three classes of C/N-containing porous 2DM with varying pore sizes and C/N ratios, namely graphitic carbon nitride (g-C3N4), C2N, and poly(heptazine imides) (PHI), are studied with various computational methods. We elucidate the performance of different models and model chemistries (the combination of electronic structure method and basis set) for water and water fragment adsorption in the low-coverage regime. Further, properties related to the photo(electro)chemical activity like electrochemical overpotentials, band gaps, and optical excitation energies are in our focus. Specifically, periodic models will be tested vs. cluster models, and density functional theory (DFT) vs. wavefunction theory (WFT). This work serves as a basis for a systematic study of trends for the photo(electro)chemical activity of C/N-containing layered materials as a function of water content, pore size and density.
Y1  - 2022
U6  - https://doi.org/10.1039/d2cp00657j
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 24
SP  - 14709
EP  - 14726
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - THES
A1  - Fischer, Eric Wolfgang
T1  - Quantum vibrational dynamics in complex environments: from vibrational strong coupling in molecular cavity QED to phonon-induced adsorbate relaxation
N2  - Molecules are often naturally embedded in a complex environment. As a consequence, characteristic properties of a molecular subsystem can be substantially altered  or new properties emerge due to interactions between molecular and environmental degrees of freedom. The present thesis is concerned with the numerical study of quantum dynamical and stationary properties of molecular vibrational systems embedded in selected complex environments. 

In the first part, we discuss "strong-coupling" model scenarios for molecular vibrations interacting with few quantized electromagnetic field modes of an optical Fabry-Pérot cavity. We thoroughly elaborate on properties of emerging "vibrational polariton" light-matter hybrid states and examine the relevance of the dipole self-energy. Further, we identify cavity-induced quantum effects and an emergent dynamical resonance in a cavity-altered thermal isomerization model, which lead to significant suppression of thermal reaction rates. Moreover, for a single rovibrating diatomic molecule in an optical cavity, we observe non-adiabatic signatures in dynamics due to "vibro-polaritonic conical intersections" and discuss spectroscopically accessible "rovibro-polaritonic" light-matter hybrid states.
 
In the second part, we study a weakly coupled but numerically challenging quantum mechanical adsorbate-surface model system comprising a few thousand surface modes. We introduce an efficient construction scheme for a "hierarchical effective mode" approach to reduce the number of surface modes in a controlled manner. In combination with the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) method, we examine the vibrational adsorbate relaxation dynamics from different excited adsorbate states by solving the full non-Markovian system-bath dynamics for the characteristic relaxation time scale. We examine half-lifetime scaling laws from vibrational populations and identify prominent non-Markovian signatures as deviations from Markovian reduced system density matrix theory in vibrational coherences, system-bath entanglement and energy transfer dynamics.

In the final part of this thesis, we approach the dynamics and spectroscopy of vibronic model systems at finite temperature by formulating the ML-MCTDH method in the non-stochastic framework of thermofield dynamics. We apply our method to thermally-altered ultrafast internal conversion in the well-known vibronic coupling model of pyrazine. Numerically beneficial representations of multilayer wave functions ("ML-trees") are identified for different temperature regimes, which allow us to access thermal effects on both electronic and vibrational dynamics as well as spectroscopic properties for several pyrazine models.
N2  - Moleküle sind für gewöhnlich in komplexe Umgebungen eingebettet. In Folge werden charakteristische Eigenschaften des molekularen Subsystems durch Wechselwirkung mit Umgebungsfreitheitsgraden potentiell deutlich verändert. Die vorliegende Dissertation behandelt die numerische Untersuchung von quantendynamischen und stationären Eigenschaften molekularer Schwingungen unter dem Einfluss ausgewählter komplexer Umgebungen.
Im ersten Teil werden stark gekoppelte Modelsysteme betrachtet, die durch Wechselwirkung von molekulare Schwingungen mit wenigen quantisierten, elektromagnetischen Feldmoden einer Fabry-Pérot Kavität realisiert werden. Die Eigenschaften von Schwingungspolaritonen und die Relevanz der Dipolselbstenergie werden im Detail untersucht. Weiterhin werden quantenmechanische Effekte sowie ein dynamisches Resonanzphänomen in einem Modelsystem für thermische Isomerisierung unter dem Einfluss einer Kavität identifiziert, die zu signifikant reduzierten thermischen Reaktionsraten führen. Für ein frei rotierendes, schwingendes CO Molekül in einer Kavität finden sich nicht-adiabatische Signaturen in Form von schwingungspolaritonischen konischen Durchschneidungen sowie spektroskopisch identifizierbaren rovibratorischen Licht-Materie-Hybridzustände. 
Im zweiten Teil wird ein schwach gekoppeltes, numerisch anspruchsvolles Adsorbat-Oberflächen-Model mit einigen tausend Oberflächenmoden diskutiert. Es wird ein numerisch effizientes Verfahren zur Konstruktion einer Hierarchie effektiver Moden vorgestellt, wodurch die Anzahl an Oberflächenmoden kontrolliert reduziert wird. In Kombination mit der "multilayer multiconfigurational time-dependent Hartree" (ML-MCTDH) Methode, wird der Relaxationsprozess der Adsorbatmode für verschiedene Anfangszustände durch Lösung der nicht-Markovschen System-Bad Dynamik auf der charakteristische Relaxationszeitskala untersucht. Skalierungsgesetze von Halbwertszeiten werden aus Schwingungspopulationen erhalten und prominente nicht-markovsche Signaturen in Schwingungskohärenzen, in System-Bad-Verschränkung und in der Energietransferdynamik werden durch Vergleich mit markovscher reduzierter Dichtematrixtheorie identifiziert. Im letzten Teil wird vibronische Dynamik bei endlichen Temperaturen untersucht und die ML-MCTDH Methode im Rahmen der nicht-stochastischen "Thermofield Theory" formuliert. Der thermisch beeinflusste, ultraschnelle interne Konversionsprozess in Pyrazin wird betrachtet. Numerisch effiziente Darstellungen der ML-MCTDH Wellenfunktionen für verschiedene Temperaturen werden vorgestellt und thermische Effekte auf Dynamik und Spektroskopie werden diskutiert.
KW  - theoretical chemistry
KW  - theoretische Chemie
KW  - quantum dynamics
KW  - Quantendynamik
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-567214
ER  - 
TY  - JOUR
A1  - Yang, Jin
A1  - Ghosh, Samrat
A1  - Roeser, Jérôme
A1  - Acharjya, Amitava
A1  - Penschke, Christopher
A1  - Tsutsui, Yusuke
A1  - Rabeah, Jabor
A1  - Wang, Tianyi
A1  - Tameu, Simon Yves Djoko
A1  - Ye, Meng-Yang
A1  - Grüneberg, Julia
A1  - Li, Shuang
A1  - Li, Changxia
A1  - Schomaecker, Reinhard
A1  - Van de Krol, Roel
A1  - Seki, Shu
A1  - Saalfrank, Peter
A1  - Thomas, Arne
T1  - Constitutional isomerism of the linkages in donor–acceptor covalent organic frameworks and its impact on photocatalysis
JF  - Nature Communications
N2  - When new covalent organic frameworks (COFs) are designed, the main efforts are typically focused on selecting specific building blocks with certain geometries and properties to control the structure and function of the final COFs. The nature of the linkage (imine, boroxine, vinyl, etc.) between these building blocks naturally also defines their properties. However, besides the linkage type, the orientation, i.e., the constitutional isomerism of these linkages, has rarely been considered so far as an essential aspect. In this work, three pairs of constitutionally isomeric imine-linked donor-acceptor (D-A) COFs are synthesized, which are different in the orientation of the imine bonds (D-C=N-A (DCNA) and D-N=C-A (DNCA)). The constitutional isomers show substantial differences in their photophysical properties and consequently in their photocatalytic performance. Indeed, all DCNA COFs show enhanced photocatalytic H2 evolution performance than the corresponding DNCA COFs. Besides the imine COFs shown here, it can be concluded that the proposed concept of constitutional isomerism of linkages in COFs is quite universal and should be considered when designing and tuning the properties of COFs.
Y1  - 2022
U6  - https://doi.org/10.1038/s41467-022-33875-9
SN  - 2041-1723
VL  - 13
IS  - 1
PB  - Nature Publishing Group UK
CY  - [London]
ER  - 
TY  - JOUR
A1  - Bapolisi, Alain Murhimalika
A1  - Kielb, Patrycja
A1  - Bekir, Marek
A1  - Lehnen, Anne-Catherine
A1  - Radon, Christin
A1  - Laroque, Sophie
A1  - Wendler, Petra
A1  - Müller-Werkmeister, Henrike
A1  - Hartlieb, Matthias
T1  - Antimicrobial polymers of linear and bottlebrush architecture
BT  - Probing the membrane interaction and physicochemical properties
JF  - Macromolecular rapid communications : publishing the newsletters of the European Polymer Federation
N2  - Polymeric antimicrobial peptide mimics are a promising alternative for the future management of the daunting problems associated with antimicrobial resistance. However, the development of successful antimicrobial polymers (APs) requires careful control of factors such as amphiphilic balance, molecular weight, dispersity, sequence, and architecture. While most of the earlier developed APs focus on random linear copolymers, the development of APs with advanced architectures proves to be more potent. It is recently developed multivalent bottlebrush APs with improved antibacterial and hemocompatibility profiles, outperforming their linear counterparts. Understanding the rationale behind the outstanding biological activity of these newly developed antimicrobials is vital to further improving their performance. This work investigates the physicochemical properties governing the differences in activity between linear and bottlebrush architectures using various spectroscopic and microscopic techniques. Linear copolymers are more solvated, thermo-responsive, and possess facial amphiphilicity resulting in random aggregations when interacting with liposomes mimicking Escheria coli membranes. The bottlebrush copolymers adopt a more stable secondary conformation in aqueous solution in comparison to linear copolymers, conferring rapid and more specific binding mechanism to membranes. The advantageous physicochemical properties of the bottlebrush topology seem to be a determinant factor in the activity of these promising APs.
KW  - antimicrobial polymers
KW  - bottlebrush copolymers
KW  - liposomes
KW  - membrane
KW  - interactions
KW  - quartz crystal microbalance
Y1  - 2022
U6  - https://doi.org/10.1002/marc.202200288
SN  - 1521-3927
SN  - 1022-1336
VL  - 43
IS  - 19
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - THES
A1  - Bastian, Philipp U.
