TY - JOUR
A1 - Lau, Skadi
A1 - Liu, Yue
A1 - Maier, Anna
A1 - Braune, Steffen
A1 - Gossen, Manfred
A1 - Neffe, Axel T.
A1 - Lendlein, Andreas
T1 - Establishment of an in vitro thrombogenicity test system with cyclic olefin copolymer substrate for endothelial layer formation
JF - MRS communications / a publication of the Materials Research Society
N2 - In vitro thrombogenicity test systems require co-cultivation of endothelial cells and platelets under blood flow-like conditions. Here, a commercially available perfusion system is explored using plasma-treated cyclic olefin copolymer (COC) as a substrate for the endothelial cell layer. COC was characterized prior to endothelialization and co-cultivation with platelets under static or flow conditions. COC exhibits a low roughness and a moderate hydrophilicity. Flow promoted endothelial cell growth and prevented platelet adherence. These findings show the suitability of COC as substrate and the importance of blood flow-like conditions for the assessment of the thrombogenic risk of drugs or cardiovascular implant materials.
Y1 - 2021
U6 - https://doi.org/10.1557/s43579-021-00072-6
SN - 2159-6867
VL - 11
IS - 5
SP - 559
EP - 567
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Zhao, Yuhang
A1 - Opitz, Andreas
A1 - Eljarrat, Alberto
A1 - Kochovski, Zdravko
A1 - Koch, Christoph
A1 - Koch, Norbert
A1 - Lu, Yan
T1 - Kinetic study on the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane on Ag nanoparticles in chloroform
BT - implications for the charge transfer complex of Ag-F(4)TCNQ
JF - ACS applied nano materials
N2 - In this study, the kinetics of the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ) on the surface of Ag nanoparticles (Ag NPs) in chloroform has been intensively investigated, as molecular doping is known to play a crucial role in organic electronic devices. Based on the results obtained from UV-visible (vis)-near-infrared (NIR) absorption spectroscopy, cryogenic transmission electron microscopy, scanning nanobeam electron diffraction, and electron energy loss spectroscopy, a two-step interaction kinetics has been proposed for the Ag NPs and F(4)TCNQ molecules, which includes the first step of electron transfer from Ag NPs to F(4)TCNQ indicated by the ionization of F(4)TCNQ and the second step of the formation of a Ag-F(4)TCNQ complex. The whole process has been followed via UV-vis-NIR absorption spectroscopy, which reveals distinct kinetics at two stages: the instantaneous ionization and the long-term complex formation. The kinetics and the influence of the molar ratio of Ag NPs/F(4)TCNQ molecules on the interaction between Ag NPs and F(4)TCNQ molecules in an organic solution are reported herein for the first time. Furthermore, the control experiment with silica-coated Ag NPs manifests that the charge transfer at the surface between Ag NPs and F(4)TCNQ molecules is prohibited by a silica layer of 18 nm.
KW - Ag nanoparticles
KW - F(4)TCNQ
KW - phase transfer
KW - kinetics
KW - electron transfer
KW - surface interaction
Y1 - 2021
U6 - https://doi.org/10.1021/acsanm.1c02153
SN - 2574-0970
VL - 4
IS - 11
SP - 11625
EP - 11635
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Xu, Xun
A1 - Nie, Yan
A1 - Wang, Weiwei
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - Periodic thermomechanical modulation of toll-like receptor expression and distribution in mesenchymal stromal cells
JF - MRS communications / a publication of the Materials Research Society
N2 - Toll-like receptor (TLR) can trigger an immune response against virus including SARS-CoV-2. TLR expression/distribution is varying in mesenchymal stromal cells (MSCs) depending on their culture environments. Here, to explore the effect of periodic thermomechanical cues on TLRs, thermally controlled shape-memory polymer sheets with programmable actuation capacity were created. The proportion of MSCs expressing SARS-CoV-2-associated TLRs was increased upon stimulation. The TLR4/7 colocalization was promoted and retained in the endoplasmic reticula. The TLR redistribution was driven by myosin-mediated F-actin assembly. These results highlight the potential of boosting the immunity for combating COVID-19 via thermomechanical preconditioning of MSCs.
