TY  - JOUR
A1  - Adesina, Morenike O.
A1  - Block, Inga
A1  - Günter, Christina
A1  - Unuabonah, Emmanuel Iyayi
A1  - Taubert, Andreas
T1  - Efficient Removal of Tetracycline and Bisphenol A from Water with a New Hybrid Clay/TiO2 Composite
JF  - ACS Omega
N2  - New TiO2 hybrid composites were prepared fromkaolinclay, predried and carbonized biomass, and titanium tetraisopropoxideand explored for tetracycline (TET) and bisphenol A (BPA) removalfrom water. Overall, the removal rate is 84% for TET and 51% for BPA.The maximum adsorption capacities (q (m))are 30 and 23 mg/g for TET and BPA, respectively. These capacitiesare far greater than those obtained for unmodified TiO2. Increasing the ionic strength of the solution does not change theadsorption capacity of the adsorbent. pH changes only slightly changeBPA adsorption, while a pH > 7 significantly reduces the adsorptionof TET on the material. The Brouers-Sotolongo fractal modelbest describes the kinetic data for both TET and BPA adsorption, predictingthat the adsorption process occurs via a complex mechanism involvingvarious forces of attraction. Temkin and Freundlich isotherms, whichbest fit the equilibrium adsorption data for TET and BPA, respectively,suggest that adsorption sites are heterogeneous in nature. Overall,the composite materials are much more effective for TET removal fromaqueous solution than for BPA. This phenomenon is assigned to a differencein the TET/adsorbent interactions vs the BPA/adsorbent interactions:the decisive factor appears to be favorable electrostatic interactionsfor TET yielding a more effective TET removal.
Y1  - 2023
U6  - https://doi.org/10.1021/acsomega.3c00184
SN  - 2470-1343
VL  - 8
IS  - 24
SP  - 21594
EP  - 21604
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Mazarei, Elham
A1  - Penschke, Christopher
A1  - Saalfrank, Peter
T1  - Band gap engineering in two-dimensional materials by functionalization
BT  - Methylation of graphene and graphene bilayers
JF  - ACS Omega
N2  - Graphene is well-knownfor its unique combination of electricaland mechanical properties. However, its vanishing band gap limitsthe use of graphene in microelectronics. Covalent functionalizationof graphene has been a common approach to address this critical issueand introduce a band gap. In this Article, we systematically analyzethe functionalization of single-layer graphene (SLG) and bilayer graphene(BLG) with methyl (CH3) using periodic density functionaltheory (DFT) at the PBE+D3 level of theory. We also include a comparisonof methylated single-layer and bilayer graphene, as well as a discussionof different methylation options (radicalic, cationic, and anionic).For SLG, methyl coverages ranging from 1/8 to 1/1, (i.e.,the fully methylated analogue of graphane) are considered. We findthat up to a coverage theta of 1/2, graphene readily accepts CH3, with neighbor CH3 groups preferring trans positions. Above theta = 1/2, the tendency to accept further CH3 weakens and the lattice constant increases. The band gapbehaves less regularly, but overall it increases with increasing methylcoverage. Thus, methylated graphene shows potential for developingband gap-tuned microelectronics devices and may offer further functionalizationoptions. To guide in the interpretation of methylation experiments,vibrational signatures of various species are characterized by normal-modeanalysis (NMA), their vibrational density of states (VDOS), and infrared(IR) spectra, the latter two are obtained from ab initio moleculardynamics (AIMD) in combination with a velocity-velocity autocorrelationfunction (VVAF) approach.
KW  - Adsorption
KW  - Alkyls
KW  - Band structure
KW  - Electrical conductivity
KW  - Two dimensional materials
Y1  - 2023
U6  - https://doi.org/10.1021/acsomega.3c02068
SN  - 2470-1343
VL  - 8
IS  - 24
SP  - 22026
EP  - 22041
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - The multiple bond character of the carbon-boron bond in boron trapped N-heterocyclic carbenes (NHCs) and cyclic(alkyl)(amino) carbenes (CAACs) on the magnetic criterion
JF  - Tetrahedron
N2  - Geometry, 11B, 13C chemical shifts and the spatial magnetic properties (Through-Space NMR Shieldings -TSNMRS) of both cations and anions of boron-trapped N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (CAACs) and of the corresponding diborane/diborene/diboryne dis-carbene adducts have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept; the TSNMRS results are visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The ICSS of the TSNMRS (actually the anisotropy effects measurable in 1H NMR spectroscopy) are employed to qualify and quantify the present multiple bond character of the Carbene-Boron bond in the trapped NHCs and CAACs. Results are confirmed by bond length and 11B/13C chemical shift variations. Thus the partial multiple bond character of the Carbene-Boron bond cannot be expressed by the arrow of weak, much longer dative bonds and should be omitted as in other covalent lone pair-it or triel bonds. & COPY; 2023 Elsevier Ltd. All rights reserved.
KW  - NHCs
KW  - CAACs
KW  - Multiple NHC(CAAC)-Boron bonds
KW  - Through -space NMR
KW  - shieldings (TSNMRS)
KW  - NICS
KW  - Anisotropy effect
KW  - Ring current effect
Y1  - 2023
U6  - https://doi.org/10.1016/j.tet.2023.133469
SN  - 0040-4020
SN  - 1464-5416
VL  - 140
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Schlappa, Stephanie
A1  - Bressel, Lena
A1  - Reich, Oliver
A1  - Münzberg, Marvin
T1  - Advanced particle size analysis in high-solid-content polymer dispersions using photon density wave spectroscopy
JF  - Polymers
N2  - High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12-55% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (X-2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques.
KW  - emulsion polymerization
KW  - multiple light scattering
KW  - photon density wave
KW  - spectroscopy
KW  - particle sizing
KW  - swelling of polymers
Y1  - 2023
U6  - https://doi.org/10.3390/polym15153181
SN  - 2073-4360
VL  - 15
IS  - 15
PB  - MDPI
CY  - Basel
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  - 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  - Rothe, Martin
A1  - Zhao, Yuhang
A1  - Müller, Johannes
A1  - Kewes, Günter
A1  - Koch, Christoph T.
A1  - Lu, Yan
A1  - Benson, Oliver
T1  - Self-assembly of plasmonic nanoantenna-waveguide structures for subdiffractional chiral sensing
JF  - ACS nano
N2  - Spin-momentum locking is a peculiar effect in the near-field of guided optical or plasmonic modes. It can be utilized to map the spinning or handedness of electromagnetic fields onto the propagation direction. This motivates a method to probe the circular dichroism of an illuminated chiral object. In this work, we demonstrate local, subdiffraction limited chiral coupling of light and propagating surface plasmon polaritons in a self-assembled system of a gold nanoantenna and a silver nanowire. A thin silica shell around the nanowire provides precise distance control and also serves as a host for fluorescent molecules, which indicate the direction of plasmon propagation. We characterize our nanoantenna-nanowire systems comprehensively through correlated electron microscopy, energy-dispersive X-ray spectroscopy, dark-field, and fluorescence imaging. Three-dimensional numerical simulations support the experimental findings. Besides our measurement of far-field polarization, we estimate sensing capabilities and derive not only a sensitivity of 1 mdeg for the ellipticity of the light field, but also find 10(3) deg cm(2)/dmol for the circular dichroism of an analyte locally introduced in the hot spot of the antenna-wire system. Thorough modeling of a prototypical design predicts on-chip sensing of chiral analytes. This introduces our system as an ultracompact sensor for chiral response far below the diffraction limit.
KW  - plasmonics
KW  - nanoparticle assemblies
KW  - core-shell
KW  - spin-orbit coupling
KW  - chirality
KW  - circular dichroism
KW  - nano-optics
Y1  - 2021
U6  - https://doi.org/10.1021/acsnano.0c05240
SN  - 1936-0851
SN  - 1936-086X
VL  - 15
IS  - 1
SP  - 351
EP  - 361
PB  - American Chemical Society
CY  - Washington
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  - 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  - 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  - Tung, Wing Tai
A1  - Sun, Xianlei
A1  - Wang, Weiwei
A1  - Xu, Xun
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - The capability of a degradable implant to provide mechanical support depends on its degradation behavior. Hydrolytic degradation was studied for a polyesteretherurethane (PEEU70), which consists of poly(p-dioxanone) (PPDO) and poly(epsilon-caprolactone) (PCL) segments with a weight ratio of 70:30 linked by diurethane junction units. PEEU70 samples prepared in the form of meshes with average fiber diameters of 1.5 mu m (mesh1.5) and 1.2 mu m (mesh1.2), and films were sterilized and incubated in PBS at 37 degrees C with 5 vol% CO2 supply for 1 to 6 weeks. Degradation features, such as cracks or wrinkles, became apparent from week 4 for all samples. Mass loss was found to be 11 wt%, 6 wt%, and 4 wt% for mesh1.2, mesh1.5, and films at week 6. The elongation at break decreased to under 20% in two weeks for mesh1.2. In case of the other two samples, this level of degradation was achieved after 4 weeks. The weight average molecular weight of both PEEU70 mesh and film samples decreased to below 30 kg/mol when elongation at break dropped below 20%. The time period of sustained mechanical stability of PEEU70-based meshes depends on the fiber diameter and molecular weight.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-020-00001-0
SN  - 2059-8521
VL  - 6
IS  - 10
SP  - 276
EP  - 282
PB  - Springer Nature Switzerland AG
CY  - Cham
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  - 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  - Zhou, Shuo
A1  - Xu, Xun
A1  - Ma, Nan
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
T1  - Influence of sterilization conditions on sulfate-functionalized polyGGE
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Sulfated biomolecules are known to influence numerous biological processes in all living organisms. Particularly, they contribute to prevent and inhibit the hypercoagulation condition. The failure of polymeric implants and blood contacting devices is often related to hypercoagulation and microbial contamination. Here, bioactive sulfated biomacromolecules are mimicked by sulfation of poly(glycerol glycidyl ether) (polyGGE) films. Autoclaving, gamma-ray irradiation and ethylene oxide (EtO) gas sterilization techniques were applied to functionalized materials. The sulfate group density and hydrophilicity of sulfated polymers were decreased while chain mobility and thermal degradation were enhanced post autoclaving when compared to those after EtO sterilization. These results suggest that a quality control after sterilization is mandatory to ensure the amount and functionality of functionalized groups are retained.