T1  - Core-shell upconversion nanoparticles - investigation of dopant intermixing and surface modification
T1  - Kern-Schale Aufkonvertierende Nanopartikel — eine Untersuchung der Dotandenvermischung und Oberflächenmodifikation
N2  - Frequency upconversion nanoparticles (UCNPs) are inorganic nanocrystals capable to up-convert incident photons of the near-infrared electromagnetic spectrum (NIR) into higher energy photons. These photons are re-emitted in the range of the visible (Vis) and even ultraviolet (UV) light. The frequency upconversion process (UC) is realized with nanocrystals doped with trivalent lanthanoid ions (Ln(III)). The Ln(III) ions provide the electronic (excited) states forming a ladder-like electronic structure for the Ln(III) electrons in the nanocrystals. The absorption of at least two low energy photons by the nanoparticle and the subsequent energy transfer to one Ln(III) ion leads to the promotion of one Ln(III) electron into higher excited electronic states. One high energy photon will be emitted during the radiative relaxation of the electron in the excited state back into the electronic ground state of the Ln(III) ion. The excited state electron is the result of the previous absorption of at least two low energy photons.
The UC process is very interesting in the biological/medical context. Biological samples (like organic tissue, blood, urine, and stool) absorb high-energy photons (UV and blue light) more strongly than low-energy photons (red and NIR light). Thanks to a naturally occurring optical window, NIR light can penetrate deeper than UV light into biological samples. Hence, UCNPs in bio-samples can be excited by NIR light. This possibility opens a pathway for in vitro as well as in vivo applications, like optical imaging by cell labeling or staining of specific organic tissue. Furthermore, early detection and diagnosis of diseases by predictive and diagnostic biomarkers can be realized with bio-recognition elements being labeled to the UCNPs. Additionally, "theranostic" becomes possible, in which the identification and the treatment of a disease are tackled simultaneously.
For this to succeed, certain parameters for the UCNPs must be met: high upconversion efficiency, high photoluminescence quantum yield, dispersibility, and dispersion stability in aqueous media, as well as availability of functional groups to introduce fast and easy bio-recognition elements. The UCNPs used in this work were prepared with a solvothermal decomposition synthesis yielding in particles with NaYF4 or NaGdF4 as host lattice. They have been doped with the Ln(III) ions Yb3+ and Er3+, which is only one possible upconversion pair. Their upconversion efficiency and photoluminescence quantum yield were improved by adding a passivating shell to reduce surface quenching.
However, the brightness of core-shell UCNPs stays behind the expectations compared to their bulk material (being at least μm-sized particles). The core-shell structures are not clearly separated from each other, which is a topic in literature. Instead, there is a transition layer between the core and the shell structure, which relates to the migration of the dopants within the host lattice during the synthesis. The ion migration has been examined by time-resolved laser spectroscopy and the interlanthanoid resonance energy transfer (LRET) in the two different host lattices from above. The results are
presented in two publications, which dealt with core-shell-shell structured nanoparticles. The core is doped with the LRET-acceptor (either Nd3+ or Pr3+). The intermediate shell serves as an insulation shell of pure host lattice material, whose shell thickness has been varied within one set of samples having the same composition, so that the spatial separation of LRET-acceptor and -donor changes. The outer shell with the same host lattice is doped with the LRET-donor (Eu3+). The effect of the increasing insulation shell thickness is significant, although the LRET cannot be suppressed completely.
Next to the Ln(III) migration within a host lattice, various phase transfer reactions were investigated in order to subsequently perform surface modifications for bioapplications. One result out of this research has been published using a promising ligand, that equips the UCNP with bio-modifiable groups and has good potential for bio-medical applications. This particular ligand mimics natural occurring mechanisms of mussel protein adhesion and of blood coagulation, which is why the UCNPs are encapsulated very effectively. At the same time, bio-functional groups are introduced. In a proof-of-concept, the encapsulated UCNP has been coupled successfully with a dye (which is representative for a biomarker) and the system’s photoluminescence properties have been investigated.
N2  - Frequenzaufkonvertierende Nanopartikel (UCNP) sind anorganische Nanokristalle. Sie können einfallende Photonen des nah-infraroten elektromagnetischen Spektrums (NIR) in höher energetische Photonen im Bereich des sichtbaren Lichtes und sogar des ultravioletten Lichtes (UV) umwandeln und wieder emittieren. Dieser Frequenzaufkonversionsprozess (UC) basiert auf Nanokristallen, die mit dreiwertigen Lanthanoid-Ionen (Ln(III)) dotiert sind. Die elektronisch angeregten Zustände der Ln(III)-Ionen stehen zur Verfügung, mit deren Hilfe Elektronen über eine leiterartige elektronische Struktur der elektronischen Zustände der Ln(III)-Ionen in höher angeregte Zustände gelangen können. Zuvor müssen mindestens zwei niederenergetische Photonen vom Nanopartikel absorbiert werden. Die absorbierte Energie muss über einen oder mehrere Energieübertragungen das gleiche Ln(III)-Ion erreichen um beim strahlenden Relaxieren des Elektrones im angeregten Zustand zurück in den elektronischen Grundzustand des Ln(III)-Ions ein höherenergetisches Photon zu emittieren.
Der Frequenzaufkonversionsprozess ist sehr interessant für die Anwendung im biologisch/medizinischen Bereich. Biologische Proben (z.B. organisches Gewebe, Blut, Urin und Stuhl) absorbieren höherenergetische Photonen (UV) stärker als niederenergetische Photonen (NIR). Dank eines natürlich vorkommenden optischen Fensters in biologischen Proben kann NIR-Licht tiefer als UV-Licht eindringen, sodass die UCNPs in biologischen Proben mit NIR-Licht angeregt werden können. Dies ermöglicht in vitro als auch in vivo Anwendungen, z.B. für die optische Bildgebung durch Markieren von Zellen oder durch Einfärben von bestimmten Bereichen organischer Gewebe. Frühzeitige Erkennung von Krankheiten kann durch prädiktive und diagnostisch geeignete Biomarker, die mit Erkennungselementen an den UCNPs detektiert werden, realisiert werden. Demnach ist „Theranostic“ ein mögliches Szenario, das die Identifikation und die gleichzeitige Behandlung einer Krankheit ermöglichen könnte.
Um diese Vision zu realisieren, müssen die UCNPs bestimmte Parameter erfüllen: Eine hohe Aufkonversionseffizienz, eine hohe Photolumineszenzquantenausbeute, eine gute Dispergierbarkeit und Stabilität der Dispersion in wässrigen Medien, sowie die Verfügbarkeit von funktionellen Gruppen, um schnell und einfach biologische Erkennungselemente daran zu koppeln. Die UCNPs dieser Arbeit wurden mit Hilfe einer solvothermalen Zersetzungsreaktion durchgeführt. Die Nanopartikel bestanden aus unterschiedlichen Wirtsgittern, entweder aus NaYF4 oder NaGdF4. Die Wirtsgitter wurden mit den Ln(III)-Ionen Yb3+ und Er3+ dotiert. Die Aufkonversionseffizienz, somit auch deren Quantenausbeute, konnte mit einer passivierenden Schale verbessert werden.
Dennoch leuchten die Kern-Schale-UCNPs schlechter als es im Vergleich mit μm-großen Partikeln zu erwarten wäre. Die Kern-Schale-Strukturen gehen ineinander über und sind nicht klar voneinander getrennt. Zwischen dem Kern und der Schale existiert eine Übergangsregion, die mit der Wanderung der Ionen des Wirtsgitters und den dotierten Ln(III)-Ionen einhergeht. Diese Beobachtung wird auch in der Literatur diskutiert. Die Ionenwanderung wurde mit Hilfe von zeitaufgelöster Laserspektroskopie und dem Interlanthanoidenergietransfer (LRET) in den beiden erwähnten Wirtsgittern untersucht. Die Ergebnisse sind in zwei Publikationen veröffentlicht, die auf Kern-Schale-Schale-Strukturen basieren. Der Kern ist mit dem LRET-Akzeptor dotiert (Nd3+ oder Pr3+). Die Zwischenschale besteht aus dem gleichen Wirtsgitter ohne Dotierstoffe und dient als Isolationsschale, deren Schalendicke innerhalb einer Experimentierreihe variiert wurde, um eine räumliche Trennung von LRET-Akzeptor und -Donor zu schaffen. Die äußere Schale, aus dem gleichen Wirtsgitter, ist mit dem LRET-donor (Eu3+) dotiert. Der Effekt der wachsenden Isolationsschalendicke ist signifikant. Aber es ist nicht möglich gewesen, den Energietransfer vom Donor auf den Akzeptor komplett zu unterbinden.
Neben der Untersuchung der Wanderung von Ln(III)-Ionen in einem Wirtsgitter wurden verschiedene Phasentransferreaktionen durchgeführt, um anschließende Oberflächenmodifikationen anzuwenden, damit die Anwendungen der UCNPs im biologischen Kontext prinzipiell demonstriert werden kann. Ein Ergebnis mit einem sehr vielversprechenden Liganden für die bio-medizinische Anwendung wurde in einer Publikation veröffentlicht. Dieser Ligand imitiert natürliche Mechanismen von Muschelproteinen und von Blutkoagulation, sodass die untersuchten Nanopartikel sehr effektiv eingekapselt werden. Gleichzeitig sind funktionelle Gruppen zur Bio-Funktionalisierung vorhanden. In einer Machbarkeitsstudie wurde der eingekapselte UCNP erfolgreich mit einem Farbstoff (der durch einen Biomarker ersetzt werden kann) gekoppelt und die Photolumineszenzeigenschaften des Systems untersucht.
KW  - upconversion
KW  - Aufkonversion
KW  - Nanopartikel
KW  - nanoparticle
KW  - bio-modification
KW  - Biomodification
KW  - Ionenmigration
KW  - ion migration
KW  - surface modification
KW  - Oberflächenmodifizierung
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-551607
ER  - 
TY  - THES
A1  - Flatken, Marion A.
T1  - The early stages of halide perovskites thin film formation
T1  - Die frühen Stadien der Bildung von Halogenid-Perowskit-Dünnschichten
N2  - As climate change worsens, there is a growing urgency to promote renewable energies and improve their accessibility to society. Here, solar energy harvesting is of particular importance. Currently, metal halide perovskite (MHP) solar cells are indispensable in future solar energy generation research. MHPs are crystalline semiconductors increasingly relevant as low-cost, high-performance materials for optoelectronics. Their processing from solution at low temperature enables easy fabrication of thin film elements, encompassing solar cells and light-emitting diodes or photodetectors. Understanding the coordination chemistry of MHPs in their precursor solution would allow control over the thin film crystallization, the material properties and the final device performance.
