TY - JOUR A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Linker, Torsten T1 - Simple Synthesis of gamma-Spirolactams by Birch Reduction of Benzoic Acids JF - European journal of organic chemistry N2 - A convenient synthesis of gamma-spirolactams in only two steps was developed. Birch reduction of benzoic acids and immediate alkylation with chloroacetonitrile afforded cyclohexadienes in high yields. The products could be isolated by crystallization on a large scale in analytically pure form. Subsequent hydrogenation with platinum(IV) oxide as the catalyst reduced the nitrile functionality and the double bonds in the same step with excellent stereoselectivity. The relative configurations were determined unequivocally by X-ray analyses. Direct cyclization of the intermediary formed amino acids afforded the desired gamma-spirolactams in excellent overall yields. The procedure is characterized by few steps, cheap reagents, and can be performed on a large scale, interesting for industrial processes. KW - Diastereoselectivity KW - Hydrogenation KW - Lactams KW - Reduction KW - Synthetic methods Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201601650 SN - 1434-193X SN - 1099-0690 IS - 6 SP - 1074 EP - 1077 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Burkhard A1 - Lorenz, Ulf T1 - WavePacket BT - a Matlab package for numerical quantum dynamics. I: Closed quantum systems and discrete variable representations JF - Computer physics communications : an international journal devoted to computational physics and computer programs in physics N2 - WavePacket is an open-source program package for the numerical simulation of quantum-mechanical dynamics. It can be used to solve time-independent or time-dependent linear Schrödinger and Liouville–von Neumann-equations in one or more dimensions. Also coupled equations can be treated, which allows to simulate molecular quantum dynamics beyond the Born–Oppenheimer approximation. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate experiments involving tailored light pulses in photo-induced physics or chemistry. The graphical capabilities allow visualization of quantum dynamics ‘on the fly’, including Wigner phase space representations. Being easy to use and highly versatile, WavePacket is well suited for the teaching of quantum mechanics as well as for research projects in atomic, molecular and optical physics or in physical or theoretical chemistry. The present Part I deals with the description of closed quantum systems in terms of Schrödinger equations. The emphasis is on discrete variable representations for spatial discretization as well as various techniques for temporal discretization. The upcoming Part II will focus on open quantum systems and dimension reduction; it also describes the codes for optimal control of quantum dynamics. The present work introduces the MATLAB version of WavePacket 5.2.1 which is hosted at the Sourceforge platform, where extensive Wiki-documentation as well as worked-out demonstration examples can be found. KW - Schrodinger equation KW - Quantum dynamics KW - Numerical propagation KW - Bound states KW - Discrete variable representation KW - Non-adiabatic transitions Y1 - 0207 U6 - https://doi.org/10.1016/j.cpc.2016.12.007 SN - 0010-4655 SN - 1879-2944 VL - 213 SP - 223 EP - 234 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Strauch, Peter A1 - Kossmann, Alexander A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - EPR on bis(1,2-dithiosquarato)cuprate(II) in the bis(1,2-dithiosquarato)nickelate(II) host lattice - structure and spectroscopy JF - Chemical papers N2 - EPR spectroscopy is a well suited analytical tool to monitor the electronic situation around paramagnetic metal centres as copper(II) and therefore the structural influences on the paramagnetic ion. 1,2-Dithiosquaratometalates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. Synthesis and characterisation of bis(benzyltributylammonium)1,2-dithiosquaratonickelate(II), (BzlBu(3)N)(2)[Ni(dtsq)(2)], and bis(benzyltributylammonium)1,2-dithiosquaratocuprate(II), (BzlBu(3)N)(2)[Cu(dtsq)(2)], with benzyltributylammonium as the counter ion is reported and the X-ray structures of two complexes, (BzlBu(3)N)(2)[Ni(dtsq)(2)] and (BzlBu(3)N)(2)[Cu(dtsq)(2)], are presented. Both complexes, crystallising in the monoclinic space group P2(1)/c, are isostructural with only small differences in the coordination sphere due to the different metal ions. The diamagnetic nickel complex is therefore well suited as a host lattice for the paramagnetic Cu(II) complex to measure EPR for additional structural information. (c) 2015 Institute of Chemistry, Slovak Academy of Sciences KW - 1,2-dithiosquarate KW - 1,2-dithiosquaratometalate KW - X-ray structure KW - EPR spectroscopy Y1 - 2016 U6 - https://doi.org/10.1515/chempap-2015-0154 SN - 0366-6352 SN - 1336-9075 VL - 70 SP - 61 EP - 68 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin T1 - Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination JF - Synthesis N2 - Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones). KW - aldehydes KW - coumarins KW - ketones KW - microwave irradiation KW - olefination KW - tandem reaction KW - ylides Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1560501 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 141 EP - 149 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Braune, Steffen A1 - Gross, M. A1 - Walter, M. A1 - Zhou, Shengqiang A1 - Dietze, Siegfried A1 - Rutschow, S. A1 - Lendlein, Andreas A1 - Tschoepe, C. A1 - Jung, Friedrich T1 - Adhesion and activation of platelets from subjects with coronary artery disease and apparently healthy individuals on biomaterials JF - Journal of biomedical materials research : an official journal of the Society for Biomaterials, the Japanese Society for Biomaterials; the Australian Society for Biomaterials N2 - On the basis of the clinical studies in patients with coronary artery disease (CAD) presenting an increased percentage of activated platelets, we hypothesized that hemocompatibility testing utilizing platelets from healthy individuals may result in an underestimation of the materials' thrombogenicity. Therefore, we investigated the interaction of polymer-based biomaterials with platelets from CAD patients in comparison to platelets from apparently healthy individuals. In vitro static thrombogenicity tests revealed that adherent platelet densities and total platelet covered areas were significantly increased for the low (polydimethylsiloxane, PDMS) and medium (Collagen) thrombogenic surfaces in the CAD group compared to the healthy subjects group. The area per single platelet—indicating the spreading and activation of the platelets—was markedly increased on PDMS treated with PRP from CAD subjects. This could not be observed for collagen or polytetrafluoroethylene (PTFE). For the latter material, platelet adhesion and surface coverage did not differ between the two groups. Irrespective of the substrate, the variability of these parameters was increased for CAD patients compared to healthy subjects. This indicates a higher reactivity of platelets from CAD patients compared to the healthy individuals. Our results revealed, for the first time, that utilizing platelets from apparently healthy donors bears the risk of underestimating the thrombogenicity of polymer-based biomaterials. KW - platelets KW - biomaterials KW - hemocompatibility KW - cardiovascular disease KW - cardiovascular implant Y1 - 2016 U6 - https://doi.org/10.1002/jbm.b.33366 SN - 1552-4973 SN - 1552-4981 VL - 104 SP - 210 EP - 217 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Prestel, Andreas A1 - Möller, Heiko Michael T1 - Spatio-temporal control of cellular uptake achieved by photoswitchable cell-penetrating peptides JF - Chemical communications N2 - The selective uptake of compounds into specific cells of interest is a major objective in cell biology and drug delivery. By incorporation of a novel, thermostable azobenzene moiety we generated peptides that can be switched optically between an inactive state and an active, cell-penetrating state with excellent spatio-temporal control. Y1 - 2016 U6 - https://doi.org/10.1039/c5cc06848g SN - 1359-7345 SN - 1364-548X VL - 52 SP - 701 EP - 704 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Brietzke, Thomas Martin A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Mickler, Wulfhard A1 - Holdt, Hans-Jürgen T1 - Heterodinuclear Ruthenium(II) Complexes of the Bridging Ligand 1,6,7,12-Tetraazaperylene with Iron(II), Cobalt(II), Nickel(II), as well as Palladium(II) and Platinum(II) JF - Zeitschrift für anorganische und allgemeine Chemie N2 - The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12-tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N4Me2) ligand, yielding complexes of the general formula [(L-N4Me2)Ru(mu-tape)M(L-N4Me2)](ClO4)(2)(PF6)(2) with M = Fe {[2](ClO4)(2)(PF6)(2)}, Co {[3](ClO4)(2)(PF6)(2)}, and Ni {[4](ClO4)(2)(PF6)(2)}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)- and platinum(II)-dichloride [(bpy)(2)Ru(-tape)PdCl2](PF6)(2) {[5](PF6)(2)} and [(dmbpy)(2)Ru(-tape)PtCl2](PF6)(2) {[6](PF6)(2)}, respectively were also prepared. The molecular structures of the complex cations [2](4+) and [4](4+) were discussed on the basis of the X-ray structures of [2](ClO4)(4)MeCN and [4](ClO4)(4)MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono- and homodinuclear ruthenium(II) complexes of the tape bridging ligand. KW - N ligands KW - Ruthenium KW - Structure elucidation KW - Charge transfer KW - Electrochemistry Y1 - 2016 U6 - https://doi.org/10.1002/zaac.201500645 SN - 0044-2313 SN - 1521-3749 VL - 642 SP - 8 EP - 13 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, Andre A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties JF - Polymer Chemistry N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl) dimethylammonio)butane- 1-sulfonate (SBP) were synthesised and polymerised by reversible addition-fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. Y1 - 2016 U6 - https://doi.org/10.1039/c5py01642h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 731 EP - 740 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Thielke, Michael W. A1 - Secker, Christian A1 - Schlaad, Helmut A1 - Theato, Patrick T1 - Electrospinning of Crystallizable Polypeptoid Fibers JF - Macromolecular rapid communications N2 - A unique fabrication process of low molar mass, crystalline polypeptoid fibers is described. Thermoresponsive fiber mats are prepared by electrospinning a homogeneous blend of semicrystalline poly(N-(n-propyl) glycine) (PPGly; 4.1 kDa) with high molar mass poly(ethylene oxide) (PEO). Annealing of these fibers at approximate to 100 degrees C selectively removes the PEO and produces stable crystalline fiber mats of pure PPGly, which are insoluble in aqueous solution but can be redissolved in methanol or ethanol. The formation of water-stable polypeptoid fiber mats is an important step toward their utilization in biomedical applications such as tissue engineering or wound dressing. KW - biomaterials KW - crystallization KW - electrospinning KW - polypeptoids KW - thermoresponsive Y1 - 2016 U6 - https://doi.org/10.1002/marc.201500502 SN - 1022-1336 SN - 1521-3927 VL - 37 SP - 100 EP - 104 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Omorogie, Martins O. A1 - Babalola, Jonathan Oyebamiji A1 - Unuabonah, Emmanuel I. A1 - Gong, Jian R. T1 - Clean technology approach for the competitive binding of toxic metal ions onto MnO2 nano-bioextractant JF - Clean technologies and environmental policy N2 - The competitive extraction of Cr(III) onto Nauclea diderrichii seed epicarp doped with MnO2 nanoparticles (MnO2 nano-bioextractant (MNB)) in a single and binary batch system was studied. For validity of experimental data, chi square test, root mean square error, sum of the square errors, hybrid fractional error function, Marquart’s percent standard deviation and standard absolute error were used. Among the kinetic models used, pseudo-second-order and Langmuir equations gave the best fits for the experimental data, with qe (mg g) for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal systems onto MNB were 2.611, then 1.989, 1.016, 2.208, 1.249 and 1.868 from kinetic standpoint, respectively. The initial sorption rates, h (mg/g/min), and half lives, t1/2 (min), for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal system onto MNB were 3.497, then 2.311, 2.274, 0.242, 2.956, 45.568 and 0.747, then 5.769, 1.766, 12.144, 1.762, and 2.415, respectively. Physicochemical surface analyses such as pH of point of zero charge, Brunauer–Emmett–Teller single point and multi-point techniques for surface area analyses, scanning electron microscopy and transmission electron microscopy were done on MNB and MnO2 nanoparticles in order to understand their surface microstructures. Desorption study showed that MNB can be recycled and used for future study. Hence, MNB showed good potential to remediate Cr(III) from wastewaters and polluted water. KW - Nauclea diderrichii KW - Nano-bioextractant KW - Doping KW - Kinetics KW - Mass transfer Y1 - 2016 U6 - https://doi.org/10.1007/s10098-015-1004-z SN - 1618-954X SN - 1618-9558 VL - 18 SP - 171 EP - 184 PB - Springer CY - New York ER - TY - JOUR A1 - Megow, Jörg A1 - Kulesza, Alexander A1 - May, Volkhard T1 - A mixed quantum-classical description of pheophorbide a linear absorption spectra: Quantum-corrections of the Q(y)- and Q(x)-absorption vibrational satellites JF - Chemical physics letters N2 - The ground-state classical path approximation is utilized to compute molecular absorption spectra in a mixed quantum-classical frame. To improve the description for high-frequency vibrational satellites, related quantum correction factors are introduced. The improved method is demonstrated for the Q(y),and Q(x)-bands of pheophorbide a. (C) 2015 Elsevier B.V. All rights reserved. Y1 - 2016 U6 - https://doi.org/10.1016/j.cplett.2015.11.016 SN - 0009-2614 SN - 1873-4448 VL - 643 SP - 61 EP - 65 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Klaper, Matthias A1 - Wessig, Pablo A1 - Linker, Torsten T1 - Base catalysed decomposition of anthracene endoperoxide JF - Chemical communications N2 - Catalytic amounts of a weak base are sufficient to induce the decomposition of anthracene endoperoxides to anthraquinone. The mechanism has been elucidated by isolation of intermediates in combination with DFT calculations. The whole process is suitable for the convenient generation of hydrogen peroxide under very mild conditions. Y1 - 2016 U6 - https://doi.org/10.1039/c5cc08606j SN - 1359-7345 SN - 1364-548X VL - 52 SP - 1210 EP - 1213 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Park, H. A1 - Walta, S. A1 - Rosencrantz, Ruben R. A1 - Koerner, A. A1 - Schulte, Christoph A1 - Elling, L. A1 - Richtering, Walter A1 - Böker, Alexander T1 - Micelles from self-assembled double-hydrophilic PHEMA-glycopolymer-diblock copolymers as multivalent scaffolds for lectin binding JF - Polymer Chemistry N2 - We introduce a novel double-hydrophilic hydroxyethylmethacrylate (HEMA) based diblock glycopolymer which self-assembles into homogeneous spherical micellar structures in water. The micellar structure renders surface-oriented N-acetylglucocosamine (GlcNAc) sugar moieties for strong multivalent glycan-mediated lectin binding. Structural analysis and lectin binding is performed by microscopy methods, dynamic light scattering (DLS) and two-focus fluorescence correlation spectroscopy (2fFCS), revealing a novel micellar type of multivalent sugar binding scaffold with high potential for biomedical applications. Y1 - 2016 U6 - https://doi.org/10.1039/c5py00797f SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 878 EP - 886 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Omorogie, Martins O. A1 - Babalola, Jonathan Oyebamiji A1 - Unuabonah, Emmanuel I. A1 - Song, Weiguo A1 - Gong, Jian Ru T1 - Efficient chromium abstraction from aqueous solution using a low-cost biosorbent: Nauclea diderrichii seed biomass waste JF - Journal of Saudi Chemical Society N2 - Toxic Cr(III) which poses environmental hazard to flora and fauna was efficiently abstracted by low-cost Nauclea diderrichii seed biomass (NDS) with good sequestral capacity for this metal was investigated in this study. The NDS surface analyses showed that it has a specific surface area of 5.36 m(2)/g and pHpzc