Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-36557 Wissenschaftlicher Artikel Hass, Roland; Reich, Oliver Photon density wave spectroscopy for dilution-free sizing of highly concentrated nanoparticles during starved-feed polymerization Malden Wiley-Blackwell 2011 4 ChemPhysChem : a European journal of chemical physics and physical chemistry 12 14 2572 2575 10.1002/cphc.201100323 Institut für Chemie OPUS4-37257 Wissenschaftlicher Artikel Bressel, Katharina; Prevost, Sylvain; Appavou, Marie-Sousai; Tiersch, Brigitte; Koetz, Joachim; Gradzielski, Michael Phase behaviour and structure of zwitanionic mixtures of perfluorocarboxylates and tetradecyldimethylamine oxide-dependence on chain length of the perfluoro surfactant Phase behaviour and the mesoscopic structure of zwitanionic surfactant mixtures based on the zwitterionic tetradecyldimethylamine oxide (TDMAO) and anionic lithium perfluoroalkyl carboxylates have been investigated for various chain lengths of the perfluoro surfactant with an emphasis on spontaneously forming vesicles. These mixtures were studied at a constant total concentration of 50 mM and characterised by means of dynamic light scattering (DLS), electric conductivity, small-angle neutron scattering (SANS), viscosity, and cryo-scanning electron microscopy (Cryo-SEM). No vesicles are formed for relatively short perfluoro surfactants. The extension of the vesicle phase becomes substantially larger with increasing chain length of the perfluoro surfactant, while at the same time the size of these vesicles increases. Head group interactions in these systems play a central role in the ability to form vesicles, as already protonating 10 mol% of the TDMAO largely enhances the propensity for vesicle formation. The range of vesicle formation in the phase diagram is not only substantially enlarged but also extends to shorter perfluoro surfactants, where without protonation no vesicles would be formed. The size and polydispersity of the vesicles are related to the chain length of the perfluoro surfactant, the vesicles becoming smaller and more monodisperse with increasing perfluoro surfactant chain length. The ability of the mixed systems to form well-defined unilamellar vesicles accordingly can be controlled by the length of the alkyl chain of the perfluorinated surfactant and depends strongly on the charge conditions, which can be tuned easily by pH-variation. Cambridge Royal Society of Chemistry 2011 11 Soft matter 7 23 11232 11242 10.1039/c1sm05618b Institut für Chemie OPUS4-36836 Wissenschaftlicher Artikel Wellert, Stefan; Tiersch, Brigitte; Koetz, Joachim; Richardt, Andre; Lapp, Alain; Holderer, Olaf; Gaeb, Juergen; Blum, Marc-Michael; Schulreich, Christoph; Stehle, Ralf; Hellweg, Thomas The DFPase from Loligo vulgaris in sugar surfactant-based bicontinuous microemulsions structure, dynamics, and enzyme activity The enzyme diisopropyl fluorophosphatase (DFPase) from the squid Loligo vulgaris is of great interest because of its ability to catalyze the hydrolysis of highly toxic organophosphates. In this work, the enzyme structure in solution (native state) was studied by use of different scattering methods. The results are compared with those from hydrodynamic model calculations based on the DFPase crystal structure. Bicontinuous microemulsions made of sugar surfactants are discussed as host systems for the DFPase. The microemulsion remains stable in the presence of the enzyme, which is shown by means of scattering experiments. Moreover, activity assays reveal that the DFPase still has high activity in this complex reaction medium. To complement the scattering experiments cryo-SEM was also employed to study the microemulsion structure. New York Springer 2011 14 European biophysics journal : with biophysics letters ; an international journal of biophysics 40 6 761 774 10.1007/s00249-011-0689-0 Institut für Chemie OPUS4-36465 Wissenschaftlicher Artikel Weber, Nancy; Tiersch, Brigitte; Unterlass, Miriam M.; Heilig, Anneliese; Tauer, Klaus "Schizomorphic" Emulsion Copolymerization Particles Cryo-electron microscopy, atomic force microscopy, and light microscopy investigations provide experimental evidence that amphiphilic emulsion copolymerization particles change their morphology in dependence on concentration. The shape of the particles is spherical at solids content above 1%, but it changes to rod-like, ring-like, and web-like structures at lower concentrations. In addition, the shape and morphology of these particles at low concentrations are not fixed but very flexible and vary with time between spheres, flexible pearlnecklace structures, and stretched rods. Malden Wiley-Blackwell 2011 5 Macromolecular rapid communications 32 23 1925 1929 10.1002/marc.201100491 Institut für Chemie OPUS4-37100 Wissenschaftlicher Artikel Koeth, Anja; Appelhans, Dietmar; Robertson, Daniela; Tiersch, Brigitte; Koetz, Joachim Use of weakly cationic dendritic glycopolymer for morphological transformation of phospholipid vesicles into tube-like networks Using cationic polyelectrolytes with different molecular architectures, only hyperbranched poly(ethyleneimine) with maltose shell is suited to tailor the morphological transformation of anionic vesicles into tube-like networks. The interaction features of those materials partly mimic biological features of tubular proteins in nature. Cambridge Royal Society of Chemistry 2011 4 Soft matter 7 22 10581 10584 10.1039/c1sm06439h Institut für Chemie OPUS4-32988 Wissenschaftlicher Artikel Kleinpeter, Erich; Neuvonen, Kari; Neuvonen, Helmi; Koch, Andreas NBO analysis of polar and steric effect using the axial-equatorial equilibrium of cyclohexyl acetates as a probe 2011 Institut für Chemie OPUS4-34084 Wissenschaftlicher Artikel Stojanovic, Milovan; Markovic, Rade; Kleinpeter, Erich; Baranac-Stojanovic, Marija endo-Mode cyclizations of vinylogous N-acyliminium ions as a route to the synthesis of condensed thiazolidines 2011 Institut für Chemie OPUS4-32712 Wissenschaftlicher Artikel Kleinpeter, Erich; Marsat, Jean-Noël; Heydenreich, Matthias; von Berlepsch, Hans; Laschewsky, André Self-Assembly into Multicompartment Micelles and Selective Solubilization by Hydrophilic-Lipophilic- Fluorophilic Block Copolymers 2011 Institut für Chemie OPUS4-33963 Wissenschaftlicher Artikel Kleinpeter, Erich; Kirpichenko, Svetlana V.; Ushakov, Igor A.; Shainyan, Bagrat A. Conformational analysis of 3-methyl-3-silathiane and 3-fluoro-3-methyl-3-silathiane The conformational equilibria of 3-methyl-3-silathiane 5, 3-fluoro-3-methyl-3-silathiane 6 and 1-fluoro-1- methyl-1-silacyclohexane 7 have been studied using low temperature 13C NMR spectroscopy and theoretical calculations. The conformer ratio at 103;K was measured to be about 5ax:5eq;=;15:85, 6ax:6eq;=;50:50 and 7ax:7eq;=;25:75. The equatorial preference of the methyl group in 5 (0.35;kcal;mol;1) is much less than in 3-methylthiane 9 (1.40;kcal;mol;1) but somewhat greater than in 1-methyl-1- silacyclohexane 1 (0.23;kcal;mol;1). Compounds 5-7 have low barriers to ring inversion: 5.65 (ax;;;eq) and 6.0 (eq;;;ax) kcal mol;1 (5), 4.6 (6), 5.1 (Meax;;;Meeq) and 5.4 (Meeq;;;Meax) kcal;mol;1 (7). Steric effects cannot explain the observed conformational preferences, like equal population of the two conformers of 6, or different conformer ratio for 5 and 7. Actually, by employing the NBO analysis, in particular, considering the second order perturbation energies, vicinal stereoelectronic interactions between the Si-X and adjacent C-H, C-S, and C-C bonds proved responsible. 2011 Institut für Chemie OPUS4-33966 Wissenschaftlicher Artikel Kleinpeter, Erich; Koch, Andreas The anisotropic effect of functional groups in 1H NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl protons are either shielded or deshielded, respectively, due to the ringe current effect of the fluorene moiety. This anisotropic effect on the 1H chemical shifts of the methyl protons has been quantified on the basis of through- space NMR shieldings (TSNMRS) and subsequently _______ compared with the experimentally observed chemical shift differences _____. In this context, the experimental anisotropic effects of functional groups in the !H NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between _______ and _____ were, for the first time, also quantified as arising from steric compression. 