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  - Fortes Martín, Rebeca
A1  - Prietzel, Claudia Christina
A1  - Koetz, Joachim
T1  - Template-mediated self-assembly of magnetite-gold nanoparticle superstructures at the water-oil interface of AOT reverse microemulsions
JF  - Journal of colloid and interface science
N2  - Hypothesis: Bimetallic magnetite-gold nanostructures are interesting candidates to combine and enhance individual properties of each metal element in catalytic and analytical applications. Microemulsions have been employed in templated synthesis of nanoparticles, and their combination with different types of nanoparticles can further mediate interactions at the water-oil interface, providing new forms of hybrid nanostructures. 

Experiments: Reverse water-in-oil microemulsions of droplet sizes below 50 nm were prepared from ternary mixtures of Aerosol-OT (AOT) as surfactant, incorporating 4 nm sized superparamagnetic nanoparticles (MNPs) to the hexane-pentanol oil phase and 5 nmsized polyethyleneimine-stabilized gold nanoparticles (Au(PEI)-NPs) to the water phase. The resulting isotropic L-2 phase, Winsor phases and organized nanostructures were investigated using conductometry, calorimetry, UV-Vis spectroscopy, cryoSEM and HRTEM. 

Findings: Droplet-droplet interactions, morphology and surfactant film properties of AOT microemulsions could be modulated in different ways by the presence of the different nanoparticles from each liquid phase. Additionally, phase separation into Winsor phases allows the formation upon solvent evaporation of films with bimetallic heterostructures on the micrometer scale. This demonstrates a new way of nanoparticle templated assembly at liquid interfaces by assisted interactions between microemulsions and nanoparticles, as a promising strategy to obtain thin films of small, isotropic nanoparticles with hierarchical ordering.
KW  - AOT
KW  - Magnetite-gold nanoparticles
KW  - Microemulsions
KW  - Percolation
KW  - Templated self-assembly
KW  - Winsor phases
Y1  - 2021
U6  - https://doi.org/10.1016/j.jcis.2020.07.079
SN  - 0021-9797
SN  - 1095-7103
VL  - 581
IS  - Part A
SP  - 44
EP  - 55
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Krüger, Tobias
A1  - Linker, Torsten
T1  - Synthesis of gamma-spirolactams by Birch reduction of arenes
JF  - European journal of organic chemistry
N2  - A convenient method for the synthesis of gamma-spirolactams in only three steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of chloroacetonitrile affords nitriles in moderate to good yields. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and anthroic acid. Subsequent catalytic hydrogenation proceeds smoothly with PtO2 or Raney Ni as catalysts and lactams are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation at different pressures, affording products with 0, 1, or 2 double bonds. Overall, more than 15 new gamma-spirolactams have been synthesized in analytically pure form.
KW  - Arenes
KW  - Birch reduction
KW  - Hydrogenation
KW  - Lactams
KW  - Synthetic methods
Y1  - 2021
U6  - https://doi.org/10.1002/ejoc.202100056
SN  - 1099-0690
VL  - 2021
IS  - 10
SP  - 1585
EP  - 1591
PB  - Wiley-VCH
CY  - Weinheim
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  - 
TY  - JOUR
A1  - Schwarze, Thomas
A1  - Sperlich, Eric
A1  - Müller, Thomas
A1  - Kelling, Alexandra
A1  - Holdt, Hans-Jürgen
T1  - Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter
JF  - Helvetica chimica acta
N2  - In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red.
KW  - copper
KW  - fumaronitrile
KW  - ligands
KW  - macrocycles
KW  - maleonitrile
Y1  - 2021
U6  - https://doi.org/10.1002/hlca.202100028
SN  - 1522-2675
VL  - 104
IS  - 6
SP  - e2100028
PB  - Wiley-VCH
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  - Frieß, Fabian
A1  - Lendlein, Andreas
A1  - Wischke, Christian
T1  - Switching microobjects from low to high aspect ratios using a shape-memory effect
JF  - Soft matter
N2  - Spherical particles from shape-memory polymers (SMP) can be stretched to ellipsoids with high aspect ratio (AR) and temporarily stabilized. They can switch back to low AR upon thermal stimulation. Here, the creation of an alternative shape-switching capability of particles from low to high AR is introduced, where a SMP matrix from polyvinyl alcohol (PVA) is used to create crosslinked high AR particles and to program the embedded micrometer-sized particles from a second SMP (oligo(epsilon-caprolactone) micronetworks, MN) with a low switching temperature T-sw. This programming proceeds through shape-recovery of the PVA matrix, from which the MN are harvested by PVA matrix dissolution. The use of a dissolvable SMP matrix may be a general strategy to efficiently create systems with complex moving capabilities.
Y1  - 2021
U6  - https://doi.org/10.1039/d1sm00947h
SN  - 1744-6848
VL  - 17
IS  - 41
SP  - 9326
EP  - 9331
PB  - Royal Society of Chemistry
CY  - London
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  - Ihlenburg, Ramona
A1  - Lehnen, Anne-Catherine
A1  - Koetz, Joachim
A1  - Taubert, Andreas
T1  - Sulfobetaine Cryogels for Preferential Adsorption of Methyl Orange from Mixed Dye Solutions
JF  - Polymers / Molecular Diversity Preservation International
N2  - New cryogels for selective dye removal from aqueous solution were prepared by free radical polymerization from the highly water-soluble crosslinker N,N,N’,N’-tetramethyl-N,N’-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The resulting white and opaque cryogels have micrometer sized pores with a smaller substructure. They adsorb methyl orange (MO) but not methylene blue (MB) from aqueous solution. Mixtures of MO and MB can be separated through selective adsorption of the MO to the cryogels while the MB remains in solution. The resulting cryogels are thus candidates for the removal of hazardous organic substances, as exemplified by MO and MB, from water. Clearly, it is possible that the cryogels are also potentially interesting for removal of other compounds such as pharmaceuticals or pesticides, but this must be investigated further.