KW  - Sulfated polymer
KW  - sulfation
KW  - sterilization
KW  - ethylene oxide
Y1  - 2021
U6  - https://doi.org/10.3233/CH-211241
SN  - 1386-0291
SN  - 1875-8622
VL  - 79
IS  - 4
SP  - 597
EP  - 608
PB  - IOS Press
CY  - Amsterdam
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  - GEN
A1  - Bande, Annika
A1  - González, Leticia
A1  - Klamroth, Tillmann
A1  - Tremblay, Jean Christophe
T1  - Theoretical chemistry and quantum dynamics at interfaces
BT  - Celebrating the career of Peter Saalfrank on the occasion of his 60th birthday
T2  - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
Y1  - 2022
U6  - https://doi.org/10.1016/j.chemphys.2022.111509
SN  - 0301-0104
SN  - 1873-4421
VL  - 558
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - 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  - 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  - Breternitz, Joachim
A1  - Schorr, Susan
T1  - Symmetry relations in wurtzite nitrides and oxide nitrides and the curious case of Pmc2(1)
JF  - Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances
N2  - Binary III-V nitrides such as AlN, GaN and InN in the wurtzite-type structure have long been considered as potent semiconducting materials because of their optoelectronic properties, amongst others. With rising concerns over the utilization of scarce elements, a replacement of the trivalent cations by others in ternary and multinary nitrides has led to the development of different variants of nitrides and oxide nitrides crystallizing in lower-symmetry variants of wurtzite. This work presents the symmetry relationships between these structural types specific to nitrides and oxide nitrides and updates some prior work on this matter. The non-existence of compounds crystallizing in Pmc2(1), formally the highest subgroup of the wurtzite type fulfilling Pauling's rules for 1:1:2 stoichiometries, has been puzzling scientists for a while; a rationalization is given, from a crystallographic basis, of why this space group is unlikely to be adopted.
KW  - group-subgroup relationships
KW  - nitride materials
KW  - wurtzite type
Y1  - 2021
U6  - https://doi.org/10.1107/S2053273320015971
SN  - 2053-2733
VL  - 77
IS  - 3
SP  - 208
EP  - 216
PB  - Blackwell
CY  - Oxford [u.a.]
ER  - 
TY  - JOUR
A1  - Mei, Shilin
A1  - Siebert, Andreas
A1  - Xu, Yaolin
A1  - Quan, Ting
A1  - Garcia-Diez, Raul
A1  - Bär, Marcus
A1  - Härtel, Paul
A1  - Abendroth, Thomas
A1  - Dörfler, Susanne
A1  - Kaskel, Stefan
A1  - Lu, Yan
T1  - Large-Scale Synthesis of Nanostructured Carbon-Ti4O7 Hollow Particles as Efficient Sulfur Host Materials for Multilayer Lithium-Sulfur Pouch Cells
JF  - Batteries & supercaps
N2  - Applications of advanced cathode materials with well-designed chemical components and/or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium-sulfur (Li-S) batteries under practical working conditions, one long-term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles (Ti4O7) using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro- & mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C-Ti4O7 based pouch cell endows a high discharge capacity of 1003 mAhg(-1) at 0.05 C, a high-capacity retention of 83.7% after 100 cycles at 0.1 C, and a high Coulombic efficiency of 97.5% at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab- to large-scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li-S pouch cells.
KW  - lithium-sulfur batteries
KW  - pouch cell
KW  - spherical polyelectrolyte brushes (SPB)
KW  - Ti4O7
Y1  - 2022
U6  - https://doi.org/10.1002/batt.202100398
SN  - 2566-6223
VL  - 5
IS  - 6
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - 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  - Haubitz, Toni
A1  - Drobot, Björn
A1  - Tsushima, Satoru
A1  - Steudtner, Robin
A1  - Stumpf, Thorsten
A1  - Kumke, Michael Uwe
T1  - Quenching mechanism of uranyl(VI) by chloride and bromide in aqueous and non-aqueous solutions
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl-halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X-2(center dot-) and the formed uranyl(V) into fully solvated ions, thereby "reigniting" U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-to-metal charge transfer is strongly reduced in acetonitrile.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpca.1c02487
SN  - 1089-5639
SN  - 1520-5215
VL  - 125
IS  - 20
SP  - 4380
EP  - 4389
PB  - American Chemical Society
CY  - Washington
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  - Reitenbach, Julija
A1  - Geiger, Christina
A1  - Wang, Peixi
A1  - Vagias, Apostolos N.
A1  - Cubitt, Robert
A1  - Schanzenbach, Dirk
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Effect of magnesium salts with chaotropic anions on the swelling behavior of PNIPMAM thin films
JF  - Macromolecules : a publication of the American Chemical Society
N2  - Poly(N-isopropylmethacrylamide) (PNIPMAM) is a stimuli responsive polymer, which in thin film geometry exhibits a volume-phase transition upon temperature increase in water vapor. The swelling behavior of PNIPMAM thin films containing magnesium salts in water vapor is investigated in view of their potential application as nanodevices. Both the extent and the kinetics of the swelling ratio as well as the water content are probed with in situ time-of-flight neutron reflectometry. Additionally, in situ Fourier-transform infrared (FTIR) spectroscopy provides information about the local solvation of the specific functional groups, while two-dimensional FTIR correlation analysis further elucidates the temporal sequence of solvation events. The addition of Mg(ClO4)2 or Mg(NO3)2 enhances the sensitivity of the polymer and therefore the responsiveness of switches and sensors based on PNIPMAM thin films. It is found that Mg(NO3)2 leads to a higher relative water uptake and therefore achieves the highest thickness gain in the swollen state.
Y1  - 2023
U6  - https://doi.org/10.1021/acs.macromol.2c02282
SN  - 0024-9297
SN  - 1520-5835
VL  - 56
IS  - 2
SP  - 567
EP  - 577
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - CHAP
A1  - Breternitz, Joachim
A1  - Schorr, Susan
T1  - Halide perovskites
BT  - structural systematisation and what we learn from it
T2  - Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances
KW  - halide perovskites
KW  - semiconductors
KW  - group-subgroup relations
KW  - twinning
Y1  - 2021
U6  - https://doi.org/10.1107/S0108767321089479
SN  - 2053-2733
VL  - 77
IS  - Suppl.
SP  - C750
EP  - C750
PB  - Blackwell
CY  - Oxford [u.a.]
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  - 
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  - 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  - 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  - 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  - Schulze, Nicole
A1  - Koetz, Joachim
T1  - Kinetically controlled growth of gold nanotriangles in a vesicular template phase by adding a strongly alternating polyampholyte
JF  - Journal of dispersion science and technology
N2  - This paper is focused on the temperature-dependent synthesis of gold nanotriangles in a vesicular template phase, containing phosphatidylcholine and AOT, by adding the strongly alternating polyampholyte PalPhBisCarb.
UV-vis absorption spectra in combination with TEM micrographs show that flat gold nanoplatelets are formed predominantly in the presence of the polyampholyte at 45°C. The formation of triangular and hexagonal nanoplatelets can be directly influenced by the kinetic approach, i.e., by varying the polyampholyte dosage rate at 45°C. Corresponding zeta potential measurements indicate that a temperature-dependent adsorption of the polyampholyte on the {111} faces will induce the symmetry breaking effect, which is responsible for the kinetically controlled hindered vertical and preferred lateral growth of the nanoplatelets.
KW  - Kinetically controlled nanocrystal growth
KW  - nanotriangles
KW  - polyampholytes
Y1  - 2016
U6  - https://doi.org/10.1080/01932691.2016.1220318
SN  - 0193-2691
SN  - 1532-2351
VL  - 38
IS  - 8
SP  - 1073
EP  - 1078
PB  - Taylor & Francis
CY  - Philadelphia
ER  - 
TY  - THES
A1  - Margraf, Johannes T.