KW - Actuation
KW - Antiviral
KW - Biomaterial
KW - COVID-19
KW - Shape memory
Y1 - 2021
U6 - https://doi.org/10.1557/s43579-021-00049-5
SN - 2159-6859
SN - 2159-6867
VL - 11
IS - 4
SP - 425
EP - 431
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Saeedi Garakani, Sadaf
A1 - Xie, Dongjiu
A1 - Khorsand Kheirabad, Atefeh
A1 - Lu, Yan
A1 - Yuan, Jiayin
T1 - Template-synthesis of a poly(ionic liquid)-derived Fe1-xS/nitrogen-doped porous carbon membrane and its electrode application in lithium-sulfur batteries
JF - Materials advances
N2 - This study deals with the facile synthesis of Fe1-xS nanoparticle-containing nitrogen-doped porous carbon membranes (denoted as Fe1-xS/N-PCMs) via vacuum carbonization of hybrid porous poly(ionic liquid) (PIL) membranes, and their successful use as a sulfur host material to mitigate the shuttle effect in lithium-sulfur (Li-S) batteries. The hybrid porous PIL membranes as the sacrificial template were prepared via ionic crosslinking of a cationic PIL with base-neutralized 1,1 '-ferrocenedicarboxylic acid, so that the iron source was molecularly incorporated into the template. The carbonization process was investigated in detail at different temperatures, and the chemical and porous structures of the carbon products were comprehensively analyzed. The Fe1-xS/N-PCMs prepared at 900 degrees C have a multimodal pore size distribution with a satisfactorily high surface area and well-dispersed iron sulfide nanoparticles to physically and chemically confine the LiPSs. The sulfur/Fe1-xS/N-PCM composites were then tested as electrodes in Li-S batteries, showing much improved capacity, rate performance and cycle stability, in comparison to iron sulfide-free, nitrogen-doped porous carbon membranes.
Y1 - 2021
U6 - https://doi.org/10.1039/d1ma00441g
SN - 2633-5409
VL - 2
IS - 15
SP - 5203
EP - 5212
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Melani, Giacomo
A1 - Nagata, Yuki
A1 - Saalfrank, Peter
T1 - Vibrational energy relaxation of interfacial OH on a water-covered alpha-Al2O3(0001) surface
BT - a non-equilibrium ab initio molecular dynamics study
JF - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2 - Vibrational relaxation of adsorbates is a sensitive tool to probe energy transfer at gas/solid and liquid/solid interfaces. The most direct way to study relaxation dynamics uses time-resolved spectroscopy. Here we report on a non-equilibrium ab initio molecular dynamics (NE-AIMD) methodology to model vibrational relaxation of OH vibrations on a hydroxylated, water-covered alpha-Al2O3(0001) surface. In our NE-AIMD approach, after exciting selected O-H bonds their coupling to surface phonons and to the water adlayer is analyzed in detail, by following both the energy flow in time, as well as the time-evolution of Vibrational Density of States (VDOS) curves. The latter are obtained from Time-dependent Correlation Functions (TCFs) and serve as prototypical, generic representatives of time-resolved vibrational spectra. As most important results, (i) we find a few-picosecond lifetime of the excited modes and (ii) identify both hydrogen-bonded aluminols and water molecules in the adsorbed water layer as main dissipative channels, while the direct coupling to Al2O3 surface phonons is of minor importance on the timescales of interest. Our NE-AIMD/TCF methodology is powerful for complex adsorbate systems, in principle even reacting ones, and opens a way towards time-resolved vibrational spectroscopy.
Y1 - 2021
U6 - https://doi.org/10.1039/d0cp03777j
SN - 1463-9076
SN - 1463-9084
VL - 23
IS - 13
SP - 7714
EP - 7723
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Wang, Zhenyu
A1 - Fritsch, Daniel
A1 - Berendts, Stefan
A1 - Lerch, Martin
A1 - Breternitz, Joachim
A1 - Schorr, Susan
T1 - Elucidation of the reaction mechanism for the synthesis of ZnGeN2 through Zn2GeO4 ammonolysis
JF - Chemical science / RSC, Royal Society of Chemistry
N2 - Ternary II-IV-N-2 materials have been considered as a promising class of materials that combine photovoltaic performance with earth-abundance and low toxicity. When switching from binary III-V materials to ternary II-IV-N-2 materials, further structural complexity is added to the system that may influence its optoelectronic properties. Herein, we present a systematic study of the reaction of Zn2GeO4 with NH3 that produces zinc germanium oxide nitrides, and ultimately approach stoichiometric ZnGeN2, using a combination of chemical analyses, X-ray powder diffraction and DFT calculations. Elucidating the reaction mechanism as being dominated by Zn and O extrusion at the later reaction stages, we give an insight into studying structure-property relationships in this emerging class of materials.