In this work, we elaborate on the key parameters to manipulate the precursor solution with the long-term objective of enabling systematic process control. We focus on the nanostructural characterization of the initial arrangements of MHPs in the precursor solutions. Small-angle scattering is particularly well suited for measuring nanoparticles in solution. This technique proved to be valuable for the direct analyzes of perovskite precursor solutions in standard processing concentrations without causing radiation damage. We gain insights into the chemical nature of widely used precursor structures such as methylammonium lead iodide (MAPbI3), presenting first insights into the complex arrangements and interaction within this precursor state. Furthermore, we transfer the preceding results to other more complex perovskite precursors. The influence of compositional engineering is investigated using the addition of alkali cations as an example. As a result, we propose a detailed working mechanism on how the alkali cations suppress the formation of intermediate phases and improve the quality of the crystalline thin film. In addition, we investigate the crystallization process of a tin-based perovskite composition (FASnI3) under the influence of fluoride chemistry. We prove that the frequently used additive, tin fluoride (SnF2), selectively binds undesired oxidized tin (Sn(IV)) in the precursor solution. This prevents its incorporation into the actual crystal structure and thus reduces the defect density of the material. Furthermore, SnF2 leads to a more homogeneous crystal growth process, which results in improved crystal quality of the thin film material.
In total, this study provides a detailed characterization of the complex system of perovskite precursor chemistry. We thereby cover relevant parameters for future MHP solar cell process control, such as (I) the environmental impact based on concentration and temperature (II) the addition of counter ions to reduce the diffuse layer surrounding the precursor nanostructures and (III) the targeted use of additives to eliminate unwanted components selectively and to ensure a more homogeneous crystal growth.
N2  - Getrieben durch den Klimawandel wächst die Dringlichkeit erneuerbare Energien zu fördern und ihre Zugänglichkeit für die Gesellschaft zu verbessern. Solarenergie ist in dieser Hinsicht von besonderer Bedeutung. Derzeit sind Metallhalogenid-Perowskit-Solarzellen ein unverzichtbarer Bestandteil der Forschung an zukünftig klimaneutraler Energiegewinnung. Metallhalogenid-Perowskite (MHP) sind kristalline Halbleiter, die als kostengünstige und leistungsstarke Materialien für die Optoelektronik zunehmend an Bedeutung gewinnen. Ihre Verarbeitung aus Flüssigkeit bei niedriger Temperatur ermöglicht eine effiziente Herstellung von Dünnschichtelementen, zu denen nicht nur Solarzellen, sondern auch Leuchtdioden oder Photodetektoren zählen. Das Verständnis der Koordinationschemie in den Vorläuferlösungen der MHPs würde es daher ermöglichen, die Kristallisation der Dünnschichten, ihre Materialeigenschaften und die finale Leistung der entsprechenden Bauelemente zu kontrollieren. In dieser Arbeit werden die wichtigsten Parameter zur systematischen Beeinflussung der Vorläuferlösung ausgearbeitet, mit dem langfristigen Ziel eine systematische Prozesskontrolle zu ermöglichen.
Dabei liegt ein Schwerpunkt auf der Anwendung einer nanostrukturellen Technik zur Charakterisierung erster Anordnungen in der Perowskit-Vorläuferlösung. Die Kleinwinkelstreuung eignet sich besonders gut zur nanostrukturellen Charakterisierung von entsprechenden Teilchen bzw. Clustern in Lösung. Mit dieser Methodik können wir auf direktem Wege Perowskit-Vorläuferlösungen in üblichen Verarbeitungs-konzentrationen analysieren. Wir erhalten Einblicke in die chemische Beschaffenheit der Vorläuferstrukturen und untersuchen zudem verschiedene Perowskit-Zusammensetzungen. Strukturelle Erkenntnisse über die Vorstufe im allgemein bekanntestem MHP, Methylammoniumbleijodid (MAPbI3) werden präsentiert und im Folgenden auf komplexere Anwendungen übertragen. Weiterhin wird der Einfluss von Kompositionsvariation am Beispiel der Zugabe von Alkali-Kationen (K, Rb, Cs) untersucht. Es wird ein detaillierter Wirkmechanismus vorgestellt, der erklärt, wie Alkali-Kationen die Bildung von Zwischenphasen unterdrücken und zudem die Qualität der kristallinen Dünnschicht verbessern.
Unter Berücksichtigung vorangehender Ergebnisse, thematisiert diese Arbeit zudem den Kristallisationsprozess einer zinnbasierten Perowskit-Zusammensetzung (FASnI3) unter dem Einfluss von Fluoridchemie. Das häufig zugesetzte Additiv, Zinnfluorid (SnF2), bindet selektiv unerwünschtes, oxidiertes Sn(IV) bereits in der Vorläuferlösung. Dieses verhindert dessen Einbau in die eigentliche Kristallstruktur und verringert so die Defektdichte des Materials. Darüber hinaus führt SnF2 zu einem homogeneren Kristallwachstumsprozess, was eine bessere Kristallqualität des Dünnschichtmaterials und somit final eine bessere Solarzellenleistung zur Folge hat.
Insgesamt bietet diese Studie eine detaillierte Charakterisierung des komplexen Systems der Perowskit-Vorläuferchemie und liefert dabei notwendige Parameter, die für die zukünftige Prozesssteuerung von Relevanz sind.
KW  - perovskite solar cells
KW  - perovskite precursors
KW  - thin film crystallization
KW  - small-angle scattering
KW  - Perowskit Solarzellen
KW  - Perowskit Vorläuferstadien
KW  - Kristallisation von Dünnschichten
KW  - Kleinwinkelstreuung
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-552599
ER  - 
TY  - JOUR
A1  - Choudhury, Arnab
A1  - DeVine, Jessalyn A. A.
A1  - Sinha, Shreya
A1  - Lau, Jascha Alexander
A1  - Kandratsenka, Alexander
A1  - Schwarzer, Dirk
A1  - Saalfrank, Peter
A1  - Wodtke, Alec Michael
T1  - Condensed-phase isomerization through tunnelling gateways
JF  - Nature : the international weekly journal of science
N2  - Quantum mechanical tunnelling describes transmission of matter waves through a barrier with height larger than the energy of the wave(1). Tunnelling becomes important when the de Broglie wavelength of the particle exceeds the barrier thickness; because wavelength increases with decreasing mass, lighter particles tunnel more efficiently than heavier ones. However, there exist examples in condensed-phase chemistry where increasing mass leads to increased tunnelling rates(2). In contrast to the textbook approach, which considers transitions between continuum states, condensed-phase reactions involve transitions between bound states of reactants and products. Here this conceptual distinction is highlighted by experimental measurements of isotopologue-specific tunnelling rates for CO rotational isomerization at an NaCl surface(3,4), showing nonmonotonic mass dependence. A quantum rate theory of isomerization is developed wherein transitions between sub-barrier reactant and product states occur through interaction with the environment. Tunnelling is fastest for specific pairs of states (gateways), the quantum mechanical details of which lead to enhanced cross-barrier coupling; the energies of these gateways arise nonsystematically, giving an erratic mass dependence. Gateways also accelerate ground-state isomerization, acting as leaky holes through the reaction barrier. This simple model provides a way to account for tunnelling in condensed-phase chemistry, and indicates that heavy-atom tunnelling may be more important than typically assumed.
Y1  - 2022
U6  - https://doi.org/10.1038/s41586-022-05451-0
SN  - 0028-0836
SN  - 1476-4687
VL  - 612
IS  - 7941
SP  - 691
EP  - 695
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Tetenoire, Auguste
A1  - Ehlert, Christopher
A1  - Juaristi, Joseba Iñaki
A1  - Saalfrank, Peter
A1  - Alducin, Maite
T1  - Why ultrafast photoinduced CO desorption dominates over oxidation on Ru(0001)
JF  - The journal of physical chemistry letters
N2  - CO oxidation on Ru(0001) is a long-standing example of a reaction that, being thermally forbidden in ultrahigh vacuum, can be activated by femtosecond laser pulses. In spite of its relevance, the precise dynamics of the photoinduced oxidation process as well as the reasons behind the dominant role of the competing CO photodesorption remain unclear. Here we use ab initio molecular dynamics with electronic friction that account for the highly excited and nonequilibrated system created by the laser to investigate both reactions. Our simulations successfully reproduce the main experimental findings: the existence of photoinduced oxidation and desorption, the large desorption to oxidation branching ratio, and the changes in the O K-edge X-ray absorption spectra attributed to the initial stage of the oxidation process. Now, we are able to monitor in detail the ultrafast CO desorption and CO oxidation occurring in the highly excited system and to disentangle what causes the unexpected inertness to the otherwise energetically favored oxidation.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpclett.2c02327
SN  - 1948-7185
VL  - 13
IS  - 36
SP  - 8516
EP  - 8521
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Picconi, David
T1  - Quantum dynamics of the photoinduced charge separation in a symmetric donor-acceptor-donor triad
BT  - the role of vibronic couplings, symmetry and temperature
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The photoinduced charge separation in a symmetric donor-acceptor-donor (D-A-D) triad is studied quantum mechanically using a realistic diabatic vibronic coupling model. The model includes a locally excited DA*D state and two charge-transfer states D(+)A(-)D and DA(-)D(+) and is constructed according to a procedure generally applicable to semirigid D-A-D structures and based on energies, forces, and force constants obtained by quantum chemical calculations. In this case, the electronic structure is described by time-dependent density functional theory, and the corrected linear response is used in conjunction with the polarizable continuum model to account for state-specific solvent effects. The multimode dynamics following the photoexcitation to the locally excited state are simulated by the hybrid Gaussian-multiconfigurational time-dependent Hartree method, and temperature effects are included using thermo field theory. The dynamics are connected to the transient absorption spectrum obtained in recent experiments, which is simulated and fully assigned from first principles. It is found that the charge separation is mediated by symmetry-breaking vibrations of relatively low frequency, which implies that temperature should be accounted for to obtain reliable estimates of the charge transfer rate.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0089887
SN  - 0021-9606
SN  - 1089-7690
VL  - 156
IS  - 18
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - THES
A1  - Nie, Yan
T1  - Modulating keratinocyte and induced pluripotent stem cell behavior by microenvironment design or temperature control
N2  - Under the in vivo condition, a cell is continually interacting with its surrounding microenvironment, which is composed of its neighboring cells and the extracellular matrix (ECM). These components generate and transmit the microenvironmental signals to regulate the fate and function of the target cells. Except the signals from the microenvironment, stimuli from the ambient environment, such as temperature changes, also play an important in modulating the cell behaviors, which are considered as regulators from the macroenvironment. In this regard, recapitulation of these environmental factors to steer cell function will be of crucial importance for therapeutic purposes and tissue regeneration. Although the role of a variety of environmental factors has been evaluated, it is still challenging to identify and provide the appropriate factors, which are required for optimizing the survival of cells and for ensuring effective cell functions.