KW  - cryogel
KW  - water treatment
KW  - dye removal
KW  - methyl orange
KW  - methylene blue
KW  - dye mixture
Y1  - 2020
U6  - https://doi.org/10.3390/polym13020208
SN  - 2073-4360
VL  - 13
IS  - 2
PB  - MDPI
CY  - Basel
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  - Bauch, Marcel
A1  - Fudickar, Werner
A1  - Linker, Torsten
T1  - Stereoselective [4+2] Cycloaddition of Singlet Oxygen to Naphthalenes Controlled by Carbohydrates
JF  - Molecules : a journal of synthetic chemistry and natural product chemistry
N2  - Stereoselective reactions of singlet oxygen are of current interest. Since enantioselective photooxygenations have not been realized efficiently, auxiliary control is an attractive alternative. However, the obtained peroxides are often too labile for isolation or further transformations into enantiomerically pure products. Herein, we describe the oxidation of naphthalenes by singlet oxygen, where the face selectivity is controlled by carbohydrates for the first time. The synthesis of the precursors is easily achieved starting from naphthoquinone and a protected glucose derivative in only two steps. Photooxygenations proceed smoothly at low temperature, and we detected the corresponding endoperoxides as sole products by NMR. They are labile and can thermally react back to the parent naphthalenes and singlet oxygen. However, we could isolate and characterize two enantiomerically pure peroxides, which are sufficiently stable at room temperature. An interesting influence of substituents on the stereoselectivities of the photooxygenations has been found, ranging from 51:49 to up to 91:9 dr (diastereomeric ratio). We explain this by a hindered rotation of the carbohydrate substituents, substantiated by a combination of NOESY measurements and theoretical calculations. Finally, we could transfer the chiral information from a pure endoperoxide to an epoxide, which was isolated after cleavage of the sugar chiral auxiliary in enantiomerically pure form.
KW  - singlet oxygen
KW  - photooxygenation
KW  - naphthalenes
KW  - carbohydrates
KW  - stereoselectivity
KW  - auxiliary control
KW  - [4+2] cycloaddition
Y1  - 2021
U6  - https://doi.org/10.3390/molecules26040804
SN  - 1420-3049
VL  - 16
IS  - 4
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kogikoski Junior, Sergio
A1  - Dutta, Anushree
A1  - Bald, Ilko
T1  - Spatial separation of plasmonic hot-electron generation and a hydrodehalogenation reaction center using a DNA wire
JF  - ACS nano
N2  - Using hot charge carriers far from a plasmonic nanoparticle surface is very attractive for many applications in catalysis and nanomedicine and will lead to a better understanding of plasmon-induced processes, such as hot-charge-carrier- or heat-driven chemical reactions. Herein we show that DNA is able to transfer hot electrons generated by a silver nanoparticle over several nanometers to drive a chemical reaction in a molecule nonadsorbed on the surface. For this we use 8-bromo-adenosine introduced in different positions within a double-stranded DNA oligonucleotide. The DNA is also used to assemble the nanoparticles into nanoparticles ensembles enabling the use of surface-enhanced Raman scattering to track the decomposition reaction. To prove the DNA-mediated transfer, the probe molecule was insulated from the source of charge carriers, which hindered the reaction. The results indicate that DNA can be used to study the transfer of hot electrons and the mechanisms of advanced plasmonic catalysts.
KW  - plasmonics
KW  - DNA nanotechnology
KW  - hot electrons
KW  - charge transfer
KW  - SERS
KW  - superlattices
Y1  - 2021
U6  - https://doi.org/10.1021/acsnano.1c09176
SN  - 1936-0851
SN  - 1936-086X
VL  - 15
IS  - 12
SP  - 20562
EP  - 20573
PB  - American Chemical Society
CY  - Washington
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  - Neffe, Axel T.
A1  - Izraylit, Victor
A1  - Hommes-Schattmann, Paul J.
A1  - Lendlein, Andreas
T1  - Soft, formstable (Co)polyester blend elastomers
JF  - Nanomaterials : open access journal
N2  - High crystallization rate and thermomechanical stability make polylactide stereocomplexes effective nanosized physical netpoints. Here, we address the need for soft, form-stable degradable elastomers for medical applications by designing such blends from (co)polyesters, whose mechanical properties are ruled by their nanodimensional architecture and which are applied as single components in implants. By careful controlling of the copolymer composition and sequence structure of poly[(L-lactide)-co-(epsilon-caprolactone)], it is possible to prepare hyperelastic polymer blends formed through stereocomplexation by adding poly(D-lactide) (PDLA). Low glass transition temperature T-g <= 0 degrees C of the mixed amorphous phase contributes to the low Young's modulus E. The formation of stereocomplexes is shown in DSC by melting transitions T-m > 190 degrees C and in WAXS by distinct scattering maxima at 2 theta = 12 degrees and 21 degrees. Tensile testing demonstrated that the blends are soft (E = 12-80 MPa) and show an excellent hyperelastic recovery R-rec = 66-85% while having high elongation at break epsilon(b) up to >1000%. These properties of the blends are attained only when the copolymer has 56-62 wt% lactide content, a weight average molar mass >140 kg center dot mol(-1), and number average lactide sequence length >= 4.8, while the blend is formed with a content of 5-10 wt% of PDLA. The devised strategy to identify a suitable copolymer for stereocomplexation and blend formation is transferable to further polymer systems and will support the development of thermoplastic elastomers suitable for medical applications.