of 4.90. Thermogravimetric analysis of NDS showed three consecutive weight losses from 50-200 degrees C (ca. 5%), 200-400 C (ca. 35%), >400 degrees C (ca. 10%), corresponding to external water molecules, structural water molecules and heat induced condensation reactions respectively. Differential thermogram of NDS presented a large endothermic peak between 20-510 degrees C suggesting bond breakage and dissociation with the ultimate release of small molecules. The experimental data showed kinetically fast biosorption with increased initial Cr(III) concentrations, indicating the role of external mass transfer mechanism as the rate controlling mechanism in this adsorption process. The Langmuir biosorption capacity of NDS was 483.81 mg/g. The use of the corrected Akaike Information Criterion tool for ranking equilibrium models suggested that the Freundlich model best described the experimental data, which is an indication of the heterogeneous nature of the active sites on the surface of NDS. N. diderrichii seed biomass is an easily sourced, cheap and environmental friendly biosorbent which will serve as a good and cost effective alternative to activated carbon for the treatment of polluted water and industrial effluents. (C) 2012 King Saud University. Production and hosting by Elsevier B.V. All rights reserved. KW - Biomass KW - Equilibrium KW - External mass transfer KW - Kinetics KW - Adsorption KW - Water Y1 - 2016 U6 - https://doi.org/10.1016/j.jscs.2012.09.017 SN - 1319-6103 SN - 2212-4640 VL - 20 SP - 49 EP - 57 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Baier, Heiko A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Investigation of the Catalytic Activity of a 2-Phenylidenepyridine Palladium(II) Complex Bearing 4,5-Dicyano-1,3-bis(mesityl)imidazol-2-ylidene in the Mizoroki-Heck Reaction JF - Zeitschrift für anorganische und allgemeine Chemie N2 - The phenylidenepyridine (ppy) palladacycles [PdCl(ppy)(IMes)] (4) [IMes = 1,3-bis(mesityl) imidazol-2-ylidene] and [PdCl(ppy){(CN)(2)IMes}] (6) [(CN)(2)IMes = 4,5-dicyano-1,3-bis(mesityl) imidazol-2-ylidene] were prepared by facile two step syntheses, starting with the reaction of palladium(II) chloride with 2-phenylpyridine followed by subsequent addition of the NHC ligand to the precatalyst precursor [PdCl(ppy)](2). Suitable crystals for the X-ray analysis of the complexes 4 and 6 were obtained. It was shown that 6 has a shorter NHC-palladium bond than the IMes complex 4. The difference of the palladium carbene bond lengths based on the higher pi-acceptor strength of (CN)(2)IMes in comparison to IMes. Thus, (CN)(2)IMes should stabilize the catalytically active central palladium atom better than IMes. As a measure for the pi-acceptor strength of (CN)(2)IMes compared to IMes, the selone (CN)(2)IMes center dot Se (7) was prepared and characterized by Se-77-NMR spectroscopy. The pi-acceptor strength of 7 was illuminated by the shift of its Se-77-NMR signal. The Se-77-NMR signal of 7 was shifted to much higher frequencies than the Se-77-NMR signal of IMes center dot Se. Catalytic experiments using the Mizoroki-Heck reaction of aryl chlorides with n-butyl acrylate showed that 6 is the superior performer in comparison to 4. Using complex 6, an extensive substrate screening of 26 different aryl bromides with n-butyl acrylate was performed. Complex 6 is a suitable precatalyst for para-substituted aryl bromides. The catalytically active species was identified by mercury poisoning experiments to be palladium nanoparticles. KW - Carbene ligands KW - Heck reaction KW - Palladium KW - Selenium KW - C-C coupling Y1 - 2016 U6 - https://doi.org/10.1002/zaac.201500625 SN - 0044-2313 SN - 1521-3749 VL - 642 SP - 140 EP - 147 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bader, Denise A1 - Klier, Dennis Tobias A1 - Hettrich, C. A1 - Bier, Frank Fabian A1 - Wessig, Pablo T1 - Detecting carbohydrate-lectin interactions using a fluorescent probe based on DBD dyes JF - Analytical methods : advancing methods and applications N2 - Herein we present an efficient synthesis of a biomimetic probe with modular construction that can be specifically bound by the mannose binding FimH protein - a surface adhesion protein of E. coli bacteria. The synthesis combines the new and interesting DBD dye with the carbohydrate ligand mannose via a Click reaction. We demonstrate the binding to E. coli bacteria over a large concentration range and also present some special characteristics of those molecules that are of particular interest for the application as a biosensor. In particular, the mix-and-measure ability and the very good photo-stability should be highlighted here. Y1 - 2016 U6 - https://doi.org/10.1039/c5ay02991k SN - 1759-9660 SN - 1759-9679 VL - 8 SP - 1235 EP - 1238 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Balderas-Valadez, Ruth Fabiola A1 - Agarwal, Vivechana A1 - Pacholski, Claudia T1 - Fabrication of porous silicon-based optical sensors using metal-assisted chemical etching JF - RSC Advances N2 - Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors. Y1 - 2016 U6 - https://doi.org/10.1039/c5ra26816h SN - 2046-2069 VL - 6 SP - 21430 EP - 21434 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Prinz, Julia A1 - Heck, Christian A1 - Ellerik, Lisa A1 - Merk, Virginia A1 - Bald, Ilko T1 - DNA origami based Au-Ag-core-shell nanoparticle dimers with single-molecule SERS sensitivity JF - Nanoscale N2 - DNA origami nanostructures are a versatile tool to arrange metal nanostructures and other chemical entities with nanometer precision. In this way gold nanoparticle dimers with defined distance can be constructed, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). We have optimized the size, composition and arrangement of Au/Ag nanoparticles to create intense SERS hot spots, with Raman enhancement up to 10(10), which is sufficient to detect single molecules by Raman scattering. This is demonstrated using single dye molecules (TAMRA and Cy3) placed into the center of the nanoparticle dimers. In conjunction with the DNA origami nanostructures novel SERS substrates are created, which can in the future be applied to the SERS analysis of more complex biomolecular targets, whose position and conformation within the SERS hot spot can be precisely controlled. Y1 - 2016 U6 - https://doi.org/10.1039/c5nr08674d SN - 2040-3364 SN - 2040-3372 VL - 8 SP - 5612 EP - 5620 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Paz, Cristian A1 - Becerra, Jose A1 - Silva, Mario A1 - Cabrera-Pardo, Jaime A1 - Burgos, Viviana A1 - Heydenreich, Matthias A1 - Schmidt, Bernd T1 - (-)-8-Oxohobartine a New Indole Alkaloid from Aristotelia chilensis (Mol.) Stuntz JF - Records of Natural Products N2 - The fruit of Aristotelia chilensis is considered a "super fruit" due to its high concentration of polyphenols displaying exceptional antioxidant capacities ORAC. From maqui berries have been reported several anthocyanins and glycosylated flavonoids, those benefits increase the attention to restudy the plant. From the leaves of A. chilensis several indole alkaloids have been reported, we in addition to aristoteline, aristone, aristoquinoline and 3-fromylindole report the spectroscopic elucidation of 8-oxo-9-dehydromakomakine (1), hobartine (2) and a new alkaloid named 8-oxohobartine (3). Compound 1 to 3 did not show bactericidal activity against E. coli and S. aureus till 200 mu g. KW - Aristotelia chilensis KW - indole alkaloids KW - 8-oxohobartine Y1 - 2016 SN - 1307-6167 VL - 10 SP - 68 EP - 73 PB - ACG Publications CY - Gebze-Kocaeli ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Marquardt, Dorothea A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Use of a 4,5-dicyanoimidazolate anion based ionic liquid for the synthesis of iron and silver nanoparticles JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - Sixteen new ionic liquids (ILs) with tetraethylammonium, 1-butyl-3-methylimidazolium, 3-methyl-1-octylimidazolium and tetrabutylphosphonium cations paired with 2-substituted 4,5-dicyanoimidazolate anions (substituent at C2 = methyl, trifluoromethyl, pentafluoroethyl, N,N′-dimethyl amino and nitro) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The effects of cation and anion type and structure of the resulting ILs, including several room temperature ionic liquids (RTILs), are reflected in the crystallization, melting points and thermal decomposition of the ILs. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of −22 to −71 °C. We selected one of the newly designed ILs due to its bigger size, compared to the common conventional IL anion and high electron-withdrawing nitrile group leads to an overall stabilization anion that may stabilize the metal nanoparticles. Stable and better separated iron and silver nanoparticles are obtained by the decomposition of corresponding Fe2(CO)9 and AgPF6, respectively, under N2-atmosphere in newly designed nitrile functionalized 4,5-dicyanoimidazolate anion based IL. Very small and uniform size for Fe-nanoparticles of about 1.8 ± 0.6 nm were achieved without any additional stabilizers or capping molecules. Comparatively bigger size of Ag-nanoparticles was obtained through the reduction of AgPF6 by hydrogen gas. Additionally, the AgPF6 precursor was decomposed under microwave irradiation (MWI), fabricating nut-in-shell-like, that is, core-separated-from-shell Ag-nano-structures. Y1 - 2016 U6 - https://doi.org/10.1039/c6dt00225k SN - 1477-9226 SN - 1477-9234 VL - 45 SP - 5476 EP - 5483 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Liebig, Ferenc A1 - Sarhan, Radwan Mohamed A1 - Prietzel, Claudia Christina A1 - Reinecke, Antje A1 - Koetz, Joachim T1 - "Green" gold nanotriangles: synthesis, purification by polyelectrolyte/micelle depletion flocculation and performance in surface-enhanced Raman scattering JF - RSC Advances N2 - The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra04808k SN - 2046-2069 VL - 6 SP - 33561 EP - 33568 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Wessig, Pablo A1 - Behrends, Nicole A1 - Kumke, Michael Uwe A1 - Eisold, Ursula A1 - Meiling, Til A1 - Hille, Carsten T1 - Two-photon FRET pairs based on coumarin and DBD dyes JF - RSC Advances N2 - The synthesis and photophysical properties of two new FRET pairs based on coumarin as a donor and DBD dye as an acceptor are described. The introduction of a bromo atom dramatically increases the two-photon excitation (2PE) cross section providing a 2PE-FRET system, which is also suitable for 2PE-FLIM. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra03983a SN - 2046-2069 VL - 6 SP - 33510 EP - 33513 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Doriti, Afroditi A1 - Brosnan, Sarah M. A1 - Weidner, Steffen M. A1 - Schlaad, Helmut T1 - Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base JF - Polymer Chemistry N2 - Polysarcosine (M-n = 3650-20 000 g mol(-1), D similar to 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator. Y1 - 2016 U6 - https://doi.org/10.1039/c6py00221h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 3067 EP - 3070 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Braune, Steffen A1 - Froehlich, G. M. A1 - Lendlein, Andreas A1 - Jung, Friedrich T1 - Effect of temperature on platelet adherence JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - BACKGROUND: Thrombogenicity is one of the main parameters tested in vitro to evaluate the hemocompatibility of artificial surfaces. While the influence of the temperature on platelet aggregation has been addressed by several studies, the temperature influence on the adherence of platelets to body foreign surfaces as an important aspect of biomedical device handling has not yet been explored. Therefore, we analyzed the influence of two typically applied incubation-temperatures (22 degrees C and 37 degrees C) on the adhesion of platelets to biomaterials. MATERIAL AND METHODS: Thrombogenicity of three different polymers - medical grade poly(dimethyl siloxane) (PDMS), polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) - were studied in an in vitro static test. Platelet adhesion was studied with stringently characterized blood from apparently healthy subjects. Collection of whole blood and preparation of platelet rich plasma (PRP) was carried out at room temperature (22 degrees C). PRP was incubated with the polymers either at 22 degrees C or 37 degrees C. Surface adherent platelets were fixed, fluorescently labelled and assessed by an image-based approach. RESULTS AND DISCUSSION: Differences in the density of adherent platelets after incubation at 22 degrees C and 37 degrees C occurred on PDMS and PET. Similar levels of adherent platelets were observed on the very thrombogenic PTFE. The covered surface areas per single platelet were analyzed to measure the state of platelet activation and revealed no differences between the two incubation temperatures for any of the analyzed polymers. Irrespective of the observed differences between the low and medium thrombogenic PDMS and PET and the higher variability at 22 degrees C, the thrombogenicity of the three investigated polymers was evaluated being comparable at both incubation temperatures. KW - Biomaterial KW - thrombogenicity KW - platelet adhesion KW - platelet activation KW - temperature Y1 - 2016 U6 - https://doi.org/10.3233/CH-152028 SN - 1386-0291 SN - 1875-8622 VL - 61 SP - 681 EP - 688 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Kumar, Reddi K. A1 - Basu, Sayantani A1 - Lemke, Horst-Dieter A1 - Jankowski, Joachim A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Tetali, Sarada D. T1 - Effect of extracts of poly(ether imide) microparticles on cytotoxicity, ROS generation and proinflammatory effects on human monocytic (THP-1) cells JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - A high cell viability of around 99 +/- 18% and 99 +/- 5% was observed when THP-1 cells were cultured in the presence of aqueous extracts of the PEI microparticles in medium A and medium B respectively. The obtained microscopic data suggested that PEI particle extracts have no significant effect on cell death, oxidative stress or differentiation to macrophages. It was further found that the investigated proinflammatory markers in THP-1 cells were not up-regulated. These results are promising with regard to the biocompatibility of PEI microparticles and in a next step the hemocompatibility of the microparticles will be examined. KW - Chronic kidney disease (CKD) KW - cytotoxicity KW - human monocytic (THP-1) cells KW - poly(ether imide) microparticles KW - reactive oxygen species (ROS) Y1 - 2016 U6 - https://doi.org/10.3233/CH-152027 SN - 1386-0291 SN - 1875-8622 VL - 61 SP - 667 EP - 680 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Tetali, Sarada D. A1 - Jankowski, Vera A1 - Luetzow, Karola A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Jankowski, Joachim T1 - Adsorption capacity of poly(ether imide) microparticles to uremic toxins JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Uremia is a phenomenon caused by retention of uremic toxins in the plasma due to functional impairment of kidneys in the elimination of urinary waste products. Uremia is presently treated by dialysis techniques like hemofiltration, dialysis or hemodiafiltration. However, these techniques in use are more favorable towards removing hydrophilic than hydrophobic uremic toxins. Hydrophobic uremic toxins, such as hydroxy hipuric acid (OH-HPA), phenylacetic acid (PAA), indoxyl sulfate (IDS) and p-cresylsulfate (pCRS), contribute substantially to the progression of chronic kidney disease (CKD) and cardiovascular disease. Therefore, objective of the present study is to test adsorption capacity of highly porous microparticles prepared from poly(ether imide) (PEI) as an alternative technique for the removal of uremic toxins. Two types of nanoporous, spherically shaped microparticles were prepared from PEI by a spraying/coagulation process. PEI particles were packed into a preparative HPLC column to which a mixture of the four types of uremic toxins was injected and eluted with ethanol. Eluted toxins were quantified by analytical HPLC. PEI particles were able to adsorb all four toxins, with the highest affinity for PAA and pCR. IDS and OH-HPA showed a partially non-reversible binding. In summary, PEI particles are interesting candidates to be explored for future application in CKD. KW - Adsorption of uremic toxins KW - chronic