Thus, in vitro recreating the environmental factors that are present in the extracellular environment would help to understand the mechanism of how cells sense and process those environmental signals. In this context, this thesis is aimed to harness these environmental parameters to guide cell responses. Here, human induced pluripotent stem cells (hiPSCs) and human keratinocytes (KTCs), HaCaT cells, were used to investigate the impact of signals from the microenvironment or stimuli from the macroenvironment.
Firstly, polydopamine (PDA) or chitosan (CS) modifications were applied to generate different substrate surfaces for hiPSCs and KTCs (Chapter 4 to Chapter 6). Our results showed that the PDA modification was efficient to increase the cell-substrate adhesion and consequently promoted cell spreading. While CS modification was able to decrease the cell-substrate adhesion and enhance the cell-cell interaction, which enabled the morphology shift from monolayered cells to multicellular spheroids. The quantitative result was acquired using the atomic force microscopy (AFM)-based single-cell force spectroscopy. The balance between the cell-substrate and cell-cell adhesion yielded a net force, which determined the preference of the cell to adhere to its neighboring cells or to the substrate. The difference in the adhesive behaviors further affected the cellular function, such as the proliferation and differentiation potential of both hiPSCs and HaCaT cells.
Next, the cyclic temperature changes (ΔT) were selected here to study the influence of macroenvironmental stimuli on hiPSCs and KTCs (Chapter 7 and Chapter 8). The macroenvironmental temperature ranging from 10.0 ± 0.1 °C to 37.0 ± 0.1 °C was achieved using a thermal chamber equipped with a temperature controller. This temperature range was selected to explore the responses of hiPSCs to the extreme environments, while a temperature variation between 25.0 ± 0.1 °C and 37.0 ± 0.1 °C was applied to mimic the ambient temperature variations experienced by the skin epithelial KTCs. The ΔT led to cell stiffening in both hiPSCs and HaCaT cells in a cytoskeleton-dependent manner, which was measured by AFM. Specifically, in hiPSCs, the cell stiffening was resulted from the rearrangement of the actin skeleton; in HaCaT cells, was due to the difference of the Keratin (KRT) filaments. Except for inducing cell hardening, ΔT also caused differences in the protein expression profiles in hiPSCs or HaCaT cells, compared to those without ΔT treatment, which might be attributed to the alterations in their cytoskeleton structures.
To sum up, the results of the thesis demonstrated how individual factors from the micro-/macro-environment can be harnessed to modulate the behaviors of hiPSCs and HaCaT cells. Engineering the microenvironmental cues using surface modification and exploiting the macroenvironmental stimuli through temperature control were identified as precise and potent approaches to steer hiPSC and HaCaT cell behaviors. The application of AFM served as a non-invasive and real-time monitoring platform to trace the change in cell topography and mechanics induced by the environmental signals, which provide novel insights into the cell-environment interactions.
N2  - In vivo interagiert eine Zelle ständig mit ihrer Mikroumgebung, die aus ihren Nachbarzellen und der extrazellulären Matrix (ECM) besteht. Diese Komponenten erzeugen und übertragen die Mikroumgebungssignale, um das Schicksal und die Funktion der Zielzellen zu regulieren. Außer den Signalen aus der Mikroumgebung spielen auch Reize aus der Makroumgebung, wie Temperaturänderungen, eine wichtige Rolle bei der Modulation des Zellverhaltens. In dieser Hinsicht ist es wichtig, diese Umweltfaktoren zur Steuerung der Zellfunktion für therapeutische Zwecke und die Geweberegeneration zu rekapitulieren. Es stellt sich immer noch eine Herausforderung, geeignete Faktoren zu identifizieren und bereitzustellen, die zur Optimierung des Überlebens von Zellen und zur Sicherstellung effektiver Zellfunktionen erforderlich sind.
Daher würde die in vitro-Nachbildung der Umweltfaktoren helfen, den Mechanismus zu verstehen, wie Zellen diese Umweltsignale wahrnehmen und verarbeiten. In diesem Zusammenhang zielt diese Dissertation darauf ab, diese externen Parameter zu nutzen, um Zellantworten zu steuern. Hier wurden humaninduzierte pluripotente Stammzellen (hiPSCs) und humane Keratinozyten (KTCs) wie HaCaT-Zellen verwendet, um den Einfluss von Signalen aus der Mikroumgebung oder Stimuli aus der Makroumgebung zu untersuchen.
Zunächst wurden Modifikationen mit Polydopamin (PDA) oder Chitosan (CS) angewendet, um unterschiedliche Substratoberflächen für hiPSCs und KTCs zu erzeugen (Kapitel 4 bis Kapitel 6). Unsere Ergebnisse zeigten, dass die PDA-Modifikation die Zell-Substrat-Adhäsion erhöhte und folglich die Zellausbreitung förderte. Während die CS-Modifikation die Zell-Substrat-Adhäsion verringerte und die Zell-Zell-Interaktion verstärkte, verändeite sich die Morphologie von einschichtigen Zellen zu mehrzelligen Sphäroiden. Das quantitative Ergebnis wurde mittels Rasterkraftmikroskopie (AFM)-basierter Einzelzellkraftspektroskopie gewonnen. Das Gleichgewicht zwischen Zell-Substrat und Zell-Zell-Adhäsion ergab eine Nettokraft, die die Präferenz der Zelle bestimmt, an ihren Nachbarzellen oder am Substrat zu haften. Der Unterschied im Adhäsionsverhalten beeinflusste außerdem die Zellfunktion, wie das Proliferations- und Differenzierungspotential von hiPSCs und HaCaT-Zellen.
Als nächstes wurden hier zyklische Temperaturänderungen (ΔT) ausgewählt, um den Einfluss von Stimuli aus der Makroumgebung auf hiPSCs und KTCs zu untersuchen (Kapitel 7 und Kapitel 8). Die Makroumgebungstemperatur im Bereich von 10,0 ± 0,1 °C bis 37,0 ± 0,1 °C wurde unter Verwendung einer mit einem Temperaturregler ausgestatteten Wärmekammer erreicht.
Dieser Temperaturbereich wurde gewählt, um die Reaktion von hiPSCs auf extreme Umgebungen zu untersuchen, während eine Temperaturvariation zwischen 25,0 ± 0,1 ° C und 37,0 ± 0,1 ° C angewendet wurde, um die Temperaturänderungen nachzuahmen, die die Epithelzellen erfahren. Das ΔT führte zytoskelettabhängig zu einer Zellversteifung sowohl in hiPSCs als auch in HaCaT-Zellen, die mittels AFM gemessen wurde. Insbesondere bei hiPSCs resultierte die Zellversteifung aus der Neuordnung des Aktinskeletts; in HaCaT-Zellen, war auf den Unterschied der Keratin (KRT)-Filamente zurückzuführen. Abgesehen von der festgestellten Erhärtung der Zellen verursachte ΔT auch Unterschiede in den Proteinexpressionsprofilen in hiPSCs oder HaCaT-Zellen im Vergleich zu denen ohne ΔT-Behandlung. Dies könnte auf die Veränderungen in ihren Zytoskelettstrukturen zurückgeführt werden.
Zusammenfassend zeigten die Ergebnisse, wie die drei Faktoren (PDA/CS-Modifikation und ΔT) aus der Mikro-/Makroumgebung genutzt werden können, um das Verhalten von hiPSCs und HaCaT-Zellen zu modulieren. Als präzise und wirksame Ansätze zur Steuerung des hiPSC- und HaCaT-Zellen-Verhaltens wurde das Engineering der Mikroumgebungssignale durch Oberflächenmodifikation und die Nutzung der Makroumgebungsreize durch Temperaturkontrolle identifiziert. Die Anwendung von AFM diente als nicht-invasive und Echtzeit-Überwachungsplattform, um die durch die Umweltsignale induzierten Veränderungen der Zelltopographie und -mechanik zu verfolgen, die neue Einblicke in die Zell-Umwelt-Interaktionen liefern.
KW  - human induced pluripotent stem cells
KW  - human keratinocytes
KW  - cell-environment interactions
KW  - surface modification
KW  - temperature variations
KW  - humaninduzierte pluripotente Stammzellen
KW  - humane Keratinozyten
KW  - Zell-Umwelt-Interaktionen
KW  - Oberflächenmodifikation
KW  - Temperaturänderungen
Y1  - 2022
ER  - 
TY  - JOUR
A1  - Reifarth, Martin
A1  - Bekir, Marek
A1  - Bapolisi, Alain M.
A1  - Titov, Evgenii
A1  - Nusshardt, Fabian
A1  - Nowaczyk, Julius
A1  - Grigoriev, Dmitry
A1  - Sharma, Anjali
A1  - Saalfrank, Peter
A1  - Santer, Svetlana
A1  - Hartlieb, Matthias
A1  - Böker, Alexander
T1  - A dual pH- and light-responsive spiropyrane-based surfactant
BT  - investigations on Its switching behavior and remote control over emulsion stability
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - A cationic surfactant containing a spiropyrane unit is prepared exhibiting a dual-responsive adjustability of its surface-active characteristics. The switching mechanism of the system relies on the reversible conversion of the non-ionic spiropyrane (SP) to a zwitterionic merocyanine (MC) and can be controlled by adjusting the pH value and via light, resulting in a pH-dependent photoactivity: While the compound possesses a pronounced difference in surface activity between both forms under acidic conditions, this behavior is suppressed at a neutral pH level. The underlying switching processes are investigated in detail, and a thermodynamic explanation based on a combination of theoretical and experimental results is provided. This complex stimuli-responsive behavior enables remote-control of colloidal systems. To demonstrate its applicability, the surfactant is utilized for the pH-dependent manipulation of oil-in-water emulsions.