T1  - Science-driven chemical machine learning
Y1  - 2023
ER  - 
TY  - JOUR
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xu, Xun
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polydopamine-based biofunctional substrate coating promotes mesenchymal stem cell migration
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - Rapid migration of mesenchymal stem cells (MSCs) on device surfaces could support in vivo tissue integration and might facilitate in vitro organoid formation. Here, polydopamine (PDA) is explored as a biofunctional coating to effectively promote MSC motility. It is hypothesized that PDA stimulates fibronectin deposition and in this way enhances integrin-mediated migration capability. The random and directional cell migration was investigated by time-lapse microscopy and gap closure assay respectively, and analysed with softwares as computational tools. A higher amount of deposited fibronectin was observed on PDA substrate, compared to the non-coated substrate. The integrin beta 1 activation and focal adhesion kinase (FAK) phosphorylation at Y397 were enhanced on PDA substrate, but the F-actin cytoskeleton was not altered, suggesting MSC migration on PDA was regulated by integrin initiated FAK signalling. This study strengthens the biofunctionality of PDA coating for regulating stem cells and offering a way of facilitating tissue integration of devices.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00091-4
SN  - 2059-8521
VL  - 6
IS  - 31
SP  - 739
EP  - 744
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Machatschek, Rainhard Gabriel
A1  - Saretia, Shivam
A1  - Lendlein, Andreas
T1  - Assessing the influence of temperature-memory creation on the degradation of copolyesterurethanes in ultrathin films
JF  - Advanced materials interfaces
N2  - Copolyesterurethanes (PDLCLs) based on oligo(epsilon-caprolactone) (OCL) and oligo(omega-pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature-memory polymers. The temperature-memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt% OPDL content are carried out under enzymatic catalysis. The temperature-memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization-modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X-ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation.
KW  - block copolymers
KW  - degradation
KW  - Langmuir monolayers
KW  - rheology
KW  - temperature-memory polymers
Y1  - 2021
U6  - https://doi.org/10.1002/admi.202001926
SN  - 2196-7350
VL  - 8
IS  - 6
PB  - Wiley-VCH
CY  - Weinheim
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  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Geiger, Christina
A1  - Wang, Peixi
A1  - Vagias, Apostolos N.
A1  - Heger, Julian Eliah
A1  - Haese, Martin
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Salt-dependent phase transition behavior of doubly thermoresponsive poly(sulfobetaine)-based diblock copolymer thin films
JF  - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society
N2  - The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely, poly(4-(N-(3'-methacrylamidopropyl)-N, N-dimethylammonio) butane-1-sulfonate) (PSBP), showing an upper critical solution temperature, and a nonionic block, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), exhibiting a lower critical solution temperature. The swelling kinetics in D2O vapor at 15 degrees C and the phase transition kinetics upon heating the swollen film to 60 degrees C and cooling back to 15 degrees C are followed with simultaneous time-of-flight neutron reflectometry and spectral reflectance measurements. These are complemented by Fourier transform infrared spectroscopy. The collapse temperature of PNIPMAM and the swelling temperature of PSBP are found at lower temperatures than in aqueous solution, which is attributed to the high polymer concentration in the thin-film geometry. Upon inclusion of sub-stoichiometric amounts (relative to the monomer units) of NaBr in the films, the water incorporation is significantly increased. This increase is mainly attributed to a salting-in effect on the zwitterionic PSBP block. Whereas the addition of NaBr notably shifts the swelling temperature of PSBP to lower temperatures, the collapse temperature of PNIPMAM remains unaffected by the presence of salt in the films.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.langmuir.1c01342
SN  - 0743-7463
SN  - 1520-5827
VL  - 37
IS  - 30
SP  - 9179
EP  - 9191
PB  - American Chemical Society
CY  - Washington
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  - THES
A1  - Savatieiev, Oleksandr
T1  - Carbon nitride semiconductors: properties and application as photocatalysts in organic synthesis
N2  - Graphitic carbon nitrides (g-CNs) are represented by melon-type g-CN, poly(heptazine imides) (PHIs), triazine-based g-CN and poly(triazine imide) with intercalated LiCl (PTI/Li+Cl‒). These materials are composed of sp2-hybridized carbon and nitrogen atoms; C:N ratio is close to 3:4; the building unit is 1,3,5-triazine or tri-s-triazine; the building units are interconnected covalently via sp2-hybridized nitrogen atoms or NH-moieties; the layers are assembled into a stack via weak van der Waals forces as in graphite. Due to medium band gap (~2.7 eV) g-CNs, such as melon-type g-CN and PHIs, are excited by photons with wavelength ≤ 460 nm. Since 2009 g-CNs have been actively studied as photocatalysts in evolution of hydrogen and oxygen – two half-reactions of full water splitting, by employing corresponding sacrificial agents. At the same time application of g-CNs as photocatalysts in organic synthesis has been remaining limited to few reactions only. Cumulative Habilitation summarizes research work conducted by the group ‘Innovative Heterogeneous Photocatalysis’ between 2017-2023 in the field of carbon nitride organic photocatalysis, which is led by Dr. Oleksandr Savatieiev.
g-CN photocatalysts activate molecules, i.e. generate their more reactive open-shell intermediates, via three modes: i) Photoinduced electron transfer (PET); ii) Excited state proton-coupled electron transfer (ES-PCET) or direct hydrogen atom transfer (dHAT); iii) Energy transfer (EnT). The scope of reactions that proceed via oxidative PET, i.e. one-electron oxidation of a substrate to the corresponding radical cation, are represented by synthesis of sulfonylchlorides from S-acetylthiophenols. The scope of reactions that proceed via reductive PET, i.e. one-electron reduction of a substrate to the corresponding radical anion, are represented by synthesis of γ,γ-dichloroketones from the enones and chloroform.
Due to abundance of sp2-hybridized nitrogen atoms in the structure of g-CN materials, they are able to cleave X-H bonds in organic molecules and store temporary hydrogen atom. ES-PCET or dHAT mode of organic molecules activation to the corresponding radicals is implemented for substrates featuring relatively acidic X-H bonds and those that are characterized by low bond dissociation energy, such as C-H bond next to the heteroelements. On the other hand, reductively quenched g-CN carrying hydrogen atom reduces a carbonyl compound to the ketyl radical via PCET that is thermodynamically more favorable pathway compared to the electron transfer. The scope of these reactions is represented by cyclodimerization of α,β-unsaturated ketones to cyclopentanoles.
g-CN excited state demonstrates complex dynamics with the initial formation of singlet excited state, which upon intersystem crossing produces triplet excited state that is characterized by the lifetime > 2 μs. Due to long lifetime, g-CN activate organic molecules via EnT. For example, g-CN sensitizes singlet oxygen, which is the key intermediate in the dehydrogenation of aldoximes to nitrileoxides. The transient nitrileoxide undergoes [3+2]-cycloaddition to nitriles and gives oxadiazoles-1,2,4.
PET, ES-PCET and EnT are fundamental phenomena that are applied beyond organic photocatalysis. Hybrid composite is formed by combining conductive polymers, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with potassium poly(heptazine imide) (K-PHI). Upon PET, K-PHI modulated population of polarons and therefore conductivity of PEDOT:PSS. The initial state of PEDOT:PSS is recovered upon material exposure to O2. K-PHI:PEDOT:PSS may be applied in O2 sensing.
In the presence of electron donors, such as tertiary amines and alcohols, and irradiation with light, K-PHI undergoes photocharging – the g-CN material accumulates electrons and charge-compensating cations. Such photocharged state is stable under anaerobic conditions for weeks, but at the same time it is a strong reductant. This feature allows decoupling in time light harvesting and energy storage in the form of electron-proton couples from utilization in organic synthesis. The photocharged state of K-PHI reduces nitrobenzene to aniline, and enables dimerization of α,β-unsaturated ketones to hexadienones in dark.
N2  - Graphitische Kohlenstoffnitride (g-CNs) werden durch g-CN vom Melonen-Typ, Poly(heptazinimide) (PHIs), g-CN auf Triazinbasis und Poly(triazinimid) mit interkaliertem LiCl (PTI/Li+Cl-) repräsentiert. Diese Materialien bestehen aus sp2-hybridisierten Kohlenstoff- und Stickstoffatomen; das C:N-Verhältnis liegt nahe bei 3:4; das Grundgerüst ist 1,3,5-Triazin oder Tri-s-Triazin; die Grundgerüste sind kovalent über sp2-hybridisierte Stickstoffatome oder NH-Moleküle miteinander verbunden; die Schichten werden über schwache van-der-Waals-Kräfte wie in Graphit zu einem Stapel zusammengefügt. Aufgrund der mittleren Bandlücke (~2,7 eV) werden g-CNs, wie z. B. g-CN vom Melonen-Typ und PHIs, durch Photonen mit einer Wellenlänge ≤ 460 nm angeregt. Seit 2009 werden g-CNs aktiv als Photokatalysatoren für die Entwicklung von Wasserstoff und Sauerstoff - zwei Halbreaktionen der vollständigen Wasserspaltung - untersucht, indem entsprechende Opferstoffe eingesetzt werden. Gleichzeitig ist die Anwendung von g-CNs als Photokatalysatoren in der organischen Synthese auf wenige Reaktionen beschränkt geblieben. Die kumulative Habilitation fasst die Forschungsarbeiten zusammen, die von der Gruppe "Innovative heterogene Photokatalyse" zwischen 2017 und 2023 auf dem Gebiet der organischen Photokatalyse mit Kohlenstoffnitrid durchgeführt wurden, die von Dr. Oleksandr Savatieiev geleitet wird.
g-CN-Photokatalysatoren aktivieren Moleküle, d. h. sie erzeugen ihre reaktiveren Zwischenprodukte mit offener Schale über drei Modi: i) photoinduzierter Elektronentransfer (PET); ii) protonengekoppelter Elektronentransfer im angeregten Zustand (ES-PCET) oder direkter Wasserstoffatomtransfer (dHAT); iii) Energietransfer (EnT). Der Bereich der Reaktionen, die über oxidativen PET ablaufen, d. h. die Ein-Elektronen-Oxidation eines Substrats zum entsprechenden Radikalkation, wird durch die Synthese von Sulfonylchloriden aus S-Acetylthiophenolen dargestellt. Der Bereich der Reaktionen, die über reduktive PET ablaufen, d. h. Reduktion eines Substrats mit einem Elektron zum entsprechenden radikalischen Anion, wird durch die Synthese von γ,γ-Dichloroketonen aus Enonen und Chloroform repräsentiert.
