TY - JOUR A1 - Yin, Jian A1 - Linker, Torsten T1 - Stereodivergent syntheses at the glucose backbone N2 - Both diastereomers of 2-C-branched carbohydrates with various functional groups are selectively available from the same malonate precursor in good yields in only a few steps. Y1 - 2009 UR - http://www.rsc.org/Publishing/Journals/OB/index.asp U6 - https://doi.org/10.1039/B918893m SN - 1477-0520 ER - TY - JOUR A1 - Yin, Jian A1 - Linker, Torsten T1 - Convenient synthesis of bicyclic carbohydrate 1,2-lactones and their stereoselective opening to 1- functionalized glucose derivatives N2 - Closed and re-opened for business: C-2 branched carbohydrates 1 cyclize under conditions of decarboxylation to the hitherto unknown carbohydrate 1,2-lactones 2 in high yields. The gluco isomer can be opened at the anomeric position with various nuceophiles in the presence of Sc(OTf)3, which allows the stereoselective synthesis of 1-functionalized glucose derivatives 3. Thus, 1,2-bis-C-branched saccharides become available in only a few steps starting from glycals. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200802178 SN - 0947-6539 ER - TY - JOUR A1 - Wischerhoff, Erik A1 - Glatzel, Stefan A1 - Uhlig, Katja A1 - Lankenau, Andreas A1 - Lutz, Jean-Francois A1 - Laschewsky, André T1 - Tuning the thickness of polymer brushes grafted from nonlinearly growing multilayer assemblies N2 - A new versatile method for tuning the thickness of surface-tethered polymer brushes is introduced. It is based on the combination of polyelectrolyte multilayer deposition and surface-initiated atom transfer radical polymerization. To control the thickness of the brushes, the nonlinear growth of certain polyelectrolyte multilayer systems is exploited. The method is demonstrated to work with different polyelectrolytes and different monomers. The relevance for applications is demonstrated by cell adhesion experiments oil grafted thermoresponsive polymer layers with varying thickness. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La804197j SN - 0743-7463 ER - TY - JOUR A1 - von Berlepsch, Hans A1 - Boettcher, Christoph A1 - Skrabania, Katja A1 - Laschewsky, André T1 - Complex domain architecture of multicompartment micelles from a linear ABC triblock copolymer revealed by cryogenic electron tomography N2 - Cryo-electron tomography of raspberry-like multicompartment micelles formed by a linear ABC triblock copolymer in water revealed that the fluorocarbon domains may be dispersed all over the hydrocarbon core. Y1 - 2009 UR - http://xlink.rsc.org/jumptojournal.cfm?journal_code=CC U6 - https://doi.org/10.1039/B903658j SN - 1359-7345 ER - TY - JOUR A1 - Vazhappilly, Tijo A1 - Klamroth, Tillmann A1 - Saalfrank, Peter A1 - Hernandez, Rigoberto T1 - Femtosecond-laser desorption of H-2 (D-2) from Ru(0001) : quantum and classical approaches N2 - The femtosecond-laser-induced, substrate-mediated associative desorption of molecular hydrogen and deuterium from a Ru(0001) surface in the so-called DIMET limit is studied theoretically. Two widely used models, a "quantum nonadiabatic" approach and a "classical adiabatic" one are employed and compared to each other. The quantum model is realized by the Monte Carlo wave packet (MCWP) method in the framework of open-system density matrix theory: The classical approach is realized with the help of (frictional) Langevin dynamics with stochastic forces. For both models the same ground-state potential energy surface is used and the same two-temperature model adopted to describe the hot- electron-driven desorption dynamics. Apart from these common features both models are different. Still, both account well for the main experimental findings (Wagner et al. Phys. Rev. B 2005, 72, 205404). In particular, an isotope effect in desorption probabilities, the energy content of the desorbing molecules, and the scaling of these observables with laser fluence are reproduced and explained. The similarity of the results obtained with both models is traced back to the fact that, in the present case, the photodynamics takes place dominantly in the ground electronic state because the electronically excited state is rapidly quenched. The short lifetime of the excited state has also the effect that photoreaction cross sections are typically very small. An IR+vis hybrid scheme, by which the adsorbate is vibrationally excited by IR photons prior to the heating of metal electrons with the vis pulse, is shown to successfully promote the reaction even for strongly coupled adsorbate-surface systems. Y1 - 2009 UR - http://pubs.acs.org/journal/jpccck U6 - https://doi.org/10.1021/Jp810709k SN - 1932-7447 ER - TY - JOUR A1 - Tremblay, Jean Christophe A1 - Saalfrank, Peter T1 - Selective subsurface absorption of hydrogen in palladium using laser distillation N2 - A theoretical model for the selective subsurface absorption of atomic hydrogen in a Pd(111) surface by infrared (IR) laser pulses is presented. The dynamics of the adsorbate is studied within the reduced density matrix approach. Energy and phase relaxation of the hydrogen atom are treated using the semigroup formalism. The vibrational excitation leading to subsurface absorption is performed using rationally designed pulses as well as IR laser pulses optimized on- the-fly. It is shown that dissipation can be used as a tool to transfer population to an otherwise inaccessible state via a mechanism known as "laser distillation." We demonstrate that when the reaction path is generalized from a reduced one-dimensional to full three-dimensional treatment of the system, the laser control strategy can prove very different. Y1 - 2009 UR - http://jcp.aip.org/ U6 - https://doi.org/10.1063/1.3212695 SN - 0021-9606 ER - TY - JOUR A1 - Strehmel, Veronika A1 - Wishart, James F. A1 - Polyansky, Dmitry E. A1 - Strehmel, Bernd T1 - Recombination of photogenerated lophyl radicals in imidazolium-based ionic liquids N2 - Laser flash photolysis is applied to study the recombination reaction of lophyl radicals in ionic liquids in comparison with dimethylsulfoxide as an example of a traditional organic solvent. The latter exhibits a similar micropolarity as the ionic liquids. The ionic liquids investigated are 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1), 1-hexyl-3-methylimidazolium hexafluorophosphate (2), and 1-butyl-3- methylimidazolium tetafluoroborate (3). The recombination of the photolytic generated lophyl radicals occur significantly faster in the ionic liquids than expected from their macroscopic viscosities and is a specific effect of these ionic liquids. On the other hand, this reaction can be compared with the macroscopic viscosity in the case of dimethylsulfoxide. Activation parameters obtained for lophyl radical recombination suggest different, anion-dependent mechanistic effects. Quantum chemical calculations based on density functional theory provide a deeper insight of the molecular properties of the lophyl radical and its precursor. Thus, excitation energies, spin densities, molar volumes, and partial charges are calculated. Calculations show a spread of spin density over the three carbon atoms of the imidazolyl moiety, while only low spin density is calculated for the nitrogens. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/72514732/ U6 - https://doi.org/10.1002/cphc.200900594 SN - 1439-4235 ER - TY - JOUR A1 - Skrabania, Katja A1 - Laschewsky, André A1 - von Berlepsch, Hans A1 - Boettcher, Christoph T1 - Synthesis and micellar self-assembly of ternary hydrophilic-lipophilic-fluorophilic block copolymers with a linear PEO chain N2 - Linear amphiphilic diblock and ternary triblock copolymers were synthesized by the RAFT method in two successive steps using a poly(ethylene oxide) (PEO) macrochain transfer agent, butyl or 2-ethylhexyl acrylate, and 1H, 1H, 2H, 2H-perfluorodecyl acrylate. The diblock and the triblock copolymers, which consist of a hydrophilic, a lipophilic, and a short fluorophilic block, self-assemble in water into spherical micellar aggregates. Imaging by cryogenic transmission electron microscopy (cryo-TEM) revealed that the micellar cores of the aggregates made from these "triphilic" copolymers can undergo local phase separation to form a unique ultrastructure. In these multicompartment micelles, it appears that extended nonspherical domains, presumably made of nanocrystallites of the fluorocarbon block, are embedded in the hydrocarbon matrix forming the spherical micellar core. This novel internal structure of a micellar core is attributed to the mutual incompatibility of the fluorocarbon and hydrocarbon side chains in combination with the tendency of the used fluorocarbon acrylate monomer to undergo side-chain crystallization. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La900253j SN - 0743-7463 ER - TY - JOUR A1 - Shkilnyy, Andriy A1 - Gräf, Ralph A1 - Hiebl, Bernhard A1 - Neffe, Axel T. A1 - Friedrich, Alwin A1 - Hartmann, Juergen A1 - Taubert, Andreas T1 - Unprecedented, low cytotoxicity of spongelike calcium phosphate/poly(ethylene imine) hydrogel composites N2 - Covalently crosslinked PEI hydrogels are efficient templates for calcium phosphate mineralization in SBF. In contrast to the PEI hydrogels, non-crosslinked PEI does not lead to calcium phosphate nucleation and growth in SBF. The precipitate is a mixture of brushite and hydroxyapatite. The PEI/calcium phosphate composite material exhibits a sponge like morphology and a chemical composition that is interesting for implants. Cytotoxicity tests using Dictyostelium discoideum amoebae show that both the non-mineralized and mineralized hydrogels have a very low cytotoxicity. This suggests that next generation PEI hydrogels, where also the degradation products are non-toxic, could be interesting for biomedical applications. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/77002860 U6 - https://doi.org/10.1002/mabi.200800266 SN - 1616-5187 ER - TY - JOUR A1 - Shkilnyy, Andriy A1 - Brandt, Jessica A1 - Mantion, Alexandre A1 - Paris, Oskar A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Calcium phosphate with a channel-like morphology by polymer templating N2 - Calcium phosphate mineralization from aqueous solution in the presence of organic growth modifiers has been intensely studied in the recent past. This is mostly due to potential applications of the resulting composites in the biomaterials field. Polymers in particular are efficient growth modifiers. As a result, there has been a large amount of work on polymeric growth modifiers. Interestingly, however, relatively little work has been done on polycationic additives. The current paper shows that poly(ethylene oxide)b-poly(L-lysine) block copolymers lead to an interesting morphology of calcium phosphate precipitated at room temperature and subjected to a mild heat treatment at 85 degrees C. Electron microscopy, synchrotron X-ray diffraction, and porosity analysis show that a (somewhat) porous material with channel-like features forms. Closer inspection using transmission electron microscopy shows that the channels are probably not real channels. Much rather the morphology is the result of the aggregation of ca. 100-nm-sized rodlike primary particles, which changes upon drying to exhibit the observed channel-like features. Comparison experiments conducted in the absence of polymer and with poly(ethylene oxide)-b-poly(L-glutamate) show that these features only form in the presence of the polycationic poly(L-lysine) block, suggesting a distinct interaction of the polycation with either the crystal or the phosphate ions prior to mineralization. Y1 - 2009 UR - http://pubs.acs.org/journal/cmatex U6 - https://doi.org/10.1021/Cm803244z SN - 0897-4756 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia T1 - Ring-size-selective enyne metathesis as a tool for desymmetrization of an enantiopure C-2-symmetric building block N2 - The enantiomerically pure C-2-syrnmetrical hexa-1,5-diene-3,4-diol is selectively monopropargylated. The products undergo ring-closing enyne metathesis to give exclusively dihydropyrans as single stereoisomers. An unprotected hydroxy group is identified as the factor controlling the ring-size selectivity. Y1 - 2009 UR - http://pubs.acs.org/journal/joceah U6 - https://doi.org/10.1021/Jo9018649 SN - 0022-3263 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hoelter, Frank T1 - A stereodivergent synthesis of all stereoisomers of centrolobine : control of selectivity by a protecting-group manipulation N2 - All stereoisomers of the natural product centrolobine are selectively synthesized, by starting from a common precursor. Key steps are an enantioselective allylation with enantiomerically pure allylsilanes, a tandem ring-closing metathesis-isomerization reaction, and a Heck reaction by using an arene diazonium salt. By choosing appropriate conditions for the final deprotection step, either the cis-configured centrolobines or their epimers are selectively obtained. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200902053 SN - 0947-6539 ER - TY - JOUR A1 - Schaal, Janina A1 - Kotzur, Nico A1 - Dekowski, Brigitte A1 - Quilitz, Jana A1 - Klimakow, Maria A1 - Wessig, Pablo A1 - Hagen, Volker T1 - A novel photorearrangement of (coumarin-4-yl)methyl phenyl ethers N2 - In the present study, we describe synthesis and photochemical behaviour of the coumarinylmethyl phenyl ethers 1 and 6-10. Irradiation of the compounds in polar solvents leads to o-, p- and m-hydroxybenzyl substituted coumarins as main products. A side reaction is the photosolvolysis of the ethers that gives the (coumarin-4-yl)methyl alcohol and the corresponding phenol. Detailed studies of the quantum yields and product distributions upon irradiation of 6 as a function of the solvents are indicative of a dominant role of an ionic pathway in photochemical conversions. The found photochemical rearrangement is a useful tool for the preparation of hydroxylated 4-benzylcoumarins. A series of such compounds have been synthesised. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/10106030 U6 - https://doi.org/10.1016/j.jphotochem.2009.09.012 SN - 1010-6030 ER - TY - JOUR A1 - Rojas, Oscar A1 - Koetz, Joachim A1 - Kosmella, Sabine A1 - Tiersch, Brigitte A1 - Wacker, Philipp A1 - Kramer, Markus T1 - Structural studies of ionic liquid-modified microemulsions N2 - This work is focused on the influence of an ionic liquid (IL), i.e. ethyl-methylimidazolium hexylsulfate, on the spontaneous formation of microemulsions with ionic surfactants. The influence of the ionic liquid on Structure formation in the optically clear phase region in water/toluene/pentanol mixtures in presence of the cationic surfactant CTAB was studied in more detail. The results show a significant increase of the transparent phase region by adding the ionic liquid. Conductometric investigations demonstrate that adding the ionic liquid can drastically reduce the droplet- droplet interactions in the L-2 phase. H-1 nuclear magnetic resonance (H-1 NMR) diffusion coefficient measurements in combination with dynamic light scattering measurements clearly show that inverse microemulsion droplets still exist, but the droplet size is decreased to 2 nm. A more detailed characterisation of the isotropic phase channel by means of conductivity measurements, dynamic light scattering (DLS), H-1 NMR and cryo-scanning electron microscopy (SEM), allows the identification of a bicontinuous sponge phase between the L-1 and L-2 phase. When the poly(ethyleneimine) is added, the isotropic phase range is reduced drastically, but the inverse microemulsion range still exists. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00219797 U6 - https://doi.org/10.1016/j.jcis.2009.02.039 SN - 0021-9797 ER - TY - JOUR A1 - Poghosyan, Armen H. A1 - Arsenyan, Levon H. A1 - Gharabekyan, Hrant H. A1 - Koetz, Joachim A1 - Shahinyan, Aram A. T1 - Molecular dynamics study of poly(diallyldimethylammonium chloride) (PDADMAC)/sodium dodecyl sulfate (SDS)/ decanol/water systems N2 - We have performed a 50 ns of molecular dynamics study of poly(diallyldimethylammonium chloride) (PDADMAC)/ sodium dodecyl sulfate (SDS)/decanol/water systems. The influence of the cationic polyelectrolyte on the anionic SDS- based lamellar liquid crystalline system was investigated. The main structural parameters have been calculated and compared with experimental data. We obtain two types of PDADMAC conformation, a more folded structure A and a structure B where the PDADMAC molecule is adsorbed at the anionic head groups of the surfactant molecules. The polyelectrolyte- induced coexistence of two lamellar phases at a concentration of 2-3% of PDADMAC is observed, which is in agreement with experimental findings. Y1 - 2009 UR - http://pubs.acs.org/journal/jpcbfk U6 - https://doi.org/10.1021/Jp806289c SN - 1520-6106 ER - TY - JOUR A1 - Paramonov, Guennaddi K. A1 - Saalfrank, Peter T1 - Time-evolution operator method for non-Markovian density matrix propagation in time and space representation : application to laser association of OH in an environment N2 - An efficient method for the numerical solution of a non-Markovian, open-system density matrix equation of motion in coordinate representation is developed. We apply the scheme to model simulations of the laser-assisted O+H -> OH association reaction in an environment. The suggested approach is based on the application of the time-evolution operator to the "closed-system" part of the overall Hamiltonian and transformation of the open-system equation of motion to the Heisenberg picture suitable for numerical propagation. A dual role of the system-environment coupling with respect to the infrared (ir) laser-driven association of OH is demonstrated: the association probability is increased due to the coupling at relatively weak laser fields, but decreased at strong laser fields. Moreover, at a certain strength of the ir laser field, the association probability does not depend on the strength of the system-bath coupling at all. Y1 - 2009 UR - http://pra.aps.org/ U6 - https://doi.org/10.1103/Physreva.79.013415 SN - 1050-2947 ER - TY - JOUR A1 - Nest, Mathias T1 - The multi-configuration electron-nuclear dynamics method N2 - An approach to the correlated quantum dynamics of electrons and nuclei is proposed. It is an ab initio method, based on a multi-configuration expansion of the full molecular wave function. The objective of this development is to be able to describe the correlated motion of electrons in molecules beyond the fixed-nuclei approximation. Neither potential energy surfaces nor diabatic couplings need to be calculated, and Pulay forces do not appear. The method is illustrated by application to the 12 + 1 dimensional LiH molecule. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00092614 U6 - https://doi.org/10.1016/j.cplett.2009.03.013 SN - 0009-2614 ER - TY - JOUR A1 - Navarro, Salvador A1 - Shkilnyy, Andriy A1 - Tiersch, Brigitte A1 - Taubert, Andreas A1 - Menzel, Henning T1 - Preparation, characterization, and thermal gelation of amphiphilic alkyl-poly(ethyleneimine) N2 - Amphiphilic alkyl-poly(ethyleneimine)s (alkyl-PEI) with different degrees of polymerization have been produced by alkaline hydrolysis of alkyl-poly(2-methyl-2-oxazoline). Potentiometric titration of the alkyl-PEI shows the influence of the alkyl chain and the degree of polymerization on the titration curves and hence on the polymer conformation. Karl Fischer titration has been used to determine the water content in the polymers. Subsequent X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) measurements prove the existence of different hydration states of the PEI even under dry storage conditions. Upon cooling from hot aqueous Solutions, hydrogels form. The gelation concentration decreases with increasing degree of polymerization of the PEI segment. Scanning electron microscopy (SEM and cryo-SEM) of the hydrogels reveal an alkyl-PEI fibrous network composed of fan-like units. DSC shows that the percentages of bound and free water in the hydrogels depend on the concentration of polar amino groups. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La9013569 SN - 0743-7463 ER - TY - JOUR A1 - Nacci, Christophe A1 - Foelsch, Stefan A1 - Zenichowski, Karl A1 - Dokic, Jadranka A1 - Klamroth, Tillmann A1 - Saalfrank, Peter T1 - Current versus temperature-induced switching in a single-molecule tunnel junction : 1,5 cyclooctadiene on Si(001) N2 - The biconformational switching of single cyclooctadiene molecules chemisorbed on a Si(001) surface was explored by quantum chemical and quantum dynamical calculations and low-temperature scanning tunneling microscopy experiments. The calculations rationalize the experimentally observed switching driven by inelastic electron tunneling (IET) at 5 K. At higher temperatures, they predict a controllable crossover behavior between IET-driven and thermally activated switching, which is fully confirmed by experiment. Y1 - 2009 UR - http://pubs.acs.org/journal/nalefd U6 - https://doi.org/10.1021/Nl901419g SN - 1530-6984 ER - TY - JOUR A1 - Müller, Peter A1 - Nikolaus, Jörg A1 - Schiller, Sabine A1 - Herrmann, Andreas A1 - Moellnitz, Kristian A1 - Czapla, Sylvia A1 - Wessig, Pablo T1 - Molecular rods with oligospiroketal backbones as anchors in biological membranes N2 - Getting stuck in: A hydrophobic molecular rod with terminal fluorescent moieties has been synthesized. The insertion of the rod into membranes was investigated and shown to incorporate efficiently into model and biological membranes (see picture; gray C, blue N, red O). Those rods can be used as stable membrane-associated anchors for functionalization of membrane surfaces. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26737/ U6 - https://doi.org/10.1002/anie.200901133 SN - 1433-7851 ER - TY - JOUR A1 - Modarresi-Alam, Ali Reza A1 - Amirazizi, Homeyra Alsadat A1 - Bagheri, Hajar A1 - Bijanzadeh, Hamid-Reza A1 - Kleinpeter, Erich T1 - Dynamic H-1 NMR spectroscopic study of the ring inversion in N-sulfonyl morpholines : studies on N-S interactions N2 - The effect of the exocyclic conjugation, via d-p orbital interaction and/or negative hyperconjugation (anomeric effect) of the N-S bond, on the inversion of the morpholine ring in some N-arylsulfonyl morpholines is studied by variable-temperature H-1 NMR spectroscopy in different solvents. The observed free energy barriers are 9.2-10.3 kcal mol(-1); the lower values were obtained with increasing conjugation (substituents of higher electron withdrawing power) along the series. The barrier to ring inversion of le was solvent independent. X-ray data of compounds 1b,d reveal the chair conformation of the six-membered ring the flattened pyramidal orientation of the ring nitrogen atom, and the sulfonyl group in equatorial position with the plane containing the C-aryl-S-N bond perpendicular to the plane of the benzene ring. In addition, the sulfonamide group prefers a conformation with the S-C bond antiperiplanar with respect to the nitrogen atom lone pair and the -CH2-N-CH2- moieties in staggered conformation with the S-O bonds of the SO2 group. Y1 - 2009 UR - http://pubs.acs.org/journal/joceah U6 - https://doi.org/10.1021/Jo900454a SN - 0022-3263 ER - TY - JOUR A1 - Marang, Laura A1 - Eidner, Sascha A1 - Kumke, Michael Uwe A1 - Benedetti, Marc F. A1 - Reiller, Pascal E. T1 - Characterization