Y1 - 2021
U6 - https://doi.org/10.1039/d1sc00328c
SN - 2041-6539
VL - 12
IS - 24
SP - 8493
EP - 8500
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Nicolai, Merle Marie
A1 - Weishaupt, Ann-Kathrin
A1 - Baesler, Jessica
A1 - Brinkmann, Vanessa
A1 - Wellenberg, Anna
A1 - Winkelbeiner, Nicola Lisa
A1 - Gremme, Anna
A1 - Aschner, Michael
A1 - Fritz, Gerhard
A1 - Schwerdtle, Tanja
A1 - Bornhorst, Julia
T1 - Effects of manganese on genomic integrity in the multicellular model organism Caenorhabditis elegans
JF - International Journal of Molecular Sciences
N2 - Although manganese (Mn) is an essential trace element, overexposure is associated with Mn-induced toxicity and neurological dysfunction. Even though Mn-induced oxidative stress is discussed extensively, neither the underlying mechanisms of the potential consequences of Mn-induced oxidative stress on DNA damage and DNA repair, nor the possibly resulting toxicity are characterized yet. In this study, we use the model organism Caenorhabditis elegans to investigate the mode of action of Mn toxicity, focusing on genomic integrity by means of DNA damage and DNA damage response. Experiments were conducted to analyze Mn bioavailability, lethality, and induction of DNA damage. Different deletion mutant strains were then used to investigate the role of base excision repair (BER) and dePARylation (DNA damage response) proteins in Mn-induced toxicity. The results indicate a dose- and time-dependent uptake of Mn, resulting in increased lethality. Excessive exposure to Mn decreases genomic integrity and activates BER. Altogether, this study characterizes the consequences of Mn exposure on genomic integrity and therefore broadens the molecular understanding of pathways underlying Mn-induced toxicity. Additionally, studying the basal poly(ADP-ribosylation) (PARylation) of worms lacking poly(ADP-ribose) glycohydrolase (PARG) parg-1 or parg-2 (two orthologue of PARG), indicates that parg-1 accounts for most of the glycohydrolase activity in worms.
KW - manganese
KW - oxidative stress
KW - DNA repair
KW - DNA damage response
KW - Caenorhabditis elegans
Y1 - 2021
U6 - https://doi.org/10.3390/ijms222010905
SN - 1422-0067
VL - 22
IS - 20
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Geiger, Christina
A1 - Reitenbach, Julija
A1 - Henschel, Cristiane
A1 - Kreuzer, Lucas
A1 - Widmann, Tobias
A1 - Wang, Peixi
A1 - Mangiapia, Gaetano
A1 - Moulin, Jean-François
A1 - Papadakis, Christine M.
A1 - Laschewsky, André
A1 - Müller-Buschbaum, Peter
T1 - Ternary nanoswitches realized with multiresponsive PMMA-b-PNIPMAM films in mixed water/acetone vapor atmospheres
JF - Advanced engineering materials
N2 - To systematically add functionality to nanoscale polymer switches, an understanding of their responsive behavior is crucial. Herein, solvent vapor stimuli are applied to thin films of a diblock copolymer consisting of a short poly(methyl methacrylate) (PMMA) block and a long poly(N-isopropylmethacrylamide) (PNIPMAM) block for realizing ternary nanoswitches. Three significantly distinct film states are successfully implemented by the combination of amphiphilicity and co-nonsolvency effect. The exposure of the thin films to nitrogen, pure water vapor, and mixed water/acetone (90 vol%/10 vol%) vapor switches the films from a dried to a hydrated (solvated and swollen) and a water/acetone-exchanged (solvated and contracted) equilibrium state. These three states have distinctly different film thicknesses and solvent contents, which act as switch positions "off," "on," and "standby." For understanding the switching process, time-of-flight neutron reflectometry (ToF-NR) and spectral reflectance (SR) studies of the swelling and dehydration process are complemented by information on the local solvation of functional groups probed with Fourier-transform infrared (FTIR) spectroscopy. An accelerated responsive behavior beyond a minimum hydration/solvation level is attributed to the fast build-up and depletion of the hydration shell of PNIPMAM, caused by its hydrophobic moieties promoting a cooperative hydration character.
KW - co-nonsolvency
KW - diblock copolymers
KW - nanoswitches
KW - neutron reflectometry
KW - thin films
Y1 - 2021
U6 - https://doi.org/10.1002/adem.202100191
SN - 1438-1656
SN - 1527-2648
VL - 23
IS - 11
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Quan, Ting
A1 - Haerk, Eneli
A1 - Xu, Yaolin
A1 - Ahmet, Ibbi
A1 - Höhn, Christian
A1 - Mei, Shilin
A1 - Lu, Yan
T1 - Unveiling the formation of solid electrolyte interphase and its temperature dependence in "Water-in-Salt" supercapacitors
JF - ACS applied materials & interfaces
N2 - "Water-in-salt" (WIS) electrolytes have emerged as an excellent superconcentrated ionic medium for high-power energy storage systems such as supercapacitors due to their extended working potential compared to the conventional dilute aqueous electrolyte. In this work, we have investigated the performance of WIS supercapacitors using hollow carbon nanoplates as electrodes and compared it to that based on the conventional "salt-in-water" electrolytes. Moreover, the potentiostatic electrochemical impedance spectroscopy has been employed to provide an insightful look into the charge transport properties, which also, for the first time, reveals the formation of a solid-electrolyte interphase (SEI and their temperature-dependent impedance for charge transfer and adsorption. Furthermore, the effect of temperature on the electrochemical performance of the WIS supercapacitors in the temperature range from 15 to 60 degrees C has been studied, which presents a gravimetric capacitance of 128 F g(-1) and a volumetric capacitance of 197.12 F cm(-3) at 55 degrees C compared to 87.5 F g(-1) and 134.75 F cm(-3) at 15 degrees C. The in-depth understanding about the formation of SEI layer and the electrochemical performance at different temperatures for WIS supercapacitors will assist the efforts toward designing better aqueous electrolytes for supercapacitors.