KW  - Dual-Responsiveness
KW  - Manipulation of Emulsion Stability
KW  - Spiropyrane
KW  - Surfactant
KW  - Switchable Surfactants
KW  - pH-Dependent Photoresponsivity
Y1  - 2022
U6  - https://doi.org/10.1002/anie.202114687
SN  - 1433-7851
SN  - 1521-3773
VL  - 61
IS  - 21
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wang, Peixi
A1  - Geiger, Christina
A1  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Reitenbach, Julija
A1  - Liang, Suzhe
A1  - Cubitt, Robert
A1  - Henschel, Cristiane
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine)-based diblock copolymer thin films in water/acetone atmosphere: modulation of water hydration and co-nonsolvency-triggered film contraction
JF  - Langmuir : the ACS journal of surfaces and colloids
N2  - The water swelling and subsequent solvent exchange including co-nonsolvency behavior of thin films of a doubly thermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, and Fourier transform infrared spectroscopy. 
The DBC consists of a thermo-responsive zwitterionic (poly(4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate)) (PSBP) block, featuring an upper critical solution temperature transition in aqueous media but being insoluble in acetone, and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, featuring a lower critical solution temperature transition in water, while being soluble in acetone. 
Homogeneous DBC films of 50-100 nm thickness are first swollen in saturated water vapor (H2OorD2O), before they are subjected to a contraction process by exposure to mixed saturated water/acetone vapor (H2OorD2O/acetone-d6 = 9:1 v/v).
The affinity of the DBC film toward H2O is stronger than for D2O, as inferred from the higher film thickness in the swollen state and the higher absorbed water content, thus revealing a pronounced isotope sensitivity. 
During the co-solvent-induced switching by mixed water/acetone vapor, a two-step film contraction is observed, which is attributed to the delayed expulsion of water molecules and uptake of acetone molecules. 
The swelling kinetics are compared for both mixed vapors (H2O/acetone-d6 and D2O/acetone-d6) and with those of the related homopolymer films. 
Moreover, the concomitant variations of the local environment around the hydrophilic groups located in the PSBP and PNIPMAM blocks are followed. 
The first contraction step turns out to be dominated by the behavior of the PSBP block, where as the second one is dominated by the PNIPMAM block. 
The unusual swelling and contraction behavior of the latter block is attributed to its co-nonsolvency behavior. 
Furthermore, we observe cooperative hydration effects in the DBC films, that is, both polymer blocks influence each other's solvation behavior.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.langmuir.2c00451
SN  - 0743-7463
SN  - 1520-5827
VL  - 38
IS  - 22
SP  - 6934
EP  - 6948
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ilic, Ivan
A1  - Schutjajew, Konstantin
A1  - Zhang, Wuyong
A1  - Oschatz, Martin
T1  - Changes of porosity of hard carbons during mechanical treatment and the relevance for sodium-ion anodes
JF  - Carbon : an international journal sponsored by the American Carbon Society
N2  - Lithium-ion batteries have revolutionized battery technology. However, the scarcity of lithium in nature is driving the search for alternatives. For that reason, sodium-ion batteries have attracted increasing attention in recent years. The main obstacle to their development is the anode as, unlike for lithium-ion batteries, graphite cannot be used due to the inability to form stoichiometrically useful intercalation compounds with sodium. A promising candidate for sodium storage is hard carbon a form of nongraphitisable carbon, that can be synthesized from various precursor materials. Processing of hard carbons is often done by using mechanochemical treatments. Although it is generally accepted and often observed that they can influence the porosity of hard carbons, their effect on battery performance not well understood. Here, the changes in porosity occurring during ball milling are elucidated and related to the properties of hard carbons in sodium storage. Analysis by combined gas physisorption and small angle X-ray scattering shows that porosity changes during ball milling with a significant increase of the open porosity, unsuitable for reversible sodium storage, and decrease of the closed porosity, suitable for reversible sodium storage. While pristine hard carbon can store 58.5 mAh g(-1) in the closed pores, upon 5 h of mechanical treatment in a ball mill it can only store 35.5 mAh g(-1). The obtained results are furthermore pointing towards the disputed "intercalation-adsorption" mechanism.
KW  - Hard carbons
KW  - Sodium-ion batteries
KW  - Anodes
KW  - Microporosity
KW  - Ball milling
Y1  - 2022
U6  - https://doi.org/10.1016/j.carbon.2021.09.063
SN  - 0008-6223
SN  - 1873-3891
VL  - 186
SP  - 55
EP  - 63
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Gupta, Banshi D.
A1  - Pathak, Anisha
A1  - Shrivastav, Anand
T1  - Optical Biomedical Diagnostics Using Lab-on-Fiber Technology
BT  - a review
JF  - Photonics : open access journal
N2  - Point-of-care and in-vivo bio-diagnostic tools are the current need for the present critical scenarios in the healthcare industry. The past few decades have seen a surge in research activities related to solving the challenges associated with precise on-site bio-sensing. Cutting-edge fiber optic technology enables the interaction of light with functionalized fiber surfaces at remote locations to develop a novel, miniaturized and cost-effective lab on fiber technology for bio-sensing applications. The recent remarkable developments in the field of nanotechnology provide innumerable functionalization methodologies to develop selective bio-recognition elements for label free biosensors. These exceptional methods may be easily integrated with fiber surfaces to provide highly selective light-matter interaction depending on various transduction mechanisms. In the present review, an overview of optical fiber-based biosensors has been provided with focus on physical principles used, along with the functionalization protocols for the detection of various biological analytes to diagnose the disease. The design and performance of these biosensors in terms of operating range, selectivity, response time and limit of detection have been discussed. In the concluding remarks, the challenges associated with these biosensors and the improvement required to develop handheld devices to enable direct target detection have been highlighted.
KW  - fiber optic sensors
KW  - synthesis
KW  - interferometry
KW  - fluorescence
KW  - SERS
KW  - SPR
KW  - immunosensors
KW  - enzymatic sensors
KW  - molecular imprinted polymers
Y1  - 2022
U6  - https://doi.org/10.3390/photonics9020086
SN  - 2304-6732
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Mayer, Dennis
A1  - Picconi, David
A1  - Robinson, Matthew S.
A1  - Gühr, Markus
T1  - Experimental and theoretical gas-phase absorption spectra of thionated uracils
JF  - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
N2  - We present a comparative study of the gas-phase UV spectra of uracil and its thionated counterparts (2-thiouracil, 4-thiouracil and 2,4-dithiouracil), closely supported by time-dependent density functional theory calculations to assign the transitions observed. We systematically discuss pure gas-phase spectra for the (thio)uracils in the range of 200-400 nm (similar to 3.2-6.4 eV), and examine the spectra of all four species with a single theoretical approach. We note that specific vibrational modelling is needed to accurately determine the spectra across the examined wavelength range, and systematically model the transitions that appear at wavelengths shorter than 250 nm. Additionally, we find in the cases of 2-thiouracil and 2,4-dithiouracil, that the gas-phase spectra deviate significantly from some previously published solution-phase spectra, especially those collected in basic environments.
KW  - Thiouracil
KW  - Uracil
KW  - UV-VIS Spectroscopy
KW  - Excited-state calculations;
KW  - TD-DFT
KW  - Gas phase
Y1  - 2022
U6  - https://doi.org/10.1016/j.chemphys.2022.111500
SN  - 0301-0104
VL  - 558
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Differential sensitivity of assays for determining vein endothelial cell senescence
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - In vivo endothelialization of polymer-based cardiovascular implant materials is a promising strategy to reduce the risk of platelet adherence and the subsequent thrombus formation and implant failure. However, endothelial cells from elderly patients are likely to exhibit a senescent phenotype that may counteract endothelialization. The senescence status of cells should therefore be investigated prior to implantation of devices designed to be integrated in the blood vessel wall. Here, human umbilical vein endothelial cells (HUVEC) were cultivated up to passage (P) 4, 10 and 26/27 to determine the population doubling time and the senescence status by four different methods. Determination of the senescence-associated beta-galactosidase activity (SA-beta-Gal) was carried out by colorimetric staining and microscopy (i), as well as by photometric quantification (ii), and the expression of senescence-associated nuclear proteins p16 and p21 as well as the proliferation marker Ki67 was assessed by immunostaining (iii), and by flow cytometry (iv). The population doubling time of P27-cells was remarkably greater (103 +/- 65 h) compared to P4-cells (24 +/- 3 h) and P10-cell (37 +/- 15 h). Among the four different methods tested, the photometric SA-beta-Gal activity assay and the flow cytometric determination of p16 and Ki67 were most effective in discriminating P27-cells from P4- and P10-cells. These methods combined with functional endothelial cell analyses might aid predictions on the performance of implant endothelialization in vivo.
KW  - Ageing
KW  - population doubling time
KW  - senescence-associated
KW  - beta-galactosidase
KW  - cell cycle inhibitors
KW  - p16
KW  - p21
KW  - Ki67
Y1  - 2022
U6  - https://doi.org/10.3233/CH-211294
SN  - 1386-0291
SN  - 1875-8622
VL  - 81
IS  - 3
SP  - 191
EP  - 203
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Abdou, Nicole
A1  - Alonso, Bruno
A1  - Brun, Nicolas
A1  - Landois, Perine
A1  - Taubert, Andreas
A1  - Hesemann, Peter
A1  - Mehdi, Ahmad
T1  - Ionic guest in ionic host
BT  - ionosilica ionogel composites via ionic liquid confinement in ionosilica supports
JF  - Materials chemistry frontiers
N2  - Ionosilica ionogels, i.e. composites consisting of an ionic liquid (IL) guest confined in an ionosilica host matrix, were synthesized via a non-hydrolytic sol-gel procedure from a tris-trialcoxysilylated amine precursor using the IL [BMIM]NTf2 as solvent. Various ionosilica ionogels were prepared starting from variable volumes of IL in the presence of formic acid. The resulting brittle and nearly colourless monoliths are composed of different amounts of IL guests confined in an ionosilica host as evidenced via thermogravimetric analysis, FT-IR, and C-13 CP-MAS solid-state NMR spectroscopy. In the following, we focused on confinement effects between the ionic host and guest. Special host-guest interactions between the IL guest and the ionosilica host were evidenced by H-1 solid-state NMR, Raman spectroscopy, and broadband dielectric spectroscopy (BDS) measurements. The three techniques indicate a strongly reduced ion mobility in the ionosilica ionogel composites containing small volume fractions of confined IL, compared to conventional silica-based ionogels. We conclude that the ionic ionosilica host stabilizes an IL layer on the host surface; this then results in a strongly reduced ion mobility compared to conventional silica hosts. The ion mobility progressively increases for systems containing higher volume fractions of IL and finally reaches the values observed in conventional silica based ionogels. These results therefore point towards strong interactions and confinement effects between the ionic host and the ionic guest on the ionosilica surface. Furthermore, this approach allows confining high volume fractions of IL into self-standing monoliths while preserving high ionic conductivity. These effects may be of interest in domains where IL phases must be anchored on solid supports to avoid leaching or IL spilling, e.g., in catalysis, in gas separation/sequestration devices or for the elaboration of solid electrolytes for (lithium-ion) batteries and supercapacitors.