KW  - thermoplastic elastomer
KW  - biomaterial
KW  - stereocomplexes
KW  - mechanical
KW  - properties
KW  - form stability
KW  - crystallinity
Y1  - 2021
U6  - https://doi.org/10.3390/nano11061472
SN  - 2079-4991
VL  - 11
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Friess, Fabian
A1  - Lendlein, Andreas
A1  - Wischke, Christian
T1  - Size control of shape switchable micronetworks by fast two-step microfluidic templating
JF  - Journal of materials research
N2  - Shape-memory polymer micronetworks (MN) are micrometer-sized objects that can switch their outer shape upon external command.This study aims to scale MN sizes to the low micrometer range at very narrow size distributions. In a two-step microfluidic strategy, the specific design of coaxial class capillary devices allowed stabilizing the thread of the dispersed phase to efficiently produce precursor particles in the tip-streaming regime at rates up to similar to 170 kHz and final sizes down to 4 mu m. In a subsequent melt-based microfluidic photocrosslinking of the methacrylate-functionalized oligo(epsilon-caprolactone) precursor material, MN could be produced without particle aggregation. A comprehensive analysis of MN properties illustrated successful crosslinking, semi-crystalline morphology, and a shape-switching functionality for all investigated MN sizes (4, 6, 9, 12, 22 mu m). Such functional micronetworks tailored to and below the dimension of cells can enable future applications in technology and medicine like controlling cell interaction.
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00295-2
SN  - 0884-2914
SN  - 2044-5326
VL  - 36
IS  - 16
SP  - 3248
EP  - 3257
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Lendlein, Andreas
A1  - Heuchel, Matthias
T1  - Shape-memory polymers designed in view of thermomechanical energy storage and conversion systems
BT  - Effective temporary shape fixation by strain-induced formation of supramolecular nanostructures enables high energy density one-way shape-memory polymers
JF  - ACS central science
KW  - Actuators
KW  - Deformation
KW  - Energy
KW  - Energy storage
KW  - Polymers
Y1  - 2021
U6  - https://doi.org/10.1021/acscentsci.1c01032
SN  - 2374-7951
VL  - 7
IS  - 10
SP  - 1599
EP  - 1601
PB  - American Chemical Society
CY  - Washington
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  - 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  - Kwesiga, George
A1  - Sperlich, Eric
A1  - Schmidt, Bernd
T1  - Scope and applications of 2,3-oxidative aryl rearrangements for the synthesis of isoflavone natural products
JF  - The journal of organic chemistry
N2  - The reaction of flavanones with hypervalent iodine reagents was investigated with a view to the synthesis of naturally occurring isoflavones. In contrast to several previous reports in the literature, we did not observe the formation of any benzofurans via a ring contraction pathway, but could isolate only isoflavones, resulting from an oxidative 2,3-aryl rearrangement, and flavones, resulting from an oxidation of the flavanones. Although the 2,3-oxidative rearrangement allows a synthetically useful approach toward some isoflavone natural products due to the convenient accessibility of the required starting materials, the overall synthetic utility and generality of the reaction appear to be more limited than previous literature reports suggest.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.joc.1c01375
SN  - 0022-3263
SN  - 1520-6904
VL  - 86
IS  - 15
SP  - 10699
EP  - 10712
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Hermanns, Jolanda
A1  - Keller, David
T1  - School-related content knowledge in organic chemistry
BT  - How does the Bachelor and Master studies?
JF  - Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society
N2  - In this paper the development, use, and evaluation of tasks based on the construct of school-related content knowledge are described. The tasks were used in seminars on organic chemistry for bachelor and master preservice chemistry teachers at a German university. For the evaluation a questionnaire with open and closed items was used. The tasks were rated by the preservice chemistry teachers as relevant for their future profession as a chemistry teacher if the content of the tasks is part of the school curriculum. If the content does not belong to the school curriculum, they rated the nature of the tasks still as relevant; they seem to recognize the importance of conceptual knowledge for their future profession. However, the master's preservice teachers argued with this conceptual knowledge more often than the bachelor's preservice teachers. Although the study is cross-sectional, a certain shift from the focus on the content to conceptual knowledge from bachelor's to master's preservice teachers can be observed.
KW  - Organic Chemistry
KW  - Second-Year Undergraduate
KW  - Analogies/Transfer
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jchemed.0c01415
SN  - 0021-9584
SN  - 1938-1328
VL  - 98
IS  - 3
SP  - 763
EP  - 773
PB  - American Chemical Society
CY  - Washington
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  - Sand, Patrick
A1  - Schmidt, Bernd
T1  - Ruthenium-catalyzed sulfoalkenylation of acetanilides and dual-use of the catalyst directing group
JF  - European journal of organic chemistry
N2  - In contrast to vinylsulfonates and vinylsulfones, vinylsulfonamides are unreactive in Pd-catalyzed oxidative Heck-coupling reactions with acetanilides. This limitation has been resolved by using a C-H-activation protocol based on Ru-Cu-Ag-catalysis. Overall, the Ru-Cu-Ag-catalyzed conditions turned out to be more reliable and showed better reproducibility than the Pd-catalyzed C-H-activation. The coupling products thus obtained are functionalized styrenyl sulfones and -sulfonamides which can be used as starting materials for the synthesis of sulfonyl pyrroles and sulfonyl pyrrolo[2,3-c]quinolines.
KW  - Arenes
KW  - C-H activation
KW  - Heterocycles
KW  - Ruthenium
KW  - Sulfonamides
Y1  - 2021
U6  - https://doi.org/10.1002/ejoc.202101216
SN  - 1434-193X
SN  - 1099-0690
VL  - 2021
IS  - 40
SP  - 5497
EP  - 5506
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Debsharma, Tapas
A1  - Schmidt, Bernd
A1  - Laschewsky, Andre
A1  - Schlaad, Helmut
T1  - Ring-opening metathesis polymerization of unsaturated carbohydrate derivatives
BT  - levoglucosenyl alkyl ethers
JF  - Macromolecules : a publication of the American Chemical Society
N2  - A series of biomass-derived levoglucosenyl alkyl ethers (alkyl = methyl, ethyl, n-propyl, isopropyl, and n-butyl) were synthesized and polymerized by ring-opening olefin metathesis polymerization using the Grubbs catalyst C793 at room temperature. Polymerizations were successfully performed in conventional solvents such as 1,4-dioxane and dichloromethane as well as in polar aprotic "green" solvents such as 2-methyltetrahydrofuran, dihydrolevoglucosenone (Cyrene), and ethyl acetate. The prepared polyacetals with degrees of polymerization of similar to 100 exhibit Schulz-Flory-type molar mass distributions and are thermoplastic materials with rather low glass transition temperatures in the range of 43-0 degrees C depending on the length of the alkyl substituent. Kinetic studies revealed that the polymerization proceeded rapidly to a steady state with a certain minimum monomer concentration threshold. When the steady state was reached, just about half of the [Ru] catalyst had been effective to initiate the polymerization, indicating that the initiation step was a slow process. The remaining catalyst was still active and did no longer react with monomers but with in-chain double bonds, cutting the formed polymer chains into shorter fragments. In the long term, all catalyst was consumed and propagating [Ru] chain ends were deactivated by the elimination of [Ru] from the chain ends to form inactive chains with terminal aldehyde groups.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.macromol.0c02821
SN  - 0024-9297
SN  - 1520-5835
VL  - 54
IS  - 6
SP  - 2720
EP  - 2728
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bastian, Philipp U.