KW - "water-in-salt"
KW - supercapacitor
KW - solid electrolyte interphase
KW - electrochemical impedance spectroscopy
KW - temperature effect
Y1 - 2021
U6 - https://doi.org/10.1021/acsami.0c19506
SN - 1944-8244
SN - 1944-8252
VL - 13
IS - 3
SP - 3979
EP - 3990
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Schlappa, Stephanie
A1 - Brenker, Lee Josephine
A1 - Bressel, Lena
A1 - Hass, Roland
A1 - Münzberg, Marvin
T1 - Process characterization of polyvinyl acetate emulsions applying inline photon density wave spectroscopy at high solid contents
JF - Polymers / Molecular Diversity Preservation International
N2 - The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (>40% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved-feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.
KW - photon density wave spectroscopy
KW - multiple light scattering
KW - emulsion
KW - polymerization
KW - process analytical technology
KW - polyvinyl acetate
Y1 - 2021
U6 - https://doi.org/10.3390/polym13040669
SN - 2073-4360
VL - 13
IS - 4
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Koch, Andreas
T1 - Intramolecular carbene stabilization via 3c,2e bonding on basis of the magnetic criterion
JF - Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry
N2 - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of bent cyclobutylcarbene 8, 1,2-diboretane-3-ylidene 9, and some carbene analogues of boron 14-18 as most intriguing examples of carbenes, which can be stabilized as homoaromatic systems with 3c,2e bonding, have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values (actually, ring current effect/anisotropy effects as measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the degree of present 3c,2e-homoaromaticity. Results are confirmed by geometry (bond angles and bond lengths) and spectroscopic data, the delta(B-11)/ppm data and the C-13 chemical shifts of the carbene electron-deficient centre.
KW - Cyclobutylcarbene
KW - 1,2-diboretane-3-ylidene
KW - 3c,2e-bonding
KW - Through-space NMR shieldings (TSNMRS)
KW - NICS
Y1 - 2021
U6 - https://doi.org/10.1016/j.tet.2021.132357
SN - 0040-4020
SN - 1464-5416
VL - 95
PB - Elsevier Science
CY - Amsterdam
ER -
TY - JOUR
A1 - Buyinza, Daniel
A1 - Derese, Solomon
A1 - Ndakala, Albert
A1 - Heydenreich, Matthias
A1 - Yenesew, Abiy
A1 - Koch, Andreas
A1 - Oriko, Richard
T1 - A coumestan and a coumaronochromone from Millettia lasiantha
JF - Biochemical systematics and ecology
N2 - The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and las-coumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.
KW - Millettia lasiantha
KW - Leguminosae
KW - Coumestan
KW - Coumaronochromone
Y1 - 2021
U6 - https://doi.org/10.1016/j.bse.2021.104277
SN - 0305-1978
SN - 1873-2925
VL - 97
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Koch, Andreas
T1 - Dative or coordinative carbon-boron bond in boron trapped N-heterocyclic carbenes (NHCs)?
BT - an answer given on the magnetic criterion
JF - Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry
N2 - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of isolated as well as B-C bond length varied model compounds (BR3 trapped NHCs) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the present dative vs. coordinative bond character of the boron-carbon bond in the trapped NHCs. Results are confirmed by bond lengths and B-11/C-13 chemical shift variations in the BR3 trapped NHCs.
KW - NHCs
KW - Dative vs. coordinative NHC -> BR3 bond
KW - Through-space NMR
KW - shieldings (TSNMRS)
KW - NICS
KW - Anisotropy effect
Y1 - 2021
U6 - https://doi.org/10.1016/j.tet.2020.131787
SN - 0040-4020
SN - 1464-5416
VL - 80
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Koch, Andreas
T1 - Quantification of sigma-acceptor and pi-donor stabilization in O, S and Hal analogues of N-heterocyclic carbenes (NHCs) on the magnetic criterion
JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2 - The spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of stable O, S and Hal analogues of N-heterocyclic carbenes (NHCs) have been calculated using the GIAO perturbation method employing the nucleus-independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSSs) of various sizes and directions. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the position of the present mesomeric equilibria (carbenes <-> ylides). The results are confirmed by geometry (bond angles and bond lengths), IR spectra, UV spectra, and C-13 chemical shifts of the electron-deficient carbon centers.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.jpca.1c05257
SN - 1089-5639
SN - 1520-5215
VL - 125
IS - 33
SP - 7235
EP - 7245
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Heydenreich, Matthias
A1 - Shainyan, Bagrat A.