2011 Institut für Chemie OPUS4-33519 Wissenschaftlicher Artikel Kleinpeter, Erich; Lammermann, Anica; Kühn, Heiner Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions. 2011 Institut für Chemie OPUS4-33066 Wissenschaftlicher Artikel Kleinpeter, Erich; Shainyan, Bagrat A.; Suslova, Elena N. Conformational analysis of 4,4-dimethyl-4-silathiane and its S-oxides 2011 Institut für Chemie OPUS4-32771 Wissenschaftlicher Artikel Kleinpeter, Erich; Pihlaja, Kalevi; Sinkkonen, Jari; Stájer, Gezá; Koch, Andreas 1-Oxo-1,3-dithiolanesùsynthesis and stereochemistry 1-Oxo-1,3-dithiolane (4) and its cis- andtrans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO4 in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with 1H and 13C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=Oax envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=Oax (30 and 27%) as well as S=Oeq (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of 1H-1H coupling constants and 1H and 13C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data. 2011 Institut für Chemie OPUS4-33215 Wissenschaftlicher Artikel Kleinpeter, Erich; Shainyan, Bagrat A.; Suslova, Elena N. Conformational analysis of N-phenyl- and N-trifyl-4,4-dimethyl-4-silathiane 1-sulfimides 2011 Institut für Chemie OPUS4-34055 Wissenschaftlicher Artikel Kleinpeter, Erich; Koch, Andreas Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS) 2011 Institut für Chemie OPUS4-36798 Wissenschaftlicher Artikel Jelicic, Aleksandra; Yasin, Muttaqin; Beuermann, Sabine Toward the description and prediction of solvent induced variations in Methacrylate Propagation Rate Coefficients on the basis of Solvatochromic Parameters Benzyl methacrylate (BzMA) propagation rate coefficients, k(p), were determined in ionic liquids and common organic solvents via pulsed-laser polymerizations with subsequent polymer analysis by size-exclusion chromatography (PLP-SEC). The aim of the work is to gain a deeper understanding of the solvent influence on k(p) and to develop a general correlation between solvent-induced variations in k(p) and solvent properties. Applying a linear solvation energy relationship (LSER), which correlates k(p) to solvent solvatochromic parameters, suggests that dipolarity/polarizability determines the solvent influence on k(p). To compare the solvent influence on BzMA k(p) with data for methyl methacrylate, hydroxypropyl methacrylate, and 2-ethoxyethyl methacrylate normalized k(p) data were treated by a single LSER, providing a universal treatment of the solvent influence on the propagation kinetics of the four monomers. Further, the predictive capabilities of this universal correlation were tested with additional monomers from the methacrylate family. Malden Wiley-Blackwell 2011 11 Macromolecular reaction engineering 5 5-6 232 242 10.1002/mren.201000058 Institut für Chemie OPUS4-36799 Wissenschaftlicher Artikel Kolocouris, Antonios; Zervos, Nikolaos; De Proft, Frank; Koch, Andreas Improper Hydrogen Bonded Cyclohexane C-H-ax center dot center dot center dot Y-ax Contacts theoretical predictions and experimental Evidence from H-1 NMR Spectroscopy of Suitable Axial Cyclohexane Models C-H-ax center dot center dot center dot Y-ax are a textbook prototype of steric hindrance in organic chemistry. The nature of these contacts is investigated in this work. MP2/6-31+G(d,p) calculations predicted the presence of improper hydrogen bonded C-H-ax center dot center dot center dot Y-ax of different strength in substituted cyclohexane rings. To support the theoretical predictions with experimental evidence, several synthetic 2-substituted adamantane analogues (1-24) with suitable improper H-bonded C-H-ax center dot