A1  - Robel, Nathalie
A1  - Schmidt, Peter
A1  - Schrumpf, Tim
A1  - Günter, Christina
A1  - Roddatis, Vladimir
A1  - Kumke, Michael U.
T1  - Resonance energy transfer to track the motion of lanthanide ions
BT  - what drives the intermixing in core-shell upconverting nanoparticles?
JF  - Biosensors : open access journal
N2  - The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF4 and NaGdF4 was monitored. These investigations have been performed by laser spectroscopy with help of lanthanide resonance energy transfer (LRET) between Eu(III) as donor and Pr(III) or Nd(III) as acceptor. The LRET is evaluated based on the Forster theory. The findings corroborate the literature and point out the migration of ions in the host lattices. Based on the introduced LRET model, the acceptor concentration in the surrounding of one donor depends clearly on the design of the applied core-shell-shell nanoparticles. In general, thinner intermediate insulating shells lead to higher acceptor concentration, stronger quenching of the Eu(III) donor and subsequently stronger sensitization of the Pr(III) or the Nd(III) acceptors. The choice of the host lattice as well as of the synthesis temperature are parameters to be considered for the intermixing process.
KW  - upconversion nanoparticles
KW  - lanthanoid migration
KW  - lanthanides
KW  - core-shell
KW  - energy transfer
Y1  - 2021
U6  - https://doi.org/10.3390/bios11120515
SN  - 2079-6374
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
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  - Kogikoski Junior, Sergio
A1  - Tapio, Kosti
A1  - Edler von Zander, Robert
A1  - Saalfrank, Peter
A1  - Bald, Ilko
T1  - Raman enhancement of nanoparticle dimers self-assembled using DNA origami nanotriangles
JF  - Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International
N2  - Surface-enhanced Raman scattering is a powerful approach to detect molecules at very low concentrations, even up to the single-molecule level. One important aspect of the materials used in such a technique is how much the signal is intensified, quantified by the enhancement factor (EF). Herein we obtained the EFs for gold nanoparticle dimers of 60 and 80 nm diameter, respectively, self-assembled using DNA origami nanotriangles. Cy5 and TAMRA were used as surface-enhanced Raman scattering (SERS) probes, which enable the observation of individual nanoparticles and dimers. EF distributions are determined at four distinct wavelengths based on the measurements of around 1000 individual dimer structures. The obtained results show that the EFs for the dimeric assemblies follow a log-normal distribution and are in the range of 10(6) at 633 nm and that the contribution of the molecular resonance effect to the EF is around 2, also showing that the plasmonic resonance is the main source of the observed signal. To support our studies, FDTD simulations of the nanoparticle's electromagnetic field enhancement has been carried out, as well as calculations of the resonance Raman spectra of the dyes using DFT. We observe a very close agreement between the experimental EF distribution and the simulated values.
KW  - surface-enhanced Raman scattering
KW  - DNA origami
KW  - resonance Raman
KW  - scattering
KW  - nanoparticle dimers
Y1  - 2021
U6  - https://doi.org/10.3390/molecules26061684
SN  - 1420-3049
VL  - 26
IS  - 6
PB  - MDPI
CY  - Basel
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  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Quantification of sigma-acceptor and pi-donor stabilization in O, S and Hal analogues of N-heterocyclic carbenes (NHCs) on the magnetic criterion
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - The spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of stable O, S and Hal analogues of N-heterocyclic carbenes (NHCs) have been calculated using the GIAO perturbation method employing the nucleus-independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSSs) of various sizes and directions. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the position of the present mesomeric equilibria (carbenes <-> ylides). The results are confirmed by geometry (bond angles and bond lengths), IR spectra, UV spectra, and C-13 chemical shifts of the electron-deficient carbon centers.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpca.1c05257
SN  - 1089-5639
SN  - 1520-5215
VL  - 125
IS  - 33
SP  - 7235
EP  - 7245
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Fudickar, Werner
A1  - Roder, Phillip
A1  - Listek, Martin
A1  - Hanack, Katja
A1  - Linker, Torsten
T1  - Pyridinium alkynylanthracenes as sensitizers for photodynamic therapy
JF  - Photochemistry and photobiology
N2  - Photodynamic therapy (PDT) is a mild but effective method to treat certain types of cancer upon irradiation with visible light. Here, three isomeric methylpyridinium alkynylanthracenes 1op were evaluated as sensitizers for PDT. Upon irradiation with blue or green light, all three compounds show the ability to initiate strand breaks of plasmid DNA. The mayor species responsible for cleavage is singlet oxygen (O-1(2)) as confirmed by scavenging reagents. Only isomers 1m and 1p can be incorporated into HeLa cells, whereas isomer 1o cannot permeate through the membrane. While isomer 1m targets the cell nucleus, isomer 1p assembles in the cellular cytoplasm and impacts the cellular integrity. This is in accordance with a moderate toxicity of 1p in the dark, whereas 1m exhibits no dark toxicity. Both isomers are suitable as PDT reagents, with a CC50 of 3 mu m and 75 nm, for 1p and 1m, respectively. Thus, derivative 1m, which can be easily synthesized, becomes an interesting candidate for cancer therapy.