kidney disease (CKD) KW - hydrophobic uremic toxins KW - poly(ether imide) KW - microparticles KW - uremia Y1 - 2016 U6 - https://doi.org/10.3233/CH-152026 SN - 1386-0291 SN - 1875-8622 VL - 61 SP - 657 EP - 665 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Olejko, Lydia A1 - Cywinski, P. J. A1 - Bald, Ilko T1 - An ion-controlled four-color fluorescent telomeric switch on DNA origami structures JF - Nanoscale N2 - The folding of single-stranded telomeric DNA into guanine (G) quadruplexes is a conformational change that plays a major role in sensing and drug targeting. The telomeric DNA can be placed on DNA origami nanostructures to make the folding process extremely selective for K+ ions even in the presence of high Na+ concentrations. Here, we demonstrate that the K+-selective G-quadruplex formation is reversible when using a cryptand to remove K+ from the G-quadruplex. We present a full characterization of the reversible switching between single-stranded telomeric DNA and G-quadruplex structures using Forster resonance energy transfer (FRET) between the dyes fluorescein (FAM) and cyanine3 (Cy3). When attached to the DNA origami platform, the G-quadruplex switch can be incorporated into more complex photonic networks, which is demonstrated for a three-color and a four-color FRET cascade from FAM over Cy3 and Cy5 to IRDye700 with G-quadruplex-Cy3 acting as a switchable transmitter. Y1 - 2016 U6 - https://doi.org/10.1039/c6nr00119j SN - 2040-3364 SN - 2040-3372 VL - 8 SP - 10339 EP - 10347 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Liu, Bing A1 - Böker, Alexander T1 - Measuring rotational diffusion of colloidal spheres with confocal microscopy JF - Soft matter N2 - We report an experimental method to measure the translational and rotational dynamics of colloidal spheres in three dimensions with confocal microscopy and show that the experimental values reasonably agree with the theoretical values. This method can be extended to study rotational dynamics in concentrated colloidal systems and complex bio-systems. Y1 - 2016 U6 - https://doi.org/10.1039/c6sm01082b SN - 1744-683X SN - 1744-6848 VL - 12 SP - 6033 EP - 6037 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kathrein, Christine C. A1 - Bai, Wubin A1 - Nunns, Adam A1 - Gwyther, Jessica A1 - Manners, Ian A1 - Böker, Alexander A1 - Tsarkova, Larisa A1 - Ross, Caroline A. T1 - Electric field manipulated nanopatterns in thin films of metalorganic 3-miktoarm star terpolymers JF - Soft matter N2 - We report the effect of electric field on the morphological transitions and ordering behavior of polyferrocenylethylmethylsilane block (PFEMS)-containing copolymers. By analyzing structures in solvent-annealed films of metalorganic sphere-and cylinder-forming diblock copolymers, as well as of 3-miktoarm polyisoprene-arm-polystyrene-arm-PFEMS (3 mu-ISF) terpolymers, we decouple two types of responses to the electric field: morphological transformations as a result of an increase in the volume fraction of the PFEMS block by oxidation of the ferrocenyl groups, and the orientation of the dielectric interfaces of microdomains parallel to the electric field vector. In the case of 3m-ISF, the former effect dominates at high electric field strengths which results in an unexpected cylinder-to-sphere transition, leading to a well-ordered hexagonal dot pattern. Our results demonstrate multiple tunability of ordered microdomain morphologies, suggesting future applications in nanofabrication and surface patterning. Y1 - 2016 U6 - https://doi.org/10.1039/c6sm00451b SN - 1744-683X SN - 1744-6848 VL - 12 SP - 4866 EP - 4874 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kathrein, Christine C. A1 - Pester, Christian A1 - Ruppel, Markus A1 - Jung, Maike A1 - Zimmermann, Marc A1 - Böker, Alexander T1 - Reorientation mechanisms of block copolymer/CdSe quantum dot composites under application of an electric field JF - Soft matter N2 - Time- and temperature-resolved in situ birefringence measurements were applied to analyze the effect of nanoparticles on the electric field-induced alignment of a microphase separated solution of poly(styrene)-block-poly(isoprene) in toluene. Through the incorporation of isoprene-confined CdSe quantum dots the reorientation behavior is altered. Particle loading lowers the order-disorder transition temperature, and increases the defect density, favoring nucleation and growth as an alignment mechanism over rotation of grains. The temperature dependent alteration in the reorientation mechanism is analyzed via a combination of birefringence and synchrotron SAXS. The detailed understanding of the effect of nanoparticles on the reorientation mechanism is an important prerequisite for optimization of electricfield-induced alignment of block copolymer/nanoparticle composites where the block copolymer guides the nanoparticle self-assembly into anisotropic structures. Y1 - 2016 U6 - https://doi.org/10.1039/c6sm01073c SN - 1744-683X SN - 1744-6848 VL - 12 SP - 8417 EP - 8424 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Baraza, Lilechi D. A1 - Neser, Wekesa A1 - Jackson, Korir Cheruiyot A1 - Fredrick, Juma B. A1 - Dennis, Ochieno A1 - Wairimu, Kamau R. A1 - Keya, Aggrey Osogo A1 - Heydenreich, Matthias T1 - Antimicrobial Coumarins from the Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes), from Kenya JF - International journal of medicinal mushrooms N2 - Pleurotus ostreatus has been widely used as food because of its nutritional and medicinal properties. These have been attributed to the presence of macronutrients, minerals, vitamins, and amino acids, among other secondary metabolites. There are, however, few reports on the antimicrobial activities of different classes of purified compounds from P. ostreatus. This led to the current study, the objective of which was to chemically characterize the antibiotic activities of P. ()streams against selected human pathogenic bacteria and endophytic fungi. Chemical structures were determined using spectroscopic methods and by comparison with values of related structures reported in the literature. Pure compounds from P. ostreatus were tested in vitro against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and endophytic fungi (Pencillium digitatum and Fusarium prolferatum). A new compound, (E)-5,7-dimethoxy-6-(3-methylbuta-1,3-dienyl)-2H-chromen-2-one (5-methoxy-(E)-suberodiene) (compound 2), along with ergosterol (compound I.) and 5,7-dimethoxy-6-(3-methylbut-2-enyl)-2H-chromen-2-one (toddaculin; compound 3), were isolated from the fruiting bodies of P. ostreatus. The growth of S. aureus,E proliferatum, and P. digitatum colonies was inhibited in media containing compound 2, with minimum inhibitory concentrations closely comparable to those of conventional antibiotics. KW - Escherichia coli KW - Fusarium proliferatum KW - medicinal mushrooms KW - Penicillium digitatum KW - Pleurotus ostreatus KW - Staphylococcus aureus Y1 - 2016 U6 - https://doi.org/10.1615/IntJMedMushrooms.v18.i10.60 SN - 1521-9437 SN - 1940-4344 VL - 18 SP - 905 EP - 913 PB - Begell House CY - Danbury ER - TY - JOUR A1 - Cywinski, Piotr J. A1 - Pietraszkiewicz, Marek A1 - Maciejczyk, Michal A1 - Gorski, Krzysztof A1 - Hammann, Tommy A1 - Liermann, Konstanze A1 - Paulke, Bernd-Reiner A1 - Löhmannsröben, Hans-Gerd T1 - Total protein concentration quantification using nanobeads with a new highly luminescent terbium(III) complex JF - RSC Advances N2 - Total protein concentration (TPC) is a key parameter in many biochemical experiments and its quantification is often necessary for isolation, separation, and analysis of proteins. A sensitive and rapid nanobead-based TPC quantification assay based on Forster Resonance Energy Transfer (FRET) has been developed. A new, highly luminescent Tb(III) complex has been synthesised and applied as donor in this FRET assay with an organic dye (Cy5) as acceptor. FRET-induced changes in luminescence have been investigated both at donor and acceptor emission wavelength using time-resolved luminescence spectroscopy with time-gated detection. In the assay, the Tb(III) complex and fine-tuned polyglycidyl methacrylate (PGMA) nanobeads ensure that an improvement in sensitivity and background reduction is achieved. Using 40 nm large PGMA nanobeads loaded with the Tb(III) complex, it is possible to determine TPC down to 50 ng mL(-1) in just 10 minutes. Through specific assay components the sensitivity has been improved when compared to existing nanobead-based assays and to currently known commercial methods. Additionally, the assay is relatively insensitive to the presence of contaminants, such as non-ionic detergents commonly found in biological samples. Due to no need for any centrifugal steps, this mix-and-measure bioassay can easily be implemented into routine TPC quantification protocols in biochemical laboratories. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra23207h SN - 2046-2069 VL - 6 SP - 115068 EP - 115073 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Mondal, Suvendu Sekhar A1 - Holdt, Hans-Jürgen T1 - Breaking Down Chemical Weapons by Metal-Organic Frameworks T2 - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Seek and destroy: Filtration schemes and self-detoxifying protective fabrics based on the ZrIV-containing metal—organic frameworks (MOFs) MOF-808 and UiO-66 doped with LiOtBu have been developed that capture and hydrolytically detoxify simulants of nerve agents and mustard gas. Both MOFs function as highly catalytic elements in these applications. KW - heterogeneous catalysis KW - hydrolysis KW - metalorganic frameworks KW - nerve agents KW - silk fibroin Y1 - 2016 U6 - https://doi.org/10.1002/anie.201508407 SN - 1433-7851 SN - 1521-3773 VL - 55 SP - 42 EP - 44 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Loncaric, Ivor A1 - Alducin, Maite A1 - Saalfrank, Peter A1 - Juaristi, J. I. T1 - Femtosecond-laser-driven molecular dynamics on surfaces: Photodesorption of molecular oxygen from Ag(110) JF - Physical review : B, Condensed matter and materials physics N2 - We simulate the femtosecond-laser-induced desorption dynamics of a diatomic molecule from a metal surface by including the effect of the electron and phonon excitations created by the laser pulse. Following previous models, the laser-induced surface excitation is treated through the two temperature model, while the multidimensional dynamics of the molecule is described by a classical Langevin equation, in which the friction and random forces account for the action of the heated electrons. In this work we propose the additional use of the generalized Langevin oscillator model to also include the effect of the energy exchange between the molecule and the heated surface lattice in the desorption dynamics. The model is applied to study the laser-induced desorption of O-2 from the Ag(110) surface, making use of a six-dimensional potential energy surface calculated within density functional theory. Our results reveal the importance of the phonon mediated process and show that, depending on the value of the electronic density in the surroundings of the molecule adsorption site, its inclusion can significantly enhance or reduce the desorption probabilities. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevB.93.014301 SN - 1098-0121 SN - 1550-235X VL - 93 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Senge, Mathias O. A1 - Flanagan, Keith J. A1 - Ryan, Aoife A. A1 - Ryppa, Claudia A1 - Donath, Mandy A1 - Twamley, Brendan T1 - Conformational and structural studies of meso monosubstituted metalloporphyrins-Edge-on molecular interactions of porphyrins in crystals JF - Tetrahedron N2 - A series of meso monosubstituted metalloporphyrins were synthesized to assess the structural chemistry of porphyrins with only one substituent. The structures of four nickel(II) and zinc(II) complexes with either alkyl or aryl residues indicate primarily planar macrocycles. This gives rise to a different type of pi-interactions in the crystal and the formation of dimeric, trimeric or tetrameric porphyrin units that function as building blocks for the overall crystal structure. Notably, some structures exhibit a unique edge-on packing of porphyrins, while the molecules of (5-n-butylporphyrinato)nickel(II) forms an unusual bilayer type structure where rows of two porphyrin macrocycles are separated by the alkyl residues arranged in a head-to-head fashion. This adds to the canon of intermolecular porphyrin packing arrangements and is of relevance for the preparation of ordered nanoscopic porphyrin devices. (C) 2015 Elsevier Ltd. All rights reserved. KW - Porphyrins KW - Conformational analysis KW - Tetrapyrroles KW - Crystal structure KW - Crystal packing Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2015.11.008 SN - 0040-4020 VL - 72 SP - 105 EP - 115 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zhong, Qi A1 - Metwalli, Ezzeldin A1 - Rawolle, Monika A1 - Kaune, Gunar A1 - Bivigou Koumba, Achille Mayelle A1 - Laschewsky, Andre A1 - Papadakis, Christine M. A1 - Cubitt, Robert A1 - Wang, Jiping A1 - Mueller-Buschbaum, Peter T1 - Influence of Hydrophobic Polystyrene Blocks on the Rehydration of Polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene Films Investigated by in Situ Neutron Reflectivity JF - Macromolecules : a publication of the American Chemical Society N2 - The rehydration of thermoresponsive polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene (PS-b-PMDEGA-b-PS) films forming a lamellar microphase-separated structure is investigated by in situ neutron reflectivity in a D2O vapor atmosphere. The rehydration of collapsed PS-b-PMDEGA-b-PS films is realized by a temperature change from 45 to 23 degrees C and comprises (1) condensation and absorption of D2O, (2) evaporation of D2O, and (3) reswelling of the film due to internal rearrangement. The hydrophobic PS layers hinder the absorption of condensed D2O, and a redistribution of embedded D2O between the hydrophobic PS layers and the hydrophilic PMDEGA layers is observed. In contrast, the rehydration of semiswollen PS-b-PMDEGA-b-PS films (temperature change from 35 to 23 degrees C) shows two prominent differences: A thicker D2O layer condenses on the surface, causing a more enhanced evaporation of D2O. The rehydrated films differ in film thickness and volume fraction of D2O, which is due to the different thermal protocols, although the final temperature is identical. Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.5b02279 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 317 EP - 326 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schwarze, Thomas A1 - Schneider, Radu A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Fluorescent Probe - Tuning the K+-Complex Stability and the K+/Na+ Selectivity by Varying the Lariat-Alkoxy Unit of a Phenylaza[18]crown-6 Ionophore JF - Chemistry : an Asian journal ; an ACES journal N2 - A desirable goal is to synthesize easily accessible and highly K+/Na+-selective fluoroionophores to monitor physiological K+ levels in vitro and in vivo. Therefore, highly K+/Na+-selective ionophores have to be developed. Herein, we obtained in a sequence of only four synthetic steps a set of K+-responsive fluorescent probes 4, 5 and 6. In a systematic study, we investigated the influence of the alkoxy substitution in ortho position of the aniline moiety in -conjugated aniline-1,2,3-triazole-coumarin-fluoroionophores 4, 5 and 6 [R=MeO (4), EtO (5) and iPrO (6)] towards the K+-complex stability and K+/Na+ selectivity. The highest K+-complex stability showed fluoroionophore 4 with a dissociation constant K-d of 19mm, but the K-d value increases to 31mm in combined K+/Na+ solutions, indicating a poor K+/Na+ selectivity. By contrast, 6 showed even in the presence of competitive Na+ ions equal K-d values (K-d(K+)=45mm and K-d(K+/Na+)=45mm) and equal K+-induced fluorescence enhancement factors (FEFs=2.3). Thus, the fluorescent probe 6 showed an outstanding K+/Na+ selectivity and is a suitable fluorescent tool to measure physiological K+ levels in the range of 10-80mm in vitro. Further, the isopropoxy-substituted N-phenylaza[18]crown-6 ionophore in 6 is a highly K+-selective building block with a feasible synthetic route. KW - crown compounds KW - fluorescence KW - fluorescent probes KW - potassium KW - sodium Y1 - 2016 U6 - https://doi.org/10.1002/asia.201500956 SN - 1861-4728 SN - 1861-471X VL - 11 SP - 241 EP - 247 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Maier, Stefan K. A1 - Poluektov, Georgiy A1 - Jester, Stefan-S. A1 - Möller, Heiko Michael A1 - Hoeger, Sigurd T1 - Fast Oxidative Cyclooligomerization towards Low- and High-Symmetry Thiophene Macrocycles JF - Chemistry - a European journal N2 - Macrocycles with quaterthiophene subunits were obtained by cyclooligomerization by direct oxidative coupling of unsubstituted dithiophene moieties. The rings were closed with high selectivity by an α,β′-connection of the thiophenes as proven by NMR spectroscopy. The reaction of the precursor with terthiophene moieties yielded the symmetric α,α′-linked macrocycle in low yield together with various differently connected isomers. Blocking of the β-position of the half-rings yielded selectively the α,α′-linked macrocycle. Selected cyclothiophenes were investigated by scanning tunneling microscopy, which displayed the formation of highly ordered 2D crystalline monolayers. KW - cyclooligomers KW - scanning tunneling microscopy KW - self-assembled monolayers KW - shape-persistent macrocycles KW - thiophenes Y1 - 2016 U6 - https://doi.org/10.1002/chem.201503211 SN - 0947-6539 SN - 1521-3765 VL - 22 SP - 1379 EP - 1384 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schönborn, Jan Boyke A1 - Saalfrank, Peter A1 - Klamroth, Tillmann T1 - Controlling the high frequency response of H-2 by ultra-short tailored laser pulses: A time-dependent configuration interaction study JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We combine the stochastic pulse optimization (SPO) scheme with the time-dependent configuration interaction singles method in order to control the high frequency response of a simple molecular model system to a tailored femtosecond laser pulse. For this purpose, we use H-2 treated in the fixed nuclei approximation. The SPO scheme, as similar genetic algorithms, is especially suited to control highly non-linear processes, which we consider here in the context of high harmonic generation. Here, we will demonstrate that SPO can be used to realize a "non-harmonic" response of H2 to a laser pulse. Specifically, we will show how adding low intensity side frequencies to the dominant carrier frequency of the laser pulse and stochastically optimizing their contribution can create a high-frequency spectral signal of significant intensity, not harmonic to the carrier frequency. At the same time, it is possible to suppress the harmonic signals in the same spectral region, although the carrier frequency is kept dominant during the optimization. (C) 2016 AIP Publishing LLC. Y1 - 2016 U6 - https://doi.org/10.1063/1.4940316 SN - 0021-9606 SN - 1089-7690 VL - 144 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Rumschöttel, Jens A1 - Kosmella, Sabine A1 - Prietzel, Claudia Christina A1 - Appelhans, Dietmar A1 - Koetz, Joachim T1 - Change in size, morphology and stability of DNA polyplexes with hyperbranched poly(ethyleneimines) containing bulky maltose units JF - Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces N2 - Polyplexes between Salmon DNA and non-modified hyperbranched poly(ethyleneimines) of varying molar mass, i.e., PEI(5 k) with 5000 g/mol and PEI(25 k) with 25,000 g/mol, and modified PEI(5 k) with maltose units (PEI-Mal) were investigated in dependence on the molar N/P ratio by using dynamic light scattering (DLS), zeta potential measurements, micro differential scanning calorimetry (mu-DSC), scanning-transmission electron microscopy (STEM), and cryo-scanning electron microscopy (cryo-SEM). A reloading of the polyplexes can be observed by adding the unmodified PEI samples of different molar mass. In excess of PEI a morphological transition from core-shell particles (at N/P 8) to loosely packed onion-like polyplexes (at N/P 40) is observed. The shift of the DSC melting peak from 88 degrees C to 76 degrees C indicates a destabilization of the DNA double helix due to the complexation with the unmodified PEI. Experiments with the maltose-modified PEI show a reloading already at a lower N/P ratio. Due to the presence of the sugar units in the periphery of the polycation electrostatic interactions between DNA become weaker, but cooperative H-bonding forces are reinforced. The resulting less-toxic, more compact polyplexes in excess of the PEI-Mal with two melting points and well distributed DNA segments are of special interest for extended gene delivery experiments. (C) 2015 Elsevier B.V. All rights reserved. KW - DNA complexation KW - Polyplexes KW - Maltose-modified poly(ethyleneimine) KW - Morphology Y1 - 2016 U6 - https://doi.org/10.1016/j.colsurfb.2015.11.061 SN - 0927-7765 SN - 1873-4367 VL - 138 SP - 78 EP - 85 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Knight, Joseph W. A1 - Wang, Xiaopeng A1 - Gallandi, Lukas A1 - Dolgounitcheva, Olga A1 - Ren, Xinguo A1 - Ortiz, J. Vincent A1 - Rinke, Patrick A1 - Körzdörfer, Thomas A1 - Marom, Noa T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules III: A Benchmark of GW Methods JF - Journal of chemical theory and computation N2 - The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, and perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green’s function (scGW0), non-self-consistent G0W0 based on several mean-field starting points, and a “beyond GW” second-order screened exchange (SOSEX) correction to G0W0. We also describe the implementation of the self-consistent Coulomb hole with screened exchange method (COHSEX), which serves as one of the mean-field starting points. The best performers overall are G0W0+SOSEX and G0W0 based on an IP-tuned long-range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00871 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 615 EP - 626 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Gallandi, Lukas A1 - Marom, Noa A1 - Rinke, Patrick A1 - Körzdörfer, Thomas T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules II: Non-Empirically Tuned Long-Range Corrected Hybrid Functionals JF - Journal of chemical theory and computation N2 - The performance of non-empirically tuned long-range corrected hybrid functionals for the prediction of vertical ionization potentials (IPs) and electron affinities (EAs) is assessed for a set of 24 organic acceptor molecules. Basis set extrapolated coupled cluster singles, doubles, and perturbative triples [CCSD(T)] calculations serve as a reference for this study. Compared to standard exchange-correlation functionals, tuned long-range corrected hybrid functionals produce highly reliable results for vertical IPs and EAs, yielding mean absolute errors on par with computationally more demanding GW calculations. In particular, it is demonstrated that long-range corrected hybrid functionals serve as ideal starting points for non-self-consistent GW calculations. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00873 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 605 EP - 614 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wessig, Pablo A1 - Gerngross, Maik A1 - Freyse, Daniel A1 - Bruhn, P. A1 - Przezdziak, Marc A1 - Schilde, Uwe A1 - Kelling, Alexandra T1 - Molecular Rods Based on Oligo-spiro-thioketals JF - The journal of organic chemistry N2 - We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.5b02670 SN - 0022-3263 VL - 81 SP - 1125 EP - 1136 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Secker, Christian A1 - Voelkel, Antje A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Schlaad, Helmut T1 - Thermo-Induced Aggregation and Crystallization of Block Copolypeptoids in Water JF - Macromolecules : a publication of the American Chemical Society N2 - Block copolypeptoids comprising a thermosensitive, crystallizable poly(N-(n-propyl)glycine) block and a watersoluble poly(N-methylglycine) block, P70My (y = 23, 42, 76, 153, and 290), were synthesized bY ring-opening polymerization of the corresponding N-alkylglycine N-carboxyanhydrides (NCAs) and examined according to their thermo-induced aggregation and crystallization in water by turbidimetty, micro-differential scanning calorimetry (micro-DSC); cryogenic scanning electron microscopy (cryo-SEM), analytical ultracentrifugation (AUC), and static light scattering (SLS). At a temperature above the cloud point temperature, the initially formed micellar aggregates started to crystallize and grow into larger complex assemblies of about 100-500 nm, exhibiting flower-like (P70M23), ellipsoidal (P70M42 and P70M72) or irregular shapes (P70M153 and.P70M290). Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.5b02481 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 979 EP - 985 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schürmann, Robin Mathis A1 - Bald, Ilko T1 - Decomposition of DNA Nucleobases by Laser Irradiation of Gold Nanoparticles Monitored by Surface-Enhanced Raman Scattering JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Different approaches have been proposed to treat cancer cells using gold nanoparticles (AuNPs) in combination with radiation ranging from infrared lasers to high-energy ion beams. Here we study the decomposition of the DNA/RNA nucleobases thymine (T) and uracil (U) and the well-known radiosensitizer 5-bromouracil (BrU) in close vicinity to AuNPs, which are irradiated with a nanosecond pulsed laser (532 nm) matching the surface plasmon resonance of the AuNPs. The induced damage of nucleobases is analyzed by UV-vis absorption spectroscopy and surface-enhanced Raman scattering (SERS). A clear DNA damage is observed upon laser irradiation. SERS spectra indicate the fragmentation of the aromatic ring system of T and U as the dominant form of damage, whereas with BrU mainly the cleavage of the Br-C bond and formation of Br- ions is observed. This is accompanied by a partial transformation of BrU into U. The observed damage is at least partly ascribed to the intermediate formation of low energy electrons from the laser-excited AuNPs and subsequent dissociative electron attachment to T, U, and BrU. These reactions represent basic DNA damage pathways occurring on the one hand in plasmon-assisted cancer therapy and on the other hand in conventional cancer radiation therapy using AuNPs as sensitizing agents. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.5b10564 SN - 1932-7447 VL - 120 SP - 3001 EP - 3009 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Dietrich, Paul M. A1 - Glamsch, Stephan A1 - Ehlert, Christopher A1 - Lippitz, Andreas A1 - Kulak, Nora A1 - Unger, Wolfgang E. S. T1 - Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon JF - Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces N2 - The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z(95) of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) - inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS. (C) 2015 Elsevier B.V. All rights reserved. KW - Synchrotron radiation XPS KW - Depth profiling KW - Silanes KW - Monolayer KW - Amines KW - Amides Y1 - 2016 U6 - https://doi.org/10.1016/j.apsusc.2015.12.052 SN - 0169-4332 SN - 1873-5584 VL - 363 SP - 406 EP - 411 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Matkovic, Aleksandar A1 - Vasic, Borislav A1 - Pesic, Jelena A1 - Prinz, Julia A1 - Bald, Ilko A1 - Milosavljevic, Aleksandar R. A1 - Gajic, Rados T1 - Enhanced structural stability of DNA origami nanostructures by graphene encapsulation JF - NEW JOURNAL OF PHYSICS N2 - We demonstrate that a single-layer graphene replicates the shape of DNA origami nanostructures very well. It can be employed as a protective layer for the enhancement of structural stability of DNA origami nanostructures. Using the AFM based manipulation, we show that the normal force required to damage graphene encapsulated DNA origami nanostructures is over an order of magnitude greater than for the unprotected ones. In addition, we show that graphene encapsulation offers protection to the DNA origami nanostructures against prolonged exposure to deionized water, and multiple immersions. Through these results we demonstrate that graphene encapsulated DNA origami nanostructures are strong enough to sustain various solution phase processing, lithography and transfer steps, thus extending the limits of DNA-mediated bottom-up fabrication. KW - graphene KW - DNA origami nanostructures KW - atomic force microscopy Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/025016 SN - 1367-2630 VL - 18 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Gangloff, Niklas A1 - Ulbricht, Juliane A1 - Lorson, Thomas A1 - Schlaad, Helmut A1 - Luxenhofer, Robert T1 - Peptoids and Polypeptoids at the Frontier of Supra- and Macromolecular Engineering JF - Chemical reviews Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemrev.5b00201 SN - 0009-2665 SN - 1520-6890 VL - 116 SP - 1753 EP - 1802 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kyriakos, Konstantinos A1 - Philipp, Martine A1 - Lin, Che-Hung A1 - Dyakonova, Margarita A1 - Vishnevetskaya, Natalya A1 - Grillo, Isabelle A1 - Zaccone, Alessio A1 - Miasnikova, Anna A1 - Laschewsky, Andre A1 - Mueller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency JF - Macromolecular rapid communications N2 - The aggregation kinetics of thermoresponsive core-shell micelles with a poly(N-isopropyl acrylamide) shell in pure water or in mixtures of water with the cosolvents methanol or ethanol at mole fractions of 5% is investigated during a temperature jump across the respective cloud point. Characteristically, these mixtures give rise to cononsolvency behavior. At the cloud point, aggregates are formed, and their growth is followed with time-resolved small-angle neutron scattering. Using the reversible association model, the interaction potential between the aggregates is determined from their growth rate in dependence on the cosolvents. The effect of the cosolvent is attributed to the interaction potential on the structured layer of hydration water around the aggregates. It is surmised that the latter is perturbed by the cosolvent and thus the residual repulsive hydration force between the aggregates is reduced. The larger the molar volume of the cosolvent, the more pronounced is the effect. This framework provides a molecular-level understanding of solvent-mediated effective interactions in polymer solutions and new opportunities for the rational control of self-assembly in complex soft matter systems. KW - colloidal aggregation KW - cononsolvency KW - interaction potential KW - polymer solutions KW - self-assembled micelles KW - thermoresponsive polymers Y1 - 2016 U6 - https://doi.org/10.1002/marc.201500583 SN - 1022-1336 SN - 1521-3927 VL - 37 SP - 420 EP - 425 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Pinyou, Piyanut A1 - Ruff, Adrian A1 - Poeller, Sascha A1 - Barwe, Stefan A1 - Nebel, Michaela A1 - Alburquerque, Natalia Guerrero A1 - Wischerhoff, Erik A1 - Laschewsky, Andre A1 - Schmaderer, Sebastian A1 - Szeponik, Jan A1 - Plumere, Nicolas A1 - Schuhmann, Wolfgang T1 - Thermoresponsive amperometric glucose biosensor JF - Biointerphases N2 - The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(omega-ethoxytriethylenglycol methacrylate-omega-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-omega-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 degrees C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol) methacrylate-co-butyl acrylate-co-2-(dimethylamino) ethyl methacrylate)-[Os(bpy)(2)(4-(((2-(2-(2-aminoethoxy) ethoxy) ethyl) amino) methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on-to an off-state without heating of the surrounding analyte solution. (C) 2015 American Vacuum Society. Y1 - 2016 U6 - https://doi.org/10.1116/1.4938382 SN - 1934-8630 SN - 1559-4106 VL - 11 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Ehlert, Christopher A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Unger, Wolfgang E. S. A1 - Saalfrank, Peter T1 - A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([C(n)C(1)im](+)[NTf2](-) and [C(4)C(1)im](+)[I](-)). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra. Y1 - 2016 U6 - https://doi.org/10.1039/c5cp07434g SN - 1463-9076 SN - 1463-9084 VL - 18 SP - 8654 EP - 8661 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - Y-aromaticity - existing: yes or no? An answer given on the magnetic criterion (TSNMRS) JF - Tetrahedron N2 - The spatial magnetic properties (Through Space NMR Shieldings - TSNMRS) of a number of Y-shaped structures possessing 4n+2 pi-electrons (i.a. the trimethylenemethane ions TMM2+, TMM2-, the guanidinium cation, substituted and hetero analogues) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, were examined subject to present Y-aromaticity and the results compared with energetic and geometric criteria obtained already. (C) 2016 Elsevier Ltd. All rights reserved. KW - Y-aromaticity KW - pi-Electron delocalization KW - Theoretical calculations KW - ICSS KW - TSNMRS Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2016.02.020 SN - 0040-4020 VL - 72 SP - 1675 EP - 1685 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Demirel, A. Levent A1 - Guner, Pinar Tatar A1 - Verbraeken, Bart A1 - Schlaad, Helmut A1 - Schubert, Ulrich S. A1 - Hoogenboom, Richard T1 - Revisiting the Crystallization of Poly(2-alkyl-2-oxazoline)s JF - Journal of polymer science : B, Polymer physics N2 - Poly(2-alkyl-2-oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (T-g) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt-recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 degrees C and PiPropOx between 90 and 150 degrees C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > T-g with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. (C) 2015 Wiley Periodicals, Inc. KW - chain mobility KW - crystallization KW - differential scanning calorimetry (DSC) KW - effect of alkyl side chains KW - glass transition temperature KW - melt KW - melt-recrystallization KW - polymer crystallization Y1 - 2016 U6 - https://doi.org/10.1002/polb.23967 SN - 0887-6266 SN - 1099-0488 VL - 54 SP - 721 EP - 729 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Vorburger, Thomas A1 - Nedielkov, Ruslan A1 - Brosig, Alexander A1 - Bok, Eva A1 - Schunke, Emina A1 - Steffen, Wojtek A1 - Mayer, Sonja A1 - Goetz, Friedrich A1 - Möller, Heiko Michael A1 - Steuber, Julia T1 - Role of the Na+-translocating NADH:quinone oxidoreductase in voltage generation and Na+ extrusion in Vibrio cholerae JF - Biochimica et biophysica acta : Bioenergetics N2 - For Vibrio cholerae, the coordinated import and export of Na+ is crucial for adaptation to habitats with different osmolarities. We investigated the Na+-extruding branch of the sodium cycle in this human pathogen by in vivo Na-23-NMR spectroscopy. The Na+ extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR). In a V. cholerae deletion mutant devoid of the Na+-NQR encoding genes (nqrA-F), rates of respiratory Na+ extrusion were decreased by a factor of four, but the cytoplasmic Na+ concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (Delta psi, inside negative) and did not grow under hypoosmotic conditions at pH 8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na+/H+ antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na+ concentrations, the Na+-NQR is crucial for generation of a transmembrane voltage to drive the import of H+ by electrogenic Na+/H+ antiporters. Our study provides the basis to understand the role of the Na+-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na+ pump for respiration. (C) 2015 Elsevier B.V. All rights reserved. KW - Nuclear magnetic resonance (NMR) KW - Sodium transport KW - Vibrio cholerae KW - Respiration KW - Na+ homeostasis KW - Hypoosmotic stress Y1 - 2016 U6 - https://doi.org/10.1016/j.bbabio.2015.12.010 SN - 0005-2728 SN - 0006-3002 VL - 1857 SP - 473 EP - 482 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kovach, Ildiko A1 - Won, Jooyoung A1 - Friberg, Stig E. A1 - Koetz, Joachim T1 - Completely engulfed olive/silicone oil Janus emulsions with gelatin and chitosan JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - Janus emulsions, formed by mixing two oil components (i.e., olive oil (OO) and silicone oil (SiO)) with water in the presence of two surface active biopolymers, i.e., gelatin and chitosan, are investigated in more detail. The stability of Janus droplets formed strongly depends on the polymer components used. The mixture of both biopolymers represents an extraordinary effect which can be related to the complex formation of gelatin and chitosan. Taken into account that under the given pH conditions, in the acidic pH range between 4 and 6, below the isoelectric point of gelatin, both polymers are polycations, one can conclude that non-Coulombic interactions are of relevance for the enhanced surface activity of the complexes. Dynamic interfacial tension (gamma) measurements by using the drop profile analysis tensiometry (PAT) indicate a strong adsorption of the polymer complexes at the olive oil/water interface in contrast to the silicone/water interface. In a first step, the polymer complexes are adsorbed at the interface, and in a second step, a more rigid skin-like polymer layer is formed. This first example of a polymer-stabilized Janus emulsion opens new perspectives for the application, e.g., in food emulsions or for making scaffold materials. KW - Janus emulsions KW - Interfacial tension KW - Ring method KW - Drop profile analysis tensiometry KW - Gelatin-chitosan composites Y1 - 2016 U6 - https://doi.org/10.1007/s00396-016-3828-4 SN - 0303-402X SN - 1435-1536 VL - 294 SP - 705 EP - 713 PB - Springer CY - New York ER - TY - JOUR A1 - Bois, Juliana A1 - Körzdörfer, Thomas T1 - 0 How Bond Length Alternation and Thermal Disorder Affect the Optical Excitation Energies of pi-Conjugated Chains: A Combined Density Functional Theory and Molecular Dynamics Study JF - Journal of chemical theory and computation N2 - We dissect the sources of error leading to inaccuracies in the description of the geometry and optical excitation energies of pi-conjugated polymers. While the ground-state bond length alternation is shown to be badly reproduced by standard functionals, the recently adapted functionals PBEh* and omega PBE* as well as the double hybrid functional XYGJ-OS manage to replicate results obtained at the CCSD(T) level. By analysis of the bond length alternation in the excited state, a sensitive dependence of the exciton localization on the long-range behavior of the functional and the amount of Hartree-Fock exchange present is shown. Introducing thermal disorder through molecular dynamics simulations allows the consideration of a range of thermally accessible configurations of each oligomer, including trans to cis rotations, which break the conjugation of the backbone. Thermal disorder has a considerable effect when combined with functionals that overestimate the delocalization of the excitation, such as B3LYP. For functionals with a larger amount of exact exchange such as our PBEh* and omega PBE*, however, the effect is small, as excitations are often localized enough to fit between twists in the chain. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b01070 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 1872 EP - 1882 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Enzenberg, Anne A1 - Laschewsky, Andre A1 - Boeffel, Christine A1 - Wischerhoff, Erik T1 - Influence of the Near Molecular Vicinity on the Temperature Regulated Fluorescence Response of Poly(N-vinylcaprolactam) JF - Polymers N2 - A series of new fluorescent dye bearing monomers, including glycomonomers, based on maleamide and maleic esteramide was synthesized. The dye monomers were incorporated by radical copolymerization into thermo-responsive poly(N‑vinyl-caprolactam) that displays a lower critical solution temperature (LCST) in aqueous solution. The effects of the local molecular environment on the polymers’ luminescence, in particular on the fluorescence intensity and the extent of solvatochromism, were investigated below as well as above the phase transition. By attaching substituents of varying size and polarity in the close vicinity of the fluorophore, and by varying the spacer groups connecting the dyes to the polymer backbone, we explored the underlying structure–property relationships, in order to establish rules for successful sensor designs, e.g., for molecular thermometers. Most importantly, spacer groups of sufficient length separating the fluorophore from the polymer backbone proved to be crucial for obtaining pronounced temperature regulated fluorescence responses. View Full-Text KW - thermo-responsive polymers KW - poly(N-vinylcaprolactam) KW - lower critical solution temperature KW - fluorescent dyemonomers KW - naphthalimide KW - solvatochromism KW - polymeric sensors KW - molecular thermometers Y1 - 2016 U6 - https://doi.org/10.3390/polym8040109 SN - 2073-4360 VL - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - Zabel, Andre A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and g(perpendicular to)) of the tensors could be determined and information on the structural changes in the [CuBr4](2-) anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 SN - 1422-0067 VL - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kopec, Maciej A1 - Rozpedzik, Anna A1 - Lapok, Lukasz A1 - Geue, Thomas A1 - Laschewsky, Andre A1 - Zapotoczny, Szczepan T1 - Stratified Micellar Multilayers-Toward Nanostructured Photoreactors JF - Chemistry of materials : a publication of the American Chemical Society N2 - Polyelectrolyte multilayers (PEMs) with stratification of the internal structure were assembled from statistical amphiphilic copolyelectrolytes of opposite charges. These polyelectrolytes organize in aqueous solutions into micellar structures with fluoroalkyl and aromatic nanodomains, respectively, that were also preserved after deposition as thin films via layer-by-layer (LbL) electrostatic self-assembly. The unimolecular micelles, formed due to statistical compositions of amphiphilic polyelectrolytes used, were shown to suppress chain interdiffusion between adjacent layers in resulting micellar PEMs, as evidenced by spectroscopic ellipsometry, atomic force microscopy (AFM), and neutron reflectometry (NR) measurements. Additionally, hydrophobic cores of the micelles were used as hosts for photoactive molecules, namely, ferrocene and perfluorinated magnesium phthalocyanine. Stratified micellar multilayers were then deposited as hollow capsules using CaCO3 microparticles as templates. Photoinduced electron transfer (PET) between ferrocene and phthalocyanine solubilized in the polymer micelles was demonstrated to occur efficiently inside the stratified, polyelectrolyte walls of the capsules, due to the polarity gradient created by the incompatible aromatic and fluoroalkyl domains. The obtained results present a new approach to construct well-organized, self-assembled nanostructured materials for solar energy conversion. Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemmater.6b00161 SN - 0897-4756 SN - 1520-5002 VL - 28 SP - 2219 EP - 2228 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - White, Alec F. A1 - Heide, Chiara Josephine A1 - Saalfrank, Peter A1 - Head-Gordon, Martin A1 - Luppi, Eleonora T1 - Computation of high-harmonic generation spectra of the hydrogen molecule using time-dependent configuration-interaction JF - Molecular physics N2 - Here we apply and expand the knowledge developed in the case of the H atom to describe high-harmonic generation (HHG) for the H-2 molecule by using time-dependent configuration interaction with single excitations. The implications of using a finite atomic orbital basis set and the impact of a heuristic lifetime model which addresses ionisation losses are discussed. We also examine the influence of the angular momentum of the basis on the computed HHG spectra. Moreover, we discuss the impact of adding diffuse functions and ghost atoms in different geometrical configurations around the molecule. The effects of these additional centres on the HHG spectra are correlated with the physical interpretation of this nonlinear optical phenomenon as given by the three-step model, relating the maximal radial extent of the electron as predicted by the model to the radial extent of the Gaussian basis sets. [GRAPHICS] . KW - High-harmonic generation KW - strong field KW - time-dependent configuration interaction Y1 - 2016 U6 - https://doi.org/10.1080/00268976.2015.1119900 SN - 0026-8976 SN - 1362-3028 VL - 114 SP - 947 EP - 956 PB - Springer CY - Abingdon ER - TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin T1 - Microwave-Promoted Deprenylation: Prenyl Ether as a Thermolabile Phenol Protecting Group JF - Synthesis N2 - para-Substituted aryl prenyl ethers undergo a deprenylation reaction upon microwave irradiation. This offers the opportunity to use a prenyl ether as a thermolabile protecting group in the synthesis of natural products with a chromone structure, which proceeds via a tandem deprenylation/6-endo-cyclization sequence. KW - microwave irradiation KW - phenols KW - chromenes KW - protecting groups KW - Claisen rearrangement Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1561366 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 1399 EP - 1406 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Draffehn, Soeren A1 - Kumke, Michael Uwe T1 - Monitoring the Collapse of pH-Sensitive Liposomal Nanocarriers and Environmental pH Simultaneously: A Fluorescence-Based Approach JF - Molecular pharmaceutics N2 - Nowadays, the encapsulation of therapeutic compounds in so-called carrier systems is a very smart method to achieve protection as well as an improvement of their temporal and spatial distribution. After the successful transport to the point of care, the delivery has to be released under controlled conditions. To monitor the triggered release from the carrier, we investigated different fluorescent probes regarding their response to the pH-induced collapse of pH-sensitive liposomes (pHSLip), which occurs when the environmental pH falls below a critical value. Depending on the probe, the fluorescence decay time as well as fluorescence anisotropy can be used equally as key parameters for monitoring the collapse. Especially the application of a fluorescein labeled fatty acid (fPA) enabled the monitoring of the pHSLips collapse and the pH of its microenvironment simultaneously without interference. Varying the pH in the range of 3 < pH < 9, anisotropy data revealed the critical pH value at which the collapse of the pHSLips occurs. Complementary methods, e.g., fluorescence correlation spectroscopy and dynamic light scattering, supported the analysis based on the decay time and anisotropy. Additional experiments with varying incubation times yielded information on the kinetics of the liposomal collapse. KW - pH-sensitive liposome KW - drug carrier system KW - selective drug release KW - intracellular pH indicator KW - time-resolved fluorescence spectroscopy KW - fluorescence anisotropy KW - fluorescence correlation spectroscopy Y1 - 2016 U6 - https://doi.org/10.1021/acs.molpharmaceut.5b00064 SN - 1543-8384 VL - 13 SP - 1608 EP - 1617 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Göbel, Ronald A1 - Stoltenberg, Marcus A1 - Krehl, Stefan A1 - Biolley, Christine A1 - Rothe, Regina A1 - Schmidt, Bernd A1 - Hesemann, Peter A1 - Taubert, Andreas T1 - A Modular Approach towards Mesoporous Silica Monoliths with Organically Modified Pore Walls: Nucleophilic Addition, Olefin Metathesis, and Cycloaddition JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - We have synthesized mesoporous silica (monoliths) with defined surface chemistry by means of a number of addition reactions: (i) coupling of an isocyanate to a surface-immobilized thiol, (ii) addition of an epoxide to a surface-immobilized thiol, (iii) cross-metathesis between two olefins, and (iv) Huisgen [2+3] cycloaddition of an alkyne-functionalized silica monolith with an azide. Functionalization of the mesopores was observed, but there are significant differences between individual approaches. Isocyanate and epoxide additions lead to high degrees of functionalization, whereas olefin metathesis and [2+3] cycloaddition are less effective. We further show that the efficiency of the modification is about twice as high in mesoporous silica particles than in macroscopic silica monoliths. KW - Mesoporous materials KW - Hybrid materials KW - Surface chemistry KW - Click chemistry KW - Nucleophilic addition Y1 - 2016 U6 - https://doi.org/10.1002/ejic.201500638 SN - 1434-1948 SN - 1099-0682 VL - 6 SP - 2088 EP - 2099 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Couturier, Jean-Philippe A1 - Wischerhoff, Erik A1 - Bernin, Robert A1 - Hettrich, Cornelia A1 - Koetz, Joachim A1 - Sutterlin, Martin A1 - Tiersch, Brigitte A1 - Laschewsky, Andre T1 - Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols JF - Langmuir N2 - Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers’ cloud point, or the induced changes of the hydrogels’ swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b00803 SN - 0743-7463 VL - 32 SP - 4333 EP - 4345 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Attallah, Ahmed G. A1 - Matthes, Philipp R. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Müller-Buschbaum, Klaus A1 - Krause-Rehberg, Reinhard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Study of the Discrepancies between Crystallographic Porosity and Guest Access into Cadmium-Imidazolate Frameworks and Tunable Luminescence Properties by Incorporation of Lanthanides JF - Chemistry - a European journal N2 - An extended member of the isoreticular family of metal-imidazolate framework structures, IFP-6 (IFP=imidazolate framework Potsdam), based on cadmium metal and an in situ functionalized 2-methylimidazolate-4-amide-5-imidate linker is reported. A porous 3D framework with 1D hexagonal channels with accessible pore windows of 0.52nm has been synthesized by using an ionic liquid (IL) linker precursor. IFP-6 shows significant gas uptake capacity only for CO2 and CH4 at elevated pressure, whereas it does not adsorb N-2, H-2, and CH4 under atmospheric conditions. IFP-6 is assumed to deteriorate at the outside of the material during the activation process. This closing of the metal-organic framework (MOF) pores is proven by positron annihilation lifetime spectroscopy (PALS), which revealed inherent crystal defects. PALS results support the conservation of the inner pores of IFP-6. IFP-6 has also been successfully loaded with luminescent trivalent lanthanide ions (Ln(III)=Tb, Eu, and Sm) in a bottom-up one-pot reaction through the in situ generation of the linker ligand and in situ incorporation of photoluminescent Ln ions into the constituting network. The results of photoluminescence investigations and powder XRD provide evidence that the Ln ions are not doped as connectivity centers into the frameworks, but are instead located within the pores of the MOFs. Under UV light irradiation, Tb@IFP-6 and Eu@IFP-6 ((exc)=365nm) exhibit observable emission changes to a greenish and reddish color, respectively, as a result of strong Ln 4f emissions. KW - adsorption KW - cadmium KW - ionic liquids KW - luminescence KW - metal-organic frameworks Y1 - 2016 U6 - https://doi.org/10.1002/chem.201504757 SN - 0947-6539 SN - 1521-3765 VL - 22 SP - 6905 EP - 6913 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Barta, Petra A1 - Szatmari, Istvan A1 - Fueloep, Ferenc A1 - Heydenreich, Matthias A1 - Koch, Andreas A1 - Kleinpeter, Erich T1 - Synthesis and stereochemistry of new naphth[1,3]oxazino[3,2-a] benzazepine and naphth[1,3]oxazino[3,2-e]thienopyridine derivatives JF - Tetrahedron N2 - Through the reactions of 1- or 2-naphthol and 4,5-dihydro-3H-benz[c]azepine or 6,7-dihydrothieno[3,2-c]pyridine, new aminonaphthol derivatives were prepared. The syntheses were extended by using N-containing naphthol analogues such as 5-hydroxyisoquinoline and 6-hydroxyquinoline. The ring closures of the novel bifunctional compounds were also achieved, resulting in new naphth[2,1-e][1,3]oxazines, naphth[1,2-e][1,3]oxazines, isoquinolino[5,6-e][1,3]oxazines and quinolino[5,6-e][1,3]oxazines. H-1 NMR spectra of the target heterocycles 16, 20 and 21 were sufficiently resolved to indentify the present stereochemistry; therefore, beside computed structures, spatial experimental (dipolar coupling-NOE) and computed (ring current effect of the naphthyl moiety-TSNMRS) NMR studies were employed. The studied heterocycles exist exclusively as S(14b),R(N), R(14b),S(N), and S(16b)S(N) isomers, respectively. The flexible moieties of the studied compounds prefer. (C) 2016 Elsevier Ltd. All rights reserved. KW - Modified Mannich reaction KW - Thienopyridine KW - Benzazepine KW - NMR spectroscopy KW - Stereochemistry KW - Theoretical calculations Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2016.03.058 SN - 0040-4020 VL - 72 SP - 2402 EP - 2410 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Wirth, Jonas A1 - Schacht, Julia A1 - Saalfrank, Peter A1 - Paulus, Beate T1 - Fluorination of the Hydroxylated alpha-Al2O3 (0001) and Its Implications for Water Adsorption: A Theoretical Study JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Fluorination of the hydroxylated alpha-Al2O3 (0001) surface is studied using periodic density functional theory calculations. On the basis of a hypothetical reaction substituting surface hydroxyl groups with fluorine atoms, we find surface fluorination to be strongly exergonic but kinetically hindered. Fluorinated surface areas turn out to be rather hydrophobic as compared to hydroxylated areas, suggesting fluorination as a potential route for tuning oxide surface properties such as hydrophilicity. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.5b10975 SN - 1932-7447 VL - 120 SP - 9713 EP - 9718 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Soliveres, Santiago A1 - Manning, Peter A1 - Prati, Daniel A1 - Gossner, Martin M. A1 - Alt, Fabian A1 - Arndt, Hartmut A1 - Baumgartner, Vanessa A1 - Binkenstein, Julia A1 - Birkhofer, Klaus A1 - Blaser, Stefan A1 - Bluethgen, Nico A1 - Boch, Steffen A1 - Boehm, Stefan A1 - Boerschig, Carmen A1 - Buscot, Francois A1 - Diekoetter, Tim A1 - Heinze, Johannes A1 - Hoelzel, Norbert A1 - Jung, Kirsten A1 - Klaus, Valentin H. A1 - Klein, Alexandra-Maria A1 - Kleinebecker, Till A1 - Klemmer, Sandra A1 - Krauss, Jochen A1 - Lange, Markus A1 - Morris, E. Kathryn A1 - Mueller, Joerg A1 - Oelmann, Yvonne A1 - Overmann, Jörg A1 - Pasalic, Esther A1 - Renner, Swen C. A1 - Rillig, Matthias C. A1 - Schaefer, H. Martin A1 - Schloter, Michael A1 - Schmitt, Barbara A1 - Schoening, Ingo A1 - Schrumpf, Marion A1 - Sikorski, Johannes A1 - Socher, Stephanie A. A1 - Solly, Emily F. A1 - Sonnemann, Ilja A1 - Sorkau, Elisabeth A1 - Steckel, Juliane A1 - Steffan-Dewenter, Ingolf A1 - Stempfhuber, Barbara A1 - Tschapka, Marco A1 - Tuerke, Manfred A1 - Venter, Paul A1 - Weiner, Christiane N. A1 - Weisser, Wolfgang W. A1 - Werner, Michael A1 - Westphal, Catrin A1 - Wilcke, Wolfgang A1 - Wolters, Volkmar A1 - Wubet, Tesfaye A1 - Wurst, Susanne A1 - Fischer, Markus A1 - Allan, Eric T1 - Locally rare species influence grassland ecosystem multifunctionality JF - Philosophical transactions of the Royal Society of London : B, Biological sciences N2 - Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 ecosystem functions on 150 grasslands across a land use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for ecosystem multifunctionality and help guiding future conservation priorities. KW - biodiversity KW - common species KW - ecosystem function KW - identity hypothesis KW - land use KW - multitrophic Y1 - 2016 U6 - https://doi.org/10.1098/rstb.2015.0269 SN - 0962-8436 SN - 1471-2970 VL - 371 SP - 3175 EP - 3185 PB - Royal Society CY - London ER - TY - JOUR A1 - Paramonov, Guennaddi K. A1 - Kuehn, O. A1 - Bandrauk, Andre D. T1 - Shaped Post-Field Electronic Oscillations in H-2(+) Excited by Two-Cycle Laser Pulses: Three-Dimensional Non-Born-Oppenheimer Simulations JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Quantum dynamics of H-2(+) excited by two-cycle laser pulses with laser carrier frequencies corresponding to the wavelengths lambda(1) = 800 and 200 nm (corresponding to the periods tau(1) = 2.667 and 0.667 fs, respectively) and being linearly polarized along the molecular axis have been studied by the numerical solution of the non-Born-Oppenheimer time-dependent Schrodinger equation within a three-dimensional (3D) model, including the internuclear distance R and electron coordinates z and rho. The amplitudes of the pulses have been chosen such that the energies of H-2(+) after the ends of the laser pulses, < E > approximate to-0.515 au, were close to the dissociation threshold of H-2(+). It is found that there exists a certain characteristic oscillation frequency omega(osc) = 0.2278 au (corresponding to the period tau(osc) = 0.667 fs and the wavelength lambda(osc) = 200 nm) that plays the role of a "carrier" frequency of temporally shaped oscillations of the expectation values <-partial derivative V/partial derivative z) emerging after the ends of the laser pulses, both at lambda(1) = 800 nm and at lambda(1) = 200 nm. Moreover, at lambda(1) = 200 nm, the expectation value < z > also demonstrates temporally shaped oscillations after the end of the laser pulse. In contrast, at lambda(1) = 800 nm, the characteristic oscillation frequency omega(osc) = 0.2278 au appears as the frequency of small-amplitude oscillations of the slowly varying expectation value < z > which makes, after the end of the pulse, an excursion with an amplitude of about 4.5 au along the z axis and returns back to < z > approximate to 0 afterward. It is found that the period of the temporally shaped post-field oscillations of <-partial derivative V/partial derivative z > and < z >, estimated as tau(shp) approximate to 30 fs, correlates with the nuclear motion. It is also shown that vibrational excitation of H-2(+) is accompanied by the formation of "hot" and "cold" vibrational ensembles along the R degree of freedom. Power spectra related to the electron motion in H-2(+) calculated for both the laser-driven z and optically passive rho degrees of freedom in the acceleration form proved to be very interesting. In particular, both odd and even harmonics can be observed. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpca.5b11599 SN - 1089-5639 VL - 120 SP - 3175 EP - 3185 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Titov, Evgenii A1 - Saalfrank, Peter T1 - Exciton Splitting of Adsorbed and Free 4-Nitroazobenzene Dimers: A Quantum Chemical Study JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Molecular photoswitches such as azobenzenes, which undergo photochemical trans <-> cis isomerizations, are often mounted for possible applications on a surface and/or surrounded by other switches, for example, in self-assembled monolayers. This may suppress the isomerization cross section due to possible steric reasons, or, as recently speculated, by exciton coupling to. neighboring switches, leading to ultrafast electronic quenching (Gahl et al., J. Am. Chem. Soc. 2010, 132, 1831). The presence of exciton coupling has been anticipated from a blue shift of the optical absorption band, compared to molecules in solution. From the theory side the need arises to properly analyze and quantify the change of absorption spectra of interacting and adsorbed switches. In particular, suitable methods should be identified, and effects of intermolecule and molecule surface interactions on spectra should be disentangled. In this paper by means of time-dependent Hartree-Fock. (TD-HF), various flavors of time-dependent density functional theory (TD-DFT), and the correlated wave function based, coupled cluster (CC2) method we investigated the 4-nitroazobenzene molecule as an:example: The low-lying singlet excited states in the isolated trans monomer and dieter as well as their composites with a silicon pentamantane nanocluster, which serves also as a crude model for a silicon surface, were determined. As most important results we found that (i) HF, CC2, range-separated density functionals, or global hybrids with large amount of exact exchange are able to describe exciton (Davydov) splitting properly, while hybrids with small amount of exact exchange fail producing spurious charge transfer. (ii) The exciton splitting in a free dimer would lead to a blue shift of the absorption signal; however, this effect is almost nullified or even overcompensated by the shift arising from van der Waals interactions between the two molecules. (iii) Adsorption on the Si "surface" leads to a further, strong red shift for the present system. (iv) At a next-nearest neighbor distance (of similar to 3.6 angstrom), the exciton splitting is similar to 0.3 eV, with or without "surface", suggesting a rapid quenching of the molecular pi ->pi* excitation. At larger distances, exciton splitting decreases rapidly. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpca.5b10376 SN - 1089-5639 VL - 120 SP - 3055 EP - 3070 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Oertel, Jana A1 - Keller, Adrian A1 - Prinz, Julia A1 - Schreiber, Benjamin A1 - Huebner, Rene A1 - Kerbusch, Jochen A1 - Bald, Ilko A1 - Fahmy, Karim T1 - Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion JF - Scientific reports N2 - Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the "outer shape" of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of similar to 10 nm diameter containing a lipid bilayer similar to 5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. Y1 - 2016 U6 - https://doi.org/10.1038/srep26718 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Vargas-Ruiz, Salome A1 - Schulreich, Christoph A1 - Kostevic, Angelika A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Kakorin, Sergej A1 - von Klitzing, Regine A1 - Jung, Martin A1 - Hellweg, Thomas A1 - Wellert, Stefan T1 - Extraction of model contaminants from solid surfaces by environmentally compatible microemulsions JF - Journal of colloid and interface science N2 - In the present contribution, we evaluate the efficiency of eco-friendly microemulsions to decontaminate solid surfaces by monitoring the extraction of non-toxic simulants of sulfur mustard out of model surfaces. The extraction process of the non-toxic simulants has been monitored by means of spectroscopic and chromatographic techniques. The kinetics of the removal process was analyzed by different empirical models. Based on the analysis of the kinetics, we can assess the influence of the amounts of oil and water and the microemulsion structure on the extraction process. (C) 2016 Elsevier Inc. All rights reserved. KW - Microemulsions KW - Decontamination KW - Surface removal KW - Kinetic analysis KW - Extraction Y1 - 2016 U6 - https://doi.org/10.1016/j.jcis.2016.03.006 SN - 0021-9797 SN - 1095-7103 VL - 471 SP - 118 EP - 126 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Dzhigaev, D. A1 - Shabalin, A. A1 - Stankevic, T. A1 - Lorenz, Ulf A1 - Kurta, R. P. A1 - Seiboth, F. A1 - Wallentin, J. A1 - Singer, A. A1 - Lazarev, S. A1 - Yefanov, O. M. A1 - Borgstrom, M. A1 - Strikhanov, M. N. A1 - Samuelson, L. A1 - Falkenberg, G. A1 - Schroer, C. G. A1 - Mikkelsen, A. A1 - Vartanyants, I. A. T1 - Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire JF - Journal of optics N2 - Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of +/- 0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires. KW - Bragg coherent x-ray diffractive imaging KW - InP nanowires KW - strain field Y1 - 2016 U6 - https://doi.org/10.1088/2040-8978/18/6/064007 SN - 2040-8978 SN - 2040-8986 VL - 18 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Sun, Haitao A1 - Ryno, Sean A1 - Zhong, Cheng A1 - Ravva, Mahesh Kumar A1 - Sun, Zhenrong A1 - Körzdörfer, Thomas A1 - Bredas, Jean-Luc T1 - Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)-Tuned Range-Separated Density Functional Approach JF - Journal of chemical theory and computation N2 - We propose a new methodology for the first principles description of the electronic properties relevant for charge transport in organic molecular crystals. This methodology, which is based on the combination of a nonempirical, optimally tuned range separated hybrid functional with the polarizable continuum model, is applied to a series of eight representative molecular semiconductor crystals. We show that it provides ionization energies, electron affinities, and transport gaps in very good agreement with experimental values, as well as with the results of many-body perturbation theory-within the GW approximation at a fraction of the computational cost. Hence, this approach represents an easily applicable and computationally efficient tool to estimate the gas-to crystal phase shifts of the frontier-orbital quasiparticle energies in organic electronic materials. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.6b00225 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 2906 EP - 2916 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Steeples, Elliot A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Esposito, Davide T1 - Amino acid-derived N-heterocyclic carbene palladium complexes for aqueous phase Suzuki-Miyaura couplings JF - New journal of chemistry N2 - In this work, three ligands produced from amino acids were synthesized and used to produce five bis- and PEPPSI-type palladium-NHC complexes using a novel synthesis route from sustainable starting materials. Three of these complexes were used as precatalysts in the aqueous-phase Suzuki-Miyaura coupling of various substrates displaying high activity. TEM and mercury poisoning experiments provide evidence for Pd-nanoparticle formation stabilized in water. Y1 - 2016 U6 - https://doi.org/10.1039/c5nj03337c SN - 1144-0546 SN - 1369-9261 VL - 40 SP - 4922 EP - 4930 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Wischke, Christian A1 - Lendlein, Andreas T1 - Functional nanocarriers by miniaturization of polymeric materials T2 - Nanomedicine KW - function KW - microscale KW - morphology KW - nanoscale KW - polymer Y1 - 2016 U6 - https://doi.org/10.2217/nnm.16.45 SN - 1743-5889 SN - 1748-6963 VL - 11 SP - 1507 EP - 1509 PB - Future Medicine CY - London ER - TY - JOUR A1 - Schmidt, Bernd A1 - Wolf, Felix A1 - Brunner, Heiko T1 - Styrylsulfonates and -Sulfonamides through Pd-Catalysed Matsuda-Heck Reactions of Vinylsulfonic Acid Derivatives and Arenediazonium Salts JF - European journal of organic chemistry N2 - Arene diazonium salts undergo Matsuda-Heck reactions with vinylsulfonates and -sulfonamides to give styrylsulfonic acid derivatives in high to excellent yields and with high to excellent selectivities. By quantifying the evolution of nitrogen over time in a gas-meter apparatus, the reactivities of ethylvinylsulfonate and the benchmark olefin methyl acrylate were compared for an electron-rich and an -deficient arene diazonium salt. Tertiary sulfonamides react in Matsuda-Heck couplings with high conversions, but require long reaction times, which prevents the determination of kinetic data through the measurement of nitrogen evolution. Secondary sulfonamides were found to be unreactive. From these results, the following order of reactivity could be deduced: H2C=CHCO2Me > H2C=CHSO2OEt > H2C=CHSO2N(Me)Bn >> H2C=CHSO2NHBn. Through the Matsuda-Heck coupling of 5-indolyldiazonium salt and a tertiary vinylsulfonamide, the synthesis of the C-5-substituted indole part of the antimigraine drug naratriptan was accomplished in high yield. KW - Homogeneous catalysis KW - Cross-coupling KW - Palladium KW - Sulfonamides KW - Alkenes KW - Drug design Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201600469 SN - 1434-193X SN - 1099-0690 SP - 2972 EP - 2982 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tritschler, Ulrich A1 - Zlotnikov, Igor A1 - Fratzl, Peter A1 - Schlaad, Helmut A1 - Gruener, Simon A1 - Coelfen, Helmut T1 - Gas barrier properties of bio-inspired Laponite-LC polymer hybrid films JF - PLoS one N2 - Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, Laponite/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective Laponite content and the underlying composite micro-and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83% Laponite loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these Laponite/LC polymer composites reported previously give rise to a multifunctional composite system. KW - gas permeation KW - liquid crystal KW - Laponite KW - liquid crystal polymer KW - bio-inspired KW - organic-inorganic composite material KW - self-organization Y1 - 2016 U6 - https://doi.org/10.1088/1748-3190/11/3/035005 SN - 1748-3182 SN - 1748-3190 VL - 11 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Pape, Simon A1 - Wessig, Pablo A1 - Brunner, Heiko T1 - Iron Trichloride and Air Mediated Guanylation of Acylthioureas. An Ecological Route to Acylguanidines: Scope and Mechanistic Insights JF - The journal of organic chemistry N2 - Recently we introduced iron trichloride as an environmentally benign and cost-efficient reagent for the synthesis of N-benzoylguanidines. This highly attractive synthetic approach grants access to a broad spectrum of N-benzoylguanidines under mild conditions in short reaction times. In this work we present an extended scope of Our methodology along with the results obtained from mechanistic studies via in situ IR spectroscopy in combination with LC (liquid chromatography)-MS analyses. On the basis of these new mechanistic insights we were able to optimize the synthetic protocol and to develop an alternative mechanistic proposal. In this context the symbiotic roles of iron trithloride and oxygen in the guanylation process are highlighted. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.6b00600 SN - 0022-3263 VL - 81 SP - 4701 EP - 4712 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wirth, Jonas A1 - Kirsch, Harald A1 - Wlosczyk, Sebastian A1 - Tong, Yujin A1 - Saalfrank, Peter A1 - Campen, Richard Kramer T1 - Characterization of water dissociation on alpha-Al2O3(1(1)over-bar02): theory and experiment JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - The interaction of water with a-alumina (i.e. alpha-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with alpha-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined alpha-Al2O3(1 (1) over bar 02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1-4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schrodinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm(-1). Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp01397j SN - 1463-9076 SN - 1463-9084 VL - 18 SP - 14822 EP - 14832 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Boese, Adrian Daniel A1 - Saalfrank, Peter T1 - CO Molecules on a NaCl(100) Surface: Structures, Energetics, and Vibrational Davydov Splittings at Various Coverages JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - In this work, we study the adsorption of CO from low to high coverage at a defect-free NaCl(100) surface by means of duster and periodic models, using highly accurate wave function-based QM:QM embedding as well as density functional theory. At low coverages, the most accurate methods predict a zero-point-corrected adsorption energy of around 13 kJ/mol, and the CO molecules are found to be oriented perpendicular to the surface. At higher coverages, lower-energy phases with nonparallel/upright, tilted orientations emerge. Besides the well-known p(2 x 1)/antiparallel phase (T/A), we find other tilted phases (tilted/irregular, T/I; tilted/spiral, T/S) as local minima. Vibrational frequencies for CO adsorbed on NaCl(100) and Davydov splittings of the C-O stretch vibration are also determined. The IR spectra are characteristic fingerprints for the relative orientation of CO molecules and may therefore be used as sensitive probes to distinguish parallel/upright from various tilted adsorption phases. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.6b03726 SN - 1932-7447 VL - 120 SP - 12637 EP - 12653 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Meiling, Till T. A1 - Cywinski, Piotr J. A1 - Bald, Ilko T1 - White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis JF - Scientific reports N2 - In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (> 1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst. Y1 - 2016 U6 - https://doi.org/10.1038/srep28557 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Andrews, Nicholas L. P. A1 - Ross, Rachel A1 - Munzke, Dorit A1 - van Hoorn, Camiel A1 - Brzezinski, Andrew A1 - Barnes, Jack A. A1 - Reich, Oliver A1 - Loock, Hans-Peter T1 - In-fiber Mach-Zehnder interferometer for gas refractive index measurements based on a hollow-core photonic crystal fiber JF - Optics express : the international electronic journal of optics N2 - We describe an in-fiber interferometer based on a gas-filled hollow-core photonic crystal fiber. Expressions for the sensitivity, figure of merit and refractive index resolution are derived, and values are experimentally measured and theoretically validated using mode field calculations. The refractive indices of nine monoatomic and molecular gases are measured with a resolution of delta(ns) < 10(-6). (C)2016 Optical Society of America Y1 - 2016 U6 - https://doi.org/10.1364/OE.24.014086 SN - 1094-4087 VL - 24 SP - 14086 EP - 14099 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Federico, Stefania A1 - Nöchel, Ulrich A1 - Löwenberg, Candy A1 - Lendlein, Andreas A1 - Neffe, Axel T. T1 - Supramolecular hydrogel networks formed by molecular recognition of collagen and a peptide grafted to hyaluronic acid JF - Acta biomaterialia N2 - The extracellular matrix (ECM) is a nano-structured, highly complex hydrogel, in which the macromolecules are organized primarily by non-covalent interactions. Here, in a biomimetic approach, the decorin-derived collagen-binding peptide LSELRLHNN was grafted to hyaluronic acid (HA) in order to enable the formation of a supramolecular hydrogel network together with collagen. The storage modulus of a mixture of collagen and HA was increased by more than one order of magnitude (G′ = 157 Pa) in the presence of the HA-grafted peptide compared to a mixture of collagen and HA (G′ = 6 Pa). The collagen fibril diameter was decreased, as quantified using electron microscopy, in the presence of the HA-grafted peptide. Here, the peptide mimicked the function of decorin by spatially organizing collagen. The advantage of this approach is that the non-covalent crosslinks between collagen molecules and the HA chains created by the peptide form a reversible and dynamic hydrogel, which could be employed for a diverse range of applications in regenerative medicine. Statement of Significance Biopolymers of the extracellular matrix (ECM) like collagen or hyaluronan are attractive starting materials for biomaterials. While in biomaterial science covalent crosslinking is often employed, in the native ECM, stabilization and macromolecular organization is primarily based on non-covalent interactions, which allows dynamic changes of the materials. Here, we show that collagen-binding peptides, derived from the small proteoglycan decorin, grafted to hyaluronic acid enable supramolecular stabilization of collagen hydrogels. These hydrogels have storage moduli more than one order of magnitude higher than mixtures of collagen and hyaluronic acid. Furthermore, the peptide supported the structural organization of collagen. Such hydrogels could be employed for a diverse range of applications in regenerative medicine. Furthermore, the rational design helps in the understanding ECM structuring. KW - Biopolymers KW - Collagen-binding peptide KW - Hyaluronic acid KW - Hydrogels KW - Mechanical properties Y1 - 2016 U6 - https://doi.org/10.1016/j.actbio.2016.04.018 SN - 1742-7061 SN - 1878-7568 VL - 38 SP - 1 EP - 10 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Schopferer, Michael A1 - Schlaad, Helmut T1 - Physical Gelation of alpha-Helical Copolypeptides JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Owing to its rod-like alpha-helical secondary structure, the synthetic polypeptide poly(gamma-benzyl-L-glutamate) (PBLG) can form physical and thermoreversible gels in helicogenic solvents such as toluene. The versatility of PBLG can be increased by introducing functionalizable comonomers, such as allylglycine (AG). In this work we examined the secondary structure of PBLG and a series of statistical poly(gamma-benzyl-L-glutamate-co-allylglycine) copolypeptides, varying in composition and chain length, by circular dichroism (CD), Fourier-transform infrared (FTIR) and Raman spectroscopy, and wide-angle X-ray scattering (WAXS). The secondary structure of PBLG and the copolypeptides presented dissimilarities that increased with increasing AG molar fraction, especially when racemic AG units were incorporated. The physical gelation behavior of these copolypeptides was analyzed by temperature-sweep H-1 NMR and rheological measurements. The study revealed that both copolypeptide composition and chain length affected secondary structure, gelation temperature, and gel stiffness. Y1 - 2016 U6 - https://doi.org/10.1021/acs.biomac.6b00427 SN - 1525-7797 SN - 1526-4602 VL - 17 SP - 2384 EP - 2391 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Hardy, John G. A1 - Torres-Rendon, Jose Guillermo A1 - Leal-Egana, Aldo A1 - Walther, Andreas A1 - Schlaad, Helmut A1 - Coelfen, Helmut A1 - Scheibel, Thomas R. T1 - Biomineralization of Engineered Spider Silk Protein-Based Composite Materials for Bone Tissue Engineering JF - Materials N2 - Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering. KW - spider silk KW - recombinant protein KW - biodegradable polymers KW - biomaterials KW - biomineralization KW - bone tissue engineering Y1 - 2016 U6 - https://doi.org/10.3390/ma9070560 SN - 1996-1944 VL - 9 SP - 93 EP - 108 PB - MDPI CY - Basel ER - TY - JOUR A1 - Rasovic, Aleksandar A1 - Blagojevic, Vladimir A1 - Baranac-Stojanovic, Marija A1 - Kleinpeter, Erich A1 - Markovic, Rade A1 - Minic, Dragica M. T1 - Quantification of the push-pull effect in 2-alkylidene-4-oxothiazolidines by using NMR spectral data and barriers to rotation around the C=C bond JF - New journal of chemistry N2 - Information about the strength of donor-acceptor interactions in push-pull alkenes is valuable, as this so-called "push-pull effect' influences their chemical reactivity and dynamic behaviour. In this paper, we discuss the applicability of NMR spectral data and barriers to rotation around the CQC double bond to quantify the push-pull effect in biologically important 2-alkylidene-4-oxothiazolidines. While olefinic proton chemical shifts and differences in C-13 NMR chemical shifts of the two carbons constituting the CQC double bond fail to give the correct trend in the electron withdrawing ability of the substituents attached to the exocyclic carbon of the double bond, barriers to rotation prove to be a reliable quantity in providing information about the extent of donor-acceptor interactions in the push-pull systems studied. In particular all relevant kinetic data, that is the Arrhenius parameters ( apparent activation energy Ea and frequency factor A) and activation parameters ( Delta S-double dagger, Delta H-double dagger and Delta G(double dagger)), were determined from the data of the experimentally studied configurational isomerization of ( E)-9a. These results were compared to previously published related data for other two compounds, ( Z)-1b and ( 2E, 5Z)-7, showing that experimentally determined Delta G(double dagger) values are a good indicator of the strength of push-pull character. Theoretical calculations of the rotational barriers of eight selected derivatives excellently correlate with the calculated CQC bond lengths and corroborate the applicability of Delta G(double dagger) for estimation of the strength of the push-pull effect in these and related systems. Y1 - 2016 U6 - https://doi.org/10.1039/c6nj00901h SN - 1144-0546 SN - 1369-9261 VL - 40 SP - 6364 EP - 6373 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Draffehn, Soeren A1 - Eichhorst, Jenny A1 - Wiesner, Burkhard A1 - Kumke, Michael Uwe T1 - Insight into the Modification of Polymeric Micellar and Liposomal Nanocarriers by Fluorescein-Labeled Lipids and Uptake-Mediating Lipopeptides JF - Langmuir N2 - Encapsulation of diagnostic and therapeutic compounds in transporters improves their delivery to the point of need. An even more efficient treatment of diseases can be achieved using carriers with targeting or protecting moieties. In the present work, we investigated micellar and liposomal nanocarriers modified with fluorescein, peptides, and polymers that are covalently bound to fatty acids or phospholipids to ensure a self-driven incorporation into the micelles or liposomes. First, we characterized the photophysics of the fluorescent probes in the absence and in the presence of nanocarriers. Changes in the fluorescence decay time, quantum yield, and intensity of a fluorescein-labeled fatty acid (fluorescein-labeled palmitic acid [fPA]) and a fluorescein-labeled lipopeptide (P2fA2) were found. By exploiting these changes, we investigated a lipopeptide (P2A2 as an uptake-mediating unit) in combination with different nanocarriers (micelles and liposomes) and determined the corresponding association constant K-ass values, which were found to be very high. In addition, the mobility of fPA was exploited using fluorescence correlation spectroscopy (FCS) and fluorescence depolarization (FD) experiments to characterize the nanocarriers. Cellular uptake experiments with mouse brain endothelial cells provided information on the uptake behavior of liposomes modified by uptake-mediating P2A2 and revealed differences in the uptake behavior between pH-sensitive and pH-insensitive liposomes. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b01487 SN - 0743-7463 VL - 32 SP - 6928 EP - 6939 PB - American Chemical Society CY - Heidelberg ER - TY - JOUR A1 - Fallah, Mohammad A. A1 - Stanglmair, Christoph A1 - Pacholski, Claudia A1 - Hauser, Karin T1 - Devising Self-Assembled-Monolayers for Surface-Enhanced Infrared Spectroscopy of pH-Driven Poly-L-lysine Conformational Changes JF - Langmuir N2 - Surface-enhanced infrared absorption spectroscopy (SEIRA) is applied to study protein conformational changes. In general, the appropriate functionalization of metal surfaces with biomolecules remains a challenge if the conformation and activity of the biomolecule shall be preserved. Here we present a SEIRA study to monitor pH-induced conformational changes of poly-L lysine (PLL) covalently bound to a thin gold layer via self assembled monolayers (SAMs). We demonstrate that the composition of the SAM is crucial. A SAM of 11-mercaptoundecanonic acid (MUA) can link PLL to the gold layer, but pH-driven conformational transitions were hindered compared to poly-L lysine in solution. To address this problem, we devised a variety of SAMs, i.e., mixed SAMs of MUA with either octanethiol (OT) or 11-mercapto-1-undecanol (MUoL) and furthermore SAMs of MT(PEG)(4) and NHS-PEG(10k)-SH. These mixed SAMs modify the surface properties by changing the polarity and the morphology of the surface present to nearby PLL molecules. Our experiments reveal that mixed SAMs of MUA-MUoL and SAMs of NHS-PEG(10k)-SH-MT(PEG)(4) are suitable to monitor pH-driven conformational changes of immobilized PLL. These SAMs might be applicable for chemoselective protein immobilization in general. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b01742 SN - 0743-7463 VL - 32 SP - 7356 EP - 7364 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schneider, Rudolf A1 - Weigert, F. A1 - Lesnyak, V. A1 - Leubner, S. A1 - Lorenz, T. A1 - Behnke, Thomas A1 - Dubavik, A. A1 - Joswig, J. -O. A1 - Resch-Genger, U. A1 - Gaponik, N. A1 - Eychmueller, A. T1 - pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which – together with alloyed CdxHg1−xTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D2O and compared to the results from previous dilution studies with a set of thiol-capped Cd1−xHgxTe SC NCs in D2O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman's test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H2O compared to D2O, underlining also the role of hydrogen bonding and solvent molecules. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp03123d SN - 1463-9076 SN - 1463-9084 VL - 18 SP - 19083 EP - 19092 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schulze, Nicole A1 - Prietzel, Claudia Christina A1 - Koetz, Joachim T1 - Polyampholyte-mediated synthesis of anisotropic gold nanoplatelets JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - This paper focused on the synthesis of triangular nanoplatelets in the presence of a tubular network structure. The tubular network structure is formed by adding a strongly alternating polyampholyte, i.e., PalPhBisCarb, to a mixed vesicle system with a negatively charged bilayer containing phosphatidylcholin and AOT. Using the tubular network as a reducing agent in a one-step procedure, triangular and hexagonal nanoplatelets are formed. One can show that the nanoplatelet yield is enhanced by increasing the temperature and decreasing the reaction time. The platelet edge length can be decreased by heating the system up to 100 A degrees C. Due to specific interactions between PalPhBisCarb and the AOT/phospholipid bilayer, stacking and welding effects lead to the formation of ordered platelet structures. The reaction pathway to flat gold nanotriangles is discussed with regard to the twin plane growth model of gold nanoplates. KW - Polyampholytes KW - Tubular network structure KW - Anisotropic gold nanoplatelets KW - Nanocrystal growth KW - Nanotriangle stacking and welding Y1 - 2016 U6 - https://doi.org/10.1007/s00396-016-3890-y SN - 0303-402X SN - 1435-1536 VL - 294 SP - 1297 EP - 1304 PB - Springer CY - New York ER - TY - JOUR A1 - Wong, Joseph K. -H. A1 - Ast, Sandra A1 - Yu, Mingfeng A1 - Flehr, Roman A1 - Counsell, Andrew J. A1 - Turner, Peter A1 - Crisologo, Patrick A1 - Todd, Matthew H. A1 - Rutledge, Peter J. T1 - Synthesis and Evaluation of 1,8-Disubstituted-Cyclam/Naphthalimide Conjugates as Probes for Metal Ions JF - ChemistryOpen : including thesis treasury N2 - Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8-disubstituted-cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8-bis-(2-azidoethyl)cyclam has been developed and used to prepare 1,8-disubstituted triazolyl-cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis-naphthalimide ligand elucidate a complex pattern of photophysical behaviour. Important differences arise from the inclusion of two fluorophores in the one probe and from the variation of triazole substitution pattern (dye at C4 vs. N1). Introducing a second fluorophore greatly extends fluorescence lifetimes, whereas the altered substitution pattern at the cyclam amines exerts a major influence on fluorescence output and metal binding. Crystal structures of two key zinc complexes evidence variations in triazole coordination that mirror the solution-phase behaviour of these systems. KW - chromophores KW - click triazoles KW - fluorescent probes KW - macrocyclic compounds KW - photophysics Y1 - 2016 U6 - https://doi.org/10.1002/open.201600010 SN - 2191-1363 VL - 5 SP - 375 EP - 385 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Trautwein, Matthias A1 - Fredriksson, Kai A1 - Möller, Heiko Michael A1 - Exner, Thomas E. T1 - Automated assignment of NMR chemical shifts based on a known structure and 4D spectra JF - Journal of biomolecular NMR N2 - Apart from their central role during 3D structure determination of proteins the backbone chemical shift assignment is the basis for a number of applications, like chemical shift perturbation mapping and studies on the dynamics of proteins. This assignment is not a trivial task even if a 3D protein structure is known and needs almost as much effort as the assignment for structure prediction if performed manually. We present here a new algorithm based solely on 4D [H-1, N-15]-HSQC-NOESY-[H-1, N-15]-HSQC spectra which is able to assign a large percentage of chemical shifts (73-82 %) unambiguously, demonstrated with proteins up to a size of 250 residues. For the remaining residues, a small number of possible assignments is filtered out. This is done by comparing distances in the 3D structure to restraints obtained from the peak volumes in the 4D spectrum. Using dead-end elimination, assignments are removed in which at least one of the restraints is violated. Including additional information from chemical shift predictions, a complete unambiguous assignment was obtained for Ubiquitin and 95 % of the residues were correctly assigned in the 251 residue-long N-terminal domain of enzyme I. The program including source code is available at https://github.com/thomasexner/4Dassign. KW - Chemical shift assignment KW - Protein KW - 3D structure KW - 4D NOESY Y1 - 2016 U6 - https://doi.org/10.1007/s10858-016-0050-0 SN - 0925-2738 SN - 1573-5001 VL - 65 SP - 217 EP - 236 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Riebe, Daniel A1 - Eder, Alexander A1 - Ritschel, Thomas A1 - Beitz, Toralf A1 - Löhmannsröben, Hans-Gerd A1 - Beil, Andreas A1 - Blaschke, Michael A1 - Ludwig, Thomas T1 - Atmospheric pressure chemical ionization of explosives induced by soft X-radiation in ion mobility spectrometry: mass spectrometric investigation of the ionization reactions of drift gasses, dopants and alkyl nitrates JF - Journal of mass spectrometr N2 - A promising replacement for the radioactive sources commonly encountered in ion mobility spectrometers is a miniaturized, energy-efficient photoionization source that produce the reactant ions via soft X-radiation (2.8 keV). In order to successfully apply the photoionization source, it is imperative to know the spectrum of reactant ions and the subsequent ionization reactions leading to the detection of analytes. To that end, an ionization chamber based on the photoionization source that reproduces the ionization processes in the ion mobility spectrometer and facilitates efficient transfer of the product ions into a mass spectrometer was developed. Photoionization of pure gasses and gas mixtures containing air, N-2, CO2 and N2O and the dopant CH2Cl2 is discussed. The main product ions of photoionization are identified and compared with the spectrum of reactant ions formed by radioactive and corona discharge sources on the basis of literature data. The results suggest that photoionization by soft X-radiation in the negative mode is more selective than the other sources. In air, adduct ions of O-2 - with H2O and CO2 were exclusively detected. Traces of CO2 impact the formation of adduct ions of O-2 - and Cl -(upon addition of dopant) and are capable of suppressing them almost completely at high CO2 concentrations. Additionally, the ionization products of four alkyl nitrates (ethylene glycol dinitrate, nitroglycerin, erythritol tetranitrate and pentaerythritol tetranitrate) formed by atmospheric pressure chemical ionization induced by X-ray photoionization in different gasses (air, N-2 and N2O) and dopants (CH2Cl2, C2H5Br and CH3I) are investigated. The experimental studies are complemented by density functional theory calculations of the most important adduct ions of the alkyl nitrates (M) used for their spectrometric identification. In addition to the adduct ions [M + NO3](-) and [M + Cl](-), adduct ions such as [M + N2O2](-), [M + Br](-) and [M+ I](-) were detected, and their gas-phase structures and energetics are investigated by density functional theory calculations. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - ion mobility spectrometry KW - mass spectrometry KW - explosives KW - X-ray KW - photoionization KW - alkyl nitrates Y1 - 2016 U6 - https://doi.org/10.1002/jms.3784 SN - 1076-5174 SN - 1096-9888 VL - 51 SP - 566 EP - 577 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Rottke, Falko O. A1 - Schulz, Burkhard A1 - Richau, Klaus A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers JF - Beilstein journal of nanotechnology N2 - The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(omega-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R-q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified. KW - ellipsometric mapping KW - Langmuir monolayer KW - polyester KW - root mean square roughness KW - spectroscopic ellipsometry Y1 - 2016 U6 - https://doi.org/10.3762/bjnano.7.107 SN - 2190-4286 VL - 7 SP - 1156 EP - 1165 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Sun, Jing A1 - Cernoch, Peter A1 - Völkel, Antje A1 - Wei, Yuhan A1 - Ruokolainen, Janne A1 - Schlaad, Helmut T1 - Aqueous Self-Assembly of a Protein-Mimetic Ampholytic Block Copolypeptide JF - Macromolecules : a publication of the American Chemical Society N2 - This report describes the aggregation behavior of an ABC-type ampholytic block copolypeptide, poly(ethylene oxide)-block-poly(L-lysine)-block-poly(L-glutamate), in aqueous media in dependence of pH. Polypeptide secondary structures and self-assemblies are investigated by circular dichroism (CD), Fourier transform infrared (FT-IR) and NMR spectroscopy, zeta potential measurements, analytical ultracentrifugation (AUC), dynamic/static light scattering (DLS/SLS), and cryogenic transmission electron microscopy (cryoTEM). The polymer chains tend to form vesicles when the hydrophobic polypeptide helix is located at the chain end (acidic pH) and are existing as single chains when it is located in the center and flanked by the two hydrophilic segments (basic pH). Precipitation occurs in the intermediate pH range due to polyion complexation of the charged polypeptide segments. Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.6b00817 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 5494 EP - 5501 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Khadem, S. M. J. A1 - Hille, Carsten A1 - Löhmannsröben, Hans-Gerd A1 - Sokolov, Igor M. T1 - What information is contained in the fluorescence correlation spectroscopy curves, and where JF - Physical review : E, Statistical, nonlinear and soft matter physics Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.94.022407 SN - 2470-0045 SN - 2470-0053 VL - 94 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Rackwitz, Jenny A1 - Kopyra, Janina A1 - Dabkowska, Iwona A1 - Ebel, Kenny A1 - Rankovic, MiloS Lj. A1 - Milosavljevic, Aleksandar R. A1 - Bald, Ilko T1 - Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - 2-Fluoroadenine ((2F)A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F)A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA. Information about negative ion resonances and anion-mediated fragmentation reactions is combined with an absolute quantification of DNA strand breaks in (2F)A-containing oligonucleotides upon irradiation with LEEs. The incorporation of (2F)A into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by (2F)A at 5.5, 10, and 15 eV are very similar. Thus, (2F)A can be considered an effective radiosensitizer operative at a wide range of electron energies. KW - ab initio calculations KW - dissociative electron attachment KW - DNA origami KW - DNA radiation damage KW - fludarabine Y1 - 2016 U6 - https://doi.org/10.1002/anie.201603464 SN - 1433-7851 SN - 1521-3773 VL - 55 SP - 10248 EP - 10252 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Park, Sungjune A1 - Cheng, Xiao A1 - Böker, Alexander A1 - Tsarkova, Larisa T1 - Hierarchical Manipulation of Block Copolymer Patterns on 3D Topographic Substrates: Beyond Graphoepitaxy JF - Advanced materials N2 - Templates of complex nanopatterns in a form of hierarchically sequenced dots and stripes can be generated in block copolymer films on lithography-free 3D topographic substrates. The approach exploits thickness- and swelling-responsive morphological behavior of block copolymers, and demonstrates novel possibilities of topography-guided registration of nanopatterns due to periodic confinement and spontaneous orthogonal flow-fields. Y1 - 2016 U6 - https://doi.org/10.1002/adma.201601098 SN - 0935-9648 SN - 1521-4095 VL - 28 SP - 6900 EP - + PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Kratz, Karl A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - Polymer architecture versus chemical structure as adjusting tools for the enzymatic degradation of oligo(epsilon-caprolactone) based films at the air-water interface JF - Polymer Degradation and Stability N2 - The enzymatic degradation of oligo(epsilon-caprolactone) (OCL) based films at the air-water interface is investigated by Langmuir monolayer degradation (LMD) experiments to elucidate the influence of the molecular architecture and of the chemical structure on the chain scission process. For that purpose, the interactions of 2D monolayers of two star-shaped poly(epsilon-caprolactone)s (PCLs) and three linear OCL based copolyesterurethanes (P(OCL-U)) with the lipase from Pseudomonas cepacia are evaluated in comparison to linear OCL. While the architecture of star-shaped PCL Langmuir layers slightly influences their degradability compared to OCL films, significantly retarded degradations are observed for P(OCL-U) films containing urethane junction units derived from 2, 2 (4), 4-trimethyl hexamethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI) or lysine ethyl ester diisocyanate (LDI). The enzymatic degradation of the OCL based 2D structures is related to the presence of hydrophilic groups within the macromolecules rather than to the packing density of the film or to the molecular weight. The results reveal that the LMD technique allows the parallel analysis of both the film/enzyme interactions and the degradation process on the molecular level. (C) 2016 Elsevier Ltd. All rights reserved. KW - Langmuir technique KW - Oligo(epsilon-caprolactone) KW - Enzymatic degradation KW - Polymer architecture Y1 - 2016 U6 - https://doi.org/10.1016/j.polymdegradstab.2016.07.010 SN - 0141-3910 SN - 1873-2321 VL - 131 SP - 114 EP - 121 PB - Elsevier CY - Oxford ER -