center dot center dot Y-ax contacts of different strength were used as models of a substituted cyclohexane ring. The H-1 NMR signal separation, Delta delta(gamma-CH2), within the cyclohexane ring gamma-CH(2)s is raised when the MP2/6-31+G(d,p) calculated parameters, reflecting the strength of the H-bonded C-H-ax center dot center dot center dot Y-ax contact, are increased. In molecules with enhanced improper H-bonded contacts C-H-ax center dot center dot center dot Y-ax, like those having sterically crowded contacts (Y-ax = t-Bu) or contacts including considerable electrostatic attractions (Y-ax = O-C or O=C) the calculated DFT steric energies of the gamma-axial hydrogens are considerably reduced reflecting their electron cloud compression. The results suggest that the proton H-ax electron cloud compression, caused by the C-H-ax center dot center dot center dot Y-ax contacts, and the resulting increase in Delta delta(gamma-CH2) value can be effected not just from van der Waals spheres compression, but more generally from electrostatic attraction forces and van der Waals repulsion, both of which are improper H-bonding components. Washington American Chemical Society 2011 12 The journal of organic chemistry 76 11 4432 4443 10.1021/jo102353f Institut für Chemie OPUS4-36831 Wissenschaftlicher Artikel Schmidt, Bernd; Berger, René; Kelling, Alexandra; Schilde, Uwe Pd-Catalyzed [2+2+1] coupling of alkynes and arenes phenol diazonium salts as mechanistic trapdoors Alkynes and phenol diazonium salts undergo a Pd-catalyzed [2+2+1] cyclization reaction to spiro[4,5]decatetraene-7-ones. This structure was confirmed for one example by X-ray single-crystal structure analysis. The reaction is believed to proceed through oxidative addition of the phenol diazonium cation to Pd(0), subsequent insertion of two alkynes, followed by irreversible spirocyclization. Malden Wiley-Blackwell 2011 9 Chemistry - a European journal 17 25 7032 7040 10.1002/chem.201100609 Institut für Chemie OPUS4-36832 Wissenschaftlicher Artikel Antoniou, Stella; Pashalidis, Ioannis; Gessner, Andre; Kumke, Michael Uwe Spectroscopic investigations on the effect of humic acid on the formation and solubility of secondary solid phases of Ln(2)(CO3)(3) The formation of secondary Ln(III) solid phases (e.g., Nd-2(CO3)(3) and Sm-2(CO3)(3)) was studied as a function of the humic acid concentration in 0.1 mol/L NaClO4 aqueous solution in the neutral pH range (5-6.5). The solid phases under investigation were prepared by alkaline precipitation under 100% CO2 atmosphere and characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), time-resolved laser fluorescence spectroscopy (TRLFS), diffuse reflectance ultraviolet-visible (DR-UV-Vis), Raman spectroscopy, and solubility measurements. The spectroscopic data obtained indicated that Nd-2(CO3)(3) and Sm-2(CO3)(3) were stable and remained the solubility limiting solid phases even in the presence of increased humic acid concentration (0.5 g/L) in solution. Upon base addition in the Ln(III)-HA system, decomplexation of the previously formed Ln(III)-humate complexes and precipitation of two distinct phases occurred, the inorganic (Ln(2)(CO3)(3)) and the organic phase (HA), which was adsorbed on the particle surface of the former. Nevertheless, humic acid affected the particle size of the solid phases. Increasing humic acid concentration resulted in decreasing crystallite size of the Nd-2(CO3)(3) and increasing crystallite size of the Sm-2(CO3)(3) solid phase, and affected inversely the solubility of the solid phases. However, this impact on the solid phase properties was expected to be of minor relevance regarding the chemical behavior and migration of trivalent lanthanides and actinides in the geosphere. Amsterdam Elsevier 2011 6 Journal of rare earths 29 6 516 521 10.1016/S1002-0721(10)60490-5 Institut für Chemie OPUS4-36848 Wissenschaftlicher Artikel Baranac-Stojanovic, Marija; Keinpeter, Erich Quantification of the aromaticity of 2-Alkylidenethiazolines subjected