Y1  - 2021
U6  - https://doi.org/10.1111/php.13554
SN  - 0031-8655
SN  - 1751-1097
VL  - 98
IS  - 1
SP  - 193
EP  - 201
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Schlappa, Stephanie
A1  - Brenker, Lee Josephine
A1  - Bressel, Lena
A1  - Hass, Roland
A1  - Münzberg, Marvin
T1  - Process characterization of polyvinyl acetate emulsions applying inline photon density wave spectroscopy at high solid contents
JF  - Polymers / Molecular Diversity Preservation International
N2  - The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (>40% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved-feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.
KW  - photon density wave spectroscopy
KW  - multiple light scattering
KW  - emulsion
KW  - polymerization
KW  - process analytical technology
KW  - polyvinyl acetate
Y1  - 2021
U6  - https://doi.org/10.3390/polym13040669
SN  - 2073-4360
VL  - 13
IS  - 4
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Figueroa Campos, Gustavo Adolfo
A1  - Perez, Jeffrey Paulo H.
A1  - Block, Inga
A1  - Sagu Tchewonpi, Sorel
A1  - Saravia Celis, Pedro
A1  - Taubert, Andreas
A1  - Rawel, Harshadrai Manilal
T1  - Preparation of activated carbons from spent coffee and coffee parchment and assessment of their adsorbent efficiency
JF  - Processes : open access journal
N2  - The valorization of coffee wastes through modification to activated carbon has been considered as a low-cost adsorbent with prospective to compete with commercial carbons. So far, very few studies have referred to the valorization of coffee parchment into activated carbon. Moreover, low-cost and efficient activation methods need to be more investigated. The aim of this work was to prepare activated carbon from spent coffee grounds and parchment, and to assess their adsorption performance. The co-calcination processing with calcium carbonate was used to prepare the activated carbons, and their adsorption capacity for organic acids, phenolic compounds and proteins was evaluated. Both spent coffee grounds and parchment showed yields after the calcination and washing treatments of around 9.0%. The adsorption of lactic acid was found to be optimal at pH 2. The maximum adsorption capacity of lactic acid with standard commercial granular activated carbon was 73.78 mg/g, while the values of 32.33 and 14.73 mg/g were registered for the parchment and spent coffee grounds activated carbons, respectively. The Langmuir isotherm showed that lactic acid was adsorbed as a monolayer and distributed homogeneously on the surface. Around 50% of total phenols and protein content from coffee wastewater were adsorbed after treatment with the prepared activated carbons, while 44, 43, and up to 84% of hydrophobic compounds were removed using parchment, spent coffee grounds and commercial activated carbon, respectively; the adsorption efficiencies of hydrophilic compounds ranged between 13 and 48%. Finally, these results illustrate the potential valorization of coffee by-products parchment and spent coffee grounds into activated carbon and their use as low-cost adsorbent for the removal of organic compounds from aqueous solutions.
KW  - coffee by-products
KW  - spent coffee grounds
KW  - parchment
KW  - valorization
KW  - calcination
KW  - activated carbon
KW  - organic compounds adsorption
Y1  - 2021
U6  - https://doi.org/10.3390/pr9081396
SN  - 2227-9717
VL  - 9
IS  - 8
PB  - MDPI
CY  - Basel
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  - 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  - Balderas-Valadez, Ruth Fabiola
A1  - Pacholski, Claudia
T1  - Plasmonic Nanohole Arrays on Top of Porous Silicon Sensors
BT  - A Win-Win Situation
JF  - ACS applied materials & interfaces
N2  - Label-free optical sensors are attractive candidates, for example, for detecting toxic substances and monitoring biomolecular interactions. Their performance can be pushed by the design of the sensor through clever material choices and integration of components. In this work, two porous materials, namely, porous silicon and plasmonic nanohole arrays, are combined in order to obtain increased sensitivity and dual-mode sensing capabilities. For this purpose, porous silicon monolayers are prepared by electrochemical etching and plasmonic nanohole arrays are obtained using a bottom-up strategy. Hybrid sensors of these two materials are realized by transferring the plasmonic nanohole array on top of the porous silicon. Reflectance spectra of the hybrid sensors are characterized by a fringe pattern resulting from the Fabry–Pérot interference at the porous silicon borders, which is overlaid with a broad dip based on surface plasmon resonance in the plasmonic nanohole array. In addition, the hybrid sensor shows a significant higher reflectance in comparison to the porous silicon monolayer. The sensitivities of the hybrid sensor to refractive index changes are separately determined for both components. A significant increase in sensitivity from 213 ± 12 to 386 ± 5 nm/RIU is determined for the transfer of the plasmonic nanohole array sensors from solid glass substrates to porous silicon monolayers. In contrast, the spectral position of the interference pattern of porous silicon monolayers in different media is not affected by the presence of the plasmonic nanohole array. However, the changes in fringe pattern reflectance of the hybrid sensor are increased 3.7-fold after being covered with plasmonic nanohole arrays and could be used for high-sensitivity sensing. Finally, the capability of the hybrid sensor for simultaneous and independent dual-mode sensing is demonstrated.