of competitive binding of Eu(III)/Cu(II) and Eu(III)/Ca(II) to Gorleben humic acid Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00167037 U6 - https://doi.org/10.1016/j.gca.2009.05.011 SN - 0016-7037 ER - TY - JOUR A1 - Lutter, Stefanie A1 - Koetz, Joachim A1 - Tiersch, Brigitte A1 - Kosmella, Sabine T1 - Polymer-modified bicontinuous microemulsions used as a template for the formation of nanorods N2 - This article is focused on the characterization of the poly(ethylene glycol) (PEG)-induced bicontinuous microemulsion of the pseudo-ternary system sodium dodecylsulfate (SDS)/xylene-pentanol/water by means of differential scanning calorimetry, rheology, and conductometry. The influence of the polymer concentration (cp) and the molecular weight (Mw) on the microstructure of the microemulsion was investigated using Cryo scanning electron microscopy. It was found that an increase of cp influences the structure of the sponge-like phase significantly. These polymer-modified microemulsions can be used as a template phase for the formation of BaSO4 nanorods, where individual nanoparticles (5nm in size) are ordered along the polymer backbone. Y1 - 2009 UR - http://www.informaworld.com/openurl?genre=journal&issn=0193-2691 U6 - https://doi.org/10.1080/01932690802643113 SN - 0193-2691 ER - TY - JOUR A1 - Lapresta-Fernández, Alejandro A1 - Cywinski, Piotr J. A1 - Moro, Artur J. A1 - Mohr, Gerhard J. T1 - Fluorescent polyacrylamide nanoparticles for naproxen recognition N2 - We present the synthesis of fluorescent acrylamide nanoparticles (FANs) capable of recognizing non-steroidal anti-inflammatory drugs (NSAIDs) in buffered aqueous solutions. Within this important group, we selected naproxen, one of the 2-arylpropionic acids (profens), due to its use for the treatment of moderate pain, fever, and inflammation. The nanosensors were prepared under mild conditions of inverse microemulsion polymerization using aqueous acrylamide as the monomer and N,N'-methylenebisacrylamide as the crosslinker, employing the surfactants polyoxyethylene-4-lauryl ether (Brij (R) 30) and sodium bis(2-ethylhexyl) sulfosuccinate in hexane. Furthermore, a fluorescent monomer, (E)-4-[4- (dimethylamino)styryl]-1-[4-(methacryloyloxymethyl)benzyl]pyridinium chloride (mDMASP) has been synthesized and incorporated into the nanoparticles. The nanosensors exhibit a broad absorbance at around 460 nm and a structureless fluorescence band with maximum at 590 nm in 0.5 M phosphate buffer (pH=7.2). The recognition process is performed on the basis of ionic interactions which are monitored by the fluorescence increase at 590 nm upon addition of different concentrations of naproxen. The FANs show a size distribution in the range of 20-80 nm, with a hydrodynamic diameter of 34 nm. In order to assess the selectivity of the FANs, a systematic study was conducted on the effect produced by drugs and biomolecules that could interfere with the analysis of naproxen. Y1 - 2009 UR - http://www.springerlink.com/content/100417 U6 - https://doi.org/10.1007/s00216-009-3007-2 SN - 1618-2642 ER - TY - JOUR A1 - Krüger, Tobias A1 - Vorndran, Katja A1 - Linker, Torsten T1 - Regioselective arene functionalization : simple substitution of carboxylate by alkyl groups N2 - Arenes with various alkyl side-chains were synthesized in high yields and excellent regioselectivities. Starting from toluic and naphthoic acids, the carboxylate group was conveniently substituted by alkyl halides by Birch reduction and subsequent decarbonylation. The method is characterized by inexpensive starting materials and reagents, and methylation of arenes was realized. Besides simple alkyl substituents, the scope of arene functionalization was extended by benzyl, fluoro, amino, and ester groups. We were able to control the alkylation of 1-naphthoic acid during Birch reduction by the addition of tert-butanol. This allowed the regioselective synthesis of mono and bis-substituted naphthalenes from the same starting material. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200901774 SN - 0947-6539 ER - TY - JOUR A1 - Kraus, Florian A1 - Aschenbrenner, Jürgen C. A1 - Klamroth, Tillmann A1 - Korber, Nikolaus T1 - Hydrogen polyphosphides P3H23- and P3H32- : synthesis and crystal structure of K3(P3H2)·2.3NH3, Rb3(P3H2)·NH3, [Rb(18-crown-6)]2(P3H3)·7.5NH3, and [Cs(18-crown-6)]2(P3H3)·7NH3 N2 - The incongruous solvation of polyphosphides and phosphanes or the direct reduction of white phosphorus in liquid ammonia leads to the hydrogen polyphosphides catena-dihydrogen triphosphide, P3H23-, and catena-trihydrogen triphosphide, P3H32-, in the crystalline compounds K-3(P3H2)center dot 2.3NH(3) (1), Rb-3(P3H2)center dot NH3 (2), [Rb(18-crown-6)](2)(P3H3)center dot 7.5NH(3) (3), and [Cs(18-crown-6)](2)(P3H3)center dot 7NH(3) (4). Y1 - 2009 UR - http://pubs.acs.org/journal/inocaj U6 - https://doi.org/10.1021/Ic8014546 SN - 0020-1669 ER - TY - JOUR A1 - Kozlevcar, Bojan A1 - Mate, Elizabeta A1 - Jaglicic, Zvonko A1 - Glažar, Lea A1 - Golobic, Amalija A1 - Strauch, Peter A1 - Moncol, Jan A1 - Kitanovski, Nives A1 - èegedin, Primož T1 - A small methanoato ligand in the structural differentiation of copper(II) complexes N2 - Several copper(II) methanoato complexes, namely mononuclear [Cu(O2CH)(2)(2-mpy)(2)] (1) (2-mpy = 2- methylpyridine), binuclear [Cu-2(mu-O2CH)(4)(2-mpy)(2)] (2), and the polynuclear {[Cu(mu-O2CH)(2)(2-mpy)(2)] [Cu-2(mu- O2CH)(4)]}(n) (3) and {Na-2[Cu(mu-O2CH)(2)(O2CH)(2)][Cu-2(mu-O2CH)(4)]}(n) (4), have been synthesized. The mononuclear complex I is formed by two asymmetric chelate methanoate anions and two 2-methylpyridine molecules, giving a highly distorted 'elongated octahedral' coordination sphere. Complex I decomposes outside the mother-liquid, transforming into a regular isolated binuclear paddle-wheel complex 2 with four intra-binuclear bridging methanoates and two axial 2-mpy ligands. The polynuclear complex 3 is formed of alternate mononuclear and binuclear building blocks resembling the central cores of I and 2, but with significant differences, especially for the methanoates of the mononuclear units. The oxygen atom of the mononuclear unit in the octahedral axial position in 3 is simultaneously coordinated to the axial position of the binuclear paddle-wheel central core, thus enabling a chain type of structure. A chain of alternate mononuclear and binuclear building blocks, as in the neutral compound 3. are found as well in the ionic polymeric compound 4, though two types of bridges are found in 4, while there is only one type in 3. Namely, the axial position of the octahedral mononuclear unit in 4 is occupied by the methanoate oxygen atom that is already a part of the binuclear paddle-wheel unit, while one equatorial methanoate from the mononuclear unit serves as a triatomic bridge to the axial position of the binuclear building block. A very strong antiferromagnetic interaction is found for all the complexes with the paddle-wheel building blocks [Cu-2(mu-O2CH)(4)] 2-4 (-2J = 444-482 cm(-1)), attributed to the methanoate intra-binuclear bridges. On the other hand, this strong antiferromagnetism, found already at room temperature, reduces the intensity of the EPR S = 1 spin signals reported for the isolated paddle-wheel complex 2. For the polymeric 3, only the spin S = 1/2 signals are found in the EPR spectra, and they are assigned to the mononuclear building blocks. No signals with a clear origin are however seen in the room temperature EPR spectrum of the polymeric analogue 4, only the S = 1/2 signals in the low temperature spectra. This feature is suggested to be due to a specific influence between the adjacent S = 1 (binuclear) and S = 1/2 (mononuclear) species via their bridges. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/02775387 U6 - https://doi.org/10.1016/j.poly.2009.05.066 SN - 0277-5387 ER - TY - JOUR A1 - Kozlevcar, Bojan A1 - Kovsca, Igor A1 - Jaglicic, Zvonko A1 - Pevec, Andrej A1 - Kitanovski, Nives A1 - Strauch, Peter A1 - èegedin, Primož T1 - Strong antiferromagnetism in isolated anionic dicopper(II) methanoato paddle-wheel complex N2 - A new ionic compound (C5H6NO)(2)[CU2(mu-O2CH)(4)(O2CH)(2)], 1 formed of 4-hydroxypyridinium cations and a complex anion was synthesized. The anion is a paddle-wheel dicopper carboxylate complex with four syn,syn-bridging and two axial anionic methanoato ligands. The XRD structure determination of 1 reveals that the molecular structure is stabilized by two H-bonds between the cations and the axial paddle-wheel anions (N-H center dot center dot center dot O 2.755(3), O-H center dot center dot center dot O 2.489(2) angstrom). The compound exhibits a very strong (2J = 500 cm(- 1)) intra-binuclear anti ferromagnetic interaction noticed already at room temperature attributed to the methanoato intra-binuclear bridges. The typical EPR S = 1 spin system signals of the dicopper paddle-wheel complexes at 90 and 450- 700 mT are found in the room temperature spectrum, but they are poorly seen in the 110 K spectrum. These signals are of very low intensity and are accompanied by a dominant signal at 320 mT, all closely related to a very strong anti ferromagnetic interaction present in 1. Y1 - 2009 UR - http://public.carnet.hr/ccacaa/ SN - 0011-1643 ER - TY - JOUR A1 - Koeppen, Robert A1 - Esslinger, Susanne A1 - Becker, Roland A1 - Nehls, Irene T1 - Hexabromcyclododecane in home freshwater fishes Y1 - 2009 SN - 1439-9598 ER - TY - JOUR A1 - Köhler, Ralf A1 - Doench, Ingo A1 - Ott, Patrick A1 - Laschewsky, André A1 - Fery, Andreas A1 - Krastev, Rumen T1 - Neutron reflectometry study of swelling of polyelectrolyte multilayers in water vapors : influence of charge density of the polycation N2 - We studied the swelling of polyelectrolyte (PE) multilayers (PEM) in water (H2O) vapors. The PEM were made from polyanion poly(styrene sulfonate) (PSS) and polycation poly(diallyldimethylammonium chloride)-N-methyl-N-vinylacetamide (pDADMAC-NMVA). While PSS is a fully charged polyanion, pDADMAC-NMVA is a random copolymer made of charged pDADMAC and uncharged NMVA monomer units. Variation of the relative amount of these two units allows for controlling the charge density of pDADMAC-NMVA. The degree of swelling was studied as it function of the relative humidity in the experimental chamber (respectively water concentration in the gas phase) for PEM prepared from PSS and pDADMAC-NMVA with their different charge densities - 100%, 89% and 75%. The films were prepared by means of spraying technique and consisted of six PE couples-PSS/pDADMAC-NMVA. Neutron reflectometry was applied as main tool to observe the swelling process. The technique allows to obtain in a single experiment information about film thickness and amount of water in the film. The experiments were complemented with AFM measurements to obtain the thickness of the films. It was found that the Film thickness increases when the charge density of the polycation decreases. The swelling of the PEM increases with the relative humidity and it depends on the charge density of pDADMAC-NMVA. The swelling behavior is 2-fold, splitting up in a charge dependent mode with relatively little volume increase, and a second mode With high volume expansion, which is independent from charge density of PEM. The "swelling transition" occurs for all samples at a relative humidity about 60% and a volume increase of ca. 20%. The results were interpreted according to the Flory-Huggins theory which assumes a phase separation in PEM network at higher water contents. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La901508w SN - 0743-7463 ER - TY - JOUR A1 - Klinkusch, Stefan A1 - Saalfrank, Peter A1 - Klamroth, Tillmann T1 - Laser-induced electron dynamics including photoionization : a heuristic model within time-dependent configuration interaction theory N2 - We report simulations of laser-pulse driven many-electron dynamics by means of a simple, heuristic extension of the time-dependent configuration interaction singles (TD-CIS) approach. The extension allows for the treatment of ionizing states as nonstationary states with a finite, energy-dependent lifetime to account for above-threshold ionization losses in laser-driven many-electron dynamics. The extended TD-CIS method is applied to the following specific examples: (i) state-to-state transitions in the LiCN molecule which correspond to intramolecular charge transfer, (ii) creation of electronic wave packets in LiCN including wave packet analysis by pump-probe spectroscopy, and, finally, (iii) the effect of ionization on the dynamic polarizability of H-2 when calculated nonperturbatively by TD-CIS. Y1 - 2009 UR - http://jcp.aip.org/ U6 - https://doi.org/10.1063/1.3218847 SN - 0021-9606 ER - TY - JOUR A1 - Klinkusch, Stefan A1 - Klamroth, Tillmann A1 - Saalfrank, Peter T1 - Long-range intermolecular charge transfer induced by laser pulses : an explicitly time-dependent configuration interaction approach N2 - In this paper, we report simulations of laser-driven many-electron dynamics by means of the time-dependent configuration interaction singles (TD-CIS) approach. The method is capable of describing explicitly time-dependent phenomena beyond perturbation theory and is systematically improvable. In contrast to most time-dependent density functional methods it also allows us to treat long-range charge-transfer states properly. As an example, the laser-pulse induced charge transfer between a donor (ethylene) and an acceptor molecule (tetracyanoethylene, TCNE) is studied by means of TD-CIS. Also, larger aggregates consisting of several donors and/or acceptors are considered. It is shown that the charge distribution and hence the dipole moments of the systems under study are switchable by (a series of) laser pulses which induce selective, state-to-state electronic transitions. Y1 - 2009 UR - http://xlink.rsc.org/jumptojournal.cfm?journal_code=CP U6 - https://doi.org/10.1039/B817873a SN - 1463-9076 ER - TY - JOUR A1 - Klaumünzer, Bastian A1 - Kroener, Dominik T1 - N-Inversion in 2-azabicyclopentane derivatives : model simulations for a laser controlled molecular switch N2 - We report model quantum simulations for the nitrogen inversion in 2-azabicyclo[1.1.1] pentane derivates controlled by laser pulses proposing to use this class of molecules as molecular switches. The derivatives trans-5- fluoro-2-methyl-2-azabicyclo[1.1.1] pentane and cis-5-fluoro-2-methyl-2-azabicyclo[1.1.1] pentane are investigated by means of density functional theory and quantum wave packet dynamics. The molecules have two stable, i.e. energetically well-separated, conformers along the N-inversion coordinate. In 1D model simulations the transformation from one conformer to the other is accomplished in the electronic ground state by using two overlapping chirped linearly polarized IR laser pulses for the trans-and cis-isomer or alternatively via an electronic excited state employing a pump- dump sequence of ultrashort UV laser pulses. Y1 - 2009 UR - http://rsc.org/Publishing/Journals/nj/ U6 - https://doi.org/10.1039/B812319e SN - 1144-0546 ER - TY - JOUR A1 - Klamroth, Tillmann A1 - Nest, Mathias T1 - Ultrafast electronic excitations of small sodium clusters and the onset of electron thermalization N2 - In this paper we report simulations of the ultrafast laser excitation and relaxation of the correlated valence electrons of a Na-8 cluster. The aim is twofold: first, while the total energy stays constant when the exciting laser pulse is over, we observe that the entropy computed from the reduced one electron density matrix