Aufgrund der zahlreichen sp2-hybridisierten Stickstoffatome in der Struktur der g-CN-Materialien können sie X-H-Bindungen in organischen Molekülen spalten und temporäre Wasserstoffatome speichern. Der ES-PCET- oder dHAT-Modus der Aktivierung organischer Moleküle zu den entsprechenden Radikalen wird bei Substraten mit relativ sauren X-H-Bindungen und solchen, die sich durch eine niedrige Bindungsdissoziationsenergie auszeichnen, wie z. B. die C-H-Bindung neben den Heteroelementen, durchgeführt. Andererseits reduziert reduktiv gequenchtes g-CN, das ein Wasserstoffatom trägt, eine Carbonylverbindung über PCET zum Ketylradikal, was im Vergleich zum Elektronentransfer der thermodynamisch günstigere Weg ist. Der Umfang dieser Reaktionen wird durch die Cyclodimerisierung von α,β-ungesättigten Ketonen zu Cyclopentanolen dargestellt.
Der angeregte Zustand von g-CN zeigt eine komplexe Dynamik mit der anfänglichen Bildung eines angeregten Singulett-Zustands, der beim Übergang zwischen den Systemen einen angeregten Triplett-Zustand erzeugt, der durch eine Lebensdauer von > 2 μs gekennzeichnet ist. Aufgrund der langen Lebensdauer aktivieren g-CN organische Moleküle über EnT. So sensibilisiert g-CN beispielsweise Singulett-Sauerstoff, der das wichtigste Zwischenprodukt bei der Dehydrierung von Aldoximen zu Nitriloxiden ist. Das transiente Nitriloxid unterliegt einer [3+2]-Cycloaddition zu Nitrilen und ergibt Oxadiazole-1,2,4.
PET, ES-PCET und EnT sind grundlegende Phänomene, die über die organische Photokatalyse hinaus Anwendung finden. Hybridkomposit wird durch die Kombination von leitfähigen Polymeren wie Poly(3,4-ethylendioxythiophen)polystyrolsulfonat (PEDOT:PSS) mit Kaliumpoly(heptazinimid) (K-PHI) gebildet. Nach PET modulierte K-PHI die Population der Polaronen und damit die Leitfähigkeit von PEDOT:PSS. Der Ausgangszustand von PEDOT:PSS wird wiederhergestellt, wenn das Material O2 ausgesetzt wird. K-PHI:PEDOT:PSS kann für die O2-Sensorik verwendet werden.
In Gegenwart von Elektronendonatoren, wie tertiären Aminen und Alkoholen, und bei Lichteinstrahlung wird K-PHI photogeladen - das g-CN-Material sammelt Elektronen und ladungsausgleichende Kationen an. Dieser photogeladene Zustand ist unter anaeroben Bedingungen wochenlang stabil, gleichzeitig ist er aber ein starkes Reduktionsmittel. Diese Eigenschaft ermöglicht die zeitliche Entkopplung von Lichtsammlung und Energiespeicherung in Form von Elektron-Protonen-Paaren von der Nutzung in der organischen Synthese. Der photogeladene Zustand von K-PHI reduziert Nitrobenzol zu Anilin und ermöglicht die Dimerisierung von α,β-ungesättigten Ketonen zu Hexadienonen im Dunkeln.
KW  - carbon nitride
KW  - photocatalysis
KW  - photochemistry
KW  - photocharging
KW  - organic synthesis
Y1  - 2023
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  - Kuntze, Kim
A1  - Viljakka, Jani
A1  - Titov, Evgenii
A1  - Ahmed, Zafar
A1  - Kalenius, Elina
A1  - Saalfrank, Peter
A1  - Priimagi, Arri
T1  - Towards low-energy-light-driven bistable photoswitches
BT  - ortho-fluoroaminoazobenzenes
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days. <br /> [GRAPHICS] <br /> .
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00145-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 159
EP  - 173
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - 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  - Neffe, Axel T.
A1  - Löwenberg, Candy
A1  - Julich-Gruner, Konstanze K.
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Thermally-induced shape-memory behavior of degradable gelatin-based networks
JF  - International journal of molecular sciences
N2  - Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) alpha,omega-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27-23 kPa and Young's moduli of 215-360 kPa at 4 degrees C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 degrees C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R-r close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.
KW  - shape-memory hydrogel
KW  - active polymer
KW  - biopolymer
KW  - mechanical
KW  - properties
KW  - degradation
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22115892
SN  - 1422-0067
SN  - 1661-6596
VL  - 22
IS  - 11
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Bochove, Bas van
A1  - Grijpma, Dirk W.
A1  - Lendlein, Andreas
A1  - Seppälä, Jukka
T1  - Designing advanced functional polymers for medicine
JF  - European polymer journal : EPJ
Y1  - 2021
U6  - https://doi.org/10.1016/j.eurpolymj.2021.110573
SN  - 0014-3057
VL  - 155
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hwang, Jinyeon
A1  - Zhang, Wuyong
A1  - Youk, Sol
A1  - Schutjajew, Konstantin
A1  - Oschatz, Martin
T1  - Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials
JF  - Energy technology : generation, conversion, storage, distribution
N2  - The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites.
KW  - anodes
KW  - hybrid materials
KW  - nitrogen-doped carbon
KW  - porous carbon
KW  - lithium-ion capacitors
Y1  - 2021
U6  - https://doi.org/10.1002/ente.202001054
SN  - 2194-4296
VL  - 9
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
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  - 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  - 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  - 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  - Zimmermann, Marc
A1  - Stomps, Benjamin René Harald
A1  - Schulte-Osseili, Christine
A1  - Grigoriev, Dmitry
A1  - Ewen, Dirk
A1  - Morgan, Andrew
A1  - Böker, Alexander
T1  - Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn
JF  - Textile Research Journal
N2  - Polypropylene as one of the world's top commodity polymers is also widely used in the textile industry. However, its non-polar nature and partially crystalline structure significantly complicate the process of industrial coloring of polypropylene. Currently, textiles made of polypropylene or with a significant proportion of polypropylene are dyed under quite harsh conditions, including the use of high pressures and temperatures, which makes this process energy intensive. This research presents a three-step synthesis of coloring agents, capable of adhering onto synthetic polypropylene yarns without harsh energy-consuming conditions. This is possible by encapsulation of organic pigments using trimethoxyphenylsilane, introduction of surface double bonds via modification of the silica shell with trimethoxysilylpropylmethacrylate and final attachment of highly adhesive anchor peptides using thiol-ene chemistry. We demonstrate the applicability of this approach by dyeing polypropylene yarns in a simple process under ambient conditions after giving a step-by-step guide for the synthesis of these new dyeing agents. Finally, the successful dyeing of the yarns is visualized, and its practicability is discussed.
KW  - anchor peptides
KW  - organic dye pigments
KW  - coloring agents
KW  - polypropylene
KW  - yarns
Y1  - 2020
U6  - https://doi.org/10.1177/0040517520932231
SN  - 0040-5175
SN  - 1746-7748
VL  - 91
IS  - 1-2
SP  - 28
EP  - 39
PB  - Sage Publ.