T1 - At the experimental limit of the NMR conformational analysis
BT - Si-29 and C-13 NMR study of the conformational equilibrium of 1-phenyl-1-tert-butylsilacyclohexane
JF - Organic letters
N2 - The low temperature (95 K) NMR study of 1-Ph-1-t-Bu-silacyclohexane (1) showed the conformational equilibrium to be extremely one-sided toward thePh(ax),t-Bueq conformer. The barrier to interconversion has been measured (4.2-4.6 kcal/mol) and the conformational equilibrium [Delta nu = 1990.64 ppm (Si-29), 618.9 ppm (C-13), 1-Ph-ax:1-Pheq = (95.6-96.6%):(3.4-4.4%), K = 25 +/- 3, Delta G degrees = -RT ln K = 0.58-0.63 kcal/mol] analyzed. The assignment and quantification of the NMR signals is supported by MP2 and DFT calculations.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.orglett.0c03878
SN - 1523-7060
SN - 1523-7052
VL - 23
IS - 2
SP - 405
EP - 409
PB - American Chemical Society
CY - Washington
ER -
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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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.
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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 - 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 - 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 - 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.
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 - 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 -
TY - JOUR
A1 - Mayer, Dennis
A1 - Lever, Fabiano
A1 - Picconi, David
A1 - Metje, Jan
A1 - Ališauskas, Skirmantas
A1 - Calegari, Francesca
A1 - Düsterer, Stefan
A1 - Ehlert, Christopher
A1 - Feifel, Raimund
A1 - Niebuhr, Mario
A1 - Manschwetus, Bastian
A1 - Kuhlmann, Marion
A1 - Mazza, Tommaso
A1 - Robinson, Matthew Scott
A1 - Squibb, Richard J.
A1 - Trabattoni, Andrea
A1 - Wallner, Måns
A1 - Saalfrank, Peter
A1 - Wolf, Thomas J. A.
A1 - Gühr, Markus
T1 - Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy
JF - Nature communications
N2 - Imaging the charge flow in photoexcited molecules would provide key information on photophysical and photochemical processes. Here the authors demonstrate tracking in real time after photoexcitation the change in charge density at a specific site of 2-thiouracil using time-resolved X-ray photoelectron spectroscopy. The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220-250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.
Y1 - 2022
U6 - https://doi.org/10.1038/s41467-021-27908-y
SN - 2041-1723
N1 - Publisher correction: https://doi.org/10.1038/s41467-022-28584-2
VL - 13
IS - 1
PB - Nature Research
CY - Berlin
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Koch, Andreas
T1 - Cyclazines-structure and aromaticity or antiaromaticity on the magnetic criterion
JF - European journal of organic chemistry
N2 - Structure and spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of all ten cycl[2.2.2]azine to cycl[4.4.4]azine, hetero-analogues and the corresponding hydrocarbons have been calculated at the B3LYP/6-311G(d,p) theory level using the GIAO perturbation method and employing the nucleus independent chemical shift (NICS) concept. The TSNMRS values (actually, the ring current effect as measurable in H-1 NMR spectroscopy) are visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction, and employed to readily qualify and quantify the degree of (anti)aromaticity. Results are confirmed by NMR [delta(H-1)/ppm, delta(N-15)/ppm] and geometry (planar, twisted, bow-shaped) data. The cyclazines N[2.2.2](-) up to N[2.4.4](-) are planar or at most slightly bowl-shaped and, due to coherent peripheral ring currents (except in N[2.3.3](-), N[2.3.4], N[3.3.4](+) and N[2.4.4](+)), develop aromaticity or anti-aromaticity of the whole molecules dependent on the number of peripheral conjugated pi electrons. The cyclazines N[2.3.3](-), N[2.3.4], N[3.3.4](+) and N[2.4.4](+) develop two ring currents of different direction within the same molecule, in which the dominating ring current proves to be paratropic (in N[3.3.4](+) diatropic) including the nodal N p(z) lone pair into the conjugation. The residual cyclazines N[3.4.4], N[4.4.4](-) and N[4.4.4](+) are heavily twisted and, therefore, are not developing peripheral or diverse ring currents. The TSNMRS information about cyclazines and the parent tricyclic annulene analogues is congruent subject to structure and number of peripheral or internal conjugated pi electrons, the corresponding (anti)aromaticity is in unequivocal accordance with Huckel's rule.