Y1  - 2022
U6  - https://doi.org/10.1039/d2qm00021k
SN  - 2052-1537
VL  - 6
IS  - 7
SP  - 939
EP  - 947
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Mullan, Thomas
A1  - Maschio, Lorenzo
A1  - Saalfrank, Peter
A1  - Usvyat, Denis
T1  - Reaction barriers on non-conducting surfaces beyond periodic local MP2
BT  - Diffusion of hydrogen on alpha-Al2O3 (0001) as a test case
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The quest for "chemical accuracy" is becoming more and more demanded in the field of structure and kinetics of molecules at solid surfaces. In this paper, as an example, we focus on the barrier for hydrogen diffusion on a alpha-Al2O3 (0001) surface, aiming for a couple cluster singles, doubles, and perturbative triples [CCSD(T)]-level benchmark. We employ the density functional theory (DFT) optimized minimum and transition state structures reported by Heiden, Usvyat, and Saalfrank [J. Phys. Chem. C 123, 6675 (2019)]. The barrier is first evaluated at the periodic Hartree-Fock and local Moller-Plesset second-order perturbation (MP2) level of theory. The possible sources of errors are then analyzed, which includes basis set incompleteness error, frozen core, density fitting, local approximation errors, as well as the MP2 method error. Using periodic and embedded fragment models, corrections to these errors are evaluated. In particular, two corrections are found to be non-negligible (both from the chemical accuracy perspective and at the scale of the barrier value of 0.72 eV): the correction to the frozen core-approximation of 0.06 eV and the CCSD(T) correction of 0.07 eV. Our correlated wave function results are compared to barriers obtained from DFT. Among the tested DFT functionals, the best performing for this barrier is B3LYP-D3.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0082805
SN  - 0021-9606
SN  - 1089-7690
VL  - 156
IS  - 7
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - JOUR
A1  - Yue, Yanhua
A1  - Melani, Giacomo
A1  - Kirsch, Harald
A1  - Paarmann, Alexander
A1  - Saalfrank, Peter
A1  - Campen, Richard Kramer
A1  - Tong, Yujin
T1  - Structure and Reactivity of a-Al2O3(0001) Surfaces: How Do Al-I and Gibbsite-like Terminations Interconvert?
JF  - The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis
N2  - The alpha-Al2O3(0001) surface has been extensively studied because of its significance in both fundamental research and application. Prior work suggests that in ultra-high-vacuum (UHV), in the absence of water, the so-called Al-I termination is thermodynamically favored, while in ambient, in contact with liquid water, a Gibbsite-like layer is created. While the view of the alpha- Al2O3(0001)/H2O(l) interface appears relatively clear in theory, experimental characterization of this system has resulted in estimates of surface acidity, i.e., isoelectric points, that differ by 4 pH units and surface structure that in some reports has non-hydrogen-bonded surface aluminol (Al-OH) groups and in others does not. In this study, we employed vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation to study the surface phonon modes of the differently terminated alpha-Al2O3(0001) surfaces in both UHV and ambient. We find that, on either water dosing of the Al-I in UHV or heat-induced dehydroxylation of the Gibbsite-like in ambient, the surfaces do not interconvert. This observation offers a new explanation for disagreements in prior work on the alpha-Al2O3(0001)/liquid water interface -different preparation methods may create surfaces that do not interconvert-and shows that the surface phonon spectral response offers a novel probe of interfacial hydrogen bonding structure.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.2c03743
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 31
SP  - 13467
EP  - 13476
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tarazona Lizcano, Natalia Andrea
A1  - Machatschek, Rainhard Gabriel
A1  - Balcucho, Jennifer
A1  - Castro-Mayorga, Jinneth Lorena
A1  - Saldarriaga, Juan Francisco
A1  - Lendlein, Andreas
T1  - Opportunities and challenges for integrating the development of sustainable polymer materials within an international circular (bio)economy concept
JF  - MRS energy & sustainability : science & technology & socio-economics & policy
N2  - The production and consumption of commodity polymers have been an indispensable part of the development of our modern society. Owing to their adjustable properties and variety of functions, polymer-based materials will continue playing important roles in achieving the Sustainable Development Goals (SDG)s, defined by the United Nations, in key areas such as healthcare, transport, food preservation, construction, electronics, and water management. Considering the serious environmental crisis, generated by increasing consumption of plastics, leading-edge polymers need to incorporate two types of functions: Those that directly arise from the demands of the application (e.g. selective gas and liquid permeation, actuation or charge transport) and those that enable minimization of environmental harm, e.g., through prolongation of the functional lifetime, minimization of material usage, or through predictable disintegration into non-toxic fragments. Here, we give examples of how the incorporation of a thoughtful combination of properties/functions can enhance the sustainability of plastics ranging from material design to waste management. We focus on tools to measure and reduce the negative impacts of plastics on the environment throughout their life cycle, the use of renewable sources for their synthesis, the design of biodegradable and/or recyclable materials, and the use of biotechnological strategies for enzymatic recycling of plastics that fits into a circular bioeconomy. Finally, we discuss future applications for sustainable plastics with the aim to achieve the SDGs through international cooperation. <br /> Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities.
KW  - biomaterial
KW  - degradable
KW  - functional
KW  - life cycle assessment
KW  - renewable
KW  - sustainability
Y1  - 2022
U6  - https://doi.org/10.1557/s43581-021-00015-7
SN  - 2329-2229
SN  - 2329-2237
VL  - 9
IS  - 1
SP  - 28
EP  - 34
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Halbrügge, Lena
A1  - Banerji, Amitabh
A1  - Meerholz, Klaus
T1  - Hallo Zukunft!
BT  - gedruckte Elektronik als Hands-on-Experiment für die Lehre in den Naturwissenschaften an (Hoch-)Schulen
JF  - Chemie konkret : CHEMKON ; Forum für Unterricht und Didaktik
N2  - Gedruckte Elektronik ist nicht nur ein aufstrebendes Forschungsfeld, sie wird in naher Zukunft auch eine wesentliche Rolle in unserem Alltag spielen. Gedruckte, elektronische Bauteile können sehr dünn und flexibel sein und somit vielfältig eingesetzt werden. Für die Implementation in der (Hoch-)Schule haben die Autoren eine flexible, lichtemittierende Folie entwickelt, die mit einfachen Materialien und Methoden manuell gedruckt werden kann.
N2  - Printed electronics is an emerging research field and is going to play a vital role in our everyday-life in the near future. Printed electronic devices can be very thin and flexible, which makes them feasible for various applications. For the implementation in High Schools and Universities the authors developed a flexible, light emitting foil, which can be printed manually using simple materials and methods.
T2  - Hello future! Printed electronics as a hands-on-experiment for teaching science in high schools and universities
KW  - curriculum innovation
KW  - experiment
KW  - electroluminescence
KW  - semiconductor
KW  - curriculare Innovation
KW  - Experiment
KW  - Elektrolumineszenz
KW  - Halbleiter
Y1  - 2022
U6  - https://doi.org/10.1002/ckon.202200030
SN  - 0944-5846
SN  - 1521-3730
VL  - 29
IS  - 51
SP  - 355
EP  - 361
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Stefancu, Andrei
A1  - Nan, Lin
A1  - Zhu, Li
A1  - Chis, Vasile
A1  - Bald, Ilko
A1  - Liu, Min
A1  - Leopold, Nicolae
A1  - Maier, Stefan A.
A1  - Cortes, Emiliano
T1  - Controlling plasmonic chemistry pathways through specific ion effects
JF  - Advanced optical materials
N2  - Plasmon-driven dehalogenation of brominated purines has been recently explored as a model system to understand fundamental aspects of plasmon-assisted chemical reactions. Here, it is shown that divalent Ca2+ ions strongly bridge the adsorption of bromoadenine (Br-Ade) to Ag surfaces. 
Such ion-mediated binding increases the molecule's adsorption energy leading to an overlap of the metal energy states and the molecular states, enabling the chemical interface damping (CID) of the plasmon modes of the Ag nanostructures (i.e., direct electron transfer from the metal to Br-Ade). 
Consequently, the conversion of Br-Ade to adenine almost doubles following the addition of Ca2+. 
These experimental results, supported by theoretical calculations of the local density of states of the Ag/Br-Ade complex, indicate a change of the charge transfer pathway driving the dehalogenation reaction, from Landau damping (in the lack of Ca2+ ions) to CID (after the addition of Ca2+). 
The results show that the surface dynamics of chemical species (including water molecules) play an essential role in charge transfer at plasmonic interfaces and cannot be ignored. It is envisioned that these results will help in designing more efficient nanoreactors, harnessing the full potential of plasmon-assisted chemistry.
KW  - chemical interface damping
KW  - Hofmeister effect
KW  - hydration layer
KW  - plasmonic chemistry
KW  - specific ion effects
KW  - surface-enhanced Raman scattering
Y1  - 2022
U6  - https://doi.org/10.1002/adom.202200397
SN  - 2195-1071
VL  - 10
IS  - 14
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schürmann, Robin
A1  - Titov, Evgenii
A1  - Ebel, Kenny
A1  - Kogikoski Junior, Sergio
A1  - Mostafa, Amr
A1  - Saalfrank, Peter
A1  - Milosavljević, Aleksandar R.
A1  - Bald, Ilko
T1  - The electronic structure of the metal-organic interface of isolated ligand coated gold nanoparticles
JF  - Nanoscale Advances
N2  - Light induced electron transfer reactions of molecules on the surface of noble metal nanoparticles (NPs) depend significantly on the electronic properties of the metal-organic interface. Hybridized metal-molecule states and dipoles at the interface alter the work function and facilitate or hinder electron transfer between the NPs and ligand. X-ray photoelectron spectroscopy (XPS) measurements of isolated AuNPs coated with thiolated ligands in a vacuum have been performed as a function of photon energy, and the depth dependent information of the metal-organic interface has been obtained. The role of surface dipoles in the XPS measurements of isolated ligand coated NPs is discussed and the binding energy of the Au 4f states is shifted by around 0.8 eV in the outer atomic layers of 4-nitrothiophenol coated AuNPs, facilitating electron transport towards the molecules. Moreover, the influence of the interface dipole depends significantly on the adsorbed ligand molecules. The present study paves the way towards the engineering of the electronic properties of the nanoparticle surface, which is of utmost importance for the application of plasmonic nanoparticles in the fields of heterogeneous catalysis and solar energy conversion.
