TY - JOUR A1 - Boggio, Jose M. Chavez A1 - Bodenmueller, D. A1 - Fremberg, T. A1 - Haynes, R. A1 - Roth, Martin M. A1 - Eisermann, R. A1 - Lisker, M. A1 - Zimmermann, L. A1 - Boehm, Michael T1 - Dispersion engineered silicon nitride waveguides by geometrical and refractive-index optimization JF - Journal of the Optical Society of America : B, Optical physics N2 - Dispersion engineering in silicon nitride (SiXNY) waveguides is investigated through the optimization of the waveguide transversal dimensions and refractive indices in a multicladding arrangement. Ultraflat dispersion of -84.0 +/- 0.5 ps/nm/km between 1700 and 2440 nm and 1.5 +/- 3 ps/nm/km between 1670 and 2500 nm is numerically demonstrated. It is shown that typical refractive index fluctuations as well as dimension fluctuations during fabrication of the SiXNY waveguides are a limitation for obtaining ultraflat dispersion profiles. Single- and multicladding waveguides are fabricated and their dispersion profiles measured (over nearly 1000 nm) using a low-coherence frequency domain interferometric technique. By appropriate thickness optimization, the zero-dispersion wavelength is tuned over a large spectral range in single-and multicladding waveguides with small refractive index contrast (3%). A flat dispersion profile with +/- 3.2 ps/nm/km variation over 500 nm is obtained in a multicladding waveguide fabricated with a refractive index contrast of 37%. Finally, we generate a nearly three-octave supercontinuum in this dispersion flattened multicladding SiXNY waveguide. (C) 2014 Optical Society of America Y1 - 2014 U6 - https://doi.org/10.1364/JOSAB.31.002846 SN - 0740-3224 SN - 1520-8540 VL - 31 IS - 11 SP - 2846 EP - 2857 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Metzler, Ralf A1 - Jeon, Jae-Hyung A1 - Cherstvy, Andrey G. A1 - Barkai, Eli T1 - Anomalous diffusion models and their properties BT - non-stationarity, non-ergodicity, and ageing at the centenary of single particle tracking JF - physical chemistry, chemical physics : PCCP N2 - Modern microscopic techniques following the stochastic motion of labelled tracer particles have uncovered significant deviations from the laws of Brownian motion in a variety of animate and inanimate systems. Such anomalous diffusion can have different physical origins, which can be identified from careful data analysis. In particular, single particle tracking provides the entire trajectory of the traced particle, which allows one to evaluate different observables to quantify the dynamics of the system under observation. We here provide an extensive overview over different popular anomalous diffusion models and their properties. We pay special attention to their ergodic properties, highlighting the fact that in several of these models the long time averaged mean squared displacement shows a distinct disparity to the regular, ensemble averaged mean squared displacement. In these cases, data obtained from time averages cannot be interpreted by the standard theoretical results for the ensemble averages. Here we therefore provide a comparison of the main properties of the time averaged mean squared displacement and its statistical behaviour in terms of the scatter of the amplitudes between the time averages obtained from different trajectories. We especially demonstrate how anomalous dynamics may be identified for systems, which, on first sight, appear to be Brownian. Moreover, we discuss the ergodicity breaking parameters for the different anomalous stochastic processes and showcase the physical origins for the various behaviours. This Perspective is intended as a guidebook for both experimentalists and theorists working on systems, which exhibit anomalous diffusion. KW - intermittent chaotic systems KW - Fokker-Planck equations KW - time random-walks KW - fluorescence photobleaching recovery KW - fluctuation-dissipation theorem KW - fractional dynamics approach KW - photon-counting statistics KW - weak ergodicity breaking KW - flight search patterns KW - levy flights Y1 - 2014 U6 - https://doi.org/10.1039/c4cp03465a SN - 1463-9076 SN - 1463-9084 VL - 2014 IS - 16 SP - 24128 EP - 24164 ER - TY - JOUR A1 - Wessig, Pablo A1 - Gerngroß, Maik A1 - Pape, Simon A1 - Bruhns, Philipp A1 - Weber, Jens T1 - Novel porous materials based on oligospiroketals (OSK) JF - RSC Advances : an international journal to further the chemical sciences N2 - New porous materials based on covalently connected monomers are presented. The key step of the synthesis is an acetalisation reaction. In previous years we used acetalisation reactions extensively to build up various molecular rods. Based on this approach, investigations towards porous polymeric materials were conducted by us. Here we wish to present the results of these studies in the synthesis of 1D polyacetals and porous 3D polyacetals. By scrambling experiments with 1D acetals we could prove that exchange reactions occur between different building blocks (evidenced by MALDI-TOF mass spectrometry). Based on these results we synthesized porous 3D polyacetals under the same mild conditions. KW - microporous organic polymers KW - molecular rods KW - construction KW - frameworks KW - membranes KW - sorption KW - models Y1 - 2014 U6 - https://doi.org/10.1039/c4ra04437a SN - 2046-2069 VL - 2014 IS - 4 SP - 31123 EP - 31129 ER - TY - JOUR A1 - Zamponi, Flavio A1 - Penfold, Thomas J. A1 - Nachtegaal, Maarten A1 - Lübcke, Andrea A1 - Rittmann, Jochen A1 - Milne, Chris J. A1 - Chergui, Majed A1 - van Bokhoven, Jeroen A. T1 - Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy JF - physical chemistry, chemical physics : PCCP N2 - Picosecond X-ray absorption spectroscopy (XAS) is used to investigate the electronic and structural dynamics initiated by plasmon excitation of 1.8 nm diameter Au nanoparticles (NPs) functionalised with 1-hexanethiol. We show that 100 ps after photoexcitation the transient XAS spectrum is consistent with an 8% expansion of the Au–Au bond length and a large increase in disorder associated with melting of the NPs. Recovery of the ground state occurs with a time constant of ∼1.8 ns, arising from thermalisation with the environment. Simulations reveal that the transient spectrum exhibits no signature of charge separation at 100 ps and allows us to estimate an upper limit for the quantum yield (QY) of this process to be <0.1. KW - TiO2 nanoparticles KW - diimine-complexes KW - electron-transfer KW - supported gold KW - visible-light KW - water KW - surface KW - reactivity KW - nanoclusters KW - excitation Y1 - 2014 U6 - https://doi.org/10.1039/c4cp03301a SN - 1463-9076 SN - 1463-9084 VL - 2014 IS - 16 SP - 23157 EP - 23163 ER - TY - JOUR A1 - Meyer, Sören A1 - Matissek, M. A1 - Müller, Sandra Marie A1 - Taleshi, M. S. A1 - Ebert, Franziska A1 - Francesconi, Kevin A. A1 - Schwerdtle, Tanja T1 - In vitro toxicological characterisation of three arsenic-containing hydrocarbons JF - Metallomics N2 - Arsenic-containing hydrocarbons are one group of fat-soluble organic arsenic compounds (arsenolipids) found in marine fish and other seafood. A risk assessment of arsenolipids is urgently needed, but has not been possible because of the total lack of toxicological data. In this study the cellular toxicity of three arsenic-containing hydrocarbons was investigated in cultured human bladder (UROtsa) and liver (HepG2) cells. Cytotoxicity of the arsenic-containing hydrocarbons was comparable to that of arsenite, which was applied as the toxic reference arsenical. A large cellular accumulation of arsenic, as measured by ICP-MS/MS, was observed after incubation of both cell lines with the arsenolipids. Moreover, the toxic mode of action shown by the three arsenic-containing hydrocarbons seemed to differ from that observed for arsenite. Evidence suggests that the high cytotoxic potential of the lipophilic arsenicals results from a decrease in the cellular energy level. This first in vitro based risk assessment cannot exclude a risk to human health related to the presence of arsenolipids in seafood, and indicates the urgent need for further toxicity studies in experimental animals to fully assess this possible risk. KW - cod-liver KW - human-cells KW - arsenolipids present KW - excision-repair KW - fatty-acids KW - marine oils KW - RP-HPLC KW - metabolites KW - identification KW - trivalent Y1 - 2014 U6 - https://doi.org/10.1039/c4mt00061g SN - 1756-591X SN - 1756-5901 VL - 2014 IS - 6 SP - 1023 EP - 1033 ER - TY - JOUR A1 - Unterberg, Marlies A1 - Leffers, Larissa A1 - Hübner, Florian A1 - Humpf, Hans-Ulrich A1 - Lepikhov, Konstantin A1 - Walter, Jörn A1 - Ebert, Franziska A1 - Schwerdtle, Tanja T1 - Toxicity of arsenite and thio-DMAV after long-term (21 days) incubation of human urothelial cells: cytotoxicity, genotoxicity and epigenetics JF - Toxicology Research N2 - This study aims to further mechanistically understand toxic modes of action after chronic inorganic arsenic exposure. Therefore long-term incubation studies in cultured cells were carried out, to display chronically attained changes, which cannot be observed in the generally applied in vitro short-term incubation studies. Particularly, the cytotoxic, genotoxic and epigenetic effects of an up to 21 days incubation of human urothelial (UROtsa) cells with pico- to nanomolar concentrations of iAsIII and its metabolite thio-DMAV were compared. After 21 days of incubation, cytotoxic effects were strongly enhanced in the case of iAsIII and might partly be due to glutathione depletion and genotoxic effects on the chromosomal level. These results are in strong contrast to cells exposed to thio-DMAV. Thus, cells seemed to be able to adapt to this arsenical, as indicated among others by an increase in the cellular glutathione level. Most interestingly, picomolar concentrations of both iAsIII and thio-DMAV caused global DNA hypomethylation in UROtsa cells, which was quantified in parallel by 5-medC immunostaining and a newly established, reliable, high resolution mass spectrometry (HRMS)-based test system. This is the first time that epigenetic effects are reported for thio-DMAV; iAsIII induced epigenetic effects occur in at least 8000 fold lower concentrations as reported in vitro before. The fact that both arsenicals cause DNA hypomethylation at really low, exposure-relevant concentrations in human urothelial cells suggests that this epigenetic effect might contribute to inorganic arsenic induced carcinogenicity, which for sure has to be further investigated in future studies. KW - induced malignant-transformation KW - genomic dna methylation KW - vitro toxicological characterization KW - thio-dimethylarsinic acid KW - bladder-cancer KW - methyltransferases dnmt3a KW - cytosine methylation KW - carcinogen exposure KW - mass-spectrometry KW - gene-expression Y1 - 2014 SN - 2045-4538 SN - 2045-452X VL - 3 IS - 6 SP - 456 EP - 464 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Ghosh, Surya K. A1 - Cherstvy, Andrey G. A1 - Metzler, Ralf ED - Metzler, Ralf T1 - Non-universal tracer diffusion in crowded media of non-inert obstacles JF - Physical Chemistry Chemical Physics N2 - We study the diffusion of a tracer particle, which moves in continuum space between a lattice of excluded volume, immobile non-inert obstacles. In particular, we analyse how the strength of the tracer–obstacle interactions and the volume occupancy of the crowders alter the diffusive motion of the tracer. From the details of partitioning of the tracer diffusion modes between trapping states when bound to obstacles and bulk diffusion, we examine the degree of localisation of the tracer in the lattice of crowders. We study the properties of the tracer diffusion in terms of the ensemble and time averaged mean squared displacements, the trapping time distributions, the amplitude variation of the time averaged mean squared displacements, and the non-Gaussianity parameter of the diffusing tracer. We conclude that tracer–obstacle adsorption and binding triggers a transient anomalous diffusion. From a very narrow spread of recorded individual time averaged trajectories we exclude continuous type random walk processes as the underlying physical model of the tracer diffusion in our system. For moderate tracer–crowder attraction the motion is found to be fully ergodic, while at stronger attraction strength a transient disparity between ensemble and time averaged mean squared displacements occurs. We also put our results into perspective with findings from experimental single-particle tracking and simulations of the diffusion of tagged tracers in dense crowded suspensions. Our results have implications for the diffusion, transport, and spreading of chemical components in highly crowded environments inside living cells and other structured liquids. KW - fluorescence correlation spectroscopy KW - single-particle tracking KW - anomalous diffusion KW - living cells KW - physiological consequences KW - langevin equation KW - infection pathway KW - excluded volume KW - brownian-motion KW - random-walks Y1 - 2014 SN - 1463-9076 VL - 3 IS - 17 SP - 1847 EP - 1858 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Shin, Jaeoh A1 - Cherstvy, Andrey G. A1 - Metzler, Ralf ED - Metzler, Ralf T1 - Kinetics of polymer looping with macromolecular crowding: effects of volume fraction and crowder size JF - Soft Matter N2 - The looping of polymers such as DNA is a fundamental process in the molecular biology of living cells, whose interior is characterised by a high degree of molecular crowding. We here investigate in detail the looping dynamics of flexible polymer chains in the presence of different degrees of crowding. From the analysis of the looping–unlooping rates and the looping probabilities of the chain ends we show that the presence of small crowders typically slows down the chain dynamics but larger crowders may in fact facilitate the looping. We rationalise these non-trivial and often counterintuitive effects of the crowder size on the looping kinetics in terms of an effective solution viscosity and standard excluded volume. It is shown that for small crowders the effect of an increased viscosity dominates, while for big crowders we argue that confinement effects (caging) prevail. The tradeoff between both trends can thus result in the impediment or facilitation of polymer looping, depending on the crowder size. We also examine how the crowding volume fraction, chain length, and the attraction strength of the contact groups of the polymer chain affect the looping kinetics and hairpin formation dynamics. Our results are relevant for DNA looping in the absence and presence of protein mediation, DNA hairpin formation, RNA folding, and the folding of polypeptide chains under biologically relevant high-crowding conditions. KW - gene-regulation kinetics KW - physiological consequences KW - spatial-organization KW - anomalous diffusion KW - folding kinetics KW - living cells KW - dna coiling KW - in-vitro KW - dynamics KW - mixtures Y1 - 2014 SN - 1744-683X SP - 472 EP - 488 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Omosa, Leonidah K. A1 - Amugune, Beatrice A1 - Ndunda, Beth A1 - Milugo, Trizah K. A1 - Heydenreich, Matthias A1 - Yenesew, Abiy A1 - Midiwo, Jacob O. T1 - Antimicrobial flavonoids and diterpenoids from Dodonaea angustifolia JF - South African journal of botany : an international interdisciplinary journal for botanical sciences KW - Dodonaea angustifolia KW - Surface exudates KW - Flavone KW - Flavanone KW - Diterpenoid KW - Antimicrobial activities Y1 - 2014 U6 - https://doi.org/10.1016/j.sajb.2013.11.012 SN - 0254-6299 SN - 1727-9321 VL - 91 SP - 58 EP - 62 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Primus, Philipp-Alexander A1 - Ritschel, Thomas A1 - Sigueenza, Pilar Y. A1 - Cauqui, Miguel Angel A1 - Hernandez-Garrido, Juan Carlos A1 - Kumke, Michael Uwe T1 - High-resolution spectroscopy of europium-doped ceria as a tool to correlate structure and catalytic activity JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Site-selective emission spectra of Eu3+-doped CeO2 nanoparticles up to the D-5(0) - F-7(5) transition were recorded under cryogenic conditions to identify the local structure around the Eu3+ dopants in ceria. It is found that pretreatment conditions are crucial for the redistribution of dopants from a broad variety of environments to six well-defined lattice sites. The influence of the dopant and the host structure on the catalytic activity was investigated. A relationship between structure and reactivity is discussed. It is shown that oxygen transport is most efficient in particles with a pronounced amorphous character. Y1 - 2014 U6 - https://doi.org/10.1021/jp505467r SN - 1932-7447 VL - 118 IS - 40 SP - 23349 EP - 23360 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schulze, Nicole A1 - Appelhans, D. A1 - Tiersch, Brigitte A1 - Koetz, Joachim T1 - Morphological transformation of vesicles into tubular structures by adding polyampholytes or dendritic glycopolymers JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - For the first time tubulating properties of spherical dendritic glycopolymers and linear alternating polyampholytes against non-uniform negatively charged giant vesicles are proven by light microscopy and cryo-scanning electron microscopy study. Real time observation of the morphological transformation from giant vesicles to tubular structures, simulating morphogenesis in living cells, is given by using the cationic and H-bond active dendritic glycopolymer accompanied by reducing the size of the giant vesicles and the evidence of vesicle-vesicle interaction which was only postulated in a previous study. Similar morphogenesis of non-uniform giant vesicles into tubular network structure can be observed by using a polyampholyte in the stretched conformation at pH 9. Pearl necklace and tubular network structure formation are also observed by applying anionic vesicles of significant smaller dimensions with average size dimensions of 35 nm, after adding the polyampholyte at pH 9. However, the fitting accuracy between the functional groups along the backbone chain of the polyampholyte on one side and the vesicle surface on the other side is of high importance for the transformation process by using polyampholytes. The resulting tubular and network structures offer new fields of application as microfluidic transport channels or template phases for the shape controlled formation of nanoparticles. (C) 2014 Elsevier B.V. All rights reserved. KW - Alternating polyampholytes KW - Maltose-modified PEI KW - Network structure KW - Template phase KW - Cryo-SEM KW - DLS Y1 - 2014 U6 - https://doi.org/10.1016/j.colsurfa.2014.06.007 SN - 0927-7757 SN - 1873-4359 VL - 457 SP - 326 EP - 332 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cisek, Richard A1 - Tokarz, Danielle A1 - Krouglov, Serguei A1 - Steup, Martin A1 - Emes, Michael J. A1 - Tetlow, Ian J. A1 - Barzda, Virginijus T1 - Second harmonic generation mediated by aligned water in starch granules JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - The origin of second harmonic generation (SHG) in starch granules was investigated using ab initio quantum mechanical modeling and experimentally examined using polarization-in, polarization-out (PIPO) second harmonic generation microscopy. Ab initio calculations revealed that the largest contribution to the SHG signal from A- and B-type allomorphs of starch originates from the anisotropic organization of hydroxide and hydrogen bonds mediated by aligned water found in the polymers. The hypothesis was experimentally tested by imaging maize starch granules under various hydration and heat treatment conditions that alter the hydrogen bond network. The highest SHG intensity was found in fully hydrated starch granules, and heat treatment diminished the SHG intensity. The PIPO SHG imaging showed that dried starch granules have a much higher nonlinear optical susceptibility component ratio than fully hydrated granules. In contrast, deuterated starch granules showed a smaller susceptibility component ratio demonstrating that SHG is highly sensitive to the organization of the hydroxyl and hydrogen bond network. The polarization SHG imaging results of potato starch granules, representing starch allomorph B, were compared to those of maize starch granules representing allomorph A. The results showed that the amount of aligned water was higher in the maize granules. Nonlinear microscopy of starch granules provides evidence that varying hydration conditions leads to significant changes in the nonlinear susceptibility ratio as well as the SHG intensity, supporting the hypothesis from ab initio calculations that the dominant contribution to SHG is due to the ordered hydroxide and hydrogen bond network. Y1 - 2014 U6 - https://doi.org/10.1021/jp508751s SN - 1520-6106 VL - 118 IS - 51 SP - 14785 EP - 14794 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Piekarczyk, Andreas A1 - Bald, Ilko A1 - Flosadottir, Helga D. A1 - Omarsson, Benedikt A1 - Lafosse, Anne A1 - Ingolfsson, Oddur T1 - Influence of metal ion complexation on the metastable fragmentation of DNA hexamers JF - The European physical journal : D, Atomic, molecular, optical and plasma physics N2 - Here, we study the metastable decay of 5'-d(TTGCTT) in the presence of 0-6 alkaline metal ions (Li+, Na+, K+, Rb+) and 0-3 alkaline earth metal ions (Mg2+ and Ca2+), which replace the corresponding number of protons in the oligonucleotide. We find that all ions studied here stabilize the oligonucleotide with respect to simple 3'-C-O backbone cleavage, but at the same time these metal ions promote a central oligonucleotide deletion accompanied by a concomitant recombination of the terminal d(TT) groups. We find that the quenching of the 3'-C-O backbone cleavage is not ion specific, since it is due to the removal of the phosphate protons upon replacement with the respective metal ions. The central nucleotide deletion competes with the 3'-C-O backbone cleavage channels and is thus promoted through the replacement of the exchangeable protons against metal ions. However, with increasing positive charge density of the metal ions the yield of the central nucleotide deletion further increases. We attribute this effect to the necessity of sufficient proximity of the terminal d(TT) group to allow for their recombination on this reaction path. Hence, the formation of a reactive conformer is mediated by the metal ions. Y1 - 2014 U6 - https://doi.org/10.1140/epjd/e2014-40838-7 SN - 1434-6060 SN - 1434-6079 VL - 68 IS - 6 PB - Springer CY - New York ER - TY - JOUR A1 - Kopyra, Janina A1 - Keller, A. A1 - Bald, Ilko T1 - On the role of fluoro-substituted nucleosides in DNA radiosensitization for tumor radiation therapy JF - RSC Advances Y1 - 2014 U6 - https://doi.org/10.1039/c3ra46735j SN - 2046-2069 VL - 4 IS - 13 SP - 6825 EP - 6829 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Christian A1 - Behl, Marc A1 - Lendlein, Andreas A1 - Beuermann, Sabine T1 - Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide JF - RSC Advances N2 - Polyglycolide (PGA) is a biodegradable polymer with multiple applications in the medical sector. Here the synthesis of high molecular weight polyglycolide by ring-opening polymerization of diglycolide is reported. For the first time stabilizer free supercritical carbon dioxide (scCO(2)) was used as a reaction medium. scCO(2) allowed for a reduction in reaction temperature compared to conventional processes. Together with the lowering of monomer concentration and consequently reduced heat generation compared to bulk reactions thermal decomposition of the product occurring already during polymerization is strongly reduced. The reaction temperatures and pressures were varied between 120 and 150 degrees C and 145 to 1400 bar. Tin(II) ethyl hexanoate and 1-dodecanol were used as catalyst and initiator, respectively. The highest number average molecular weight of 31 200 g mol(-1) was obtained in 5 hours from polymerization at 120 degrees C and 530 bar. In all cases the products were obtained as a dry white powder. Remarkably, independent of molecular weight the melting temperatures were always at (219 +/- 2)degrees C. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra06815g SN - 2046-2069 VL - 4 IS - 66 SP - 35099 EP - 35105 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Ghobadi, Ehsan A1 - Heuchel, Matthias A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Atomistic simulation of the shape-memory effect in dry and water swollen Poly[(rac-lactide)-co-glycolide] and copolyester urethanes thereof JF - Macromolecular chemistry and physics N2 - An atomistic molecular dynamics simulation approach is applied to model the influence of urethane linker units as well as the addition of water molecules on the simulated shape-memory properties of poly[(rac-lactide)-co-glycolide] (PLGA) and PLGA-based copolyester urethanes comprising different urethane linkers. The shape-memory performance of these amorphous packing models is explored in a simulated heating-deformation-cooling-heating procedure. Depending on the type of incorporated urethane linker, the mechanical properties of the dry copolyester urethanes are found to be significantly improved compared with PLGA, which can be attributed to the number of intermolecular hydrogen bonds between the urethane units. Good shape-memory properties are observed for all the modeled systems. In the dry state, the shape fixation is found to be improved by implementation of urethane units. After swelling of the copolymer models with water, which results in a reduction of their glass transition temperatures, the relaxation kinetics during unloading and shape recovery are found to be substantially accelerated. KW - molecular dynamics simulations KW - polyesterurethane KW - shape-memory effect Y1 - 2014 U6 - https://doi.org/10.1002/macp.201300507 SN - 1022-1352 SN - 1521-3935 VL - 215 IS - 1 SP - 65 EP - 75 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Friess, Fabian A1 - Lendlein, Andreas A1 - Wischke, Christian T1 - Photoinduced synthesis of polyester networks from methacrylate functionalized precursors: analysis of side reactions JF - Polymers for advanced technologies N2 - Polyester networks can be prepared by ultraviolet (UV)-light-induced radical polymerization of methacrylate functionalized oligo(epsilon-caprolactone)s. The properties and functions of the obtained materials depend on defined network structures and may be altered, if crosslinking would occur by side reactions in other positions than the methacrylate endgroups. In order to explore whether and to which extent such side reactions occur, network synthesis as well as related model reactions were performed in the absence of photoinitiator. Hereby precursor structures (linear and four-arm star-shaped) and reaction conditions (in solution and in the melt) were varied. Unspecific side reactions were found only upon extensive UV irradiation for 60min (26 mW cm(-2)) with minor but detectable alterations of physicochemical properties of the networks. The analysis of model reactions suggested minor photolytic cleavage of ester bonds during polymer network synthesis. However, the effect of these side reactions on network properties and functions appeared to be less relevant than an incomplete precursor integration because of a too short UV irradiation for crosslinking. Copyright (c) 2014 John Wiley & Sons, Ltd. KW - poly(epsilon-caprolactone) methacrylate KW - crosslinking KW - excimer UV light KW - side reaction KW - photoinduced radical polymerization Y1 - 2014 U6 - https://doi.org/10.1002/pat.3313 SN - 1042-7147 SN - 1099-1581 VL - 25 IS - 11 SP - 1285 EP - 1292 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Schwarze, Thomas A1 - Müller, Holger A1 - Ast, Sandra A1 - Steinbrück, Dörte A1 - Eidner, Sascha A1 - Geißler, Felix A1 - Kumke, Michael Uwe A1 - Holdt, Hans-Jürgen ED - Kumke, Michael Uwe T1 - Fluorescence lifetime-based sensing of sodium by an optode JF - Chemical Communications N2 - We report a 1,2,3-triazol fluoroionophore for detecting Na+ that shows in vitro enhancement in the Na+-induced fluorescence intensity and decay time. The Na+-selective molecule 1 was incorporated into a hydrogel as a part of a fiber optical sensor. This sensor allows the direct determination of Na+ in the range of 1–10 mM by measuring reversible fluorescence decay time changes. KW - ion optodes KW - sensors KW - indicators KW - chromoionophore KW - ionophore KW - membrane KW - switches KW - systems KW - samples KW - green Y1 - 2014 SN - 0022-4936 SN - 0009-241X SP - 14167 EP - 14170 PB - The Royal Society Chemistry CY - Cambridge ER - TY - JOUR A1 - Baier, Heiko A1 - Metzner, Philipp A1 - Körzdörfer, Thomas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Efficient palladium(II) precatalysts bearing 4,5-dicyanoimidazol-2-ylidene for the Mizoroki-Heck reaction JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - The new N-heterocyclic carbene (NHC) complex [PdCl2{(CN)(2)IMes}(PPh3)] (2) ({(CN)(2)IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) and the NHC palladacycle [PdCl(dmba){(CN)(2)IMes}] (3) (dmba: N,N-dimethylbenzylamine) have been synthesized by thermolysis of 4,5-dicyano-1,3-dimesityl-2-(pentafluorophenyl) imidazoline (1) in the presence of suitable palladium(II) precursors. The acyclic complex 2 was formed by ligand exchange using the mononuclear precursor [PdCl2(PPh3)(2)] and the palladacycle 3 was formed by cleavage of the dinuclear chloro-bridged precursor [Pd(mu-Cl)(dmba)](2). The new NHC precursor 1-benzyl-4,5-dicyano-2-(pentafluorophenyl)-3-picolylimidazoline (5) was formed by condensation of pentafluorobenzaldehyde with N-benzyl-N'-picolyldiaminomaleonitrile (4). The NHC palladacycle [PdCl2{(CN)(2)IBzPic}] (6) ({(CN)(2)IBzPic}: 1-benzyl-4,5-dicyano-3-picolylimidazol-2-ylidene) was prepared by in situ thermolysis of 5 in the presence of [PdCl2(PhCN)(2)]. The three palladium(II) complexes were characterized by NMR and IR spectroscopy, mass spectrometry and elemental analysis. In addition, the molecular structures of 2 and 3 were determined by X-ray diffraction. The pi-acidity of (CN)(2)IBzPic was compared with (CN)(2)IMes and perviously reported pi-acidic imidazol-2-ylidenes by NBO analysis. The Mizoroki-Heck (MH) reactions of various aryl halides with n-butyl acrylate were performed in the presence of complexes 2, 3 and 6. The new precatalysts showed high activity in the MH reactions giving good-to-excellent product yields with 0.1 mol-% pre-catalyst. The nature of the catalytically active species of 2, 3 and 6 was investigated by poisoning experiments with mercury and transmission electron microscopy. It was found that palladium nanoparticles formed from the precatalysts were involved in the catalytic process. KW - Homogeneous catalysis KW - Palladium KW - Cross coupling KW - Carbene ligands Y1 - 2014 U6 - https://doi.org/10.1002/ejic.201402040 SN - 1434-1948 SN - 1099-0682 IS - 18 SP - 2952 EP - 2960 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Trautmann, Michael A1 - Lubahn, Susanne A1 - Holdt, Hans-Jürgen T1 - Preparation, characterisation and properties of sulphoxide modified polystyrene resins for solid-phase extraction of Pt-IV, Ru-III and Ru-IV from hydrochloric acid JF - Reactive & functional polymers N2 - New sulphoxide modified resins were synthesized using poly(styrene-co-divinylbenzene) (PS-DVB) as matrix. Infrared spectroscopy and elemental analysis were used for characterisation. Solid-phase extraction of Pt-IV, Ru-III and Ru-IV from acidic chloride solutions was performed via batch experiments. Influence of spacer length between sulphoxide and matrix (ethylene, hexamethylene), substitution of sulphoxide (R-1: ethyl, hexyl, phenyl) and bead size of PS-DVB (spherical beads: d(50) < 155 mu m, d(50) < 80 mu m; powder: d(50) < 30 mu m) on adsorption was investigated subjected to acidity. Experimental results showed that ethyl substituted sulphoxide immobilised onto ground PS-DVB and hexamethylene spacer exhibited best adsorption properties. Different kinetic models and isotherms were fitted to the experimental data to identify extraction mechanism. Pt-IV was quantitative sorbed at [HCl] <= 0.1 mol/L whereas Ru-III and Ru-IV sorption ranged between 90% and 95% at [HCl] 5 mol/L. Desorption was reached using a solution of 0.5 M thiourea (Tu) in 0.1 M HCl at 90 degrees C. Separation of Pt-IV and Rum occurred at [HCl] <= 0.1 mol/L whereas Pt-IV was extracted and Ru-III remained in solution. A further separation was achieved by extracting Pt-IV and Ru-IV at 5 M HCl followed by sequential elution of Pt-IV with concentrated HCl and Ru-IV with 0.5 M Tu in 0.1 M HCl at 90 degrees C. 2014 Elsevier B.V. All rights reserved. KW - Solid-phase extraction KW - Platinum group metals KW - Polystyrene-divinylbenzene KW - Sulphoxide KW - Adsorption kinetic Y1 - 2014 U6 - https://doi.org/10.1016/j.reactfunctpolym.2014.07.001 SN - 1381-5148 SN - 1873-166X VL - 83 SP - 84 EP - 97 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schwarze, Thomas A1 - Mueller, Holger A1 - Ast, Sandra A1 - Steinbrück, Dorte A1 - Eidner, Sascha A1 - Geißler, Felix A1 - Kumke, Michael Uwe A1 - Holdt, Hans-Jürgen T1 - Fluorescence lifetime-based sensing of sodium by an optode JF - Chemical communications N2 - We report a 1,2,3-triazol fluoroionophore for detecting Na+ that shows in vitro enhancement in the Na+-induced fluorescence intensity and decay time. The Na+-selective molecule 1 was incorporated into a hydrogel as a part of a fiber optical sensor. This sensor allows the direct determination of Na+ in the range of 1-10 mM by measuring reversible fluorescence decay time changes. Y1 - 2014 U6 - https://doi.org/10.1039/c4cc06112h SN - 1359-7345 SN - 1364-548X VL - 50 IS - 91 SP - 14167 EP - 14170 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schwarze, Thomas A1 - Garz, Andreas A1 - Teuchner, Klaus A1 - Menzel, Ralf A1 - Holdt, Hans-Jürgen T1 - Two-photon probes for metal ions based on phenylaza[18]crown-6 ethers and 1,2,3-triazoles as pi-linkers JF - ChemPhysChem : a European journal of chemical physics and physical chemistry KW - absorption KW - cations KW - click chemistry KW - dyes/pigments KW - fluorescence Y1 - 2014 U6 - https://doi.org/10.1002/cphc.201402232 SN - 1439-4235 SN - 1439-7641 VL - 15 IS - 12 SP - 2436 EP - 2439 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tritschler, Ulrich A1 - Zlotnikov, Igor A1 - Keckeis, Philipp A1 - Schlaad, Helmut A1 - Cölfen, Helmut T1 - Optical properties of self-organized gold nanorod-polymer hybrid films JF - Langmuir N2 - High fractions of gold nanorods were locally aligned by means of a polymeric liquid crystalline phase. The gold nanorods constituting >80 wt % of the thin organic-inorganic composite films form a network with side-by-side and end-to-end combinations. Organization into these network structures was induced by shearing gold nanorod-LC polymer dispersions via spin-coating. The LC polymer is a polyoxazoline functionalized with pendent cholesteryl and carboxyl side groups enabling the polymer to bind to the CTAB stabilizer layer of the gold nanorods via electrostatic interactions, thus forming the glue between organic and inorganic components, and to form a chiral nematic lyotropic phase. The self-assembled locally oriented gold nanorod structuring enables control over collective optical properties due to plasmon resonance coupling, reminiscent of enhanced optical properties of natural biomaterials. Y1 - 2014 U6 - https://doi.org/10.1021/la503507u SN - 0743-7463 VL - 30 IS - 46 SP - 13781 EP - 13790 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Brosnan, Sarah M. A1 - Schlaad, Helmut T1 - Modification of polypeptide materials by Thiol-X chemistry JF - Polymer : the international journal for the science and technology of polymers N2 - Thiol-X chemistry has proven to be a valuable toolbox for modification of peptides, proteins, monomers, and polymers. Recently, this has become especially true for the modification of polypeptides (monomers or polymers), which has resulted in a plethora of novel polymers and materials. With this in mind, this highlight focuses on the recent literature concerning the modification of polypeptides by the use of thiol-X chemistry, in particular to synthetic polypeptides either at the monomer or polymer stage modified by thiol-ene, -Michael addition, and -yne chemistries. (C) 2014 Published by Elsevier Ltd. KW - Polypeptide KW - Thiol-X KW - Click chemistry Y1 - 2014 U6 - https://doi.org/10.1016/j.polymer.2014.08.067 SN - 0032-3861 SN - 1873-2291 VL - 55 IS - 22 SP - 5511 EP - 5516 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schmidt, Bernd A1 - Elizarov, Nelli A1 - Berger, René A1 - Hölter, Frank T1 - Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes: a protecting-group economic synthesis of phenolic stilbenes N2 - 4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4ï-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior. Y1 - 2014 UR - http://pubs.rsc.org/en/content/articlepdf/2013/ob/c3ob40420j U6 - https://doi.org/10.1039/C3OB40420J SN - 1477-0520 ER - TY - JOUR A1 - Schönborn, Jan Boyke A1 - Hartke, Bernd T1 - Photochemical dynamics of Photochemical dynamics of E-methylfurylfulgide - Kinematic effects in photorelaxation dynamics of furylfulgides N2 - With the present theoretical study of the photochemical switching of E-methylfurylfulgide we contribute an important step towards the understanding of the photochemical processes in furylfulgide-related molecules. We have carried out large-scale, full-dimensional direct semiempirical configuration-interaction surface-hopping dynamics of the photoinduced ring-closure reaction. Simulated static and dynamical UV/Vis-spectra show good agreement with experimental data of the same molecule. By a careful investigation of our dynamical data, we were able to identify marked differences to the dynamics of the previously studied E-isopropylfurylfulgide. With our simulations we can not only reproduce the experimentally observed quantum yield differences qualitatively but we can also pinpoint two reasons for them: kinematics and pre-orientation. With our analysis, we thus offer straightforward molecular explanations for the high sensitivity of the photodynamics towards seemingly minor changes in molecular constitution. Beyond the realm of furylfulgides, these insights provide additional guidance to the rational design of photochemically switchable molecules. Y1 - 2014 UR - http://pubs.rsc.org/en/content/articlehtml/2014/cp/c3cp53495b U6 - https://doi.org/10.1039/C3CP53495B ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hauke, Sylvia T1 - Cross metathesis of allyl alcohols: how to suppress and how to promote double bond isomerization N2 - Under standard conditions the cross metathesis of allyl alcohols and methyl acrylate is accompanied by the formation of ketones, resulting from uncontrolled and undesired double bond isomerization. By conducting the CM in the presence of phenol, the catalyst loading and the reaction time required for quantiative conversion can be reduced, and isomerization can be suppressed. On the other hand, consecutive isomerization can be deliberately promoted by evaporating excess methyl acrylate after completing cross metathesis and by adding a base or silane as chemical triggers. Y1 - 2014 UR - http://pubs.rsc.org/en/content/articlepdf/2013/ob/c3ob40167g U6 - https://doi.org/10.1039/c3ob40167g SN - 1477-0520 ER - TY - JOUR A1 - Magadula, Joseph J. A1 - Masimba, Pax J. A1 - Tarimo, Rose B. A1 - Msengwa, Zaituni A1 - Mbwambo, Zakariah H. A1 - Heydenreich, Matthias A1 - Breard, Dimitri A1 - Richomme, Pascal T1 - Mammea-type coumarins from Mammea usambarensis Verdc. JF - Biochemical systematics and ecology N2 - Phytochemical investigations of Mammea usambarensis resulted into the isolation a delta-tocotrienol (1) and five known mammea-type coumarins (2-6). Their structures were determined by NMR, IR, and LC-MS spectroscopic methods and by comparison of their spectral and physical data with those reported previously in the literature. The presence of these compounds is consistent with the compound classes reported from other members of the genus Mammal. Compound 6 is isolated from the Mammea genus for the first time. This is the new source of mammea-type coumarin compounds while the chemotaxonomic significance of this investigation is summarized. (C) 2014 Elsevier Ltd. All rights reserved. KW - Mammea usambarensis KW - Isolations KW - Mammea-type coumarins KW - Chemotaxonomy Y1 - 2014 U6 - https://doi.org/10.1016/j.bse.2014.05.004 SN - 0305-1978 SN - 1873-2925 VL - 56 SP - 65 EP - 67 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Hasinovic, H. A1 - Friberg, S. E. A1 - Kovach, Ildyko A1 - Koetz, Joachim T1 - Destabilization of a dual emulsion to form a Janus emulsion JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - A vegetable oil (VO) was added to an emulsion of silicone oil in water (SO/W) with mixing limited to once turning the test tube upside down. Initially, the VO was dispersed into virtually centimeter-sized drops and the emulsion contained effectively no Janus drops, while after 1 h of agitation at a low level to prevent creaming, drops of 50-100-mu m size of the two oils were observed: in addition to an insignificant number of Janus drops. The topology of the latter showed them to emanate from flocculated individual drops of the two oils, but with no discernible effect by the interfacial tension equilibrium on the drop topology. Continued gentle mixing gave increasing fraction of Janus drops of increased size with a topology gradually approaching the one expected from the interfacial equilibrium at the contact line. The spontaneous formation of Janus drops indicated a reduction of the interfacial free energy in the process and the interfacial energy difference between separate and Janus drops was calculated for an appropriate range of interfacial tensions and for all oil fractions. The calculations enabled a distinction of the decrease due to interfacial area changes from the reduction of interfacial tensions per se, with the latter only a minor fraction. KW - Emulsion destabilization KW - Janus emulsions KW - Interfacial equilibrium KW - Microfluidics Y1 - 2014 U6 - https://doi.org/10.1007/s00396-014-3263-3 SN - 0303-402X SN - 1435-1536 VL - 292 IS - 9 SP - 2319 EP - 2324 PB - Springer CY - New York ER - TY - JOUR A1 - Plehn, Thomas A1 - Megow, Jörg A1 - May, Volkhard T1 - Concerted charge and energy transfer processes in a highly flexible fullerene-dye system: a mixed quantum-classical study JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Photoinduced excitation energy transfer and accompanying charge separation are elucidated for a supramolecular system of a single fullerene covalently linked to six pyropheophorbide-a dye molecules. Molecular dynamics simulations are performed to gain an atomistic picture of the architecture and the surrounding solvent. Excitation energy transfer among the dye molecules and electron transfer from the excited dyes to the fullerene are described by a mixed quantum-classical version of the Forster rate and the semiclassical Marcus rate, respectively. The mean characteristic time of energy redistribution lies in the range of 10 ps, while electron transfer proceeds within 150 ps. In between, on a 20 to 50 ps time-scale, conformational changes take place in the system. This temporal hierarchy of processes guarantees efficient charge separation, if the structure is exposed to a solvent. The fast energy transfer can adopt the dye excitation to the actual conformation. In this sense, the probability to achieve charge separation is large enough since any dominance of unfavorable conformations that exhibit a large dye-fullerene distance is circumvented. And the slow electron transfer may realize an averaging with respect to different conformations. To confirm the reliability of our computations, ensemble measurements on the charge separation dynamics are simulated and a very good agreement with the experimental data is obtained. Y1 - 2014 U6 - https://doi.org/10.1039/c4cp01081g SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 25 SP - 12949 EP - 12958 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Ermeydan, Mahmut Ali A1 - Cabane, Etienne A1 - Hass, Philipp A1 - Koetz, Joachim A1 - Burgert, Ingo T1 - Fully biodegradable modification of wood for improvement of dimensional stability and water absorption properties by poly(epsilon-caprolactone) grafting into the cell walls JF - Green chemistry : an international journal and green chemistry resource N2 - Materials derived from renewable resources are highly desirable in view of more sustainable manufacturing. Among the available natural materials, wood is one of the key candidates, because of its excellent mechanical properties. However, wood and wood-based materials in engineering applications suffer from various restraints, such as dimensional instability upon humidity changes. Several wood modification treatments increase water repellence, but the insertion of hydrophobic polymers can result in a composite material which cannot be considered as renewable anymore. In this study, we report on the grafting of the fully biodegradable poly(epsilon-caprolactone) (PCL) inside the wood cell walls by Sn(Oct)(2) catalysed ring-opening polymerization (ROP). The presence of polyester chains within the wood cell wall structure is monitored by confocal Raman imaging and spectroscopy as well as scanning electron microscopy. Physical tests reveal that the modified wood is more hydrophobic due to the bulking of the cell wall structure with the polyester chains, which results in a novel fully biodegradable wood material with improved dimensional stability. Y1 - 2014 U6 - https://doi.org/10.1039/c4gc00194j SN - 1463-9262 SN - 1463-9270 VL - 16 IS - 6 SP - 3313 EP - 3321 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis JF - Journal of materials chemistry : B, Materials for biology and medicine N2 - A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction. Y1 - 2014 U6 - https://doi.org/10.1039/c4tb00336e SN - 2050-750X SN - 2050-7518 VL - 2 IS - 21 SP - 3196 EP - 3203 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Sangoro, Joshia R. A1 - Iacob, C. A1 - Agapov, A. L. A1 - Wang, Yangyang A1 - Berdzinski, Stefan A1 - Rexhausen, Hans A1 - Strehmel, Veronika A1 - Friedrich, C. A1 - Sokolov, A. P. A1 - Kremer, F. T1 - Decoupling of ionic conductivity from structural dynamics in polymerized ionic liquids JF - Soft matter N2 - Charge transport and structural dynamics in low molecular weight and polymerized 1-vinyl-3-pentylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquids (ILs) are investigated by a combination of broadband dielectric spectroscopy, dynamic mechanical spectroscopy and differential scanning calorimetry. While the dc conductivity and fluidity exhibit practically identical temperature dependence for the non-polymerized IL, a significant decoupling of ionic conduction from structural dynamics is observed for the polymerized IL. In addition, the dc conductivity of the polymerized IL exceeds that of its molecular counterpart by four orders of magnitude at their respective calorimetric glass transition temperatures. This is attributed to the unusually high mobility of the anions especially at lower temperatures when the structural dynamics is significantly slowed down. A simple physical explanation of the possible origin of the remarkable decoupling of ionic conductivity from structural dynamics is proposed. Y1 - 2014 U6 - https://doi.org/10.1039/c3sm53202j SN - 1744-683X SN - 1744-6848 VL - 10 IS - 20 SP - 3536 EP - 3540 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Cywinski, Piotr J. A1 - Nono, Katia Nchimi A1 - Charbonniere, Loic J. A1 - Hammann, Tommy A1 - Löhmannsröben, Hans-Gerd T1 - Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Forster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surfacefunctionalised with streptavidins. The permanent spatial donor-acceptor proximity is assured through strong and stable biotin-streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Forster theory, Forsterradii (R0) were found to be around 60 angstrom for organic dyes and around 105 angstrom for QDs. The FRET efficiency (Z) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor-acceptor distances (r) have been determined in the range 45-60 angstrom for organic dye acceptors, while for acceptor QDs between 120 angstrom and 145 angstrom. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing. Y1 - 2014 U6 - https://doi.org/10.1039/c3cp54883j SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 13 SP - 6060 EP - 6067 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Bauer, Maximilian A1 - Godec, Aljaz A1 - Metzler, Ralf T1 - Diffusion of finite-size particles in two-dimensional channels with random wall configurations JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Diffusion of chemicals or tracer molecules through complex systems containing irregularly shaped channels is important in many applications. Most theoretical studies based on the famed Fick-Jacobs equation focus on the idealised case of infinitely small particles and reflecting boundaries. In this study we use numerical simulations to consider the transport of finite-size particles through asymmetrical two-dimensional channels. Additionally, we examine transient binding of the molecules to the channel walls by applying sticky boundary conditions. We consider an ensemble of particles diffusing in independent channels, which are characterised by common structural parameters. We compare our results for the long-time effective diffusion coefficient with a recent theoretical formula obtained by Dagdug and Pineda Y1 - 2014 U6 - https://doi.org/10.1039/c3cp55160a SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 13 SP - 6118 EP - 6128 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Intermediates in the formation and thermolysis of peroxides from oxidations with singlet oxygen JF - Australian journal of chemistry N2 - Herein we describe the recent mechanistic understandings of the singlet oxygen ene reaction to give hydroperoxides and the [4+2] cycloaddition affording endoperoxides. Both experimental findings and theoretical work conclude in the formation of intermediates structurally similar to perepoxides during the ene reaction. Such intermediates mainly control the regio- and stereoselectivities of this reaction class. For the [4+2] cycloaddition, both a synchronous concerted reaction (benzene, naphthalenes) and a stepwise reaction with a non-symmetric zwitterionic intermediate (larger acenes) have been found. The thermolysis of endoperoxides derived from acenes proceeds stepwise for anthracenes, but in a concerted manner for less stable adducts such as naphthalene. Y1 - 2014 U6 - https://doi.org/10.1071/CH13423 SN - 0004-9425 SN - 1445-0038 VL - 67 IS - 3 SP - 320 EP - 327 PB - CSIRO CY - Clayton ER - TY - JOUR A1 - Ermeydan, Mahmut Ali A1 - Cabane, Etienne A1 - Gierlinger, Notburga A1 - Koetz, Joachim A1 - Burgert, Ingo T1 - Improvement of wood material properties via in situ polymerization of styrene into tosylated cell walls JF - RSC Advances N2 - As an engineering material derived from renewable resources, wood possesses excellent mechanical properties in view of its light weight but also has some disadvantages such as low dimensional stability upon moisture changes and low durability against biological attack. Polymerization of hydrophobic monomers in the cell wall is one of the potential approaches to improve the dimensional stability of wood. A major challenge is to insert hydrophobic monomers into the hydrophilic environment of the cell walls, without increasing the bulk density of the material due to lumen filling. Here, we report on an innovative and simple method to insert styrene monomers into tosylated cell walls (i.e. -OH groups from natural wood polymers are reacted with tosyl chloride) and carry out free radical polymerization under relatively mild conditions, generating low wood weight gains. In-depth SEM and confocal Raman microscopy analysis are applied to reveal the distribution of the polystyrene in the cell walls and the lumen. The embedding of polystyrene in wood results in reduced water uptake by the wood cell walls, a significant increase in dimensional stability, as well as slightly improved mechanical properties measured by nanoindentation. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra00741g SN - 2046-2069 VL - 4 IS - 25 SP - 12981 EP - 12988 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Jeon, Jae-Hyung A1 - Chechkin, Aleksei V. A1 - Metzler, Ralf T1 - Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Anomalous diffusion is frequently described by scaled Brownian motion (SBM), a Gaussian process with a power-law time dependent diffusion coefficient. Its mean squared displacement is < x(2)(t) similar or equal to 2K(t)t with K(t) similar or equal to t(alpha-1) for 0 < alpha < 2. SBM may provide a seemingly adequate description in the case of unbounded diffusion, for which its probability density function coincides with that of fractional Brownian motion. Here we show that free SBM is weakly non-ergodic but does not exhibit a significant amplitude scatter of the time averaged mean squared displacement. More severely, we demonstrate that under confinement, the dynamics encoded by SBM is fundamentally different from both fractional Brownian motion and continuous time random walks. SBM is highly non-stationary and cannot provide a physical description for particles in a thermalised stationary system. Our findings have direct impact on the modelling of single particle tracking experiments, in particular, under confinement inside cellular compartments or when optical tweezers tracking methods are used. Y1 - 2014 U6 - https://doi.org/10.1039/c4cp02019g SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 30 SP - 15811 EP - 15817 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, André A1 - Zehm, Daniel T1 - On the hydrophilicity of polyzwitterion poly (N, N-dimethyl-N(3-(methacrylamido)propyl)ammoniopropane sulfonate) in water, deuterated water, and aqueous salt solutions JF - Journal of biomaterials science : Polymer edition KW - polyzwitterion KW - sulfobetaine KW - synthesis KW - fluorescence label KW - upper critical solution temperature KW - isotope effect KW - anti-polyelectrolyte effect Y1 - 2014 U6 - https://doi.org/10.1080/09205063.2014.939918 SN - 0920-5063 SN - 1568-5624 VL - 25 IS - 14-15 SP - 1602 EP - 1618 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Wessig, Pablo A1 - Gerngross, Maik A1 - Pape, Simon A1 - Bruhns, Philipp A1 - Weber, Jens T1 - Novel porous materials based on oligospiroketals (OSK) JF - RSC Advances N2 - New porous materials based on covalently connected monomers are presented. The key step of the synthesis is an acetalisation reaction. In previous years we used acetalisation reactions extensively to build up various molecular rods. Based on this approach, investigations towards porous polymeric materials were conducted by us. Here we wish to present the results of these studies in the synthesis of 1D polyacetals and porous 3D polyacetals. By scrambling experiments with 1D acetals we could prove that exchange reactions occur between different building blocks (evidenced by MALDI-TOF mass spectrometry). Based on these results we synthesized porous 3D polyacetals under the same mild conditions. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra04437a SN - 2046-2069 VL - 4 IS - 59 SP - 31123 EP - 31129 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Grunzel, Petra A1 - Pilarek, Maciej A1 - Steinbrueck, Doerte A1 - Neubauer, Antje A1 - Brand, Eva A1 - Kumke, Michael Uwe A1 - Neubauer, Peter A1 - Krause, Mirja T1 - Mini-scale cultivation method enables expeditious plasmid production in Escherichia coli JF - Biotechnology journal : systems & synthetic biology, nanobiotech, medicine N2 - The standard procedure in the lab for plasmid isolation usually involves a 2-mL, 16 h over-night cultivation in 15-mL bioreaction tubes in LB medium. This is time consuming, and not suitable for high-throughput applications. This study shows that it is possible to produce plasmid DNA (pDNA) in a 1.5-mL microcentrifuge tube with only 100 L cultivation volume in less than 7 h with a simple protocol. Compared with the standard LB cultivation for pDNA production reaching a final pDNA concentration range of 1.5-4 mu g mL(-1), a 6- to 10-fold increase in plasmid concentration (from 10 up to 25 mu g mL(-1) cultivation volume) is achieved using an optimized medium with an internal substrate delivery system (EnBase (R)). Different strains, plasmids, and the applicability of different inoculation tools (i.e. different starting ODs) were compared, demonstrating the robustness of the system. Additionally, dissolved oxygen was monitored in real time online, indicating that under optimized conditions oxygen limitation can be avoided. We developed a simple protocol with a significantly decreased procedure time, enabling simultaneous handling of more samples, while a consistent quality and a higher final pDNA concentration are ensured. KW - Escherichia coli KW - High-cell-density culture KW - Miniaturized cultivations KW - Optical oxygen sensor KW - Plasmid DNA production Y1 - 2014 U6 - https://doi.org/10.1002/biot.201300177 SN - 1860-6768 SN - 1860-7314 VL - 9 IS - 1 SP - 128 EP - 136 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Vaskova, Zuzana A1 - Kitanovski, Nives A1 - Jaglicic, Zvonko A1 - Strauch, Peter A1 - Ruzickova, Zdenka A1 - Valigura, Dusan A1 - Koman, Marian A1 - Kozlevcar, Bojan A1 - Moncol, Jan T1 - Synthesis and magneto-structural characterization of copper(II) nitrobenzoate complexes containing nicotinamide or methylnicotinamide ligands JF - Polyhedron : the international journal of inorganic and organometallic chemistry N2 - Three new copper(II) 4-nitrobenzoato coordination compounds (4-NO(2)bz(-) = 4-nitrobenzoate anions) with N-methylnicotinamide (mna) [Cu(4-NO(2)bz)(2)(mna)(2)(H2O)] (1), [Cu(4-NO(2)bz)(2)(mu-mna)(H2O)](2) (2) and [Cu(mu-4-NO(2)bz)(2)(mna)](2) (3) were synthesized and characterized. Due to a comparison, additional two related compounds [Cu(3,5-(NO2)(2)bz)(2)(mna)(2)(H2O)] (4) (nia = nicotinamide, 3,5-(NO2)(2)bz(-) = 3,5-dinitrobenzoate anions) and [Cu(mu-2-NO(2)bz)(2)(mna)](2) (5) (2-NO(2)bz(-) = 2-nitrobenzoate anions) were isolated. The mononuclear compounds with mna 1 and nia 4 show CuO2N2O chromophores with the water molecule placed at the apex of the square pyramid. The square-pyramidal coordination sphere CuO3NO in 2 differs to CuO2N2O in 1 and 4. Differently, the water molecule is in 2 at the basal-plane, while two mna molecules serve also as bridges via N-py and 0-amido enabling a dinuclear molecular structure 1, 2 and 4 are paramagnetic though a dinuclear structure is seen in 2, while a clear-cut strong antiferromagnetic (AFM) coupling (2J -300 cm(-1)) is found for the compounds 3 and 5. (C) 2014 Elsevier Ltd. All rights reserved. KW - Copper(II) KW - Nicotinamide KW - N-methylnicotinamide KW - Crystal structure KW - Magnetic properties Y1 - 2014 U6 - https://doi.org/10.1016/j.poly.2014.07.017 SN - 0277-5387 VL - 81 SP - 555 EP - 563 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Pereira, Fernanda S. A1 - Nascimento, Heliara D. L. A1 - Magalhaes, Alvicler A1 - Peter, Martin G. A1 - Bataglion, Giovana Anceski A1 - Eberlin, Marcos N. A1 - Gonzalez, Eduardo R. P. T1 - ESI(+)-MS and GC-MS study of the hydrolysis of N-azobenzyl derivatives of chitosan JF - Molecules N2 - New N-p-chloro-, N-p-bromo-, and N-p-nitrophenylazobenzylchitosan derivatives, as well as the corresponding azophenyl and azophenyl-p-sulfonic acids, were synthesized by coupling N-benzylvchitosan with aryl diazonium salts. The synthesized molecules were analyzed by UV-Vis, FT-IR, H-1-NMR and N-15-NMR spectroscopy. The capacity of copper chelation by these materials was studied by AAS. Chitosan and the derivatives were subjected to hydrolysis and the products were analyzed by ESI(+)-MS and GC-MS, confirming the formation of N-benzyl chitosan. Furthermore, the MS results indicate that a nucleophilic aromatic substitution (SnAr) reaction occurs under hydrolysis conditions, yielding chloroaniline from N-p-bromo-, and N-p-nitrophenylazo-benzylchitosan as well as bromoaniline from N-p-chloro-, and N-p-nitrophenylazobenzyl-chitosan. KW - chitosan KW - N-azobenzylchitosan KW - ESI-MS KW - GC-MS KW - SnAr reaction Y1 - 2014 U6 - https://doi.org/10.3390/molecules191117604 SN - 1420-3049 VL - 19 IS - 11 SP - 17604 EP - 17618 PB - MDPI CY - Basel ER - TY - JOUR A1 - Cywinski, Piotr J. A1 - Hammann, Tommy A1 - Huehn, Dominik A1 - Parak, Wolfgang J. A1 - Hildebrandt, Niko A1 - Löhmannsröben, Hans-Gerd T1 - Europium-quantum dot nanobioconjugates as luminescent probes for time-gated biosensing JF - Journal of biomedical optics N2 - Nanobioconjugates have been synthesized using cadmium selenide quantum dots (QDs), europium complexes (EuCs), and biotin. In those conjugates, long-lived photoluminescence (PL) is provided by the europium complexes, which efficiently transfer energy via Forster resonance energy transfer (FRET) to the QDs in close spatial proximity. As a result, the conjugates have a PL emission spectrum characteristic for QDs combined with the long PL decay time characteristic for EuCs. The nanobioconjugates synthesis strategy and photo-physical properties are described as well as their performance in a time-resolved streptavidin-biotin PL assay. In order to prepare the QD-EuC-biotin conjugates, first an amphiphilic polymer has been functionalized with the EuC and biotin. Then, the polymer has been brought onto the surface of the QDs (either QD655 or QD705) to provide functionality and to make the QDs water dispersible. Due to a short distance between EuC and QD, an efficient FRET can be observed. Additionally, the QD-EuC-biotin conjugates' functionality has been demonstrated in a PL assay yielding good signal discrimination, both from autofluorescence and directly excited QDs. These newly designed QD-EuC-biotin conjugates expand the class of highly sensitive tools for bioanalytical optical detection methods for diagnostic and imaging applications. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) KW - quantum dots KW - europium complex KW - amphiphilic polymer assembly KW - nanobioconjugate KW - biosensor KW - time-resolved fluorescence Y1 - 2014 U6 - https://doi.org/10.1117/1.JBO.19.10.101506 SN - 1083-3668 SN - 1560-2281 VL - 19 IS - 10 PB - SPIE CY - Bellingham ER - TY - JOUR A1 - Sarauli, David A1 - Peters, Kristina A1 - Xu, Chenggang A1 - Schulz, Burkhard A1 - Fattakhova-Rohlfing, Dina A1 - Lisdat, Fred T1 - 3D-Electrode architectures for enhanced direct bioelectrocatalysis of pyrroloquinoline quinone-dependent glucose dehydrogenase JF - ACS applied materials & interfaces N2 - We report on the fabrication of a complex electrode architecture for efficient direct bioelectrocatalysis. In the developed procedure, the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase entrapped in a sulfonated polyaniline [poly(2-methoxyaniline-5-sulfonic acid)-co-aniline] was immobilized on macroporous indium tin oxide (macroITO) electrodes. The use of the 3D-conducting scaffold with a large surface area in combination with the conductive polymer enables immobilization of large amounts of enzyme and its efficient communication with the electrode, leading to enhanced direct bioelectrocatalysis. In the presence of glucose, the fabricated bioelectrodes show an exceptionally high direct bioelectrocatalytical response without any additional mediator. The catalytic current is increased more than 200-fold compared to planar ITO electrodes. Together with a high long-term stability (the current response is maintained for >90% of the initial value even after 2 weeks of storage), the transparent 3D macroITO structure with a conductive polymer represents a valuable basis for the construction of highly efficient bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction. KW - 3D electrode structures KW - macroITO KW - conductive polymer KW - PQQ-GDH KW - direct bioelectrocatalysis KW - bioelectrochemistry Y1 - 2014 U6 - https://doi.org/10.1021/am5046026 SN - 1944-8244 VL - 6 IS - 20 SP - 17887 EP - 17893 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Goetze, Jan P. A1 - Kröner, Dominik A1 - Banerjee, Shiladitya A1 - Karasulu, Bora A1 - Thiel, Walter T1 - Carotenoids as a shortcut for chlorophyll Soret-to-Q band energy flow JF - ChemPhysChem : a European journal of chemical physics and physical chemistry N2 - It is proposed that xanthophylls, and carotenoids in general, may assist in energy transfer from the chlorophyll Soret band to the Q band. Ground-state (1A(g)) and excited-state (1B(u)) optimizations of violaxanthin (Vx) and zeaxanthin (Zx) are performed in an environment mimicking the light-harvesting complex II (LHCII), including the closest chlorophyll b molecule (Chl). Time-dependent density functional theory (TD-DFT, CAM-B3LYP functional) is used in combination with a semi-empirical description to obtain the excited-state geometries, supported by additional DFT/multireference configuration interaction calculations, with and without point charges representing LHCII. In the ground state, Vx and Zx show similar properties. At the 1B(u) minimum, the energy of the Zx 1Bu state is below the Chl Q band, in contrast to Vx. Both Vx and Zx may act as acceptors of Soret-state energy; transfer to the Q band seems to be favored for Vx. These findings suggest that carotenoids may generally mediate Soret-to-Q energy flow in LHCII. KW - carotenoids KW - chlorophyll KW - density functional calculations KW - energy transfer KW - xanthophylls Y1 - 2014 U6 - https://doi.org/10.1002/cphc.201402233 SN - 1439-4235 SN - 1439-7641 VL - 15 IS - 15 SP - 3391 EP - 3400 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Comminges, Clement A1 - Frasca, Stefano A1 - Suetterlin, Martin A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Wollenberger, Ursula T1 - Surface modification with thermoresponsive polymer brushes for a switchable electrochemical sensor JF - RSC Advances N2 - Elaboration of switchable surfaces represents an interesting way for the development of a new generation of electrochemical sensors. In this paper, a method for growing thermoresponsive polymer brushes from a gold surface pre-modified with polyethyleneimine (PEI), subsequent layer-by-layer polyelectrolyte assembly and adsorption of a charged macroinitiator is described. We propose an easy method for monitoring the coil-to-globule phase transition of the polymer brush using an electrochemical quartz crystal microbalance with dissipation (E-QCM-D). The surface of these polymer modified electrodes shows reversible switching from the swollen to the collapsed state with temperature. As demonstrated from E-QCM-D measurements using an original signal processing method, the switch is operating in three reversible steps related to different interfacial viscosities. Moreover, it is shown that the one electron oxidation of ferrocene carboxylic acid is dramatically affected by the change from the swollen to the collapsed state of the polymer brush, showing a spectacular 86% decrease of the charge transfer resistance between the two states. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra07190e SN - 2046-2069 VL - 4 IS - 81 SP - 43092 EP - 43097 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Braune, Steffen A1 - Walter, M. A1 - Schulze, F. A1 - Lendlein, Andreas A1 - Jung, Friedrich T1 - Changes in platelet morphology and function during 24 hours of storage JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood-and PRP-storage times on changes in platelet morphology and function. Whole blood PFA100 closure times increased after stimulation with collagen/ADP and collagen/epinephrine. Twenty four hours after blood collection, both parameters were prolonged pathologically above the upper limit of the reference range. Numbers of circulating platelets, measured in PRP, decreased after four hours, but no longer after twenty four hours. Mean platelet volumes (MPV) and platelet large cell ratios (P-LCR, 12 fL - 40 fL) decreased over time. Immediately after blood collection, no debris or platelet aggregates could be visualized microscopically. After four hours, first debris and very small aggregates occurred. After 24 hours, platelet aggregates and also debris progressively increased. In accordance to this, the CASY system revealed an increase of platelet aggregates (up to 90 mu m diameter)with increasing storage time. The percentage of CD62P positive platelets and PF4 increased significantly with storage time in resting PRP. When soluble ADP was added to stored PRP samples, the number of activatable platelets decreased significantly over storage time. The present study reveals the importance of a consequent standardization in the preparation of WB and PRP. Platelet morphology and function, particularly platelet reactivity to adherent or soluble agonists in their surrounding milieu, changed rapidly outside the vascular system. This knowledge is of crucial interest, particularly in the field of biomaterial development for cardiovascular applications, and may help to define common standards in the in vitro hemocompatibility testing of biomaterials. KW - Platelet KW - platelet function KW - platelet rich plasma KW - whole blood KW - platelet aging KW - platelet storage KW - hemocompatibility KW - biomaterials Y1 - 2014 U6 - https://doi.org/10.3233/CH-141876 SN - 1386-0291 SN - 1875-8622 VL - 58 IS - 1 SP - 159 EP - 170 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Kovach, Ildyko A1 - Koetz, Joachim A1 - Friberg, Stig E. T1 - Janus emulsions stabilized by phospholipids JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - Janus emulsions were formed by mixing three immiscible liquids; this implies two oil components (i.e. olive oil (00) and silicone oil (SiO)) with water in presence of interfacial active components. The morphology and size of Janus droplets formed strongly depended on the type of surfactant used. In presence of a non-ionic surfactant, i.e. Tween 80, large engulfed Janus droplets were formed. By adding phospholipids to the system the droplet size was decreased and more stable Janus droplets formed. Interfacial tension measurements carried out using a spinning drop apparatus and a ring tensiometer demonstrate that interfacial tension is the most important factor controlling the size, morphology and stability of Janus droplets. When the interfacial tension between oil and water becomes <= 1 mN/m, smaller Janus droplets are formed. Such conditions are fulfilled when phospholipids are used in combination with non-ionic surfactant Tween 80. The morphology of the double droplets is predominantly controlled by the viscosity and interfacial tension between the two oil phases. By using different types of phospholipids, i.e. asolectin and lecithin instead of a more concentrated phosphatidylcholine (phospholipon), the interfacial tension is decreased and different morphologies of engulfing can be observed. KW - Janus emulsions KW - Spinning drop KW - Interfacial tension KW - Phospholipids Y1 - 2014 U6 - https://doi.org/10.1016/j.colsurfa.2013.08.065 SN - 0927-7757 SN - 1873-4359 VL - 441 SP - 66 EP - 71 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kroener, Dominik A1 - Schimka, Selina A1 - Klamroth, Tillmann T1 - Laser control for coupled torsions in chiroptical switches: a combined quantum and classical dynamics approach JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - We present a novel laser pulse control for the chiroptical switch 1-(2-cis-fluoroethenyl)-2-fluoro-3,5-dibromobenzene mounted on adamantane, where the latter imitates a linker group or part of a solid surface. This molecular device offers three switching states: a true achiral "off"-state and two chiral "on"-states of opposite handedness. Due to the alignment of its chiral axis along the surface normal several defined orientations of the switch have to be considered for an efficient stereocontrol strategy. In addition to these different initial conditions, coupled torsional degrees of freedom around the chiral axis make the quest for highly stereoselective laser pulses a challenge. The necessary flexibility in pulse accomplished by employing the iterative stochastic pulse optimization method we presented recently. Still, the complexity of the system dictates a combined treatment by fast molecular dynamics and computationally intensive quantum dynamics. Although quantum effects are found to be of importance, the pulses optimized within the classical treatment allow us to turn on the chirality of the switch, achieving high enantioselectivity in the quantum treatment for all orientations at the same time. Y1 - 2014 U6 - https://doi.org/10.1021/jp410342a SN - 1932-7447 VL - 118 IS - 2 SP - 1322 EP - 1331 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Metzler, Ralf A1 - Jeon, Jae-Hyung A1 - Cherstvy, Andrey G. A1 - Barkai, Eli T1 - Anomalous diffusion models and their properties: non-stationarity, non-ergodicity, and ageing at the centenary of single particle tracking JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Modern microscopic techniques following the stochastic motion of labelled tracer particles have uncovered significant deviations from the laws of Brownian motion in a variety of animate and inanimate systems. Such anomalous diffusion can have different physical origins, which can be identified from careful data analysis. In particular, single particle tracking provides the entire trajectory of the traced particle, which allows one to evaluate different observables to quantify the dynamics of the system under observation. We here provide an extensive overview over different popular anomalous diffusion models and their properties. We pay special attention to their ergodic properties, highlighting the fact that in several of these models the long time averaged mean squared displacement shows a distinct disparity to the regular, ensemble averaged mean squared displacement. In these cases, data obtained from time averages cannot be interpreted by the standard theoretical results for the ensemble averages. Here we therefore provide a comparison of the main properties of the time averaged mean squared displacement and its statistical behaviour in terms of the scatter of the amplitudes between the time averages obtained from different trajectories. We especially demonstrate how anomalous dynamics may be identified for systems, which, on first sight, appear to be Brownian. Moreover, we discuss the ergodicity breaking parameters for the different anomalous stochastic processes and showcase the physical origins for the various behaviours. This Perspective is intended as a guidebook for both experimentalists and theorists working on systems, which exhibit anomalous diffusion. Y1 - 2014 U6 - https://doi.org/10.1039/c4cp03465a SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 44 SP - 24128 EP - 24164 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kopec, Maciej A1 - Niemiec, Wiktor A1 - Laschewsky, André A1 - Nowakowska, Maria A1 - Zapotoczny, Szczepan T1 - Photoinduced energy and electron transfer in micellar multilayer films JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Micellar multilayer films were prepared from an amphiphilic comb-like polycation ("polysoap") and the polyanion poly(styrene sulfonate) (PSS) using alternate polyelectrolyte layer-by-layer (LbL) self-assembly. Linear growth of the film thickness was evidenced by UV-vis spectroscopy and spectroscopic ellipsometry. Imaging by atomic force microscopy (AFM) indicated that the micellar conformation adopted by the polycation in solutions was preserved in the films. Thus, hydrophobic photoactive molecules, which were solubilized by the hydrophobic nanodomains of the micellar polymer prior to deposition, could be transferred into the films. Photoinduced energy transfer was observed in the nanostructured multilayers between naphthalene (donor) and perylene (acceptor) molecules embedded inside the polymer micelles. The efficiency of the energy transfer process can be controlled to some extent by introducing spacer layers between the layers containing the donor or acceptor, revealing partial stratification of the micellar LbL films. Also, photoinduced electron transfer was evidenced between perylene (donor) and butyl viologen (acceptor) molecules embedded inside the multilayers by steady-state fluorescence spectroscopy. The obtained photoactive nanostructures are promising candidates for solar-to-chemical energy conversion systems. Y1 - 2014 U6 - https://doi.org/10.1021/jp410808z SN - 1932-7447 VL - 118 IS - 4 SP - 2215 EP - 2221 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kosmella, Sabine A1 - Venus, Jane A1 - Hahn, Jennifer A1 - Prietzel, Claudia Christina A1 - Koetz, Joachim T1 - Low-temperature synthesis of polyethyleneimine-entrapped CdS quantum dots JF - Chemical physics letters N2 - This Letter is focused on the one-pot formation of CdS nanoparticles in aqueous medium in presence of polyethyleneimine (PEI). Quantum dots can be obtained by adding a pre-cooled aqueous Na2S solution to a pre-cooled aqueous CdCl2 solution dropwise in presence of PEI. Field flow fractionation in combination with TEM experiments show a time dependent agglomeration of individual quantum dots from 1.6 nm up to 3.2 nm in size. The hyperbranched PEI of moderate molar mass (>20000 g/mol) is an excellent polymer to prevent a further increase of the particle size. Therefore, stable fluorescent PEI-capped CdS quantum dots are available. Y1 - 2014 U6 - https://doi.org/10.1016/j.cplett.2013.12.019 SN - 0009-2614 SN - 1873-4448 VL - 592 SP - 114 EP - 119 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Degtyar, Elena A1 - Harrington, Matthew J. A1 - Politi, Yael A1 - Fratzl, Peter T1 - The mechanical role of metal ions in biogenic protein-based materials JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Protein-metal interactions-traditionally regarded for roles in metabolic processes-are now known to enhance the performance of certain biogenic materials, influencing properties such as hardness, toughness, adhesion, and self-healing. Design principles elucidated through thorough study of such materials are yielding vital insights for the design of biomimetic metallopolymers with industrial and biomedical applications. Recent advances in the understanding of the biological structure-function relationships are highlighted here with a specific focus on materials such as arthropod biting parts, mussel byssal threads, and sandcastle worm cement. KW - adhesives KW - biomaterials KW - metal coordination KW - sacrificial bonds KW - self-healing materials Y1 - 2014 U6 - https://doi.org/10.1002/anie.201404272 SN - 1433-7851 SN - 1521-3773 VL - 53 IS - 45 SP - 12026 EP - 12044 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin A1 - Schilde, Uwe T1 - Chroman-4-ones via microwave-promoted domino claisen rearrangement-oxa-michael addition: Synthesis of tabchromones A and B JF - Synlett : accounts and rapid communications in synthetic organic chemistry N2 - Allyl phenyl ethers with a pendant enone substituent undergo, upon microwave irradiation, a domino sequence of Claisen rearrangement and 6-endo-trig-cyclization to furnish functionalized chroman-4-ones. The natural products tabchromones A and B were synthesized via this method. KW - cyclization KW - Michael addition KW - rearrangement KW - tandem reaction KW - Wacker reaction Y1 - 2014 U6 - https://doi.org/10.1055/s-0034-1379364 SN - 0936-5214 SN - 1437-2096 VL - 25 IS - 20 SP - 2943 EP - 2946 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Moskalik, Mikhail Yu. A1 - Astakhova, Vera V. A1 - Schilde, Uwe A1 - Sterkhova, Irina V. A1 - Shainyan, Bagrat A. T1 - Assembling of 3,6-diazabicyclo[3.1.0]hexane framework in oxidative triflamidation of substituted buta-1,3-dienes JF - Tetrahedron KW - Trifluoromethanesulfonamide KW - Arenesulfonamides KW - Cycloaddition KW - 1,3-Dienes KW - 3,6-Diazabicyclo[3.1.0]hexanes KW - X-ray Y1 - 2014 U6 - https://doi.org/10.1016/j.tet.2014.09.050 SN - 0040-4020 VL - 70 IS - 45 SP - 8636 EP - 8641 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Schulz, Burkhard A1 - Richau, Klaus A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments JF - Macromolecular chemistry and physics N2 - A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments. KW - brewster angle microscopy KW - ellipsometry KW - Langmuir layers KW - morphology KW - polyesterurethanes Y1 - 2014 U6 - https://doi.org/10.1002/macp.201400377 SN - 1022-1352 SN - 1521-3935 VL - 215 IS - 24 SP - 2437 EP - 2445 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tsendra, Oksana A1 - Scott, Andrea Michalkova A1 - Gorb, Leonid A1 - Boese, Adrian Daniel A1 - Hill, Frances C. A1 - Ilchenko, Mykola M. A1 - Leszczynska, Danuta A1 - Leszczynski, Jerzy T1 - Adsorption of Nitrogen-Containing Compounds on the (100) alpha-Quartz Surface: Ab Initio Cluster Approach JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - A cluster approach extended to the ONIOM methodology has been applied using several density functionals and Moller-Plesset perturbation theory (MP2) to simulate the adsorption of selected nitrogen-containing compounds [NCCs, 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 3-nitro-1,2,4-triazole-5-one (NTO)] on the hydroxyated (100) surface of a-quartz. The structural properties were calculated using the M06-2X functional and 6-31G(d,p) basis set. The M06-2X-D3, PBE-D3, and MP2 methods were used to calculate the adsorption energies. Results have been compared with the data from other studies of adsorption of compounds of similar nature on silica. Effect of deformation of the silica surface and adsorbates on the binding energy values was also studied. The atoms in molecules (AIM) analysis was employed to characterize the adsorbate-adsorbent binding and to calculate the bond energies. The silica surface shows different sorption affinity toward the chemicals considered depending on their electronic structure. All target NCCs are physisorbed on the modeled silica surface. Adsorption occurs due to the formation of multiple hydrogen bonds between the functional groups of NCCs and surface silanol groups. Parallel orientation of NCCs interacting with the silica surface was found to be favorable when compared with perpendicularly oriented NCCs. NTO was found to be the most strongly adsorbed on the silica surface among all of the considered compounds. Dispersion correction was shown to play an important role in the DFT calculations of the adsorption energies of silica-NCC systems. Y1 - 2014 U6 - https://doi.org/10.1021/jp406827h SN - 1932-7447 VL - 118 IS - 6 SP - 3023 EP - 3034 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Sutton, Christopher A1 - Körzdörfer, Thomas A1 - Gray, Matthew T. A1 - Brunsfeld, Max A1 - Parrish, Robert M. A1 - Sherrill, C. David A1 - Sears, John S. A1 - Bredas, Jean-Luc T1 - Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We investigate the torsion potentials in two prototypical pi-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains. Y1 - 2014 U6 - https://doi.org/10.1063/1.4863218 SN - 0021-9606 SN - 1089-7690 VL - 140 IS - 5 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Cywinski, Piotr J. A1 - Moro, Artur J. A1 - Löhmannsröben, Hans-Gerd T1 - Cyclic GMP recognition using ratiometric QD-fluorophore conjugate nanosensors JF - Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics KW - Quantum dots KW - Naphthyridines KW - Cyclic GMP KW - Base pairing KW - Fluorescent nanoconjugate KW - Nanosensor Y1 - 2014 U6 - https://doi.org/10.1016/j.bios.2013.09.002 SN - 0956-5663 SN - 1873-4235 VL - 52 SP - 288 EP - 292 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Yu, Mingfeng A1 - Ast, Sandra A1 - Yu, Qun A1 - Lo, Anthony T. S. A1 - Flehr, Roman A1 - Todd, Matthew H. A1 - Rutledge, Peter J. T1 - Incorporating a piperidinyl group in the fluorophore extends the fluorescence lifetime of click-derived cyclam-naphthalimide conjugates JF - PLoS one N2 - Ligands incorporating a tetraazamacrocycle receptor, a 'click'-derived triazole and a 1,8-naphthalimide fluorophore have proven utility as probes for metal ions. Three new cyclam-based molecular probes are reported, in which a piperidinyl group has been introduced at the 4-position of the naphthalimide fluorophore. These compounds have been synthesized using the copper(I)-catalyzed azide-alkyne Huisgen cycloaddition and their photophysical properties studied in detail. The alkylamino group induces the expected red-shift in absorption and emission spectra relative to the simple naphthalimide derivatives and gives rise to extended fluorescence lifetimes in aqueous buffer. The photophysical properties of these systems are shown to be highly solvent-dependent. Screening the fluorescence