KW - Aromaticity
KW - Cyclazines
KW - NMR spectroscopy
KW - Peripheral ring current
Y1 - 2022
U6 - https://doi.org/10.1002/ejoc.202101362
SN - 1434-193X
SN - 1099-0690
VL - 2022
IS - 8
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Neusser, David
A1 - Sun, Bowen
A1 - Tan, Wen Liang
A1 - Thomsen, Lars
A1 - Schultz, Thorsten
A1 - Perdigon-Toro, Lorena
A1 - Koch, Norbert
A1 - Shoaee, Safa
A1 - McNeill, Christopher R.
A1 - Neher, Dieter
A1 - Ludwigs, Sabine
T1 - Spectroelectrochemically determined energy levels of PM6:Y6 blends and their relevance to solar cell performance
JF - Journal of materials chemistry : C, Materials for optical and electronic devices
N2 - Recent advances in organic solar cell performance have been mainly driven forward by combining high-performance p-type donor-acceptor copolymers (e.g.PM6) and non-fullerene small molecule acceptors (e.g.Y6) as bulk-heterojunction layers. A general observation in such devices is that the device performance, e.g., the open-circuit voltage, is strongly dependent on the processing solvent. While the morphology is a typically named key parameter, the energetics of donor-acceptor blends are equally important, but less straightforward to access in the active multicomponent layer. Here, we propose to use spectral onsets during electrochemical cycling in a systematic spectroelectrochemical study of blend films to access the redox behavior and the frontier orbital energy levels of the individual compounds. Our study reveals that the highest occupied molecular orbital offset (Delta E-HOMO) in PM6:Y6 blends is similar to 0.3 eV, which is comparable to the binding energy of Y6 excitons and therefore implies a nearly zero driving force for the dissociation of Y6 excitons. Switching the PM6 orientation in the blend films from face-on to edge-on in bulk has only a minor influence on the positions of the energy levels, but shows significant differences in the open circuit voltage of the device. We explain this phenomenon by the different interfacial molecular orientations, which are known to affect the non-radiative decay rate of the charge-transfer state. We compare our results to ultraviolet photoelectron spectroscopy data, which shows distinct differences in the HOMO offsets in the PM6:Y6 blend compared to neat films. This highlights the necessity to measure the energy levels of the individual compounds in device-relevant blend films.
Y1 - 2022
U6 - https://doi.org/10.1039/d2tc01918c
SN - 2050-7526
SN - 2050-7534
VL - 10
IS - 32
SP - 11565
EP - 11578
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Brinkmann, Pia
A1 - Köllner, Nicole
A1 - Merk, Sven
A1 - Beitz, Toralf
A1 - Altenberger, Uwe
A1 - Löhmannsröben, Hans-Gerd
T1 - Comparison of handheld and echelle spectrometer to assess copper in ores by means of laser-induced breakdown spectroscopy (LIBS)
JF - Minerals
N2 - Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A promising technique to perform these tasks is Laser Induced Breakdown Spectroscopy (LIBS). Its unique feature, among others, is the ability to measure on site without sample collection and preparation. In this work, copper-bearing minerals from two different deposits are studied. The first set of field samples come from a volcanogenic massive sulfide (VMS) deposit, the second part from a stratiform sedimentary copper (SSC) deposit. Different approaches are used to analyze the data. First, univariate regression (UVR) is used. However, due to the strong influence of matrix effects, this is not suitable for the quantitative analysis of copper grades. Second, the multivariate method of partial least squares regression (PLSR) is used, which is more suitable for quantification. In addition, the effects of the surrounding matrices on the LIBS data are characterized by principal component analysis (PCA), alternative regression methods to PLSR are tested and the PLSR calibration is validated using field samples.
KW - LIBS
KW - copper-bearing minerals
KW - UVR
KW - PCA
KW - PLSR
Y1 - 2023
U6 - https://doi.org/10.3390/min13010113
SN - 2075-163X
VL - 13
IS - 1
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Dettmann, Sophie
A1 - Huittinen, Nina Maria
A1 - Nicolas, Jahn
A1 - Kretzschmar, Jerome
A1 - Kumke, Michael
A1 - Kutyma, Tamara
A1 - Lohmann, Janik
A1 - Reich, Tobias
A1 - Schmeide, Katja
A1 - Azzam, Salim Shams Aldin
A1 - Spittler, Leon
A1 - Stietz, Janina
T1 - Influence of gluconate on the retention of Eu(III), Am(III), Th(IV), Pu(IV), and U(VI) by C-S-H (C/S = 0.8)
JF - Frontiers in Nuclear Engineering
N2 - The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. ¹³C and ²⁹Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10⁻² M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.