KW  - optical sensors
KW  - porous silicon
KW  - surface plasmon resonance
KW  - plasmonic
KW  - nanohole arrays
KW  - bottom-up fabrication
Y1  - 2021
U6  - https://doi.org/10.1021/acsami.1c07034
SN  - 1944-8244
SN  - 1944-8252
VL  - 13
IS  - 30
SP  - 36436
EP  - 36444
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Fudickar, Werner
A1  - Linker, Torsten
T1  - Photooxygenation of naphthalene
JF  - ChemPhotoChem
N2  - The photooxygenation of naphthalene to the corresponding endoperoxide (EPO) under various conditions is described. Substantial conversion is only observed at -10 degrees C and after more than two days, indicating that the [4+2] cycloaddition of singlet oxygen to this acene proceeds much more slowly than corresponding reactions of substituted naphthalenes, a rate constant of k = 5.4 +/- 0.3 M(-1)s(-1) was determined by competition kinetics. Another problem is the thermal lability and photochemical cleavage of the naphthalene EPO. We investigated the mechanism of this radical process depending on the light source and sensitizer in comparison to known cyclohexadiene EPO. Thus, bisepoxides and keto epoxides are formed after homolysis of the O-O bond by irradiation with sodium lamps or blue LEDs and subsequent cyclization. This process is accelerated by the sensitizers methylene blue and 9,10-dicyanoanthracene, indicating an electron transfer mechanism. Finally, the cleavage of the peroxidic bond is inhibited with red LEDs, and photooxygenation under such conditions affords 20 % EPO. Thus, we could demonstrate that contrary to literature statements singlet oxygen does indeed react with naphthalene.
KW  - naphthalene
KW  - photooxygenation
KW  - reaction mechanisms
KW  - reactive
KW  - intermediates
KW  - singlet oxygen
Y1  - 2021
U6  - https://doi.org/10.1002/cptc.202100097
VL  - 5
IS  - 11
SP  - 1004
EP  - 1008
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Titov, Evgenii
A1  - Sharma, Anjali
A1  - Lomadze, Nino
A1  - Saalfrank, Peter
A1  - Santer, Svetlana
A1  - Bekir, Marek
T1  - Photoisomerization of an azobenzene-containing surfactant within a micelle
JF  - ChemPhotoChem
N2  - Photosensitive azobenzene-containing surfactants have attracted great attention in past years because they offer a means to control soft-matter transformations with light. At concentrations higher than the critical micelle concentration (CMC), the surfactant molecules aggregate and form micelles, which leads to a slowdown of the photoinduced trans -> cis azobenzene isomerization. Here, we combine nonadiabatic dynamics simulations for the surfactant molecules embedded in the micelles with absorption spectroscopy measurements of micellar solutions to uncover the reasons responsible for the reaction slowdown. Our simulations reveal a decrease of isomerization quantum yields for molecules inside the micelles. We also observe a reduction of extinction coefficients upon micellization. These findings explain the deceleration of the trans -> cis switching in micelles of the azobenzene-containing surfactants.
KW  - azobenzene
KW  - micelles
KW  - photoswitches
KW  - rate constants
KW  - surfactants
KW  - surface hopping
Y1  - 2021
U6  - https://doi.org/10.1002/cptc.202100103
SN  - 2367-0932
VL  - 5
IS  - 10
SP  - 926
EP  - 932
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Zühlke, Martin
A1  - Meiling, Till Thomas
A1  - Roder, Phillip
A1  - Riebe, Daniel
A1  - Beitz, Toralf
A1  - Bald, Ilko
A1  - Löhmannsröben, Hans-Gerd
A1  - Janßen, Traute
A1  - Erhard, Marcel
A1  - Repp, Alexander
T1  - Photodynamic inactivation of E. coli bacteria via carbon nanodots
JF  - ACS omega / American Chemical Society
N2  - The increasing development of antibiotic resistance in bacteria has been a major problem for years, both in human and veterinary medicine. Prophylactic measures, such as the use of vaccines, are of great importance in reducing the use of antibiotics in livestock. These vaccines are mainly produced based on formaldehyde inactivation. However, the latter damages the recognition elements of the bacterial proteins and thus could reduce the immune response in the animal. An alternative inactivation method developed in this work is based on gentle photodynamic inactivation using carbon nanodots (CNDs) at excitation wavelengths λex > 290 nm. The photodynamic inactivation was characterized on the nonvirulent laboratory strain Escherichia coli K12 using synthesized CNDs. For a gentle inactivation, the CNDs must be absorbed into the cytoplasm of the E. coli cell. Thus, the inactivation through photoinduced formation of reactive oxygen species only takes place inside the bacterium, which means that the outer membrane is neither damaged nor altered. The loading of the CNDs into E. coli was examined using fluorescence microscopy. Complete loading of the bacterial cells could be achieved in less than 10 min. These studies revealed a reversible uptake process allowing the recovery and reuse of the CNDs after irradiation and before the administration of the vaccine. The success of photodynamic inactivation was verified by viability assays on agar. In a homemade flow photoreactor, the fastest successful irradiation of the bacteria could be carried out in 34 s. Therefore, the photodynamic inactivation based on CNDs is very effective. The membrane integrity of the bacteria after irradiation was verified by slide agglutination and atomic force microscopy. The method developed for the laboratory strain E. coli K12 could then be successfully applied to the important avian pathogens Bordetella avium and Ornithobacterium rhinotracheale to aid the development of novel vaccines.
KW  - Bacteria
KW  - Genetics
KW  - Fluorescence
KW  - Photodynamics
KW  - Irradiation
Y1  - 2021
U6  - https://doi.org/10.1021/acsomega.1c01700
SN  - 2470-1343
VL  - 6
IS  - 37
SP  - 23742
EP  - 23749
PB  - ACS Publications
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Behl, Marc
A1  - Balk, Maria
A1  - Mansfeld, Ulrich
A1  - Lendlein, Andreas
T1  - Phase morphology of multiblock copolymers differing in sequence of blocks
JF  - Macromolecular materials and engineering
N2  - The chemical nature, the number length of integrated building blocks, as well as their sequence structure impact the phase morphology of multiblock copolymers (MBC) consisting of two non-miscible block types. It is hypothesized that a strictly alternating sequence should impact phase segregation. A library of well-defined MBC obtained by coupling oligo(epsilon-caprolactone) (OCL) of different molecular weights (2, 4, and 8 kDa) with oligotetrahydrofuran (OTHF, 2.9 kDa) via Steglich esterification results in strictly alternating (MBCalt) or random (MBCran) MBC. The three different series has a weight average molecular weight (M-w) of 65 000, 165 000, and 168 000 g mol(-1) for MBCalt and 80 500, 100 000, and 147 600 g mol(-1) for MBCran. When the chain length of OCL building blocks is increased, the tendency for phase segregation is facilitated, which is attributed to the decrease in chain mobility within the MBC. Furthermore, it is found that the phase segregation disturbs the crystallization by causing heterogeneities in the semi-crystalline alignment, which is attributed to an increase of the disorder of the OCL semi-crystalline alignment.