CY  - London
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  - 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  - Kreuzer, Lucas
A1  - Lindenmeir, Christoph
A1  - Geiger, Christina
A1  - Widmann, Tobias
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine) versus poly(N-isopropylmethacrylamide)
BT  - co-nonsolvency-type behavior of thin films in a water/methanol atmosphere
JF  - Macromolecules : a publication of the American Chemical Society
N2  - The swelling and co-nonsolvency behaviors in pure H2O and in a mixed H2O/CH3OH vapor atmosphere of two different polar, water-soluble polymers in thin film geometry are studied in situ. Films of a zwitterionic poly(sulfobetaine), namely, poly[3-((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a polar nonionic polymer, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), are investigated in real time by spectral reflectance (SR) measurements and Fourier transform infrared (FTIR) spectroscopy. Whereas PSPE is insoluble in methanol, PNIPMAM is soluble but exhibits cononsolvency behavior in water/methanol mixtures. First, the swelling of PSPE and PNIPMAM thin films in H2O vapor is followed. Subsequently, CH3OH is added to the vapor atmosphere, and its contracting effect on the water-swollen films is monitored, revealing a co-nonsolvency-type behavior for PNIPMAM and PSPE. SR measurements indicate that PSPE and PNIPMAM behave significantly different during the H2O swelling and subsequent exposure to CH3OH, not only with respect to the amounts of absorbed water and CH3OH, but also to the cosolvent-induced contraction mechanisms. While PSPE thin films exhibit an abrupt one-step contraction, the contraction of PNIPMAM thin films occurs in two steps. FTIR studies corroborate these findings on a molecular scale and reveal the role of the specific functional groups, both during the swelling and the cosolvent-induced switching of the solvation state.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.macromol.0c02281
SN  - 0024-9297
SN  - 1520-5835
VL  - 54
IS  - 3
SP  - 1548
EP  - 1556
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xua, Xun
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polymeric sheet actuators with programmable bioinstructivity
JF  - PNAS
N2  - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
KW  - reversible shape-memory actuator
KW  - mesenchymal stem cells
KW  - calcium influx
KW  - HDAC1
KW  - RUNX2
Y1  - 2020
U6  - https://doi.org/10.1073/pnas.1910668117
SN  - 1091-6490
VL  - 117
IS  - 4
SP  - 1895
EP  - 1901
PB  - National Academy of Sciences
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Saretia, Shivam
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Degradation kinetics of oligo(ε-caprolactone) ultrathin films
BT  - Influence of crystallinity
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(epsilon-caprolactone) (OCL) are prepared at the air-water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH similar to 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00067-4
SN  - 2059-8521
VL  - 6
IS  - 33
SP  - 790
EP  - 795
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Yue, Yanhua
A1  - Melani, Giacomo
A1  - Kirsch, Harald
A1  - Paarmann, Alexander
A1  - Saalfrank, Peter
A1  - Campen, Richard Kramer
A1  - Tong, Yujin
T1  - Structure and Reactivity of a-Al2O3(0001) Surfaces: How Do Al-I and Gibbsite-like Terminations Interconvert?
JF  - The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis
N2  - The alpha-Al2O3(0001) surface has been extensively studied because of its significance in both fundamental research and application. Prior work suggests that in ultra-high-vacuum (UHV), in the absence of water, the so-called Al-I termination is thermodynamically favored, while in ambient, in contact with liquid water, a Gibbsite-like layer is created. While the view of the alpha- Al2O3(0001)/H2O(l) interface appears relatively clear in theory, experimental characterization of this system has resulted in estimates of surface acidity, i.e., isoelectric points, that differ by 4 pH units and surface structure that in some reports has non-hydrogen-bonded surface aluminol (Al-OH) groups and in others does not. In this study, we employed vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation to study the surface phonon modes of the differently terminated alpha-Al2O3(0001) surfaces in both UHV and ambient. We find that, on either water dosing of the Al-I in UHV or heat-induced dehydroxylation of the Gibbsite-like in ambient, the surfaces do not interconvert. This observation offers a new explanation for disagreements in prior work on the alpha-Al2O3(0001)/liquid water interface -different preparation methods may create surfaces that do not interconvert-and shows that the surface phonon spectral response offers a novel probe of interfacial hydrogen bonding structure.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.2c03743
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 31
SP  - 13467
EP  - 13476
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tarazona Lizcano, Natalia Andrea
A1  - Machatschek, Rainhard Gabriel
A1  - Balcucho, Jennifer
A1  - Castro-Mayorga, Jinneth Lorena
A1  - Saldarriaga, Juan Francisco
A1  - Lendlein, Andreas
T1  - Opportunities and challenges for integrating the development of sustainable polymer materials within an international circular (bio)economy concept
JF  - MRS energy & sustainability : science & technology & socio-economics & policy
N2  - The production and consumption of commodity polymers have been an indispensable part of the development of our modern society. Owing to their adjustable properties and variety of functions, polymer-based materials will continue playing important roles in achieving the Sustainable Development Goals (SDG)s, defined by the United Nations, in key areas such as healthcare, transport, food preservation, construction, electronics, and water management. Considering the serious environmental crisis, generated by increasing consumption of plastics, leading-edge polymers need to incorporate two types of functions: Those that directly arise from the demands of the application (e.g. selective gas and liquid permeation, actuation or charge transport) and those that enable minimization of environmental harm, e.g., through prolongation of the functional lifetime, minimization of material usage, or through predictable disintegration into non-toxic fragments. Here, we give examples of how the incorporation of a thoughtful combination of properties/functions can enhance the sustainability of plastics ranging from material design to waste management. We focus on tools to measure and reduce the negative impacts of plastics on the environment throughout their life cycle, the use of renewable sources for their synthesis, the design of biodegradable and/or recyclable materials, and the use of biotechnological strategies for enzymatic recycling of plastics that fits into a circular bioeconomy. Finally, we discuss future applications for sustainable plastics with the aim to achieve the SDGs through international cooperation. <br /> Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities.
KW  - biomaterial
KW  - degradable
KW  - functional
KW  - life cycle assessment
KW  - renewable
KW  - sustainability
Y1  - 2022
U6  - https://doi.org/10.1557/s43581-021-00015-7
SN  - 2329-2229
SN  - 2329-2237
VL  - 9
IS  - 1
SP  - 28
EP  - 34
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Folikumah, Makafui Y.
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols
JF  - MRS communications / a publication of the Materials Research Society
N2  - Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an alpha,omega-dithiol crosslinker in situ in a 'pseudo intramolecular' TTE. Competitive intermolecular TTE of TDP with externally added "basic" thiols increased the crosslinker concentration whilst "acidic" thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications.
KW  - Biomaterials
KW  - Biomimetic
KW  - Mass spectrometry
KW  - Nuclear magnetic resonance
KW  - (NMR)
Y1  - 2021
U6  - https://doi.org/10.1557/s43579-021-00041-z
SN  - 2159-6859
SN  - 2159-6867
VL  - 11
IS  - 4
SP  - 402
EP  - 410
PB  - Springer
CY  - Berlin
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  - 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  - Mawire, Phillip
A1  - Mozirandi, Winnie
A1  - Heydenreich, Matthias
A1  - Chi, Godloves Fru
A1  - Mukanganyama, Stanley
T1  - Isolation and antimicrobial activities of phytochemicals from Parinari curatellifolia (Chrysobalanaceae)
JF  - Advances in pharmacological and pharmaceutical sciences
N2  - The widespread use of antimicrobial agents to treat infectious diseases has led to the emergence of antibiotic resistant pathogens. Plants have played a central role in combating many ailments in humans, and Parinari curatellifolia has been used for medicinal purposes. Seven extracts from P. curatellifolia leaves were prepared using serial exhaustive extraction of nonpolar to polar solvents. The microbroth dilution method was used to evaluate antimicrobial bioactivities of extracts. Five of the extracts were significantly active against at least one test microbe. Mycobacterium smegmatis was the most susceptible to most extracts. The methanol and ethanol extracts were the most active against M. smegmatis with an MIC of 25 mu g/mL. The hexane extract was the most active against Candida krusei with an MIC of 25 mu g/mL. None of the extracts significantly inhibited growth of Klebsiella pneumoniae and Staphylococcus aureus. Active extracts were selected for fractionation and isolation of pure compounds using gradient elution column chromatography. TLC analyses was carried out for pooling fractions of similar profiles. A total of 43 pools were obtained from 428 fractions. Pools 7 and 10 were selected for further isolation of single compounds. Four compounds, Pc4963r, Pc4962w, Pc6978p, and Pc6978o, were isolated. Evaluation of antimicrobial activities of Pc4963r, Pc4962w, and Pc6978p showed that the compounds were most active against C. krusei with MFC values ranging from 50 to 100 mu g/mL. Only Pc6978p was shown to be pure. Using spectroscopic analyses, the structure of Pc6978p was determined to be beta-sitosterol. The antifungal effects of beta-sitosterol were evaluated against C. krusei in vitro and on fabrics. Results showed that beta-sitosterol reduced the growth of C. krusei attached to Mendy fabric by 83%. Therefore, P. curatellifolia can be a source of lead compounds for prospective development of novel antimicrobial agents. Further work needs to be done to improve the antifungal activity of the isolated compound using quantitative structure-activity relationships.
Y1  - 2021
U6  - https://doi.org/10.1155/2021/8842629
SN  - 2633-4682
SN  - 2633-4690
PB  - Hindawi
CY  - London
ER  - 
TY  - JOUR
A1  - Bekir, Marek
A1  - Jelken, Joachim
A1  - Jung, Se-Hyeong
A1  - Pich, Andrij
A1  - Pacholski, Claudia
A1  - Kopyshev, Alexey
A1  - Santer, Svetlana
T1  - Dual responsiveness of microgels induced by single light stimulus
JF  - Applied physics letters
N2  - We report on the multiple response of microgels triggered by a single optical stimulus. Under irradiation, the volume of the microgels is reversibly switched by more than 20 times. The irradiation initiates two different processes: photo-isomerization of the photo-sensitive surfactant, which forms a complex with the anionic microgel, rendering it photo-responsive; and local heating due to a thermo-plasmonic effect within the structured gold layer on which the microgel is deposited. The photo-responsivity is related to the reversible accommodation/release of the photo-sensitive surfactant depending on its photo-isomerization state, while the thermo-sensitivity is intrinsically built in. We show that under exposure to green light, the thermo-plasmonic effect generates a local hot spot in the gold layer, resulting in the shrinkage of the microgel. This process competes with the simultaneous photo-induced swelling. Depending on the position of the laser spot, the spatiotemporal control of reversible particle shrinking/swelling with a predefined extent on a per-second base can be implemented.