Y1  - 2022
U6  - https://doi.org/10.1039/d1na00737h
SN  - 2516-0230
VL  - 4
IS  - 6
SP  - 1599
EP  - 1607
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Michaelis, Vivien
A1  - Aengenheister, Leonie
A1  - Tuchtenhagen, Max
A1  - Rinklebe, Jörg
A1  - Ebert, Franziska
A1  - Schwerdtle, Tanja
A1  - Buerki-Thurnherr, Tina
A1  - Bornhorst, Julia
T1  - Differences and interactions in placental manganese and iron transfer across an in vitro model of human villous trophoblasts
JF  - International journal of molecular sciences
N2  - Manganese (Mn) as well as iron (Fe) are essential trace elements (TE) important for the maintenance of physiological functions including fetal development. However, in the case of Mn, evidence suggests that excess levels of intrauterine Mn are associated with adverse pregnancy outcomes. Although Mn is known to cross the placenta, the fundamentals of Mn transfer kinetics and mechanisms are largely unknown. Moreover, exposure to combinations of TEs should be considered in mechanistic transfer studies, in particular for TEs expected to share similar transfer pathways. Here, we performed a mechanistic in vitro study on the placental transfer of Mn across a BeWo b30 trophoblast layer. Our data revealed distinct differences in the placental transfer of Mn and Fe. While placental permeability to Fe showed a clear inverse dose-dependency, Mn transfer was largely independent of the applied doses. Concurrent exposure of Mn and Fe revealed transfer interactions of Fe and Mn, indicating that they share common transfer mechanisms. In general, mRNA and protein expression of discussed transporters like DMT1, TfR, or FPN were only marginally altered in BeWo cells despite the different exposure scenarios highlighting that Mn transfer across the trophoblast layer likely involves a combination of active and passive transport processes.
KW  - manganese
KW  - iron
KW  - placental transfer
KW  - TE interactions
KW  - BeWo b30
KW  - trophoblasts
Y1  - 2022
U6  - https://doi.org/10.3390/ijms23063296
SN  - 1422-0067
VL  - 23
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Crovetto, Andrea
A1  - Kojda, Danny
A1  - Yi, Feng
A1  - Heinselman, Karen N.
A1  - LaVan, David A.
A1  - Habicht, Klaus
A1  - Unold, Thomas
A1  - Zakutayev, Andriy
T1  - Crystallize It before It diffuses
BT  - kinetic stabilization of thin-film phosphorus-rich semiconductor CuP2
JF  - Journal of the american chemical society
N2  - Numerous phosphorus-rich metal phosphides containing both P-P bonds and metal-P bonds are known from the solid-state chemistry literature. A method to grow these materials in thin-film form would be desirable, as thin films are required in many applications and they are an ideal platform for high-throughput studies. In addition, the high density and smooth surfaces achievable in thin films are a significant advantage for characterization of transport and optical properties. Despite these benefits, there is hardly any published work on even the simplest binary phosphorus-rich phosphide films. Here, we demonstrate growth of single-phase CuP2 films by a two-step process involving reactive sputtering of amorphous CuP2+x and rapid annealing in an inert atmosphere. At the crystallization temperature, CuP2 is thermodynamically unstable with respect to Cu3P and P-4. However, CuP2 can be stabilized if the amorphous precursors are mixed on the atomic scale and are sufficiently close to the desired composition (neither too P poor nor too P rich). Fast formation of polycrystalline CuP2, combined with a short annealing time, makes it possible to bypass the diffusion processes responsible for decomposition. We find that thin-film CuP2 is a 1.5 eV band gap semiconductor with interesting properties, such as a high optical absorption coefficient (above 10(5) cm(-1)), low thermal conductivity (1.1 W/(K m)), and composition-insensitive electrical conductivity (around 1 S/cm). We anticipate that our processing route can be extended to other phosphorus-rich phosphides that are still awaiting thin-film synthesis and will lead to a more complete understanding of these materials and of their potential applications.
Y1  - 2022
U6  - https://doi.org/10.1021/jacs.2c04868
SN  - 0002-7863
SN  - 1520-5126
VL  - 144
IS  - 29
SP  - 13334
EP  - 13343
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lepre, Enrico
A1  - Heske, Julian
A1  - Nowakowski, Michal
A1  - Scoppola, Ernesto
A1  - Zizak, Ivo
A1  - Heil, Tobias
A1  - Kühne, Thomas D.
A1  - Antonietti, Markus
A1  - Lopez-Salas, Nieves
A1  - Albero, Josep
T1  - Ni-based electrocatalysts for unconventional CO2 reduction reaction to formic acid
JF  - Nano energy
N2  - Electrochemical reduction stands as an alternative to revalorize CO2. Among the different alternatives, Ni single atoms supported on carbonaceous materials are an appealing catalytic solution due to the low cost and versatility of the support and the optimal usage of Ni and its predicted selectivity and efficiency (ca. 100% towards CO). Herein, we have used noble carbonaceous support derived from cytosine to load Ni subnanometric sites. The large heteroatom content of the support allows the stabilization of up to 11 wt% of Ni without the formation of nanoparticles through a simple impregnation plus calcination approach, where nickel promotes the stabilization of C3NOx frameworks and the oxidative support promotes a high oxidation state of nickel. EXAFS analysis points at nickel single atoms or subnanometric clusters coordinated by oxygen in the material surface. Unlike the wellknown N-coordinated Ni single sites selectivity towards CO2 reduction, O-coordinated-Ni single sites (ca. 7 wt% of Ni) reduced CO2 to CO, but subnanometric clusters (11 wt% of Ni) foster the unprecedented formation of HCOOH with 27% Faradaic efficiency at - 1.4 V. Larger Ni amounts ended up on the formation of NiO nanoparticles and almost 100% selectivity towards hydrogen evolution.
KW  - CO 2 reduction reaction
KW  - Noble carbon
KW  - Ni-O4 electrocatalysts
KW  - Formic acid
Y1  - 2022
U6  - https://doi.org/10.1016/j.nanoen.2022.107191
SN  - 2211-2855
SN  - 2211-3282
VL  - 97
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Bande, Annika
A1  - González, Leticia
A1  - Klamroth, Tillmann
A1  - Tremblay, Jean Christophe
T1  - Theoretical chemistry and quantum dynamics at interfaces
BT  - Celebrating the career of Peter Saalfrank on the occasion of his 60th birthday
T2  - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
Y1  - 2022
U6  - https://doi.org/10.1016/j.chemphys.2022.111509
SN  - 0301-0104
SN  - 1873-4421
VL  - 558
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Mei, Shilin
A1  - Siebert, Andreas
A1  - Xu, Yaolin
A1  - Quan, Ting
A1  - Garcia-Diez, Raul
A1  - Bär, Marcus
A1  - Härtel, Paul
A1  - Abendroth, Thomas
A1  - Dörfler, Susanne
A1  - Kaskel, Stefan
A1  - Lu, Yan
T1  - Large-Scale Synthesis of Nanostructured Carbon-Ti4O7 Hollow Particles as Efficient Sulfur Host Materials for Multilayer Lithium-Sulfur Pouch Cells
JF  - Batteries & supercaps
N2  - Applications of advanced cathode materials with well-designed chemical components and/or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium-sulfur (Li-S) batteries under practical working conditions, one long-term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles (Ti4O7) using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro- & mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C-Ti4O7 based pouch cell endows a high discharge capacity of 1003 mAhg(-1) at 0.05 C, a high-capacity retention of 83.7% after 100 cycles at 0.1 C, and a high Coulombic efficiency of 97.5% at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab- to large-scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li-S pouch cells.
KW  - lithium-sulfur batteries
KW  - pouch cell
KW  - spherical polyelectrolyte brushes (SPB)
KW  - Ti4O7
Y1  - 2022
U6  - https://doi.org/10.1002/batt.202100398
SN  - 2566-6223
VL  - 5
IS  - 6
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Göttlich, Richard
A1  - Graulich, Nicole
A1  - Huwer, Johannes
A1  - Banerji, Amitabh
T1  - Analog und digital
BT  - Chemieunterricht mit Potenzial
JF  - Chemie konkret : CHEMKON ; Forum für Unterricht und Didaktik
Y1  - 2022
U6  - https://doi.org/10.1002/ckon.202200046
SN  - 0944-5846
SN  - 1521-3730
VL  - 29
SP  - 182
EP  - 182
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tung, Wing Tai
A1  - Maring, Janita A.
A1  - Xu, Xun
A1  - Liu, Yue
A1  - Becker, Matthias
A1  - Somesh, Dipthi Bachamanda
A1  - Klose, Kristin
A1  - Wang, Weiwei
A1  - Sun, Xianlei
A1  - Ullah, Imran
A1  - Kratz, Karl
A1  - Neffe, Axel T.
A1  - Stamm, Christof
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - In vivo performance of a cell and factor free multifunctional fiber mesh modulating postinfarct myocardial remodeling
JF  - Advanced Functional Materials
N2  - Guidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post-MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28-32%) and increased wall thickness (854 mu m vs 400-600 mu m), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7-31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.
KW  - bioinstructive materials
KW  - cardiac regeneration
KW  - function by structure;
KW  - modulation of in vivo regeneration
KW  - multifunctional biomaterials
Y1  - 2022
U6  - https://doi.org/10.1002/adfm.202110179
SN  - 1616-301X
SN  - 1616-3028
VL  - 32
IS  - 31
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Ning, Jiaoyi
A1  - Yu, Hongtao
A1  - Mei, Shilin
A1  - Schütze, Yannik
A1  - Risse, Sebastian
A1  - Kardjilov, Nikolay
A1  - Hilger, André
A1  - Manke, Ingo
A1  - Bande, Annika
A1  - Ruiz, Victor G.