KW  - electron microscopy
KW  - multiblock copolymers
KW  - phase morphology
KW  - polymer
KW  - libraries
KW  - sequence structures
KW  - wide angle x‐ ray scattering
Y1  - 2021
U6  - https://doi.org/10.1002/mame.202000672
SN  - 1439-2054
VL  - 306
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
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  - 2159-6867
VL  - 11
IS  - 4
SP  - 425
EP  - 431
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Sand, Patrick
A1  - Schmidt, Bernd
T1  - Pd-catalyzed oxidative sulfoalkenylation of acetanilides and traceless removal of the catalyst directing group
JF  - ChemistrySelect
N2  - The palladium-catalyzed oxidative Heck-reaction, also referred to as Fujiwara-Moritani-reaction, has been investigated for the synthesis of styrenylsulfonyl compounds. Acetanilides and vinylsulfonyl compounds undergo dehydrogenative coupling reactions in moderate to quantitative yields, using benzoquinone as the oxidant of choice. Potassium peroxodisulfate, which had previously been identified as a superior oxidant for the coupling with acrylates, did not provide any coupling products with these olefins. Traceless removal of the catalyst directing group through a deacetylation-diazotation-coupling (DDC) sequence was demonstrated for 2-arylethene sulfones.
KW  - arenes
KW  - C− H activation
KW  - Heck reactions
KW  - Palladium
KW  - sulfones
Y1  - 2021
U6  - https://doi.org/10.1002/slct.202101009
SN  - 2365-6549
VL  - 6
IS  - 14
SP  - 3563
EP  - 3567
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Farhan, Muhammad
A1  - Behl, Marc
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Origami hand for soft robotics driven by thermally controlled polymeric fiber actuators
JF  - MRS communications / a publication of the Materials Research Society
N2  - Active fibers can serve as artificial muscles in robotics or components of smart textiles. Here, we present an origami hand robot, where single fibers control the reversible movement of the fingers. A recovery/contracting force of 0.2 N with a work capacity of 0.175 kJ kg(-1) was observed in crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) fibers, which could enable the bending movement of the fingers by contraction upon heating. The reversible opening of the fingers was attributed to a combination of elastic recovery force of the origami structure and crystallization-induced elongation of the fibers upon cooling.
KW  - Robotics
KW  - Polymer
KW  - Fiber
KW  - Actuation
KW  - Shape-memory
Y1  - 2021
U6  - https://doi.org/10.1557/s43579-021-00058-4
SN  - 2159-6859
SN  - 2159-6867
VL  - 11
IS  - 4
SP  - 476
EP  - 482
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Titov, Evgenii
T1  - On the low-lying electronically excited states of azobenzene dimers
BT  - Transition density matrix analysis
JF  - Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International
N2  - Azobenzene-containing molecules may associate with each other in systems such as self-assembled monolayers or micelles. The interaction between azobenzene units leads to a formation of exciton states in these molecular assemblies. Apart from local excitations of monomers, the electronic transitions to the exciton states may involve charge transfer excitations. Here, we perform quantum chemical calculations and apply transition density matrix analysis to quantify local and charge transfer contributions to the lowest electronic transitions in azobenzene dimers of various arrangements. We find that the transitions to the lowest exciton states of the considered dimers are dominated by local excitations, but charge transfer contributions become sizable for some of the lowest pi pi* electronic transitions in stacked and slip-stacked dimers at short intermolecular distances. In addition, we assess different ways to partition the transition density matrix between fragments. In particular, we find that the inclusion of the atomic orbital overlap has a pronounced effect on quantifying charge transfer contributions if a large basis set is used.
KW  - azobenzene
KW  - dimer
KW  - transition density matrix
KW  - exciton
KW  - charge transfer
KW  - excited states
KW  - TD-DFT
KW  - ADC(2)
Y1  - 2021
U6  - https://doi.org/10.3390/molecules26144245
SN  - 1420-3049
VL  - 26
IS  - 14
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Gaebel, Tina
A1  - Bein, Daniel
A1  - Mathauer, Daniel
A1  - Utecht, Manuel
A1  - Palmer, Richard E.