responses of the new conjugates to a wide variety of metal ions reveals significant and selective fluorescence quenching in the presence of copper(II), yet no fluorescence enhancement with zinc(II) as observed previously for the simple naphthalimide derivatives. Reasons for this different behaviour are proposed. Cytotoxicity testing shows that these new cyclam-triazole-dye conjugates display little or no toxicity against either DLD-1 colon carcinoma cells or MDA-MB-231 breast carcinoma cells, suggesting a potential role for these and related systems in biological sensing applications. Y1 - 2014 U6 - https://doi.org/10.1371/journal.pone.0100761 SN - 1932-6203 VL - 9 IS - 7 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Ortmann, Thomas A1 - Ahrens, Heiko A1 - Milewski, Sven A1 - Lawrenz, Frank A1 - Groening, Andreas A1 - Laschewsky, André A1 - Garnier, Sebastien A1 - Helm, Christiane A. T1 - Lipid monolayers with adsorbed oppositely charged polyelectrolytes: Influence of reduced charge densities JF - Polymers N2 - Polyelectrolytes in dilute solutions (0.01 mmol/L) adsorb in a two-dimensional lamellar phase to oppositely charged lipid monolayers at the air/water interface. The interchain separation is monitored by Grazing Incidence X-ray Diffraction. On monolayer compression, the interchain separation decreases to a factor of two. To investigate the influence of the electrostatic interaction, either the line charge density of the polymer is reduced (a statistic copolymer with 90% and 50% charged monomers) or mixtures between charged and uncharged lipids are used (dipalmitoylphosphatidylcholine (DPPC)/dioctadecyldimethylammonium bromide (DODAB)) On decrease of the surface charge density, the interchain separation increases, while on decrease of the linear charge density, the interchain separation decreases. The ratio between charged monomers and charged lipid molecules is fairly constant; it decreases up to 30% when the lipids are in the fluid phase. With decreasing surface charge or linear charge density, the correlation length of the lamellar order decreases. KW - lipid monolayer KW - polyelectrolyte adsorption KW - statistical copolymer KW - two-dimensional phases KW - surface charge KW - nematic phase KW - grazing incidence X-ray diffraction Y1 - 2014 U6 - https://doi.org/10.3390/polym6071999 SN - 2073-4360 VL - 6 IS - 7 SP - 1999 EP - 2017 PB - MDPI CY - Basel ER - TY - JOUR A1 - Marom, Noa A1 - Körzdörfer, Thomas A1 - Ren, Xinguo A1 - Tkatchenko, Alexandre A1 - Chelikowsky, James R. T1 - Size effects in the interface level alignment of dye-Sensitized TiO2 clusters JF - The journal of physical chemistry letters N2 - The efficiency of dye-sensitized solar cells (DSCs) depends critically on the electronic structure of the interfaces in the active region. We employ recently developed dispersion-inclusive density functional theory (DFT) and GW methods to study the electronic structure of TiO2 clusters sensitized with catechol molecules. We show that the energy level alignment at the dye-TiO2 interface is the result of an intricate interplay of quantum size effects and dynamic screening effects and that it may be manipulated by nanostructuring and functionalizing the TiO2. We demonstrate that the energy difference between the catechol LUMO and the TiO2 LUMO, which is associated with the injection loss in DSCs, may be reduced significantly by reducing the dimensions of nanostructured TiO2 and by functionalizing the TiO2 with wide-gap moieties, which contribute additional screening but do not interact strongly with the frontier orbitals of the TiO2 and the dye. Precise control of the electronic structure may be achieved via "interface engineering" in functional nanostructures. Y1 - 2014 U6 - https://doi.org/10.1021/jz5008356 SN - 1948-7185 VL - 5 IS - 14 SP - 2395 EP - 2401 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Brennecke, Johannes A1 - Ochs, Christopher J. A1 - Boudhar, Aicha A1 - Reux, Bastien A1 - Subramanian, Gomathy Sandhya A1 - Lear, Martin J. A1 - Trau, Dieter A1 - Hobley, Jonathan T1 - Design, preparation and assessment of surface-immobilised tetraphenylethenes for biosensing applications JF - Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces N2 - Tetraphenylethene (TPE) shows a significant increase of fluorescence intensity when the rotational freedom of its phenyl groups is restricted. This special property allows the use of TPE in sensor applications, which have been previously described for the liquid phase only. However, some applications utilising arrays require the immobilisation of TPE dyes on solid surfaces. In this work, we synthesised and investigated the fluorescence behaviour of TPE derivatives on silica particles and quartz slides and suggest ways to employ the dye's properties in solid phase biosensor applications. 2014 Published by Elsevier B.V. KW - Tetraphenylethene Bioassay Fluorescent dye KW - Microparticles Reagentless assay Y1 - 2014 U6 - https://doi.org/10.1016/j.apsusc.2014.04.061 SN - 0169-4332 SN - 1873-5584 VL - 307 SP - 475 EP - 481 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Moskalik, Mikhail Yu A1 - Astakhova, Vera V. A1 - Schilde, Uwe T1 - Novel design of 3,8-diazabicyclo[3.2.1]octane framework in oxidative sulfonamidation of 1,5-hexadiene JF - Tetrahedron N2 - 1,5-Hexadiene reacts with trifluoromethanesulfonamide in the oxidative system (t-BuOCl+Nal) to give trans-2,5-bis(iodomethyl)-1-(trifluoromethylsulfonyl)pyrrolidine 5 and 3,8-bis(trifluoromethylsulfonyl)-3,8-diazabicyclo[3.2.1]octane 6. With arenesulfonamides ArSO2NH2 (Ar=Ph, Tol), the reaction stops at the formation of the trans and cis isomers of 2,5-bis(iodomethyl)-1-(arenesulfonyl)pyrrolidine 7 and 8 (1:1). The cis isomers of 7 and 8 do not undergo cyclization to the corresponding 3,8-disubstituted 3,8-diazabicyclo[3.2.1]octanes. The reaction with triflamide represents the first example of one-pot two-step route to 3,8-diazabicyclo[3.2.1]octane system. (C) 2014 Elsevier Ltd. All rights reserved. KW - Trifluoromethanesulfonamide KW - Arenesulfonamides KW - 1,5-Dienes KW - Cycloaddition KW - 3,8-Diazabicyclo[3.2.1]octane KW - X-ray Y1 - 2014 U6 - https://doi.org/10.1016/j.tet.2014.04.095 SN - 0040-4020 VL - 70 IS - 30 SP - 4547 EP - 4551 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hauke, Sylvia T1 - Metathesis-Based de novo synthesis of noviose JF - European journal of organic chemistry N2 - The rare carbohydrate L-(+)-noviose was synthesized from enantiomerically pure L-lactate. The configuration at C-4 was established by diastereoselective nucleophilic addition to an in-situ-generated lactaldehyde. The resulting homoallylic alcohol was further transformed into a set of ring-closing metathesis (RCM) precursors. These compounds were converted into noviose in few steps using RCM and RCM-allylic-oxidation sequences. KW - Carbohydrates KW - Allylic oxidation KW - Oxygen heterocycles KW - Metathesis KW - Ruthenium Y1 - 2014 U6 - https://doi.org/10.1002/ejoc.201301615 SN - 1434-193X SN - 1099-0690 VL - 2014 IS - 9 SP - 1951 EP - 1960 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Strehmel, Veronika A1 - Berdzinski, Stefan A1 - Strauch, Peter A1 - Hoffmann-Jacobsen, Kerstin A1 - Strehmel, Bernd T1 - Investigation of molecular solvents and ionic liquids with a dual probe JF - Zeitschrift für physikalische Chemie : international journal of research in physical chemistry and chemical physics N2 - A dual probe was investigated by UV-Vis, fluorescence, and ESR spectroscopy. It comprises the pyrene chromophore and the paramagnetic 2,2,6,6-tetramethylpiperidinyl-N-oxyl radical that are covalently linked together via an ester bridge. The dual probe was used to investigate molecular solvents of different polarity as well as ionic liquids bearing either imidazolium or pyrrolidinium cations and various anions, such as bis(trifluoromethylsulfonyl)imide, tetrafluoroborate, tris(pentafluoroethyl)trifluorophosphate, or dicyanamide. The dual probe does not show solvatochromism that is typical for some pyrenes. Furthermore, the dual probe is considerable less mobile compared to 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) without additional substituent as detected by ESR spectroscopy. This is caused by the bulky pyrenyl substituent bound at the dual probe resulting in a reduced mobility of the dual probe. KW - Ionic Liquid KW - Fluorescence KW - ESR KW - Molecular Probe Y1 - 2014 U6 - https://doi.org/10.1515/zpch-2014-0453 SN - 0942-9352 VL - 228 IS - 2-3 SP - 155 EP - 169 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Hartmann, Heike A1 - Lewerenz, Susann T1 - Campaigning against Apartheid in East and West Germany JF - Radical history review Y1 - 2014 U6 - https://doi.org/10.1215/01636545-2402068 SN - 0163-6545 IS - 119 SP - 191 EP - 204 PB - Duke Univ. Press CY - Durham ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hauke, Sylvia A1 - Muehlenberg, Nino T1 - Imino glycals via Ruthenium-catalyzed RCM and isomerization JF - Synthesis N2 - N-Allyl-N-homoallylamines were converted in one step into cyclic enamides via a ruthenium-catalyzed assisted tandem catalytic ring-closing metathesis-isomerization sequence. The sequence relies on the in situ transformation of a metathesis active Ru-carbene into an isomerization active Ru-hydride by addition of hydroxide as a chemical trigger. KW - heterocycles KW - isomerization KW - metathesis KW - ruthenium KW - tandem reaction Y1 - 2014 U6 - https://doi.org/10.1055/s-0033-1338615 SN - 0039-7881 SN - 1437-210X VL - 46 IS - 12 SP - 1648 EP - 1658 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hauke, Sylvia T1 - Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative JF - Beilstein journal of organic chemistry N2 - Cross metathesis of a lactate derived allylic alcohol and acrolein is the entry point to a de novo synthesis of 4-benzoate protected L-amicetose and a cinerulose derivative protected at C5 and C1. KW - carbohydrates KW - de novo synthesis KW - lactate KW - metathesis KW - ruthenium Y1 - 2014 U6 - https://doi.org/10.3762/bjoc.10.102 SN - 1860-5397 VL - 10 SP - 1023 EP - 1031 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Hasinovic, Hida A1 - Boggs, Cami A1 - Friberg, Stig E. A1 - Kovach, Ildiko A1 - Koetz, Joachim T1 - Janus emulsions from a one-step process; optical microscopy images JF - Journal of dispersion science and technology N2 - The optical microscopy images of an emulsion are commonly distorted when viewed between a cover glass and a planar microscopy slide. An alternative method is to place the sample on a slide with a cavity, which in turn suffers from incomplete information for high internal phase ratio (HIPR) emulsions, due to the inevitable crowding of the drops. This problem is particularly acute for more complex emulsions, such as those with Janus drops, for which a detailed image of the drop is essential. A number of publications have recently described Janus emulsions prepared by a one-step high energy emulsification process with microscopy images obtained by the sample between a planar slide and a cover glass. The correlation to the morphology of emulsions in bulk of these images is critical, but, so far, a potential equivalence has not been established. Since the images are central in order to understand why Janus emulsions should form under such conditions, the need to ascertain any such association is urgent. With this contribution, we compare images from different microscopy methods to those of gently diluted HIPR emulsions. The results reveal that the images of the emulsion samples between a cover glass and a planar microscope slide actually present a realistic representation of the drop topology in bulk emulsions. KW - Janus drops KW - Emulsification KW - microemulsions KW - emulsion microscopy Y1 - 2014 U6 - https://doi.org/10.1080/01932691.2013.801019 SN - 0193-2691 SN - 1532-2351 VL - 35 IS - 5 SP - 613 EP - 618 PB - Taylor & Francis Group CY - Philadelphia ER - TY - JOUR A1 - Stumpe, Joachim A1 - Sakhno, O. A1 - Gritsai, Y. A1 - Rosenhauer, R. A1 - Fischer, Th. A1 - Rutloh, Michael A1 - Schaal, F. A1 - Weidenfeld, S. A1 - Jetter, M. A1 - Michler, P. A1 - Pruss, C. A1 - Osten, W. T1 - Active and passive LC based polarization elements JF - Molecular crystals and liquid crystals N2 - Passive and active polarization elements were created by surface and bulk photo-alignment of LCs, reactive LCs, photo-sensitive LCP and photo-curable monomer/LC composites. The use of different photo-sensitive liquid crystalline materials for the development of highly anisotropic elements with high spatial resolution and stability or, alternatively, fast switch ability will be discussed. Photo-active and voltage tunable polarization and diffraction elements are presented. For active micro-optic application a photo-addressed patterned retarder was created. Electrically switchable diffraction gratings were generated by interference exposure of photo-curable LC composites at room temperature characterized by droplet free morphology. These polarization sensitive diffraction elements are characterized be excellent optical properties and low switching times. KW - electrically switchable gratings. KW - diffractive elements KW - polymer/LC composites KW - switchable retarder KW - polarization gratings KW - Polarization elements Y1 - 2014 U6 - https://doi.org/10.1080/15421406.2014.917503 SN - 1542-1406 SN - 1563-5287 VL - 594 IS - 1 SP - 140 EP - 149 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin T1 - Suzuki-Miyaura coupling of halophenols and phenol boronic acids: systematic investigation of positional isomer effects and conclusions for the synthesis of phytoalexins from Pyrinae JF - The journal of organic chemistry N2 - The Suzuki-Miyaura couplings of o-, m-, and p-halophenols with o-, m-, and p-phenol boronic acids were investigated for all combinations under standardized conditions, using Pd/C as a heterogeneous catalyst and water as a solvent. In the case of iodophenols, conventional heating was used, while for bromophenols significantly better results could be obtained using microwave irradiation. This systematic study revealed that 2,4'-biphenol is particularly difficult to access, irrespective of the starting materials used, but that these difficulties can be overcome by using different additives. The conclusions drawn from this investigation allowed us to identify conditions for the protecting group-free or minimized total synthesis of biaryl-type phytoalexins. These compounds possess antibacterial activity and are produced by fruit trees as a response to microbial infection. Y1 - 2014 U6 - https://doi.org/10.1021/jo500675a SN - 0022-3263 VL - 79 IS - 9 SP - 4104 EP - 4118 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Victora, Andrea A1 - Moeller, Heiko M. A1 - Exner, Thomas E. T1 - Accurate ab initio prediction of NMR chemical shifts of nucleic acids and nucleic acids/protein complexes JF - Nucleic acids research N2 - NMR chemical shift predictions based on empirical methods are nowadays indispensable tools during resonance assignment and 3D structure calculation of proteins. However, owing to the very limited statistical data basis, such methods are still in their infancy in the field of nucleic acids, especially when non-canonical structures and nucleic acid complexes are considered. Here, we present an ab initio approach for predicting proton chemical shifts of arbitrary nucleic acid structures based on state-of-the-art fragment-based quantum chemical calculations. We tested our prediction method on a diverse set of nucleic acid structures including double-stranded DNA, hairpins, DNA/protein complexes and chemically-modified DNA. Overall, our quantum chemical calculations yield highly/very accurate predictions with mean absolute deviations of 0.3-0.6 ppm and correlation coefficients (r(2)) usually above 0.9. This will allow for identifying misassignments and validating 3D structures. Furthermore, our calculations reveal that chemical shifts of protons involved in hydrogen bonding are predicted significantly less accurately. This is in part caused by insufficient inclusion of solvation effects. However, it also points toward shortcomings of current force fields used for structure determination of nucleic acids. Our quantum chemical calculations could therefore provide input for force field optimization. Y1 - 2014 U6 - https://doi.org/10.1093/nar/gku1006 SN - 0305-1048 SN - 1362-4962 VL - 42 IS - 22 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Strehmel, Veronika A1 - Berdzinski, Stefan A1 - Rexhausen, Hans T1 - Interactions between ionic liquids and radicals JF - Journal of molecular liquids N2 - Ionic liquids were investigated with both stable radicals on the basis of 2,2,6,6-tetramethylpiperidine-1-yloxyl (TEMPO) and photogenerated lophyl radicals. The ionic liquids are composed either of bis(trifluoromethylsulfonyl)imide (NTf2) as anion and various cations or they contain an imidazolium ion in combination with various anions. The cations include