A1  - Dzubiella, Joachim
A1  - Meng, Hong
A1  - Lu, Yan
T1  - Constructing binder- and carbon additive-free organosulfur cathodes based on conducting thiol-polymers through electropolymerization for lithium-sulfur batteries
JF  - ChemSusChem
N2  - Herein, the concept of constructing binder- and carbon additive-free organosulfur cathode was proved based on thiol-containing conducting polymer poly(4-(thiophene-3-yl) benzenethiol) (PTBT). The PTBT featured the polythiophene-structure main chain as a highly conducting framework and the benzenethiol side chain to copolymerize with sulfur and form a crosslinked organosulfur polymer (namely S/PTBT). Meanwhile, it could be in-situ deposited on the current collector by electro-polymerization, making it a binder-free and free-standing cathode for Li-S batteries. The S/PTBT cathode exhibited a reversible capacity of around 870 mAh g(-1) at 0.1 C and improved cycling performance compared to the physically mixed cathode (namely S&PTBT). This multifunction cathode eliminated the influence of the additives (carbon/binder), making it suitable to be applied as a model electrode for operando analysis. Operando X-ray imaging revealed the remarkable effect in the suppression of polysulfides shuttle via introducing covalent bonds, paving the way for the study of the intrinsic mechanisms in Li-S batteries.
KW  - electrochemistry
KW  - energy storage
KW  - lithium-sulfur batteries
KW  - operando
KW  - studies
KW  - organosulfur
Y1  - 2022
U6  - https://doi.org/10.1002/cssc.202200434
SN  - 1864-5631
SN  - 1864-564X
VL  - 15
IS  - 14
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Pham, Duong Tung
A1  - Quan, Ting
A1  - Mei, Shilin
A1  - Lu, Yan
T1  - Colloidal metal sulfide nanoparticles for high performance electrochemical energy storage systems
JF  - Current opinion in green and sustainable chemistry
N2  - Transition metal sulfides have emerged as excellent replacement candidates of traditional insertion electrode materials based on their conversion or alloying mechanisms, facilitating high specific capacity and rate ability. However, parasitic reactions such as massive volume change during the discharge/ charge processes, intermediate polysulfide dissolution, and passivating solid electrolyte interface formation have led to poor cyclability, hindering their feasibility and applicability in energy storage systems. Colloidal metal sulfide nanoparticles, a special class that integrates the intrinsic chemical properties of metal sulfides and their specified structural features, have fairly enlarged their contribution due to the synergistic effect. This review highlights the latest synthetic approaches based on colloidal process. Their corresponding electrochemical outcomes will also be discussed, which are thoroughly updated along with their insight scientific standpoints.
Y1  - 2022
U6  - https://doi.org/10.1016/j.cogsc.2022.100596
SN  - 2452-2236
VL  - 34
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Xie, Dongjiu
A1  - Jouini, Oumeima
A1  - Mei, Shilin
A1  - Quan, Ting
A1  - Xu, Yaolin
A1  - Kochovski, Zdravko
A1  - Lu, Yan
T1  - Spherical polyelectrolyte brushes templated hollow C@MnO nanospheres as sulfur host materials for Li-S batteries
JF  - ChemNanoMat : Chemistry of Nanomaterials for Energy, Biology and More
N2  - Li-S battery has been considered as the next-generation energy storage device, which still suffers from the shuttle effect of lithium polysulfides (LiPSs). In this work, mesoporous hollow carbon-coated MnO nanospheres (C@MnO) have been designed and synthesized using spherical polyelectrolyte brushes (SPB) as template, KMnO4 as MnO precursor, and polydopamine as carbon source to improve the electrochemical performance of Li-S battery. The hollow C@MnO nanospheres enable the combination of physical confinement and chemical adsorption of the LiPSs. The thin carbon coating layer can provide good electrical conductivity and additional physical confinement to polysulfides. Moreover, the encapsulated MnO inside the carbon shell exhibits strong chemical adsorption to polysulfides. The constructed C@MnO/S cathode shows the discharge capacity of 1026 mAh g(-1) at 0.1 C with 79% capacity retention after 80 cycles. The synthesized hollow C@MnO nanoparticles can work as highly efficient sulfur host materials, providing an effective solution to suppress the shuttle effect in Li-S battery.
KW  - hollow nanospheres
KW  - lithium-sulfur battery
KW  - manganese monoxide
KW  - sperical
KW  - polyelectrolyte brushes
Y1  - 2022
U6  - https://doi.org/10.1002/cnma.202100455
SN  - 2199-692X
VL  - 8
IS  - 4
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Pessanha, Tatiana
A1  - Paschoalino, Waldemir J.
A1  - Deroco, Patricia B.
A1  - Kogikoski Junior, Sergio
A1  - Moraes, Ana C. M. de
A1  - Carvalho Castro de Silva, Cecilia de
A1  - Kubota, Lauro T.
T1  - Interfacial capacitance of graphene oxide films electrodes
BT  - Fundamental studies on electrolytes interface aiming (bio)sensing applications
JF  - Electroanalysis : an internatinal journal devoted to electroanalysis, sensors and bioelectronic devices
N2  - The understanding of bidimensional materials dynamics and its electrolyte interface equilibrium, such as graphene oxide (GO), is critical for the development of a capacitive biosensing platform. The interfacial capacitance (C-i) of graphene-based materials may be tuned by experimental conditions such as pH optimization and cation size playing key roles at the enhancement of their capacitive properties allowing their application as novel capacitive biosensors. Here we reported a systematic study of C-i of multilayer GO films in different aqueous electrolytes employing electrochemical impedance spectroscopy for the application in a capacitive detection system. We demonstrated that the presence of ionizable oxygen-containing functional groups within multilayer GO film favors the interactions and the accumulation of cations in the structure of the electrodes enhancing the GO C-i in aqueous solutions, where at pH 7.0 (the best condition) the C-i was 340 mu F mg(-1) at -0.01 V vs Ag/AgCl. We also established that the hydrated cation radius affects the mobility and interaction with GO functional groups and it plays a critical role in the Ci, as demonstrated in the presence of different cations Na+=640 mu F mg(-1), Li+=575 mu F mg(-1) and TMA(+)=477 mu F mg(-1). As a proof-of-concept, the capacitive behaviour of GO was explored as biosensing platform for standard streptavidin-biotin systems. For this system, the C-i varied linearly with the log of the concentration of the targeting analyte in the range from 10 pg mL(-1) to 100 ng mL(-1), showing the promising applicability of capacitive GO based sensors for label-free biosensing.
KW  - Interfacial capacitance
KW  - Graphene oxide
KW  - Functional groups
KW  - Electrochemical impedance
KW  - Graphene derivates
Y1  - 2021
U6  - https://doi.org/10.1002/elan.202100220
SN  - 1521-4109
SN  - 1040-0397
VL  - 34
IS  - 4
SP  - 692
EP  - 700
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Xu, Yaolin
A1  - Dong, Kang
A1  - Jie, Yulin
A1  - Adelhelm, Philipp
A1  - Chen, Yawei
A1  - Xu, Liang
A1  - Yu, Peiping
A1  - Kim, Junghwa
A1  - Kochovski, Zdravko
A1  - Yu, Zhilong
A1  - Li, Wanxia
A1  - LeBeau, James
A1  - Shao-Horn, Yang
A1  - Cao, Ruiguo
A1  - Jiao, Shuhong
A1  - Cheng, Tao
A1  - Manke, Ingo
A1  - Lu, Yan
T1  - Promoting mechanistic understanding of lithium deposition and solid-electrolyte interphase (SEI) formation using advanced characterization and simulation methods: recent progress, limitations, and future perspectives
JF  - Avanced energy materials
N2  - In recent years, due to its great promise in boosting the energy density of lithium batteries for future energy storage, research on the Li metal anode, as an alternative to the graphite anode in Li-ion batteries, has gained significant momentum. However, the practical use of Li metal anodes has been plagued by unstable Li (re)deposition and poor cyclability. Although tremendous efforts have been devoted to the stabilization of Li metal anodes, the mechanisms of electrochemical (re-)deposition/dissolution of Li and solid-electrolyte-interphase (SEI) formation remain elusive. This article highlights the recent mechanistic understandings and observations of Li deposition/dissolution and SEI formation achieved from advanced characterization techniques and simulation methods, and discusses major limitations and open questions in these processes. In particular, the authors provide their perspectives on advanced and emerging/potential methods for obtaining new insights into these questions. In addition, they give an outlook into cutting-edge interdisciplinary research topics for Li metal anodes. It pushes beyond the current knowledge and is expected to accelerate development toward a more in-depth and comprehensive understanding, in order to guide future research on Li metal anodes toward practical application.
KW  - advanced characterization
KW  - Li deposition
KW  - Li dissolution
KW  - Li metal
KW  - anodes
KW  - mechanistic understanding
KW  - solid-electrolyte-interphase
KW  - theoretical simulation
Y1  - 2022
U6  - https://doi.org/10.1002/aenm.202200398
SN  - 1614-6832
SN  - 1614-6840
VL  - 12
IS  - 19
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Sandmann, Michael
A1  - Münzberg, Marvin
A1  - Bressel, Lena
A1  - Reich, Oliver
A1  - Hass, Roland
T1  - Inline monitoring of high cell density cultivation of Scenedesmus rubescens in a mesh ultra-thin layer photobioreactor by photon density wave spectroscopy
JF  - BMC Research Notes / Biomed Central
N2  - Objective Due to multiple light scattering that occurs inside and between cells, quantitative optical spectroscopy in turbid biological suspensions is still a major challenge. This includes also optical inline determination of biomass in bioprocessing. Photon Density Wave (PDW) spectroscopy, a technique based on multiple light scattering, enables the independent and absolute determination of optical key parameters of concentrated cell suspensions, which allow to determine biomass during cultivation. Results A unique reactor type, called "mesh ultra-thin layer photobioreactor" was used to create a highly concentrated algal suspension. PDW spectroscopy measurements were carried out continuously in the reactor without any need of sampling or sample preparation, over 3 weeks, and with 10-min time resolution. Conventional dry matter content and coulter counter measurements have been employed as established offline reference analysis. The PBR allowed peak cell dry weight (CDW) of 33.4 g L-1. It is shown that the reduced scattering coefficient determined by PDW spectroscopy is strongly correlated with the biomass concentration in suspension and is thus suitable for process understanding. The reactor in combination with the fiber-optical measurement approach will lead to a better process management.
KW  - Photon density wave spectroscopy
KW  - Multiple light scattering
KW  - Process
KW  - analytical technology
KW  - Fiber-optical spectroscopy
KW  - Mesh ultra-thin layer
KW  - photobioreactor
Y1  - 2022
U6  - https://doi.org/10.1186/s13104-022-05943-2
SN  - 1756-0500
VL  - 15
IS  - 1
PB  - Biomed Central (London)
CY  - London
ER  -