A1  - Klamroth, Tillmann
T1  - Nonlocal STM manipulation of chlorobenzene on Si(111)-7 x 7
BT  - Potentials, kinetics, and first-principles molecular dynamics calculations for open systems
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - We use quantum chemical cluster models together with constrained density STM Ph CI functional theory (DFT) and ab initio molecular dynamics (AIMD) for open system to simulate tip and rationalize nonlocal scanning tunneling microscope (STM) manipulation experiments for Philh ci chlorobenzene (PhCl) on a Si(111)-7 X 7 surface. We consider three different processes, namely, the electron-induced dissociation of the carbon-chlorine bond for physisorbed PhCl molecules at low temperatures and the electron- or hole-induced desorption of chemisorbed PhCl at 300 K. All processes can be induced nonlocally, i.e., up to several nanometers (nm) away from the injection site, in STM experiments. We rationalize and explain the experimental findings regarding the STM-induced dissociation using constrained DFT. The coupling of STM-induced ion resonances to nuclear degrees of freedom is simulated with AIMD using the Gadzuk averaging approach for open systems. From this data, we predict a 4 fs lifetime for the cationic resonance. For the anion model, desorption could not be observed. In addition, the same cluster models are used for transition-state theory calculations, which are compared to and validated against time-lapse STM experiments.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpcc.1c02612
SN  - 1932-7447
SN  - 1932-7455
VL  - 125
IS  - 22
SP  - 12175
EP  - 12184
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Picconi, David
T1  - Nonadiabatic quantum dynamics of the coherent excited state intramolecular proton transfer of 10-hydroxybenzo[h]quinoline
JF  - Photochemical & photobiological sciences
N2  - The photoinduced nonadiabatic dynamics of the enol-keto isomerization of 10-hydroxybenzo[h]quinoline (HBQ) are studied computationally using high-dimensional quantum dynamics. The simulations are based on a diabatic vibronic coupling Hamiltonian, which includes the two lowest pi pi* excited states and a n pi* state, which has high energy in the Franck-Condon zone, but significantly stabilizes upon excited state intramolecular proton transfer. A procedure, applicable to large classes of excited state proton transfer reactions, is presented to parametrize this model using potential energies, forces and force constants, which, in this case, are obtained by time-dependent density functional theory. The wave packet calculations predict a time scale of 10-15 fs for the photoreaction, and reproduce the time constants and the coherent oscillations observed in time- resolved spectroscopic studies performed on HBQ. In contrast to the interpretation given to the most recent experiments, it is found that the reaction initiated by 1 pi pi* <- S-0 photoexcitation proceeds essentially on a single potential energy surface, and the observed coherences bear signatures of Duschinsky mode-mixing along the reaction path. The dynamics after the 2 pi pi* <- S-0 excitation are instead nonadiabatic, and the n pi* state plays a major role in the relaxation process. The simulations suggest a mainly active role of the proton in the isomerization, rather than a passive migration assisted by the vibrations of the benzoquinoline backbone. <br /> [GRAPHICS] <br /> .
KW  - Excited state proton transfer
KW  - Quantum dynamics
KW  - Nonadiabatic effects
KW  - Spectroscopy
KW  - Coherences
Y1  - 2021
U6  - https://doi.org/10.1007/s43630-021-00112-z
SN  - 1474-905X
SN  - 1474-9092
VL  - 20
IS  - 11
SP  - 1455
EP  - 1473
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Izraylit, Victor
A1  - Heuchel, Matthias
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Non-woven shape-memory polymer blend actuators
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - The hierarchical design approach provides various opportunities to adjust the structural performance of polymer materials. Electrospinning processing techniques give access to molecular orientation as a design parameter, which we consider here in view of the shape-memory actuation performance. The aim of this work is to investigate how the reversible strain epsilon'(rev) can be affected by a morphology change from a bulk material to an electrospun mesh. epsilon'(rev) could be increased from 5.5 +/- 0.5% to 15 +/- 1.8% for a blend from a multiblock copolymer with poly(epsilon-caprolactone) (PCL) and poly(L-lactide) (PLLA) segments with oligo(D-lactide) (ODLA). This study demonstrates an effective design approach for enhancing soft actuator performance, which can be broadly applied in soft robotics and medicine.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00063-8
SN  - 2059-8521
VL  - 6
IS  - 33
SP  - 781
EP  - 785
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Krebs, Saskia
T1  - N-aroylsulfonamide-photofragmentation (ASAP)
BT  - a versatile route to biaryls
JF  - European journal of organic chemistry
N2  - The photochemical fragmentation of N-aroylsulfonamides 9 (ASAP) is a powerful method for the preparation of various biaryls. Compounds 9 are easily accessible in two steps from amines by treatment with arenesulfonyl chlorides and aroyl chlorides. Many of these compounds were prepared for the first time. The irradiation takes place in a previously developed continuous-flow reactor using inexpensive UVB or UVC fluorescent lamps. Isocyanates and sulphur dioxide are formed as the only by-products. The ASAP tolerates a variety of functional groups and is even suited for the preparation of phenylnaphthalenes and terphenyls. The ASAP mechanism was elucidated by interaction of photophysical and quantum chemical (DFT) methods and revealed a spirocyclic biradical as key intermediate.
KW  - Biaryls
KW  - Fragmentation
KW  - Isocyanates
KW  - Photochemistry
KW  - Sulfonamides
Y1  - 2021
U6  - https://doi.org/10.1002/ejoc.202100955
SN  - 1434-193X
SN  - 1099-0690
VL  - 2021
IS  - 46
SP  - 6367
EP  - 6374
PB  - Wiley-VCH
CY  - Weinheim
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  - Keckeis, Philipp
A1  - Zeller, Enriko
A1  - Jung, Carina
A1  - Besirske, Patricia
A1  - Kirner, Felizitas
A1  - Ruiz-Agudo, Cristina
A1  - Schlaad, Helmut
A1  - Cölfen, Helmut
T1  - Modular toolkit of multifunctional block copoly(2-oxazoline)s for the synthesis of nanoparticles
JF  - Chemistry - a European journal
N2  - Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.
KW  - block copolymers
KW  - click chemistry
KW  - nanoparticles
KW  - ring-opening
KW  - polymerization
KW  - surfactants
Y1  - 2021
U6  - https://doi.org/10.1002/chem.202101327
SN  - 0947-6539
SN  - 1521-3765
VL  - 27
IS  - 32
SP  - 8283
EP  - 8287
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Balischewski, Christian
A1  - Choi, Hyung-Seok
A1  - Behrens, Karsten
A1  - Beqiraj, Alkit
A1  - Körzdörfer, Thomas
A1  - Gessner, Andre
A1  - Wedel, Armin
A1  - Taubert, Andreas
T1  - Metal sulfide nanoparticle synthesis with ionic liquids state of the art and future perspectives
JF  - ChemistryOpen
N2  - Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nano-particle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.
KW  - Ionic liquids
KW  - ionic liquid crystals
KW  - ionic liquid precursors
KW  - metal
KW  - sulfides
KW  - catalysis
KW  - electrochemistry
KW  - energy materials
KW  - LED
KW  - solar
KW  - cells
Y1  - 2021
U6  - https://doi.org/10.1002/open.202000357
SN  - 2191-1363
VL  - 10
IS  - 2
SP  - 272
EP  - 295
PB  - Wiley-VCH
CY  - Weinheim
ER  -