to push-pull activity Through-space NMR shieldings (TSNMRSs) of a series of 2-alkylidenethiazolines subjected to push-pull activity have been calculated by the GIAO method employing the nucleus-independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSSs). The ICSSs were applied to quantify and visualize the degree of aromaticity of the studied compounds, which has been shown to be in excellent correlation with the push-pull behavior, quantified by the quotient (pi*/pi) method. Dissection of the absolute magnetic shielding values into individual contributions of bonds and lone pairs by the natural chemical shielding-natural bond orbital (NCS-NBO) analysis has revealed unexpected details. Washington American Chemical Society 2011 11 The journal of organic chemistry 76 10 3861 3871 10.1021/jo200294f Institut für Chemie OPUS4-36840 Wissenschaftlicher Artikel Poghosyan, Armen H.; Arsenyan, Levon H.; Gharabekyan, Hrant H.; Falkenhagen, Sandra; Koetz, Joachim; Shahinyan, Aram A. Molecular dynamics simulations of inverse sodium dodecyl sulfate (SDS) micelles in a mixed toluene/pentanol solvent in the absence and presence of poly(diallyldimethylammonium chloride) (PDADMAC) We have performed a 15 ns molecular dynamics simulation of inverse sodium dodecyl sulfate (SDS) micelles in a mixed toluene/pentanol solvent in the absence and presence of a cationic polyelectrolyte, i.e. poly(diallyldimethylammonium chloride) (PDADMAC). The NAMD code and CHARMM force field were used. During the simulation time, the radii of SOS inverse micelles changed and the radii of the water droplets have been calculated. The behavior of SDS hydrocarbon chains has been characterized by calculating the orientation order parameter and the chain average length. The water droplet properties (water flow, water molecules displacement) have been examined. In summary the MD simulations indicate a more rigid and ordered surfactant film due to the formation of a polyelectrolyte palisade layer in full agreement with the experimental findings, e.g. the viscosity increase and shift of the percolation boundary. San Diego Elsevier 2011 7 Journal of colloid and interface science 358 1 175 181 10.1016/j.jcis.2011.01.091 Institut für Chemie OPUS4-36865 Wissenschaftlicher Artikel Kafka, Stanislav; Hauke, Sylvia; Salcinovic, Arjana; Soidinsalo, Otto; Urankar, Damijana; Kosmrlj, Janez Copper(I)-Catalyzed [3+2] Cycloaddition of 3-Azidoquinoline-2,4(1H,3H)-diones with terminal alkynes 3-Azidoquinoline-2,4(1H,3H)-diones 1, which are readily available from 4-hydroxyquinolin-2(1H)-ones 4 via 3-chloroquinoline-2,4(1H, 3H)-diones 5, afford, in copper(I)-catalyzed [3 + 2] cycloaddition reaction with terminal acetylenes, 1,4-disubstituted 1,2,3-triazoles 3 in moderate to excellent yields. The structures of compounds 3 were confirmed by (1)H and (13)C-NMR spectroscopy, combustion analyses and mass spectrometry. Basel MDPI 2011 12 Molecules 16 5 4070 4081 10.3390/molecules16054070 Institut für Chemie OPUS4-36855 Wissenschaftlicher Artikel Adamovich, Sergey N.; Mirskova, Anna N.; Mirskov, Rudolf G.; Schilde, Uwe Synthesis and crystal structure of 1,4,10,13-tetraoxa-7,16-diazoniumcyclo-octadecane bis(4-chloro-2-methyl-phenoxyacetate) The title compound was prepared by the reaction of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane with 4-chloro-2-methyl-phenoxyacetic acid in a ratio of 1:2. The structure has been proved by the data of elemental analysis, IR spectroscopy, NMR ((1)H, (13)C) technique and by X-ray diffraction analysis. Intermolecular hydrogen bonds between the azonium protons and oxygen atoms of the carboxylate groups were found. Immunoactive properties of the title compound have been screened. The compound has the ability to suppress spontaneous and Con A-stimulated cell proliferation in vitro and therefore can be considered as immunodepressant. London BioMed Central 2011 4 Chemistry central journal 5 17 10.1186/1752-153X-5-23 Institut für Chemie OPUS4-36856 Wissenschaftlicher Artikel