imidazolium, pyrrolidinium, piperidinium, polymethine or ammonium ions. Furthermore, BF4-, PF6-, triflate, camphorsulfonate, lactate, tosylate or tris(pentafluoroethyl) trifluorophosphate (FAP) are the counter ions in the imidazolium salts. The structural variation of the ionic liquids results in differences in glass formation, semiaystallinity, or crystallinity, as well as in viscosity differences. Furthermore, a vinyl substituent at the imidazolium ion and a methacryloyloxyethyl substituent at the ammonium ion result in polymerizable ionic liquids that were converted via a radical mechanism in amorphous polymerized ionic liquids with a glass transition temperature, which is significantly higher compared to the ionic liquids. An additional substituent at TEMPO causes additional hydrogen bond formation or additional Coulomb interactions with the individual ions of the ionic liquids compared to TEMPO. This influences the mobility of these radicals in the ionic liquid expressed by differences in the average rotational correlation time (T-rot). The mobility of the radicals in the ionic liquids as function of the temperature describes ionic liquids either as continuum in analogy to molecular solvents using the Stokes-Einstein model, that is the case for 1-butyl-3-methylimidazolium NTf2, or as medium where free volume effects are important for the mobility of a solute in the ionic liquid using the model of Spernol, Gierer, and Wirtz. The 1-butyl-3-methylimidazolium BF4- fits well into the latter. Furthermore, the isotropic hyperfine coupling constant (A(iso)(N-14)) of the stable radicals gives information about micropolarity of the ionic liquids only if the mobility of the radical is high enough in the ionic liquid. In addition to the rotational mobility of the stable radicals, the photogenerated lophyl radicals give information about translational diffusion of radicals and solvent cage effects in the ionic liquids. The application of the Eyring equation results mostly in the expected negative values of the activation entropy for the transition state that is typical for bimolecular reactions. Only few examples show a less negative or positive activation entropy for the bimolecular reaction, which may be attributed to radical recombination within the solvent cage to a high extent. The results obtained during investigation of radicals in ionic liquids are important to understand the radical processes in ionic liquids that may occur for example in dye sensitized solar cells, photo or thermally induced reactions or radical polymerizations in ionic liquids. KW - Ionic liquids KW - Radicals KW - Spin probes KW - Polymerized ionic liquids KW - Microviscosity KW - Micropolarity Y1 - 2014 U6 - https://doi.org/10.1016/j.molliq.2013.12.007 SN - 0167-7322 SN - 1873-3166 VL - 192 SP - 153 EP - 170 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Eisold, Ursula A1 - Kupstat, Annette A1 - Klier, Dennis Tobias A1 - Primus, Philipp-A. A1 - Pschenitza, Michael A1 - Niessner, Reinhard A1 - Knopp, Dietmar A1 - Kumke, Michael Uwe T1 - Probing the physicochemical interactions of 3-hydroxy-benzo[a]pyrene with different monoclonal and recombinant antibodies by use of fluorescence line-narrowing spectroscopy JF - Analytical & bioanalytical chemistry N2 - Characterization of interactions between antigens and antibodies is of utmost importance both for fundamental understanding of the binding and for development of advanced clinical diagnostics. Here, fluorescence line-narrowing (FLN) spectroscopy was used to study physicochemical interactions between 3-hydroxybenzo[a]pyrene (3OH-BaP, as antigen) and a variety of solvent matrices (as model systems) or anti-polycyclic aromatic hydrocarbon antibodies (anti-PAH). We focused the studies on the specific physicochemical interactions between 3OH-BaP and different, previously obtained, monoclonal and recombinant anti-PAH antibodies. Control experiments performed with non-binding monoclonal antibodies and bovine serum albumin (BSA) indicated that nonspecific interactions did not affect the FLN spectrum of 3OH-BaP. The spectral positions and relative intensities of the bands in the FLN spectra are highly dependent on the molecular environment of the 3OH-BaP. The FLN bands correlate with different vibrational modes of 3OH-BaP which are affected by interactions with the molecular environment (pi-pi interactions, H-bonding, or van-der-Waals forces). Although the analyte (3OH-BaP) was the same for all the antibodies investigated, different binding interactions could be identified from the FLN spectra on the basis of structural flexibility and conformational multiplicity of the antibodies' paratopes. KW - FLNS KW - Antibody KW - Paratope KW - Hapten KW - Polycyclic aromatic hydrocarbons Y1 - 2014 U6 - https://doi.org/10.1007/s00216-013-7584-8 SN - 1618-2642 SN - 1618-2650 VL - 406 IS - 14 SP - 3387 EP - 3394 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Weiss, Jan A1 - Wienk, Hans A1 - Boelens, Rolf A1 - Laschewsky, André T1 - Block copolymer micelles with an intermediate star-/flower-like structure studied by H-1 NMR relaxometry JF - Macromolecular chemistry and physics N2 - H-1 NMR relaxation is used to study the self-assembly of a double thermoresponsive diblock copolymer in dilute aqueous solution. Above the first transition temperature, at which aggregation into micellar structures is observed, the trimethylsilyl (TMS)-labeled end group attached to the shell-forming block shows a biphasic T-2 relaxation. The slow contribution reflects the TMS groups located at the periphery of the hydrophilic shell, in agreement with a star-like micelle. The fast T-2 contribution corresponds to the TMS groups, which fold back toward the hydrophobic core, reflecting a flower-like micelle. These results confirm the formation of block copolymer micelles of an intermediate nature (i.e., of partial flower-like and star-like character), in which a part of the TMS end groups folds back to the core due to hydrophobic interactions. KW - block copolymers KW - polymer micelles KW - relaxation NMR spectroscopy KW - self-assembly KW - thermoresponsive materials Y1 - 2014 U6 - https://doi.org/10.1002/macp.201300753 SN - 1022-1352 SN - 1521-3935 VL - 215 IS - 9 SP - 915 EP - 919 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Meyners, Christian A1 - Wawrzinek, Robert A1 - Kraemer, Andreas A1 - Hinz, Steffen A1 - Wessig, Pablo A1 - Meyer-Almes, Franz-Josef T1 - A fluorescence lifetime-based binding assay for acetylpolyamine amidohydrolases from Pseudomonas aeruginosa using a [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD) ligand probe JF - Analytical & bioanalytical chemistry N2 - High-throughput assays for drug screening applications have to fulfill particular specifications. Besides the capability to identify even compounds with low potency, one of the major issues is to minimize the number of false-positive hits in a screening campaign in order to reduce the logistic effort for the subsequent cherry picking and confirmation procedure. In this respect, fluorescence lifetime (FLT) appears as an ideal readout parameter that is supposed to be robust against autofluorescent and light-absorbing compounds, the most common source of systematic false positives. The extraordinary fluorescence features of the recently discovered [1,3]dioxolo[4,5-f][1,3]benzodioxole dyes were exploited to develop an FLT-based binding assay with exceptionally robust readout. The assay setup was comprehensively validated and shown to comply not only with all requirements for a powerful high-throughput screening assay but also to be suitable to determine accurate binding constants for inhibitors against enzymes of the histone deacetylase family. Using the described binding assay, the first inhibitors against three members of this enzyme family from Pseudomonas aeruginosa were identified. The compounds were characterized in terms of potency and selectivity profile. The novel ligand probe should also be applicable to other homologues of the histone deacetylase family that are inhibited by N-hydroxy-N'-phenyloctandiamide. KW - Histone deacetylases KW - Acetylpolyamine amidohydrolases KW - Fluorescence life time KW - Binding assay KW - Pseudomonas aeruginosa Y1 - 2014 U6 - https://doi.org/10.1007/s00216-014-7886-5 SN - 1618-2642 SN - 1618-2650 VL - 406 IS - 20 SP - 4889 EP - 4897 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Utecht, Manuel Martin A1 - Pan, Tianluo A1 - Klamroth, Tillmann A1 - Palmer, Richard E. T1 - Quantum chemical cluster models for chemi- and physisorption of chlorobenzene on Si(111)-7x7 JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Motivated by recent atomic manipulation experiments, we report quantum chemical calculations for chemi- and physisorption minima of chlorobenzene on the Si(111)-7x7 surface. A density functional theory cluster approach is applied, using the B3LYP hybrid functional alongside Grimme's empirical dispersion corrections (D3). We were able to identify chemisorption sites of binding energies of 1.6 eV and physisorption energies of 0.6 eV, both in encouraging agreement with the trend of experimental data. The cluster approach opens up the possibility of a first-principles based dynamical description of STM manipulation experiments on this system, the interpretation of which involves both the chemi- and physisorbed states. However, we found that special care has to be taken regarding the choice of clusters, basis sets, and the evaluation of the dispersion corrections. Y1 - 2014 U6 - https://doi.org/10.1021/jp504208d SN - 1089-5639 VL - 118 IS - 33 SP - 6699 EP - 6704 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Jahn, Karolina A1 - Hille, Carsten T1 - Asante calcium green and asante calcium red-novel calcium indicators for two-photon fluorescence lifetime imaging JF - PLoS one N2 - For a comprehensive understanding of cellular processes and potential dysfunctions therein, an analysis of the ubiquitous intracellular second messenger calcium is of particular interest. This study examined the suitability of the novel Ca2+-sensitive fluorescent dyes Asante Calcium Red (ACR) and Asante Calcium Green (ACG) for two-photon (2P)-excited time-resolved fluorescence measurements. Both dyes displayed sufficient 2P fluorescence excitation in a range of 720-900 nm. In vitro, ACR and ACG exhibited a biexponential fluorescence decay behavior and the two decay time components in the ns-range could be attributed to the Ca2+-free and Ca2+-bound dye species. The amplitude-weighted average fluorescence decay time changed in a Ca2+-dependent way, unraveling in vitro dissociation constants K-D of 114 nM and 15 nM for ACR and ACG, respectively. In the presence of bovine serum albumin, the absorption and steady-state fluorescence behavior of ACR was altered and its biexponential fluorescence decay showed about 5-times longer decay time components indicating dye-protein interactions. Since no ester derivative of ACG was commercially available, only ACR was evaluated for 2P-excited fluorescence lifetime imaging microscopy (2P-FLIM) in living cells of American cockroach salivary glands. In living cells, ACR also exhibited a biexponential fluorescence decay with clearly resolvable short (0.56 ns) and long (2.44 ns) decay time components attributable to the Ca2+-free and Ca2+-bound ACR species. From the amplitude-weighted average fluorescence decay times, an in situ K-D of 180 nM was determined. Thus, quantitative [Ca2+](i) recordings were realized, unraveling a reversible dopamine-induced [Ca2+](i) elevation from 21 nM to 590 nM in salivary duct cells. It was concluded that ACR is a promising new Ca2+ indicator dye for 2P-FLIM recordings applicable in diverse biological systems. Y1 - 2014 U6 - https://doi.org/10.1371/journal.pone.0105334 SN - 1932-6203 VL - 9 IS - 8 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Schott, Juliane A1 - Kretzschmar, Jerome A1 - Acker, Margret A1 - Eidner, Sascha A1 - Kumke, Michael Uwe A1 - Drobot, Bjoern A1 - Barkleit, Astrid A1 - Taut, Steffen A1 - Brendler, Vinzenz A1 - Stumpf, Thorsten T1 - Formation of a Eu(III) borate solid species from a weak Eu(III) borate complex in aqueous solution JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - In the presence of polyborates (detected by B-11-NMR) the formation of a weak Eu(III) borate complex (lg beta(11) similar to 2, estimated) was observed by time-resolved laser-induced fluorescence spectroscopy (TRLFS). This complex is a precursor for the formation of a solid Eu(III) borate species. The formation of this solid in solution was investigated by TRLFS as a function of the total boron concentration: the lower the total boron concentration, the slower is the solid formation. The solid Eu(III) borate was characterized by IR spectroscopy, powder XRD and solid-state TRLFS. The determination of the europium to boron ratio portends the existence of pentaborate units in the amorphous solid. Y1 - 2014 U6 - https://doi.org/10.1039/c4dt00843j SN - 1477-9226 SN - 1477-9234 VL - 43 IS - 30 SP - 11516 EP - 11528 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Riebe, Daniel A1 - Beitz, Toralf A1 - Dosche, Carsten A1 - Löhmannsröben, Hans-Gerd A1 - Raab, Volker A1 - Raab, Corinna A1 - Unverzagt, Matthias T1 - High-resolution spectrometer using combined dispersive and interferometric wavelength separation for raman and laser-induced Breakdown Spectroscopy (LIBS) JF - Applied spectroscopy : an international journal of spectroscopy ; official publication of the Society for Applied Spectroscopy N2 - In this paper the concept of a compact high-resolution spectrometer based on the combination of dispersive and interferometric elements is presented. Dispersive elements are used to spectrally resolve the light in one direction with coarse resolution (Delta lambda < 0.5 nm), while perpendicular to that direction an etalon provides high spectral resolution (Delta lambda < 50 pm). This concept for two-dimensional spectroscopy has been implemented for the wavelength range lambda = 350-650 nm. Appropriate algorithms for reconstructing spectra from the two-dimensional raw data and for wavelength calibration were established in an analysis software. Potential applications for this new spectrometer are Raman and laser-induced breakdown spectroscopy (LIBS). Resolutions down to 28 pm (routinely 54 pm) could be realized for these applications. KW - Raman spectroscopy KW - Laser-induced breakdown spectroscopy KW - LIBS KW - Fabry-Perot etalon KW - High-resolution spectrometer Y1 - 2014 U6 - https://doi.org/10.1366/13-07426 SN - 0003-7028 SN - 1943-3530 VL - 68 IS - 9 SP - 1030 EP - 1038 PB - Society for Applied Spectroscopy CY - Frederick ER - TY - JOUR A1 - Kopec, Maciej A1 - Lapok, Lukasz A1 - Laschewsky, André A1 - Zapotoczny, Szczepan A1 - Nowakowska, Maria T1 - Polyelectrolyte multilayers with perfluorinated phthalocyanine selectively entrapped inside the perfluorinated nanocompartments JF - Soft matter N2 - A novel perfluorinated magnesium phthalocyanine (MgPcF64) was synthesized and employed to probe nanodomains in hydrophobically modified, amphiphilic cationic polyelectrolytes bearing alkyl and/or fluoroalkyl side chains. MgPcF64 was found to be solubilized exclusively in the aqueous solutions of the fluorocarbon modified polycations, occupying the perfluorinated nanocompartments provided, while analogous polyelectrolytes with alkyl side chains forming hydrocarbon nanocompartments could not host the MgPcF64 dye. Multilayer films were fabricated by means of the layer-by-layer (LbL) deposition method using sodium poly(styrene sulfonate) as a polyanion. Linear multilayer growth was confirmed by UV-Vis spectroscopy and spectroscopic ellipsometry. Atomic force microscopy studies indicated that the micellar conformation of the polycations is preserved in the multilayer films. Fluorescence spectroscopy measurements confirmed that MgPcF64 stays embedded inside the fluorocarbon domains after the deposition process. This facile way of selectively incorporating water-insoluble, photoactive molecules into the structure of polyelectrolyte multilayers may be utilized for nanoengineering of ultrathin film-based optoelectronic devices. Y1 - 2014 U6 - https://doi.org/10.1039/c2sm26938d SN - 1744-683X SN - 1744-6848 VL - 10 IS - 10 SP - 1481 EP - 1488 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schönborn, Jan Boyke A1 - Hartke, Bernd T1 - Photochemical dynamics of E-methylfurylfulgide-kinematic effects on photorelaxation dynamics of furylfulgides JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - With the present theoretical study of the photochemical switching of E-methylfurylfulgide we contribute an important step towards the understanding of the photochemical processes in furylfulgide-related molecules. We have carried out large-scale, full-dimensional direct semiempirical configuration-interaction surface-hopping dynamics of the photoinduced ring-closure reaction. Simulated static and dynamical UV/Vis-spectra show good agreement with experimental data of the same