KW - actinide
KW - organic ligand
KW - sorption
KW - cementitious material
KW - concrete
KW - luminescence
Y1 - 2023
U6 - https://doi.org/10.3389/fnuen.2023.1124856
SN - 2813-3412
VL - 2
PB - Frontiers Media
CY - Lausanne
ER -
TY - JOUR
A1 - Sperlich, Eric
A1 - Köckerling, Martin
T1 - The double cluster compound [Nb6Cl14(MeCN)(4)] [Nb6Cl14(pyz)(4)].6MeCN (Me: methyl, pyz: pyrazine) with a layered structure resulting from weak intermolecular interactions
JF - Zeitschrift für Naturforschung
N2 - The synthesis and the crystal structure of the double cluster compound [Nb6Cl14(MeCN)(4)][Nb6Cl14(pyz)(4)]middot6CH(3)CN are described. The synthesis is based on a partial ligand exchange reaction, which proceeds upon dissolving [Nb6Cl14(pyz)(4)]middot2CH(2)Cl(2) in acetonitrile. The compound is built up of two discrete neutral cluster units, which consist of octahedra of Nb-6 atoms coordinated by 12 edge-bridging chlorido and two terminal chlorido ligands, and four acetonitrile ligands on one and four pyrazine ligands on the other cluster unit. Co-crystallized acetonitrile molecules are also present. The single-crystal structure determination has revealed a cluster arrangement in which the [Nb6Cl14(pyz)(4)] units are connected by (halogen) lone-pair-(pyrazine) pi interactions. These lead to chains of [Nb6Cl14(pyz)(4)] clusters. These chains are further connected to cluster layers by (nitrile-halogen) dipole-dipole interactions, in which the [Nb6Cl14(MeCN)(4)] and co-crystallized MeCN molecules are also involved. These cluster layers are arranged parallel to the crystallographic {011} plane.
KW - cluster
KW - crystal structure
KW - dipole-dipole interaction
KW - halide
KW - lone-pair-pi interactions
KW - niobium
Y1 - 2023
U6 - https://doi.org/10.1515/znb-2023-0001
SN - 0932-0776
SN - 1865-7117
VL - 78
IS - 5
SP - 279
EP - 283
PB - De Gruyter
CY - Berlin
ER -
TY - JOUR
A1 - Akampurira, Denis
A1 - Akala, Hoseah M.
A1 - Derese, Solomon
A1 - Heydenreich, Matthias
A1 - Yenesew, Abiy
T1 - A new C-C linked benzophenathridine-2-quinoline dimer, and the antiplasmodial activity of alkaloids from Zanthoxylum holstzianum
JF - Natural product research
N2 - The CH2Cl2/MeOH (1:1) extract of Zanthoxylum holstzianum stem bark showed good antiplasmodial activity (IC50 2.5 +/- 0.3 and 2.6 +/- 0.3 mu g/mL against the W2 and D6 strains of Plasmodium falciparum, respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (1), nitidine (2), dihydrochelerythine (3), norchelerythrine (5), arnottianamide (8)]; a 2-quinolone alkaloid [N-methylflindersine (4)]; a lignan [4,4 '-dihydroxy-3,3 '-dimethoxylignan-9,9 '-diyl diacetate (7)] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline (6)] were isolated. The CH2Cl2/MeOH (1:1) extract of the root bark afforded 1, 3-6, 8, chelerythridimerine (9) and 9-demethyloxychelerythrine (10). Holstzianoquinoline (6) is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds (1-5) tested against two strains of P. falciparum, nitidine (IC50 0.11 +/- 0.01 mu g/mL against W2 and D6 strains) and norchelerythrine (IC50 value of 0.15 +/- 0.01 mu g/mL against D6 strain) were the most active.
KW - Antiplasmodial
KW - benzophenanthridine alkaloid
KW - holstzianoquinoline;
KW - rutaceae
KW - Zanthoxylum holstzianum
Y1 - 2022
U6 - https://doi.org/10.1080/14786419.2022.2034810
SN - 1478-6419
SN - 1478-6427
VL - 37
IS - 13
SP - 2161
EP - 2171
PB - Taylor & Francis
CY - London [u.a.]
ER -
TY - JOUR
A1 - Hu, Neng
A1 - Lin, Li
A1 - Metwalli, Ezzeldin
A1 - Bießmann, Lorenz
A1 - Philipp, Martine
A1 - Hildebrand, Viet
A1 - Laschewsky, André
A1 - Papadakis, Christine M.
A1 - Cubitt, Robert
A1 - Zhong, Qi
A1 - Müller-Buschbaum, Peter
T1 - Kinetics of water transfer between the LCST and UCST thermoresponsive blocks in diblock copolymer thin films monitored by in situ neutron reflectivity
JF - Advanced materials interfaces
N2 - The kinetics of water transfer between the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) thermoresponsive blocks in about 10 nm thin films of a diblock copolymer is monitored by in situ neutron reflectivity. The UCST-exhibiting block in the copolymer consists of the zwitterionic poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate), abbreviated as PSBP. The LCST-exhibiting block consists of the nonionic poly(N-isopropylacrylamide), abbreviated as PNIPAM. The as-prepared PSBP80-b-PNIPAM(400) films feature a three-layer structure, i.e., PNIPAM, mixed PNIPAM and PSBP, and PSBP. Both blocks have similar transition temperatures (TTs), namely around 32 degrees C for PNIPAM, and around 35 degrees C for PSBP, and with a two-step heating protocol (20 degrees C to 40 degrees C and 40 degrees C to 80 degrees C), both TTs are passed. The response to such a thermal stimulus turns out to be complex. Besides a three-step process (shrinkage, rearrangement, and reswelling), a continuous transfer of D2O from the PNIPAM to the PSBP block is observed. Due to the existence of both, LCST and UCST blocks in the PSBP80-b-PNIPAM(400 )film, the water transfer from the contracting PNIPAM, and mixed layers to the expanding PSBP layer occurs. Thus, the hydration kinetics and thermal response differ markedly from a thermoresponsive polymer film with a single LCST transition.