Y1  - 2021
U6  - https://doi.org/10.1063/5.0036376
SN  - 0003-6951
SN  - 1077-3118
VL  - 118
IS  - 9
PB  - American Institute of Physics
CY  - Melville
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  - Neffe, Axel T.
A1  - Löwenberg, Candy
A1  - Lendlein, Andreas
T1  - Hydrogel networks by aliphatic dithiol Michael addition to glycidylmethacrylated gelatin
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - Functionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by H-1 NMR and FT-IR spectroscopy. Hydrogel swelling (460-1900 vol%) and mechanical properties (Young's modulus E = 59-512 kPa, elongation at break epsilon(b) = 44-127%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 degrees C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00136-8
SN  - 2059-8521
VL  - 6
IS  - 33
SP  - 796
EP  - 800
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Maier, Anna
A1  - Braune, Steffen
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
T1  - Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials
JF  - International journal of molecular sciences
N2  - Near-physiological in vitro thrombogenicity test systems for the evaluation of blood-contacting endothelialized biomaterials requires co-cultivation with platelets (PLT). However, the addition of PLT has led to unphysiological endothelial cell (EC) detachment in such in vitro systems. A possible cause for this phenomenon may be PLT activation triggered by the applied endothelial cell medium, which typically consists of basal medium (BM) and nine different supplements. To verify this hypothesis, the influence of BM and its supplements was systematically analyzed regarding PLT responses. For this, human platelet rich plasma (PRP) was mixed with BM, BM containing one of nine supplements, or with BM containing all supplements together. PLT adherence analysis was carried out in six-channel slides with plasma-treated cyclic olefin copolymer (COC) and poly(tetrafluoro ethylene) (PTFE, as a positive control) substrates as part of the six-channel slides in the absence of EC and under static conditions. PLT activation and aggregation were analyzed using light transmission aggregometry and flow cytometry (CD62P). Medium supplements had no effect on PLT activation and aggregation. In contrast, supplements differentially affected PLT adherence, however, in a polymer- and donor-dependent manner. Thus, the use of standard endothelial growth medium (BM + all supplements) maintains functionality of PLT under EC compatible conditions without masking the differences of PLT adherence on different polymeric substrates. These findings are important prerequisites for the establishment of a near-physiological in vitro thrombogenicity test system assessing polymer-based cardiovascular implant materials in contact with EC and PLT.
KW  - cyclic olefin copolymer
KW  - poly(tetrafluoroethylene)
KW  - endothelial cells
KW  - platelets
KW  - in vitro thrombogenicity testing
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22137006
SN  - 1422-0067
SN  - 1661-6596
VL  - 22
IS  - 13
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Schönemann, Eric
A1  - Koc, Julian
A1  - Karthäuser, Jana
A1  - Özcan, Onur
A1  - Schanzenbach, Dirk
A1  - Schardt, Lisa
A1  - Rosenhahn, Axel
A1  - Laschewsky, André
T1  - Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties
JF  - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2  - Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.biomac.0c01705
SN  - 1525-7797
SN  - 1526-4602
VL  - 22
IS  - 4
SP  - 1494
EP  - 1508
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ihlenburg, Ramona
A1  - Mai, Tobias
A1  - Thünemann, Andreas F.
A1  - Baerenwald, Ruth
A1  - Saalwächter, Kay
A1  - Koetz, Joachim
A1  - Taubert, Andreas
T1  - Sulfobetaine hydrogels with a complex multilength-scale hierarchical structure
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N',N'-tetramethyl-N,N'-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers.
KW  - Defects
KW  - Hydrogels
KW  - Nuclear magnetic resonance spectroscopy
KW  - Scattering
KW  - X-ray scattering
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpcb.0c10601
SN  - 1520-6106
SN  - 1520-5207
VL  - 125
IS  - 13
SP  - 3398
EP  - 3408
PB  - American Chemical Society
CY  - Washington
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  - Zhang, Pengfei
A1  - Rešetič, Andraž
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Multifunctionality in polymer networks by dynamic of coordination bonds
JF  - Macromolecular chemistry and physics
N2  - The need for multifunctional materials is driven by emerging technologies and innovations, such as in the field of soft robotics and tactile or haptic systems, where minimizing the number of operational components is not only desirable, but can also be essential for realizing such devices. This study report on designing a multifunctional soft polymer material that can address a number of operating requirements such as solvent resistance, reshaping ability, self-healing capability, fluorescence stimuli-responsivity, and anisotropic structural functions. The numerous functional abilities are associated to rhodium(I)-phosphine coordination bonds, which in a polymer network act with their dynamic and non-covalently bonded nature as multifunctional crosslinks. Reversible aggregation of coordination bonds leads to changes in fluorescence emission intensity that responds to chemical or mechanical stimuli. The fast dynamics and diffusion of rhodium-phosphine ions across and through contacting areas of the material provide for reshaping and self-healing abilities that can be further exploited for assembly of multiple pieces into complex forms, all without any loss to material-sensing capabilities.
KW  - assembly capabilities
KW  - fluorescence stimuli‐ responsivity
KW  - multiple functions
KW  - reshaping abilities
KW  - rhodium(I)– phosphine
KW  - coordination bonds
KW  - solvent resistance
Y1  - 2021
U6  - https://doi.org/10.1002/macp.202000394
SN  - 1521-3935
VL  - 222
IS  - 3
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  - Machatschek, Rainhard Gabriel
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Hydrolytic stability of polyetherimide investigated in ultrathin films
JF  - Journal of materials research : JMR / Materials Research Society
N2  - Increasing the surface hydrophilicity of polyetherimide (PEI) through partial hydrolysis of the imide groups while maintaining the length of the main-chain was explored for adjusting its function in biomedical and membrane applications. The outcome of the polymer analogous reaction, i.e., the degree of ring opening and chain cleavage, is difficult to address in bulk and microstructured systems, as these changes only occur at the interface. Here, the reaction was studied at the air-water interface using the Langmuir technique, assisted by atomic force microscopy and vibrational spectroscopy. Slow PEI hydrolysis sets in at pH > 12. At pH = 14, the ring opening is nearly instantaneous. Reduction of the layer viscosity with time at pH = 14 suggested moderate chain cleavage. No hydrolysis was observed at pH = 1. Hydrolyzed PEI films had a much more cohesive structure, suggesting that the nanoporous morphology of PEI can be tuned via hydrolysis.
KW  - 2D materials
KW  - Membrane
KW  - Polymer
KW  - Water
KW  - Nanostructure
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00267-6
SN  - 0884-2914
SN  - 2044-5326
VL  - 36
IS  - 14
SP  - 2987
EP  - 2994
PB  - Springer
CY  - Berlin
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  - THES
A1  - Breternitz, Joachim
T1  - Structural systematic investigations of photovoltaic absorber materials
N2  - The direct conversion of light from the sun into usable forms of energy marks one of the central cornerstones of the change of our living from the use of fossil, non-renewable energy resources towards a more sustainable economy. Besides the necessary societal changes necessary, it is  the understanding of the solids employed that is of particular importance for the success of this target. In this work, the principles and approaches of systematic-crystallographic characterisation and systematisation of solids is used and employed to allow a directed tuning of the materials properties. The thorough understanding of the solid-state forms hereby the basis, on which more applied approaches are founded.
Two material systems, which are considered as promising solar absorber materials, are at the core of this work: halide perovskites and II-IV-N2 nitride materials. While the first is renowned for its high efficiencies and rapid development in the last years, the latter is putting an emphasis on true sustainability in that toxic and scarce elements are avoided.
N2  - Die direkte Umwandlung der Energie der Sonne bildet einen zentralen Baustein im Umbau unserer Gesellschaft von der Nutzung fossiler, nicht nachhaltiger Energieträger zum Erreichen einer nachhaltigen Wirtschaft. Neben den gesellschaftlichen Veränderungen ist es insbesondere das Verständnis der genutzten Festkörper, das den Motor dieser Entwicklung bildet. In dieser Arbeit werden Prinzipien der systematisch-kristallographischen Untersuchung und Kategorisierung von Festkörpern genutzt, um die Eigenschaften der Materialien gezielt steuern zu können. Dabei bildet das Verständnis des kristallinen Zustands und seine Untersuchung die Basis, auf der angewandtere Forschungsansätze aufbauen.
In dieser Arbeit werden vor allem zwei Materialsysteme betrachtet, die als Absorbermaterialien in Solarzellen in Betracht gezogen werden: Halid-Perowskite und II-IV-N2-Nitrid Materialien. Die ersteren zeichnen sich insbesondere durch ihre erstaunlich hohen Effizienzen und rapide Entwicklung in den letzten Jahren aus, während das letztere System in besonderer Weise auf Nachhaltigkeit optimiert ist, und giftige oder seltene Elemente zu vermeiden sucht.
KW  - Materials Chemistry
KW  - Crystallography
KW  - Photovoltaics
Y1  - 2023
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  - 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  - 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  - Hartlieb, Matthias
A1  - Mansfield, Edward D. H.