Tremblay, Jean Christophe Laser control of molecular excitations in stochastic dissipative media In the present work, ideas for controlling photochemical reactions in dissipative environments using shaped laser pulses are presented. New time-local control algorithms for the stochastic Schrodinger equation are introduced and compared to their reduced density matrix analog. The numerical schemes rely on time-dependent targets for guiding the reaction along a preferred path. The methods are tested on the vibrational control of adsorbates at metallic surfaces and on the ultrafast electron dynamics in a strong dissipative medium. The selective excitation of the specific states is achieved with improved yield when using the new algorithms. Both methods exhibit similar convergence behavior and results compare well with those obtained using local optimal control for the reduced density matrix. The favorable scaling of the methods allows to tackle larger systems and to control photochemical reactions in dissipative media of molecules with many more degrees of freedom. Melville American Institute of Physics 2011 16 The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr 134 17 10.1063/1.3587093 Institut für Chemie OPUS4-36858 Wissenschaftlicher Artikel Fechner, Mabya; Koetz, Joachim Polyampholyte-Surfactant film tuning in reverse microemulsions The pH-dependent influence of two different strongly alternating copolymers [poly(N,N'-diallyl-N,N'-dimethylammonium-alt-N-phenylmaleamic carboxylate) (PalPh) and poly(N,N'-diallyl-N,a-dimethylammonium-alt-3,5-bis(carboxyphenyl) maleamic carboxylate) (PalPhBisCarb)] based on N,N'-diallyl-N, -dimethylarnmonium chloride and maleamic acid derivatives on the phase behavior of a water-in-oil (w/o) microemulsion system made from toluene pentanol (1:1) and sodium dodecyl sulfate was investigated. It was shown that the optically dear phase range can be extended after incorporation of these copolymers, leading to an increased water solubilization capacity. Additionally, the required amount of surfactant to establish a clear w/o microemulsion depends on the pH value, which means the hydrophobicity of the copolymers. Conductivity measurements show that droplet droplet interactions in the w/o microemulsion are decreased at acidic but increased at alkaline pH in the presence of the copolymers. From differenctial scanning calorimetry measurements one can further conclude that these results are in agreement with a change of the position of the copolymer in the interfacial region of the surfactant film. The more hydrophobic PalPh can be directly incorporated into the surfactant film, whereas the phenyl groups of PalPhBisCarb flip into the water core by increasing the pH value. Washington American Chemical Society 2011 8 Langmuir 27 9 5316 5323 10.1021/la200791k Institut für Chemie OPUS4-36862 Wissenschaftlicher Artikel Dudek, Melanie; Clegg, Jack K.; Glasson, Christopher R. K.; Kelly, Norman; Gloe, Kerstin; Gloe, Karsten; Kelling, Alexandra; Buschmann, Hans-Jürgen; Jolliffe, Katrina A.; Lindoy, Leonard F.; Meehan, George V. Interaction of Copper(II) with Ditopic Pyridyl-beta-diketone Ligands dimeric, framework, and metallogel structures The interaction of Cu(II) with three beta-diketone ligands of type R(1)C(O)CH(2)C(O)R(2) (where R(1) = 2-, 3-, or 4-pyridyl and R(2) = C(6)H(5), respectively), HL(1)-HL(3), along with the X-ray structures and the pK(a) values of each ligand, are reported. HL(1) yields a dimeric complex of type [Cu(L(1))(2)](2). In this structure, two deprotonated HL(1) ligands coordinate in a trans planar fashion around each Cu(II) center, one oxygen from each CuL(2) unit bridges to an axial site of the second complex unit such that both Cu(II) centers attain equivalent five-coordinate square pyramidal geometries. The two-substituted pyridyl groups in this complex do not coordinate, perhaps reflecting steric factors associated with the closeness of the pyridyl nitrogen to the attached (conjugated) beta-diketonato backbone of