KW - block copolymer
KW - dual thermoresponsive
KW - kinetic water transfer
KW - neutron
KW - reflectivity
KW - thin film
Y1 - 2022
U6 - https://doi.org/10.1002/admi.202201913
SN - 2196-7350
VL - 10
IS - 3
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Bhattacharyya, Biswajit
A1 - Balischewski, Christian
A1 - Sperlich, Eric
A1 - Günter, Christina
A1 - Mies, Stefan
A1 - Kelling, Alexandra
A1 - Taubert, Andreas
T1 - N-Butyl Pyridinium Diiodido Argentate(I)
BT - A One-Dimensional Ag-I Network with Superior Solid-State Ionic Conductivity at Room Temperature
JF - Advanced materials interfaces
N2 - A new solid-state material, N-butyl pyridinium diiodido argentate(I), is synthesized using a simple and effective one-pot approach. In the solid state, the compound exhibits 1D ([AgI2](-))(n) chains that are stabilized by the N-butyl pyridinium cation. The 1D structure is further manifested by the formation of long, needle-like crystals, as revealed from electron microscopy. As the general composition is derived from metal halide-based ionic liquids, the compound has a low melting point of 100-101 degrees C, as confirmed by differential scanning calorimetry. Most importantly, the compound has a conductivity of 10(-6) S cm(-1) at room temperature. At higher temperatures the conductivity increases and reaches to 10(-4 )S cm(-1) at 70 degrees C. In contrast to AgI, however, the current material has a highly anisotropic 1D arrangement of the ionic domains. This provides direct and tuneable access to fast and anisotropic ionic conduction. The material is thus a significant step forward beyond current ion conductors and a highly promising prototype for the rational design of highly conductive ionic solid-state conductors for battery or solar cell applications.
KW - AgI
KW - ionic conductivity
KW - Ionic liquids
KW - thermal properties
Y1 - 2023
U6 - https://doi.org/10.1002/admi.202202363
SN - 2196-7350
VL - 10
IS - 12
PB - Wiley
CY - Hoboken
ER -
TY - JOUR
A1 - Nchiozem-Ngnitedem, Vaderament-Alexe
A1 - Sperlich, Eric
A1 - Matieta, Valaire Yemene
A1 - Kuete, Jenifer Reine Ngnouzouba
A1 - Kuete, Victor
A1 - Omer, Ejlal A. A.
A1 - Efferth, Thomas
A1 - Schmidt, Bernd
T1 - Synthesis and bioactivity of isoflavones from ficus carica and some non-natural analogues
JF - Journal of natural products : Lloydia
N2 - FicucariconeD (1) and its 4 '-demethyl congener 2 are isoflavones isolated from fruits of Ficus carica that share a 5,7-dimethoxy-6-prenyl-substituted A-ring. Both naturalproducts were, for the first time, obtained by chemical synthesisin six steps, starting from 2,4,6-trihydroxyacetophenone. Key stepsare a microwave-promoted tandem sequence of Claisen- and Cope-rearrangementsto install the 6-prenyl substituent and a Suzuki-Miyaura crosscoupling for installing the B-ring. By using various boronic acids,non-natural analogues become conveniently available. All compoundswere tested for cytotoxicity against drug-sensitive and drug-resistanthuman leukemia cell lines, but were found to be inactive. The compoundswere also tested for antimicrobial activities against a panel of eightGram-negative and two Gram-positive bacterial strains. Addition ofthe efflux pump inhibitor phenylalanine-arginine-beta-naphthylamide(PA beta N) significantly improved the antibiotic activity in mostcases, with MIC values as low as 2.5 mu M and activity improvementfactors as high as 128-fold.
KW - Antimicrobial activity
KW - Bacteria
KW - Ethers
KW - Flavonoids
KW - Mixtures
Y1 - 2023
U6 - https://doi.org/10.1021/acs.jnatprod.3c00219
SN - 0163-3864
SN - 1520-6025
VL - 86
IS - 6
SP - 1520
EP - 1528
PB - American Chemical Society
CY - Washington, DC
ER -