A1  - Perrier, Sebastien
T1  - A guide to supramolecular polymerizations
JF  - Polymer Chemistry
N2  - Supramolecular polymers or fibers are non-covalent assemblies of unimeric building blocks connected by secondary interactions such as hydrogen bonds or pi-pi interactions. Such structures hold enormous potential in the development of future materials, as their non-covalent nature makes them highly modular and adaptive. Within this review we aim to provide a broad overview over the area of linear supramolecular polymers including the different mechanisms of their polymerization as well as methods essential for their characterization. The different non-covalent interactions able to form supramolecular polymers are discussed, and key examples for each species are shown. Particular emphasis is laid on the development of living supramolecular polymerization able to produce fibers with a controlled length and low length dispersity, and even enable the production of supramolecular block copolymers. Another important and very recent field is the development of out-of-equilibrium supramolecular polymers, where the polymerization process can be temporally controlled enabling access to highly adaptive materials.
Y1  - 2020
U6  - https://doi.org/10.1039/c9py01342c
SN  - 1759-9954
SN  - 1759-9962
VL  - 11
IS  - 6
SP  - 1083
EP  - 1110
PB  - Royal Society of Chemistry
CY  - Cambridge
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  - Machatschek, Rainhard Gabriel
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Thin-layer studies on surface functionalization of polyetherimide
BT  - hydrolysis versus amidation
JF  - Journal of materials research : JMR / Materials Research Society
N2  - Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties.
KW  - Membrane
KW  - Nanostructure
KW  - Polymer
KW  - Raman spectroscopy
KW  - Scanning probe microscopy (SPM)
KW  - Surface reaction
KW  - Thin film
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00339-7
SN  - 0884-2914
SN  - 2044-5326
VL  - 37
IS  - 1
SP  - 67
EP  - 76
PB  - Springer
CY  - Berlin
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  - 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  - GEN
A1  - Moerschbacher, Bruno
A1  - Jaworska, Małgorzata
A1  - Peter, Martin G.
T1  - Obituary of George A.F. Roberts (1939-2018)
T2  - Reactive & functional polymers
Y1  - 2020
U6  - https://doi.org/10.1016/j.reactfunctpolym.2020.104711
SN  - 1381-5148
SN  - 1873-166X
VL  - 156
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Franz, Alexandra
A1  - Többens, Daniel M.
A1  - Lehmann, Frederike
A1  - Kärgell, Martin
A1  - Schorr, Susan
T1  - The influence of deuteration on the crystal structure of hybrid halide perovskites: a temperature-dependent neutron diffraction study of FAPbBr(3)
JF  - Acta crystallographica; Section B, Structural science, crystal engineering and materials
N2  - This paper discusses the full structural solution of the hybrid perovskite formamidinium lead tribromide (FAPbBr(3)) and its temperature-dependent phase transitions in the range from 3 K to 300 K using neutron powder diffraction and synchrotron X-ray diffraction. Special emphasis is put on the influence of deuteration on formamidinium, its position in the unit cell and disordering in comparison to fully hydrogenated FAPbBr(3). The temperature-dependent measurements show that deuteration critically influences the crystal structures, i.e. results in partially-ordered temperature-dependent structural modifications in which two symmetry-independent molecule positions with additional dislocation of the molecular centre atom and molecular angle inclinations are present.
KW  - hybrid perovskite
KW  - FAPbBr(3)
KW  - deuteration
KW  - neutron powder diffraction
KW  - crystal structure
Y1  - 2020
U6  - https://doi.org/10.1107/S2052520620002620
SN  - 2052-5206
VL  - 76
IS  - 2
SP  - 267
EP  - 274
PB  - Wiley-Blackwell
CY  - Oxford [u.a.]
ER  - 
TY  - JOUR
A1  - Gu, Sasa
A1  - Risse, Sebastian
A1  - Lu, Yan
A1  - Ballauff, Matthias
T1  - Mechanism of the oxidation of 3,3′,5,5′-tetramethylbenzidine catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes
BT  - a kinetic study
JF  - ChemPhysChem
N2  - Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3 ',5,5 '-tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H2O2) catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB-Pt). Due to the high stability of SPB-Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time-dependent concentration of the blue-colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H2O2 and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir-Hinshelwood mechanism. A true rate constant k, characterizing the rate-determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase-like nanoparticles.
KW  - kinetics
KW  - nanoparticles
KW  - reaction mechanisms
KW  - spherical polyelectrolyte
KW  - brushes
KW  - UV
KW  - vis spectroscopy
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201901087
SN  - 1439-4235
SN  - 1439-7641
VL  - 21
IS  - 5
SP  - 450
EP  - 458
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Gharabekyan, Hrant H.
A1  - Koetz, Joachim
A1  - Poghosyan, Armen H.
T1  - A protonated L-cysteine adsorption on gold surface
BT  - a molecular dynamics study
JF  - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects
N2  - The adsorption of protonated L-cysteine onto Au(111) surface was studied via molecular dynamics method. The detailed examination of trajectories reveals that a couple of picoseconds need to be strongly adsorbed at the gold surface via L-cysteine's sulfur and oxygen atoms. The average distances of L-cysteine's adsorbed sulfur and oxygen from gold plane are-2.7 angstrom and-3.2 angstrom, correspondingly. We found that the adsorption of L-cysteine takes place preferentially at bridge site with possibility of-82%. Discussing the conformation features of protonated L-cysteine, we consider that the most stable conformation of protonated L-cysteine is "reverse boat" position, where sulfur and oxygen pointed down to the gold surface, while the amino group is far from the gold surface.
KW  - MD simulations
KW  - gold surface
KW  - GOIP
KW  - l-cysteine
KW  - adsorption
KW  - protonation
Y1  - 2021
U6  - https://doi.org/10.1016/j.colsurfa.2021.127452
SN  - 0927-7757
SN  - 1873-4359
VL  - 629
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bouakline, Foudhil
A1  - Saalfrank, Peter
T1  - Seemingly asymmetric atom-localized electronic densities following laser-dissociation of homonuclear diatomics
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
N2  - Recent experiments on laser-dissociation of aligned homonuclear diatomic molecules show an asymmetric forward-backward (spatial) electron-localization along the laser polarization axis. Most theoretical models attribute this asymmetry to interference effects between gerade and ungerade vibronic states. Presumably due to alignment, these models neglect molecular rotations and hence infer an asymmetric (post-dissociation) charge distribution over the two identical nuclei. In this paper, we question the equivalence that is made between spatial electron-localization, observed in experiments, and atomic electron-localization, alluded by these theoretical models. We show that (seeming) agreement between these models and experiments is due to an unfortunate omission of nuclear permutation symmetry, i.e., quantum statistics. Enforcement of the latter requires mandatory inclusion of the molecular rotational degree of freedom, even for perfectly aligned molecules. Unlike previous interpretations, we ascribe spatial electron-localization to the laser creation of a rovibronic wavepacket that involves field-free molecular eigenstates with opposite space-inversion symmetry i.e., even and odd parity. Space-inversion symmetry breaking would then lead to an asymmetric distribution of the (space-fixed) electronic density over the forward and backward hemisphere. However, owing to the simultaneous coexistence of two indistinguishable molecular orientational isomers, our analytical and computational results show that the post-dissociation electronic density along a specified space-fixed axis is equally shared between the two identical nuclei-a result that is in perfect accordance with the principle of the indistinguishability of identical particles. Published under an exclusive license by AIP Publishing.
Y1  - 2021
U6  - https://doi.org/10.1063/5.0049710
SN  - 0021-9606
SN  - 1089-7690
VL  - 154
IS  - 23
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Qiu, Liang
A1  - Zhang, Haoran
A1  - Bick, Thomas
A1  - Martin, Johannes
A1  - Wendler, Petra
A1  - Böker, Alexander
A1  - Glebe, Ulrich
A1  - Xing, Chengfen
T1  - Construction of highly ordered glyco-inside nano-assemblies through RAFT dispersion polymerization of galactose-decorated monomer
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - Glyco-assemblies derived from amphiphilic sugar-decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco-assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco-inside nano-assemblies by utilizing RAFT polymerization of a galactose-decorated methacrylate for polymerization-induced self-assembly (PISA). Using this approach, a series of highly ordered glyco-inside nano-assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco-assemblies with tunable morphologies and variable sizes, which is significant to enable the large-scale fabrication and wide application of glyco-assemblies.
KW  - galactose-decorated monomer
KW  - glyco-inside nano-assemblies
KW  - morphology
KW  - evolution
KW  - PISA
KW  - RAFT dispersion polymerization
Y1  - 2021
U6  - https://doi.org/10.1002/anie.202015692
SN  - 1433-7851
SN  - 1521-3773
VL  - 60
IS  - 20
SP  - 11098
EP  - 11103
PB  - Wiley-VCH
CY  - Weinheim
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  - Sperlich, Eric
A1  - Köckerling, Martin
T1  - Cluster salts [Nb6Cl12(HIm)(6)]A(n) (with HIm=1H-imidazole and A=Mineral Acid Anion, n=1 or 2) made in and with Bronsted-basic ionic liquids and liquid mixtures
JF  - ChemistryOpen
N2  - Four new hexanuclear niobium cluster compounds of the general formula [Nb6Cl12(HIm)(6)](A)(n) . x(solvent molecule) (HIm=1H-imidazole, A=mineral acid anion, Cl- (n=2) (1), (SO4)(2-) (n=1) (2), (CrO4)(2-) (n=1) (3), and (HAsO4)(2-) (n=1) (4)) were prepared. Their synthesis can be done in basic ionic liquids, which form on the addition of a mineral acid, which also delivers the counter anion for the final cluster compound, to an excess of the 1H-imidazole. Some addition of an auxiliary solvent, like methanol, improves the speed of crystallisation. The cluster unit comprises a hexanuclear Nb-6 unit of octahedral shape with the edges bridged by Cl atoms and the exo sites being occupied by N-bonded 1H-imidazole ligands. The cluster cation carries sixteen cluster-based electrons. Between the NH groups of the ligands of the cluster unit, the anions and the co-crystallised water (1), or 1H-imidazole and methanol molecules (2, 3, and 4) a network of hydrogen bonds exists.