molecule. By a careful investigation of our dynamical data, we were able to identify marked differences to the dynamics of the previously studied E-isopropylfurylfulgide. With our simulations we can not only reproduce the experimentally observed quantum yield differences qualitatively but we can also pinpoint two reasons for them: kinematics and pre-orientation. With our analysis, we thus offer straightforward molecular explanations for the high sensitivity of the photodynamics towards seemingly minor changes in molecular constitution. Beyond the realm of furylfulgides, these insights provide additional guidance to the rational design of photochemically switchable molecules. Y1 - 2014 U6 - https://doi.org/10.1039/c3cp53495b SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 6 SP - 2483 EP - 2490 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Meyer, Sören A1 - Schulz, Jacqueline A1 - Jeibmann, Astrid A1 - Taleshi, Mojtaba S. A1 - Ebert, Franziska A1 - Francesconi, Kevin A1 - Schwerdtle, Tanja ED - Schwerdtle, Tanja T1 - Arsenic-containing hydrocarbons are toxic in the in vivo model Drosophila melanogaster JF - Metallomics N2 - Arsenic-containing hydrocarbons (AsHC) constitute one group of arsenolipids that have been identified in seafood. In this first in vivo toxicity study for AsHCs, we show that AsHCs exert toxic effects in Drosophila melanogaster in a concentration range similar to that of arsenite. In contrast to arsenite, however, AsHCs cause developmental toxicity in the late developmental stages of Drosophila melanogaster. This work illustrates the need for a full characterisation of the toxicity of AsHCs in experimental animals to finally assess the risk to human health related to the presence of arsenolipids in seafood. KW - arsenolipids present KW - cod-liver KW - fatty-acids KW - identification KW - rp-hplc KW - fish KW - oil Y1 - 2014 SN - 1756-5901 SP - 2010 EP - 2014 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Roder, Phillip A1 - Hille, Carsten ED - Hille, Carsten T1 - ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy JF - Photochemical & Photobiological Sciences N2 - Sodium ions (Na+) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na+ concentrations ([Na+]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na+-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na+-sensitivity appropriate for recordings in living cells. The Na+-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na+]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na+]i rise in cockroach salivary gland cells, which was dependent on a Na+-K+-2Cl− cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems. KW - cockroach salivary-glands KW - intracellular na+ KW - sodium green KW - periplaneta-americana KW - ventricular myocytes KW - lifetime microscopy KW - cytosolic sodium KW - acinar-cells KW - hela-cells KW - rat Y1 - 2014 SN - 1474-905X VL - 12 IS - 13 SP - 1699 EP - 1710 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Neffe, Axel T. A1 - von Rüsten-Lange, Maik A1 - Braune, Steffen A1 - Lützow, Karola A1 - Roch, Toralf A1 - Richau, Klaus A1 - Krüger, Anne A1 - Becherer, Tobias A1 - Thünemann, Andreas F. A1 - Jung, Friedrich A1 - Haag, Rainer A1 - Lendlein, Andreas T1 - Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility JF - Journal of materials chemistry : B, Materials for biology and medicine N2 - Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo-and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials. Y1 - 2014 U6 - https://doi.org/10.1039/c4tb00184b SN - 2050-750X SN - 2050-7518 VL - 2 IS - 23 SP - 3626 EP - 3635 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Mueller, Holger A1 - Junginger, Matthias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strehmel, Veronika A1 - Holdt, Hans-Jürgen T1 - Imidazolium 2-substituted 4,5-dicyanoimidazolate ionic liquids: synthesis, crystal structures and structure-thermal property relationships JF - Chemistry - a European journal N2 - Thirty six novel ionic liquids (ILs) with 1-butyl-3-methylimidazolium and 3-methyl-1-octylimidazolium cations paired with 2-substitited 4,5-dicyanoimidazolate anions (substituent at C2=chloro, bromo, methoxy, vinyl, amino, methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and phenyl) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the thermal properties of the resulting ionic liquids, including several room temperature ionic liquids (RTILs) are examined and discussed. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of -22 to -68 degrees C. The effects of alkyl substituents of the imidazolate anion reflected the crystallization, melting points and thermal decomposition of the ILs. The Coulombic packing force, van der Waals forces and size of the anions can be considered for altering the thermal transitions. Three crystal structures of the ILs were determined and the effects of changes to the cations and anions on the packing of the structure were investigated. KW - crystal structures KW - imidazole KW - ion exchange KW - ionic liquids KW - pi-pi stacking Y1 - 2014 U6 - https://doi.org/10.1002/chem.201304934 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 26 SP - 8170 EP - 8181 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Giant Zn-14 molecular building block in hydrogen-bonded network with permanent porosity for gas uptake JF - Journal of the American Chemical Society N2 - In situ imidazolate-4,5-diamide-2-olate linker generation leads to the formation of a [Zn-14(L2)(12)(O)-(OH)(2)(H2O)(4)] molecular building block (MBB) with a Zn-6 octahedron inscribed in a Zn-8 cube. The MBBs connect by amide-amide hydrogen bonds to a 3D robust supramolecular network which can be activated for N-2, CO2, CH4, and H-2 gas sorption. Y1 - 2014 U6 - https://doi.org/10.1021/ja410595q SN - 0002-7863 VL - 136 IS - 1 SP - 44 EP - 47 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - A supramolecular Co(II)(14)- metal-organic cube in a hydrogen-bonded network and a Co(II)-organic framework with a flexible methoxy substituent JF - Chemical communications N2 - The reaction of 4,5-dicyano-2-methoxyimidazole (L1) with Co(NO3)(2.) 6H(2)O under solvothermal conditions in DMF, a MOF, IFP-8 and a hydrogen-bonded network consisting of tetradecanuclear Co(II)(14)-metal organic cube (1) are achieved. 1 shows the bcu net with 14 cobalt atoms. Y1 - 2014 U6 - https://doi.org/10.1039/c3cc49698h SN - 1359-7345 SN - 1364-548X VL - 50 IS - 41 SP - 5441 EP - 5443 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Demeshko, Serhiy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Synthesis of a Co(II)-imidazolate framework from an anionic linker precursor: gas-sorption and magnetic properties JF - CrystEngComm N2 - A Co(II)-imidazolate-4-amide-5-imidate based MOF, IFP-5, is synthesized by using an imidazolate anion-based novel ionic liquid as a linker precursor under solvothermal conditions. IFP-5 shows significant amounts of gas (N-2, CO2, CH4 and H-2) uptake capacities. IFP-5 exhibits an independent high spin Co(II) centre and antiferromagnetic coupling. Y1 - 2014 U6 - https://doi.org/10.1039/c3ce42040j SN - 1466-8033 VL - 16 IS - 1 SP - 39 EP - 42 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Xie, Zai-Lai A1 - Huang, Xing A1 - Titirici, Maria-Magdalena A1 - Taubert, Andreas T1 - Mesoporous graphite nanoflakes via ionothermal carbonization of fructose and their use in dye removal JF - RSC Advances N2 - The large-scale green synthesis of graphene-type two-dimensional materials is still challenging. Herein, we describe the ionothermal synthesis of carbon-based composites from fructose in the iron-containing ionic liquid 1-butyl-3-methylimidazolium tetrachloridoferrate(III), [Bmim][FeCl4] serving as solvent, catalyst, and template for product formation. The resulting composites consist of oligo-layer graphite nanoflakes and iron carbide particles. The mesoporosity, strong magnetic moment, and high specific surface area of the composites make them attractive for water purification with facile magnetic separation. Moreover, Fe3Cfree graphite can be obtained via acid etching, providing access to fairly large amounts of graphite material. The current approach is versatile and scalable, and thus opens the door to ionothermal synthesis towards the larger-scale synthesis of materials that are, although not made via a sustainable process, useful for water treatment such as the removal of organic molecules. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra05146g SN - 2046-2069 VL - 4 IS - 70 SP - 37423 EP - 37430 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Xie, Zai-Lai A1 - Huang, Xing A1 - Taubert, Andreas T1 - DyeIonogels: proton-responsive ionogels based on a dye-ionic liquid exhibiting reversible color change JF - Advanced functional materials N2 - Transparent, ion-conducting, and flexible ionogels based on the room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide [Bmim][N(Tf)(2)], the dye-IL (DIL) 1-butyl-3-methylimidazolium methyl orange [Bmim][MO], and poly(methylmethacrylate) (PMMA) are prepared. Upon IL incorporation the thermal stability of the PMMA matrix significantly increases from 220 to 280 degrees C. The ionogels have a relatively high ionic conductivity of 10(-4) S cm(-1) at 373 K. Most importantly, the ionogels exhibit a strong and reversible color change when exposed to aqueous or organic solutions containing protons or hydroxide ions. The resulting material is thus a prototype of soft multifunctional matter featuring ionic conductivity, easy processability, response to changes in the environment, and a strong readout signal, the color change, that could be used in optical data storage or environmental sensing. Y1 - 2014 U6 - https://doi.org/10.1002/adfm.201303016 SN - 1616-301X SN - 1616-3028 VL - 24 IS - 19 SP - 2837 EP - 2843 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tentschert, Jutta A1 - Jungnickel, Harald A1 - Reichardt, Philipp A1 - Leube, Peter A1 - Kretzschmar, Bernd A1 - Taubert, Andreas A1 - Luch, A. T1 - Identification of nano clay in composite polymers JF - Surface and interface analysis : an international journal devoted to the development and application of techniques for the analysis surfaces, interfaces and thin films N2 - Industrialized food production is in urgent search for alternative packaging materials, which can serve the requirements of a globalized world in terms of longer product shelf lives, reduced freight weight to decrease transport costs, and better barrier functionality to preserve its freshness. Polymer materials containing organically modified nano clay particles as additives are one example for a new generation of packaging materials with specific barrier functionality to actually hit the market. Clay types used for these applications are aluminosilicates, which belong to the mineral group of phyllosilicates. These consist of nano-scaled thin platelets, which are organically modified with quaternary ammonium compounds acting as spacers between the different clay layers, thereby increasing the hydrophobicity of the mineral additive. A variety of different organically modified clays are already available, and the use as additive for food packaging materials is one important application. To ensure valid risk assessments of emerging nano composite polymers used in the food packaging industry, exact analytical characterization of the organically modified clay within the polymer matrix is of paramount importance. Time-of-flight SIMS in combination with multivariate statistical analysis was used to differentiate modified clay reference materials from another. Time-of-flight SIMS spectra of a reference polymer plate, which contained one specific nano clay composite, were acquired. For each modified clay additive, a set of characteristic diagnostic ions could be identified, which then was used to successfully assign unknown clay additives to the corresponding reference material. Thus, the described methodology could be used to define and characterize nano clay within polymer matrices. Copyright (c) 2014 John Wiley & Sons, Ltd. KW - ToF-SIMS KW - nanoparticles KW - nano clay KW - polymer KW - food contact material Y1 - 2014 U6 - https://doi.org/10.1002/sia.5546 SN - 0142-2421 SN - 1096-9918 VL - 46 SP - 334 EP - 336 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Friedrich, Alwin A1 - Rothe, Regina A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls JF - Chemistry - a European journal N2 - The surface modification of mesoporous silica monoliths through thiol-ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol-gel hydrolysis-poly-condensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3-mercaptopropyl) trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore-wall chemistries. Nitrogen sorption, small-angle X-ray scattering, solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization. This report demonstrates that thiol-ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces. KW - mesoporous materials KW - photochemistry KW - sol-gel processes KW - surface chemistry Y1 - 2014 U6 - https://doi.org/10.1002/chem.201403982 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 52 SP - 17579 EP - 17589 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Winter, Alette A1 - Thiel, Kerstin A1 - Zabel, Andre A1 - Klamroth, Tillmann A1 - Poeppl, Andreas A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas A1 - Strauch, Peter T1 - Tetrahalidocuprates(II) - structure and EPR spectroscopy. Part 2: tetrachloridocuprates(II) JF - New journal of chemistry N2 - We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4](2-) moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium) tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4](2-) anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g(parallel to) and g(perpendicular to), could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations. Y1 - 2014 U6 - https://doi.org/10.1039/c3nj01039b SN - 1144-0546 SN - 1369-9261 VL - 38 IS - 3 SP - 1019 EP - 1030 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Di Florio, Giuseppe A1 - Bruendermann, Erik A1 - Yadavalli, Nataraja Sekhar A1 - Santer, Svetlana A1 - Havenith, Martina T1 - Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings: chromophore orientation in azo-doped polymer films JF - Soft matter N2 - We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy. Y1 - 2014 U6 - https://doi.org/10.1039/c3sm51787j SN - 1744-683X SN - 1744-6848 VL - 10 IS - 10 SP - 1544 EP - 1554 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Banerjee, Shiladitya A1 - Saalfrank, Peter T1 - Vibrationally resolved absorption, emission and resonance Raman spectra of diamondoids: a study based on time-dependent correlation functions JF - Physical chemistry, chemical physics : a journal of European Chemical Societies Y1 - 2014 U6 - https://doi.org/10.1039/c3cp53535e SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 1 SP - 144 EP - 158 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Ehlert, Christopher A1 - Unger, Wolfgang E. S. A1 - Saalfrank, Peter T1 - C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Recently, C K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of graphite (HOPG) surfaces have been measured for the pristine material, and for HOPG treated with either bromine or krypton plasmas (Lippitz et al., Surf. Sci., 2013, 611, L1). Changes of the NEXAFS spectra characteristic for physical (krypton) and/or chemical/physical modifications of the surface (bromine) upon plasma treatment were observed. Their molecular origin, however, remained elusive. In this work we study by density functional theory, the effects of selected point and line defects as well as chemical modifications on NEXAFS carbon K-edge spectra of single graphene layers. For Br-treated surfaces, also Br 3d X-ray Photoelectron Spectra (XPS) are simulated by a cluster approach, to identify possible chemical modifications. We observe that some of the defects related to plasma treatment lead to characteristic changes of NEXAFS spectra, similar to those in experiment. Theory provides possible microscopic origins for these changes. Y1 - 2014 U6 - https://doi.org/10.1039/c4cp01106f SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 27 SP - 14083 EP - 14095 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Wirth, Jonas A1 - Neumann, Rainer A1 - Antonietti, Markus A1 - Saalfrank, Peter T1 - Adsorption and photocatalytic splitting of water on graphitic carbon nitride: a combined first principles and semiempirical study JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Graphitic carbon nitride, g-C3N4, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C3N4 by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H+ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H-2 production O-2 evolution is only possible in the presence of oxidation cocatalysts. Y1 - 2014 U6 - https://doi.org/10.1039/c4cp02021a SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 30 SP - 15917 EP - 15926 PB - Royal Society of Chemistry CY - Cambridge ER -