each ligand. The remaining two Cu(II) species, derived from HL(2) and HL(3), are both coordination polymers of type [Cu(L)(2)](n) in which the terminal pyridine group of each ligand is intermolecularly linked to an adjacent copper center to generate the respective infinite structures. HL(2) was also demonstrated to form a fibrous metallogel when reacted with CuCl(2) in an acetonitrile/water mixture under defined conditions. Washington American Chemical Society 2011 8 Crystal growth & design : integrating the fields of crystal engineering and crystal growth for the synthesis and applications of new materials 11 5 1697 1704 10.1021/cg101629w Institut für Chemie OPUS4-36818 Wissenschaftlicher Artikel Lahn, Mattes; Dosche, Carsten; Hille, Carsten Two-photon microscopy and fluorescence lifetime imaging reveal stimulus-induced intracellular Na+ and Cl- changes in cockroach salivary acinar cells Lahn M, Dosche C, Hille C. Two-photon microscopy and fluorescence lifetime imaging reveal stimulus-induced intracellular Na+ and Cl- changes in cockroach salivary acinar cells. Am J Physiol Cell Physiol 300: C1323-C1336, 2011. First published February 23, 2011; doi: 10.1152/ajpcell.00320.2010.-The intracellular ion homeostasis in cockroach salivary acinar cells during salivation is not satisfactorily understood. This is mainly due to technical problems regarding strong tissue autofluorescence and ineffective ion concentration quantification. For minimizing these problems, we describe the successful application of two-photon (2P) microscopy partly in combination with fluorescence lifetime imaging microscopy (FLIM) to record intracellular Na+ and Cl- concentrations ([Na+](i), [Cl-](i)) in cockroach salivary acinar cells. Quantitative 2P-FLIM Cl- measurements with the dye N-(ethoxycarbonylmethyl)-6-methoxy-quinolinium bromide indicate that the resting [Cl-](i) is 1.6 times above the Cl- electrochemical equilibrium but is not influenced by pharmacological inhibition of the Na+-K+-2Cl(-) cotransporter (NKCC) and anion exchanger using bumetanide and 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid disodium salt. In contrast, rapid Cl- reuptake after extracellular Cl- removal is almost totally NKCC mediated both in the absence and presence of dopamine. However, in physiological saline [Cl-](i) does not change during dopamine stimulation although dopamine stimulates fluid secretion in these glands. On the other hand, dopamine causes a decrease in the sodium-binding benzofuran isophthalate tetra-ammonium salt (SBFI) fluorescence and an increase in the Sodium Green fluorescence after 2P excitation. This opposite behavior of both dyes suggests a dopamine-induced [Na+](i) rise in the acinar cells, which is supported by the determined 2P-action cross sections of SBFI. The [Na+](i) rise is Cl- dependent and inhibited by bumetanide. The Ca2+-ionophore ionomycin also causes a bumetanide-sensitive [Na+](i) rise. We propose that a Ca2+-mediated NKCC activity in acinar peripheral cells attributable to dopamine stimulation serves for basolateral Na+ uptake during saliva secretion and that the concomitantly transported Cl- is recycled back to the bath. Bethesda American Chemical Society 2011 14 American journal of physiology : Cell physiology 300 6 C1323 C1336 10.1152/ajpcell.00320.2010 Institut für Chemie OPUS4-36809 Wissenschaftlicher Artikel Cockburn, Robert A.; Siegmann, Rebekka; Payne, Kevin A.; Beuermann, Sabine; McKenna, Timothy F. L.; Hutchinson, Robin A. Free Radical Copolymerization Kinetics of gamma-Methyl-alpha-methylene-gamma-butyrolactone (MeMBL) The propagation kinetics and copolymerization behavior of the biorenewable monomer gamma-methyl-alpha-methylene-gamma-butyrolactone (MeMBL) are studied using the Pulsed laser polymerization (PLP)/size exclusion chromatography (SEC) technique. The propagation rate coefficent for MeMBL is 15% higher than that of its structural analogue, methyl methacrylate (MMA), with a similar activation energy of 21.8 kJ . mol(-1). When compared