KW  - cluster
KW  - ionic liquid
KW  - structure elucidation
KW  - heterocyclic ligand
KW  - Niobium
Y1  - 2021
U6  - https://doi.org/10.1002/open.202000266
SN  - 2191-1363
VL  - 10
IS  - 2
SP  - 248
EP  - 254
PB  - Wiley-VCH
CY  - Weinheim
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  - 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  - Wojcik, Michal
A1  - Brinkmann, Pia
A1  - Zdunek, Rafał
A1  - Riebe, Daniel
A1  - Beitz, Toralf
A1  - Merk, Sven
A1  - Cieslik, Katarzyna
A1  - Mory, David
A1  - Antonczak, Arkadiusz
T1  - Classification of copper minerals by handheld laser-induced breakdown spectroscopy and nonnegative tensor factorisation
JF  - Sensors
N2  - Laser-induced breakdown spectroscopy (LIBS) analysers are becoming increasingly common for material classification purposes. However, to achieve good classification accuracy, mostly noncompact units are used based on their stability and reproducibility. In addition, computational algorithms that require significant hardware resources are commonly applied. For performing measurement campaigns in hard-to-access environments, such as mining sites, there is a need for compact, portable, or even handheld devices capable of reaching high measurement accuracy. The optics and hardware of small (i.e., handheld) devices are limited by space and power consumption and require a compromise of the achievable spectral quality. As long as the size of such a device is a major constraint, the software is the primary field for improvement. In this study, we propose a novel combination of handheld LIBS with non-negative tensor factorisation to investigate its classification capabilities of copper minerals. The proposed approach is based on the extraction of source spectra for each mineral (with the use of tensor methods) and their labelling based on the percentage contribution within the dataset. These latent spectra are then used in a regression model for validation purposes. The application of such an approach leads to an increase in the classification score by approximately 5% compared to that obtained using commonly used classifiers such as support vector machines, linear discriminant analysis, and the k-nearest neighbours algorithm.
KW  - LIBS
KW  - NTF
KW  - HALS
KW  - classification
KW  - copper minerals
Y1  - 2020
U6  - https://doi.org/10.3390/s20185152
SN  - 1424-8220
VL  - 20
IS  - 18
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kaya, Kerem
A1  - Debsharma, Tapas
A1  - Schlaad, Helmut
A1  - Yagci, Yusuf
T1  - Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether
JF  - Polymer Chemistry
N2  - This study aims to explore the photoinitiated cationic ring-opening polymerization of levoglucosenyl methyl ether (LGME), a chemical obtained from the most abundant biomass - cellulose. Direct and sensitized photopolymerizations of LGME using photoinitiators acting at the near UV or visible range in conjunction with diphenyliodonium hexafluoroantimonate (DPI) yielded unsaturated polyacetals with varying molar masses and distributions.
Y1  - 2020
U6  - https://doi.org/10.1039/d0py01307b
SN  - 1759-9954
SN  - 1759-9962
VL  - 11
IS  - 43
SP  - 6884
EP  - 6889
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Yan, Runyu
A1  - Oschatz, Martin
A1  - Wu, Feixiang
T1  - Towards stable lithium-sulfur battery cathodes by combining physical and chemical confinement of polysulfides in core-shell structured nitrogen-doped carbons
JF  - Carbon
N2  - Despite intensive research on porous carbon materials as hosts for sulfur in lithium-sulfur battery cathodes, it remains a problem to restrain the soluble lithium polysulfide intermediates for a long-term cycling stability without the use of metallic or metal-containing species. Here, we report the synthesis of nitrogen-doped carbon materials with hierarchical pore architecture and a core-shell-type particle design including an ordered mesoporous carbon core and a polar microporous carbon shell. The initial discharge capacity with a sulfur loading up to 72 wt% reaches over 900 mA h g(sulf)(ur)(-1) at a rate of C/2. Cycling performance measured at C/2 indicates similar to 90% capacity retention over 250 cycles. In comparison to other carbon hosts, this architecture not only provides sufficient space for a high sulfur loading induced by the high-pore-volume particle core, but also enables a dual effect of physical and chemical confinement of the polysulfides to stabilize the cycle life by adsorbing the soluble intermediates in the polar microporous shell. This work elucidates a design principle for carbonaceous hosts that is capable to provide simultaneous physical-chemical confinement. This is necessary to overcome the shuttle effect towards stable lithium-sulfur battery cathodes, in the absence of additional membranes or inactive metal-based anchoring materials.
KW  - lithium-sulfur battery
KW  - sulfur
KW  - porous carbon
KW  - cathode
KW  - polysulfides
Y1  - 2020
U6  - https://doi.org/10.1016/j.carbon.2020.01.046
SN  - 0008-6223
SN  - 1873-3891
VL  - 161
SP  - 162
EP  - 168
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Zhang, Pengfei
A1  - Behl, Marc
A1  - Balk, Maria
A1  - Peng, Xingzhou
A1  - Lendlein, Andreas
T1  - Shape-programmable architectured hydrogels sensitive to ultrasound
JF  - Macromolecular rapid communications
N2  - On-demand motion of highly swollen polymer systems can be triggered by changes in pH, ion concentrations, or by heat. Here, shape-programmable, architectured hydrogels are introduced, which respond to ultrasonic-cavitation-based mechanical forces (CMF) by directed macroscopic movements. The concept is the implementation and sequential coupling of multiple functions (swellability in water, sensitivity to ultrasound, shape programmability, and shape-memory) in a semi-interpenetrating polymer network (s-IPN). The semi-IPN-based hydrogels are designed to function through rhodium coordination (Rh-s-IPNH). These coordination bonds act as temporary crosslinks. The porous hydrogels with coordination bonds (degree of swelling from 300 +/- 10 to 680 +/- 60) exhibit tensile strength sigma(max) up to 250 +/- 60 kPa. Shape fixity ratios up to 90% and shape recovery ratios up to 94% are reached. Potential applications are switches or mechanosensors.
KW  - cavitation-based mechanical force
KW  - rhodium-phosphine coordination bonds
KW  - semi-IPN hydrogels
KW  - shape-memory effect
Y1  - 2020
U6  - https://doi.org/10.1002/marc.201900658
SN  - 1022-1336
SN  - 1521-3927
VL  - 41
IS  - 7
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Akarsu, Pinar
A1  - Grobe, Richard
A1  - Nowaczyk, Julius
A1  - Hartlieb, Matthias
A1  - Reinicke, Stefan
A1  - Böker, Alexander
A1  - Sperling, Marcel
A1  - Reifarth, Martin
T1  - Solid-phase microcontact printing for precise patterning of rough surfaces
BT  - using polymer-tethered elastomeric stamps for the transfer of reactive silanes
JF  - ACS applied polymer materials
N2  - We present a microcontact printing (mu CP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition-fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (H-1-H-1-NOESY-NMR). We analyze the mu CP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates.
KW  - microcontact printing
KW  - capillary-active substrates
KW  - silane chemistry
KW  - PDMS surface grafting
KW  - surface patterning
KW  - shuttled RAFT-polymerization
Y1  - 2021
U6  - https://doi.org/10.1021/acsapm.1c00024
SN  - 2637-6105
VL  - 3
IS  - 5
SP  - 2420
EP  - 2431
PB  - American Chemical Society
CY  - Washington
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  - Riemer, Nastja
A1  - Riemer, Martin
A1  - Krüger, Mandy
A1  - Clarkson, Guy J.
A1  - Shipman, Michael
A1  - Schmidt, Bernd
T1  - Synthesis of arylidene-beta-lactams via exo-selective Matsuda-Heck arylation of methylene-beta-lactams
JF  - The journal of organic chemistry : JOC
N2  - exo-Methylene-beta-lactams were synthesized in two steps from commercially available 3-bromo-2-(bromomethyl)-propionic acid and reacted with arene diazonium salts in a Heck-type arylation in the presence of catalytic amounts of Pd(OAc)(2) under ligand-free conditions. The products, arylidene-beta-lactams, were obtained in high yields as single isomers. The beta-hydride elimination step of the Pd-catalyzed coupling reaction proceeds with high exo-regioselectivity and E-stereoselectivity. With aryl iodides, triflates, or bromides, the coupling products were isolated only in low yields, due to extensive decomposition of the starting material at elevated temperatures. This underlines that arene diazonium salts can be superior arylating reagents in Heck-type reactions and yield coupling products in synthetically useful yields and selectivities when conventional conditions fail.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.joc.1c00638
SN  - 0022-3263
SN  - 1520-6904
VL  - 86
IS  - 13
SP  - 8786
EP  - 8796
PB  - American Chemical Society
CY  - Washington
ER  -