rises on a much longer time scale. We discuss whether this can be understood as the onset of the thermalization of a finite system. Second, we describe this process with eight different methods of wavefunction-based electronic structure theory, which have been adapted for an explicitly time-dependent description. Their respective advantages and limitations for the simulation of the excitation and subsequent relaxation are explained. Y1 - 2009 UR - http://pubs.rsc.org/en/Journals/JournalIssues/CP U6 - https://doi.org/10.1039/B813619j SN - 1463-9076 ER - TY - JOUR A1 - Kind, Lucy A1 - Plamper, Felix A. A1 - Goebel, Ronald A1 - Mantion, Alexandre A1 - Mueller, Axel H. E. A1 - Pieles, Uwe A1 - Taubert, Andreas A1 - Meier, Wolfgang P. T1 - Silsesquioxane/polyamine nanoparticle-templated formation of star- or raspberry-like silica nanoparticles N2 - Silica is an important mineral in biology and technology, and many protocols have been developed for the synthesis of complex silica architectures. The current report shows that silsesquioxane nanoparticles carrying polymer arms on their surface are efficient templates for the fabrication of silica particles with a star- or raspberry-like morphology. The shape of the resulting particles depends on the chemistry of the polymer arms. With poly(N,N- dimethylaminoethyl methacrylate) (PDMAEMA) arms, spherical particles with a less electron dense core form. With poly {[2- (methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI), star- or raspberry-like particles form. Electron microscopy, electron tomography, and small-angle X-ray scattering show that the resulting silica particles have a complex structure, where a silsequioxane nanoparticle carrying the polymer arms is in the center. Next is a region that is polymer-rich. The outermost region of the particle is a silica layer, where the outer parts of the polymer arms are embedded. Time- resolved zeta-potential and pH measurements, dynamic light scattering, and electron microscopy reveal that silica formation proceeds differently if PDMAEMA is exchanged for PMETAI. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La900229n SN - 0743-7463 ER - TY - JOUR A1 - Kadjane, Pascal A1 - Starck, Matthieu A1 - Camerel, Franck A1 - Hill, Diana A1 - Hildebrandt, Niko A1 - Ziessel, Raymond A1 - Charbonnière, Loïc J. T1 - Divergent approach to a large variety of versatile luminescent lanthanide complexes N2 - Using a regioselective strategy for nucleophilic aromatic substitution on polyfluoropyridines, a nonacoordinating precursor was designed that is adequately suited for complexation of lanthanide cations. Further functionalizations afforded numerous applications for near-IR emission, two-photon absorption spectroscopy, or the formation of luminescent gels. Y1 - 2009 UR - http://pubs.acs.org/journal/inocaj U6 - https://doi.org/10.1021/Ic9001169 SN - 0020-1669 ER - TY - JOUR A1 - Jyotishkumar, P. A1 - Koetz, Joachim A1 - Tiersch, Brigitte A1 - Strehmel, Veronika A1 - oezdilek, Ceren A1 - Moldenaers, Paula A1 - Hässler, Rüdiger A1 - Thomas, Sabu T1 - Complex phase separation in poly(acrylonitrile-butadiene-styrene)-modified epoxy/4,4 '-diaminodiphenyl sulfone blends : generation of new micro- and nanosubstructures N2 - The epoxy system containing diglycidyl ether of bisphenol A and 4,4'-diaminodiphenyl sulfone is modified with poly(acrylonitrile-butadiene-styrene) (ABS) to explore the effects of the ABS content on the phase morphology, mechanism of phase separation, and viscoelastic properties. The amount of ABS in the blends was 5, 10, 15, and 20 parts per hundred of epoxy resin (phr). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to investigate the final morphology of ABS-modified epoxy blends. Scanning electron microscopic studies of 15 phr ABS-modified epoxy blends reveal a bicontinuous structure in which both epoxy and ABS are continuous, with substructures of the ABS phase dispersed in the continuous epoxy phase and substructures of the epoxy phase dispersed in the continuous ABS phase. TEM micrographs of 15 phr ABS-modified epoxy blends confirm the results observed by SEM. TEM micrographs reveal the existence of nanosubstructures of ABS in 20 phr ABS-modified epoxy blends. To the best of our knowledge, to date, nanosubstructures have never been reported in any epoxy/thermoplastic blends. The influence of the concentration of the thermoplastic on the generated morphology as analyzed by SEM and TEM was explained in detail. The evolution and mechanism of phase separation was investigated in detail by optical microscopy (OM) and small-angle laser light scattering (SALLS). At concentrations lower than 10 phr the system phase separates through nucleation and growth (NG). However, at higher concentrations, 15 and 20 phr, the blends phase separate through both NG and spinodal decomposition mechanisms. On the basis of OM and SALLS, we conclude that the phenomenon of complex substructure formation in dynamic asymmetric blends is due to the combined effect of hydrodynamics and viscoelasticity. Additionally, dynamic mechanical analysis was carried out to evaluate the viscoelastic behavior of the cross-linked epoxy/ABS blends. Finally, apparent weight fractions of epoxy and ABS components in epoxy- and ABS-rich phases were evaluated from T-g analysis. Y1 - 2009 UR - http://pubs.acs.org/journal/jpcbfk U6 - https://doi.org/10.1021/Jp8094566 SN - 1520-6106 ER - TY - JOUR A1 - Graf, Philipp A1 - Mantion, Alexandre A1 - Foelske, Annette A1 - Shkilnyy, Andriy A1 - MaÜic, Admir A1 - Thuenemann, Andreas F. A1 - Taubert, Andreas T1 - Peptide-coated silver nanoparticles : synthesis, surface chemistry, and pH-triggered, reversible assembly into particle assemblies N2 - Simple tripeptides are scaffolds for the synthesis and further assembly of peptide/silver nanoparticle composites. Herein, we further explore peptide-con trolled silver nanoparticle assembly processes. Silver nanoparticles with a pH-responsive peptide coating have been synthesized by using a one-step precipitation/coating route. The nature of the peptide/silver interaction and the effect of the peptide oil the formation of the silver particles have been studied via UV/Vis, X-ray photoelectron, and surface-enhanced Raman spectroscopies as well as through electron microscopy, small angle X-ray scattering and powder Xray diffraction with Rietveld refinement. The particles reversibly form aggregates of different sizes in aqueous solution. The state of aggregation call be controlled by the solution pH value. At low pH values, individual particles are present. At neutral pH values, small clusters form and at high pH values, large precipitates are observed. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200802329 SN - 0947-6539 ER - TY - JOUR A1 - Götze, Jan A1 - Saalfrank, Peter T1 - Serine in BLUF domains displays spectral importance in computational models N2 - The BLUF (blue-light sensing using flavine) domain of the AppA photoreceptor protein from Rhodobacter sphaeroides was modelled by using quantum chemical chromophore plus amino acid models at the (TD-)B3LYP/6-31G* level of theory. The models were based on NMR structures, and further refined by CHARM force field molecular dynamics simulations. The goal is to explain the total redshift by about 10 nm in the UV/Vis spectra of BLUF domains after illumination, and to relate it to structural changes. For this purpose UV/Vis spectra of the available NMR structures were calculated and related to geometrical features. In particular, the hydrogen network embedding the central chromophore is discussed. Specifically, the position of a conserved glutamine, Q63, is found to be important in agreement with findings from previous works. Additionally, however, we find a systematic dependence also on the geometry of a conserved serine, S41. Based on a series of calculations with known structures and with artificial structural models, we argue that indeed the light-induced switching of both Q63 and S41 is necessary to explain the full similar to 10 nm redshift in the light (signalling) state of serine containing BLUF domains. Following or accompanying the double switching, two structurally highly important residues W104 and M106 exchange places, but do not affect the overall UV/ Vis properties of the chromophore. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/10111344 U6 - https://doi.org/10.1016/j.jphotobiol.2008.10.003 SN - 1011-1344 ER - TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Weber, Jens A1 - Moeller, Eléonore A1 - Friedrich, Alwin A1 - Beuermann, Sabine A1 - Taubert, Andreas T1 - Surprisingly high, bulk liquid-like mobility of silica-confined ionic liquids N2 - Mesoporous silica monoliths were prepared by the sol - gel technique and. lled with 1-ethyl-3-methyl imidazolium [Emim]-X (X = dicyanamide [N(CN)(2)], ethyl sulfate [EtSO4], thiocyanate [SCN], and triflate [TfO]) ionic liquids (ILs) using a methanol-IL exchange technique. The structure and behavior of the ILs inside the silica monoliths were studied using X-ray scattering, nitrogen sorption, IR spectroscopy, solid-state NMR, and thermal analysis. DSC finds shifts in both the glass transition temperature and melting points (where applicable) of the ILs. Glass transition and melting occur well below room temperature. There is thus no conflict with the NMR and IR data, which show that the ILs are as mobile at room temperature as the bulk (not confined) ILs. The very narrow line widths of the NMR spectra suggest that the ILs in our materials have the highest mobility reported for confined ILs so far. As a result, our data suggest that it is possible to generate IL/silica hybrid materials (ionogels) with bulk-like properties of the IL. This could be interesting for applications in, e.g., the solar cell or membrane fields. Y1 - 2009 UR - http://xlink.rsc.org/jumptojournal.cfm?journal_code=CP U6 - https://doi.org/10.1039/B821833a SN - 1463-9076 ER - TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Photoimaging with singlet oxygen at the solid-air interface N2 - Films of anthracene carboxylic acids were irradiated through photomasks and oxidized at the exposed regions by singlet oxygen upon sensitization. The efficiency of a photomask to protect the material underneath was investigated by optical and infrared spectroscopy. As the thickness of the film is reduced, the efficiency of the mask drops. This is explained by the migration of singlet oxygen at the solid-air interface, which in turn reacts at the masked area. For films with a thickness of < 15 nm, the efficiency of the mask approaches zero: sufficient efficiency is achieved at thicknesses > 100 nm. From the investigations, it will become clear that the contrast between the irradiated and masked area of an image is affected by reduction of the film thickness. On the other hand, the resolution of an image, which relates to the minimum feature size of an image, is not dependent on the thickness of the film. The contributions of "inside" and "outside" reactions are examined separately, and it quantitative approximation of the spatial range of both modes of the oxygenation is given. We set tip an approximate relation between mask efficiency and experimental conditions comprising internal and external oxygen diffusion, film thickness, and mask dimensions. These results give it deeper insight into the limits of resolution and contrast in singlet oxygen lithography. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La9008976 SN - 0743-7463 ER - TY - JOUR A1 - Elamparuthi, Elangovan A1 - Linker, Torsten T1 - Carbohydrate-2-deoxy-2-phosphonates : simple synthesis and Horner-Emmons reaction N2 - Phosphorus meets carbohydrates: Dimethyl phosphite reacts with ceric(IV) ammonium nitrate (CAN) to give phosphonyl radicals that add to glycals 1. The derivatives 2 were isolated in high yields and during a subsequent Horner-Emmons reaction underwent an interesting elimination to give 3,6-dihydro-2H-pyrans 3. The short sequence with simple precursors is applicable to the transformation of hexoses, pentoses, and disaccharides. Bn=benzyl. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1002/(28ISSN)291521-3773 U6 - https://doi.org/10.1002/anie.200804725 SN - 1433-7851 ER - TY - JOUR A1 - Dokic, Jadranka A1 - Gothe, Marcel A1 - Wirth, Jonas A1 - Peters, Maike V. A1 - Schwarz, Jutta A1 - Hecht, Stefan A1 - Saalfrank, Peter T1 - Quantum chemical investigation of thermal cis-to-trans isomerization of azobenzene derivatives : substituent effects, solvent effects, and comparison to experimental data N2 - Quantum chemical calculations of various azobenzene (AB) derivatives have been carried out with the goal to describe the energetics and kinetics of their thermal cis -> trans isomerization. The effects of substituents, in particular their type, number, and positioning, on activation energies have been systematically studied with the ultimate goal to tailor the switching process. Trends observed for mono- and disubstituted species are discussed. A polarizable continuum model is used to study, in an approximate fashion, the cis -> trans isomerization of azobenzenes in solution. The nature of the transition state(s) and its dependence on substituents and the environment is discussed. In particular for push-pull azobenzenes, the reaction mechanism is found to change from inversion in nonpolar solvents to rotation in polar solvents. Concerning kinetics, calculations based on the Eyring transition state theory give usually reliable activation energies and enthalpies when compared to experimentally determined values. Also, trends in the resulting rate constants are correct. Other computed properties such as activation entropies and thus preexponential rate factors are in only moderate agreement with experiment. Y1 - 2009 UR - http://pubs.acs.org/journal/jpcafh U6 - https://doi.org/10.1021/jp9021344 SN - 1089-5639 ER - TY - JOUR A1 - Coy-Barrera, Ericsson David A1 - Cuca-Sußrez, Luis Enrique A1 - Sefkow, Michael T1 - PAF-antagonistic bicyclo[3.2.1]octanoid neolignans from leaves of Ocotea macrophylla Kunth (Lauraceae) N2 - Di-nor-benzofuran neolignan aldehydes, Delta(7)-3,4-methylenedioxy-3'-methoxy-8',9'-dinor- 4',7-epoxy-8,3'-neolignan-7'-aldehyde (ocophyllal A) 1, Delta(7)-3,4,5,3'-tetramethoxy- 8',9'-dinor-4',7-epoxy-8,3'-neolignan-7'-aldehyde (ocophyllal B) 2, and macrophyllin-type bicyclo[3.2.1]octanoid neolignans (7R, 8R, 3'S, 4'S, 5'R)-Delta(8)'-4'-hydroxy-5'- methoxy-3,4-methylenedioxy-2',3'.4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol A) 3, (7R, 8R, 3'S, 4'S, 5'R)-Delta 8'-4'-hydroxy-3,4,5'-trimethoxy- 2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol B) 4, (7R, 8R, 3'S, 4'S, 5'R)-Delta(8)'-4'-hydroxy-3,4,5,5'-tetramethoxy- 2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol C) 5, as well as 2'-epi-guianin 6 and (+)-licarin B 7, were isolated and characterized from leaves of Ocotea macrophylla (Lauraceae). The structures and configuration of these compounds were determined by extensive spectroscopic analyses. Inhibition of platelet activating factor (PAF)-induced aggregation of rabbit platelets were tested with neolignans 1-7. Although compound 6 was the most potent PAF-antagonist, compounds 3-5 showed some activity. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00319422 U6 - https://doi.org/10.1016/j.phytochem.2009.07.010 SN - 0031-9422 ER - TY - JOUR A1 - Coy-Barrera, Ericsson David A1 - Cuca-Sußrez, Luis Enrique A1 - Sefkow, Michael T1 - Macrophyllin-type bicyclo[3.2.1]octanoid neolignans from the leaves of Pleurothyrium cinereum N2 - Four new macrophyllin-type bicyclo[3.2.1]octanoid neolignans, (7S,8R,3'S,5'R)-Delta(8')- 5,5',3'-trimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2',4'-dioxo- 7.3',8.5'-neolignan (cinerin A), 1, (7R,8R,3'S,4'R,5'R)-Delta(8')-4'-hydroxy- 5,5'-dimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2'-oxo- 7.3',8.5'-neolignan (cinerin B), 2, (7S,8R,3'R,4'S,5'R)-Delta(8')-4'-hydroxy- 5,5',3'-trimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2'-oxo- 7.3',8.5'-neolignan (cinerin C), 3, and (7S,8R,2'RYS,5'R)-Delta(8')-2'-hydroxy- 5,5'-dimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-4'-oxo- 7.3',8.5'-neolignan (cinerin D). 4, along with the known diterpene kaurenoic acid 5, were isolated from the leaves of Pleurothyrium cinercum. The structures and configuration of these compounds were determined by extensive spectroscopic analysis. Cinerins A-D (1-4) were tested for their inhibition efficacy of platelet activating factor (PAF)- induced aggregation of rabbit platelets. Compound 3 was the most potent PAF antagonist. Compounds 1-5 were tested against Mycobacterium tuberculosis (H(37)Rv strain) using the MABA method. Compound 5 induced 91.3% growth inhibition at 50 mu g mL(-1). Compounds 1-5 showed no significant inhibitory activity against some Gram-positive and Gram-negative bacteria by the agar-well diffusion method. Y1 - 2009 UR - http://pubs.acs.org/journal/jnprdf U6 - https://doi.org/10.1021/Np9000569 SN - 0163-3864 ER - TY - JOUR A1 - Coy-Barrera, Ericsson David A1 - Cuca-Sußrez, Luis Enrique A1 - Sefkow, Michael T1 - COX, LOX and platelet aggregation inhibitory properties of Lauraceae neolignans N2 - The anti-inflammatory potential of 26 neolignans (14 of the bicyclooctane-type and 12 of the benzofuran-type), isolated from three Lauraceae species (Pleurothyrium cinereum, Ocotea macrophylla and Nectandra amazonum), was evaluated in vitro through inhibition of COX-1, COX-2, 5-LOX and agonist-induced aggregation of rabbit platelets. Benzofuran neolignans were found to be selective COX-2 inhibitors, whereas bicyclooctane neolignans inhibit selectively the PAF- action as well as COX-1 and 5-LOX. The neolignan 9-nor-7,8-dehydro-isolicarin B 15 and cinerin C 7 were found to be the most potent COX-2 inhibitor and PAF-antagonist, respectively. Nectamazin C 10 exhibited dual 5-LOX/COX-2 inhibition. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/0960894X U6 - https://doi.org/10.1016/j.bmcl.2009.10.069 SN - 0960-894X ER - TY - JOUR A1 - Brown, Lauren E. A1 - Landaverry, Yakira R. A1 - Davies, James R. A1 - Milinkevich, Kristin A. A1 - Ast, Sandra A1 - Carlson, Joseph S. A1 - Oliver, Allen G. A1 - Konopelski, Joseph P. T1 - Progress toward the total synthesis of Psymberin/Irciniastatin A N2 - In this paper, we describe our synthesis of four key building blocks for the total synthesis of psymberin (1) and its C4 epimer (2). Despite early difficulties in processing material to the advanced intermediate stage, we have been successful in developing high-yielding syntheses for the pyran core, natural side chain, 4-epi side chain, and aryl fragments of the molecule. Our findings from the optimization process are presented herein. Y1 - 2009 UR - http://pubs.acs.org/journal/joceah U6 - https://doi.org/10.1021/Jo9009003 SN - 0022-3263 ER - TY - JOUR A1 - Breininger, Eugenia A1 - Imran-ul-haq, Muhammad A1 - Tuerk, Michael A1 - Beuermann, Sabine T1 - Effect of polymer properties on poly(vinylidene fluoride) particles produced by rapid expansion of CO2 + polymer mixtures N2 - The generation of nanoscale primary poly(vinylidene fluoride) (PVDF) particles by rapid expansion of supercritical solutions (RESS) is reported. The experimental results show that RESS enables the formation of PVDF particles with median particle diameters ranging from 56 to 226 nm and that the size of PVDF particles can be influenced by polymer properties. The particle size can be decreased either by increasing molar mass, in case of identical polymer end groups, or by increasing the degree of crystallinity, in case of similar molar mass and different end groups. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/08968446 U6 - https://doi.org/10.1016/j.supflu.2008.09.016 SN - 0896-8446 ER - TY - JOUR A1 - Boehm, Stanislav A1 - Tomašciková, Jana A1 - Imrich, Ján A1 - Danihel, Ivan A1 - Kristian, Pavol A1 - Koch, Andreas A1 - Kleinpeter, Erich A1 - Klika, Karel D. T1 - Computational study to assign structure, tautomerism, E/Z and s-cis/s-trans isomerism, pi-delocalization, partial aromaticity, and the ring size of 1,3-thiazolidin-4-ones and 1,3-thiazin-4-ones formed from thiosemicarbazides N2 - A set of structures encompassing 1-(9-acridinyl)thiosemicarbazide and its 2-methyl derivative together with their various tautomeric structures; the 5-membered ring 1,3-thiazolidin-4-one products resulting from the reaction of 1- (9-acridinyl)thiosemicarbazide and its 2-methyl derivative with dimethyl acetylenedicarboxylate (DMAD) together with the alternative 6-membered ring isomeric reaction products as well as other potential isomeric structures; and the 6- membered ring 1,3-thiazin-4-one product resulting from the reaction of 2-methyl-1-(9-acridinyl)thiosemicarbazide with methyl propiolate (MP) together with the alternative 5-membered ring isomeric reaction product were all extensively studied by molecular modeling calculations using DFT at the B3LYP/6-31G(d,p) level of theory. The ring-chain tautomerism of the thiosemicarbazides, the regio- and stereoselectivity of the reactions, the adopted conformations and E/Z configurations of the products, the prototropic tautomerism of all the compounds, and the reasons for the predominance of the s-cis conformation of the Z configuration of the 1,3-thiazolidin-4-one product in particular were all extensively analyzed. Comparison of the modeled structures were also made to the 1,3-thiazolidin-4-one and 1,3-thiazin-4-one structures of the methyl derivative as well as 1-(9-acridinyl)thiosemicarbazide available from X-ray crystallographic analysis. Tactics utilizing spectroscopic methods {1R frequencies (nu) and NMR chemical shifts (delta), scalar coupling constants (J), and NOEs (eta)} in conjunction with molecular modeling calculations of the spectral parameters (frequency calculations (v) and NMR 6 using the GIAO method and J by calculation of the Fermi contact term) were evaluated in terms of proving 5- or 6-membered ring formation. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/01661280 U6 - https://doi.org/10.1016/j.theochem.2009.09.019 SN - 0166-1280 ER - TY - JOUR A1 - Bivigou Koumba, Achille Mayelle A1 - Kristen, Juliane A1 - Laschewsky, André A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Synthesis of symmetrical triblock copolymers of styrene and N-isopropylacrylamide using bifunctional bis(trithiocarbonate)s as RAFT agents N2 - Six new bifunctional bis(trithiocarbonate)s were explored as RAFT agents for synthesizing amphiphilic triblock copolymers ABA and BAB, with hydrophilic "A" blocks made from N-isopropylacrylamide and hydrophobic "B" blocks made from styrene. Whereas the extension of poly(N-isopropylacrylamide) by styrene was not effective, polystyrene macroRAFT agents provided the block copolymers efficiently. End group analysis by H-1 NMR spectroscopy supported molar mass analysis and revealed an unexpected side reaction for certain bis(trithiocarbonate)s, namely a fragmentation to simple trithiocarbonates while extruding ethylene-trithiocarbonate. The amphiphilic block copolymers with short polystyrene blocks are directly soluble in water and self-organize into thermo-responsive micellar aggregates. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291521-3935 U6 - https://doi.org/10.1002/macp.200800575 SN - 1022-1352 ER -