to MMA, MeMBL is preferentially incorporated into copolymers when reacted with styrene (ST), MMA, and n-butyl acrylate (BA); the monomer reactivity ratios fit from bulk MeMBL/ST, MeMBL/MMA, and MeMBL/BA copolymerizations are r(MeMBL) = 0.80 +/- 0.04 and r(ST) = 0.34 +/- 0.04, r(MeMBL), = 3.0 +/- 0.3 and r(MMA) = 0.33 +/- 0.01, and r(MeMBL) = 7.0 +/- 2.0 and r(BA) = 0.16 +/- 0.03, respectively. In all cases, no significant variation with temperature was found between 50 and 90 degrees C. The implicit penultimate unit effect (IPUE) model was found to adequately fit the composition-averaged copolymerization propagation rate coefficient, k(p,cop), for the three systems. Washington American Chemical Society 2011 8 Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences 12 6 2319 2326 10.1021/bm200400s Institut für Chemie OPUS4-36743 Wissenschaftlicher Artikel Wessig, Pablo; Pick, Charlotte Photochemical synthesis and properties of axially chiral naphthylpyridines Five alkynyl pyridines were prepared and cyclized to naphthylpyridines as the main products in the course of a Photo-Dehydro-Diels-Alder reaction. Four of the final products are axially chiral and the determination of the rotational barrier by DFT calculations, dynamic NMR and H PLC experiments is demonstrated. (C) 2011 Elsevier B.V. All rights reserved. Lausanne Elsevier 2011 3 Journal of photochemistry and photobiology : A, Chemistry 222 1 263 265 10.1016/j.jphotochem.2011.06.006 Institut für Chemie OPUS4-36713 Wissenschaftlicher Artikel Shainyan, Bagrat A.; Suslova, Elena N.; Kleinpeter, Erich Conformational analysis of N-phenyl- and N-trifyl-4,4-dimethyl-4-silathiane 1-sulfimides N-Substituted 4,4-dimethyl-4-silathiane 1-sulfimides Me2Si(sic)S=NSO2R [R- Ph (1), CF3 (2)] were studied experimentally by variable temperature dynamic NMR spectroscopy. Low temperature 13 C NMR spectra of the two compounds revealed the frozen ring inversion process and approximately equal content of the axial and equatorial conformers. Calculations of the 4-silathiane derivatives 1, 2 and the model compound [R Me (3)] as well as their carbon analogs, the similarly N-substituted (sic)S=NSO2R thiane 1-sulfimides [R = Ph (4), CF3 (5), Me (6)] at the DFT/B3LYP/6-311G(d, p) level in the gas phase and in chloroform solution using the PCM model at the same level of theory showed a strong dependence of the relative stability of the conformer on the solvent. The electronegative trifluoromethyl group increases the relative stability of the axial conformer. Malden Wiley-Blackwell 2011 7 Journal of physical organic chemistry 24 8 698 704 10.1002/poc.1811 Institut für Chemie OPUS4-36764 Wissenschaftlicher Artikel Pihlaja, Kalevi; Sinkkonen, Jari; Stajer, Geza; Koch, Andreas; Kleinpeter, Erich 1-Oxo-1,3-dithiolanes - synthesis and stereochemistry 1-Oxo-1,3-dithiolane (4) and its cis- and trans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO(4) in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with (1)H and (13)C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=O(ax) envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=O(ax) (30 and 27%) as well as S=O(eq) (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of (1)H-(1)H coupling constants and (1)H and (13)C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data. Malden Wiley-Blackwell 2011 7 Magnetic resonance in chemistry 49 7 443 449 10.1002/mrc.2764 Institut für Chemie OPUS4-36699 Wissenschaftlicher Artikel Kozlevcar, Bojan; Gamez, Patrick; de Gelder, Rene; Jaglicic, Zvonko; Strauch, Peter; Kitanovski, Nives; Reedijk, Jan Counterion and solvent effects on the primary coordination sphere of copper(II) Bis(3,5-dimethylpyrazol-1-yl)acetic acid coordination compounds Four copper(II) coordination compounds with the neutral ligand bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza, C(12)H(16)N(4)O(2)) and its anionic form (bdmpza(-)), namely [Cu(Hbdmpza)(2)](HSO(4))(2) (1), [Cu(Hbdmpza)(2)]Cl(2) (2), [Cu(bdmpza)(2)](CH(3)COOH)(H(2)O) (3), and [Cu(bdmpza)(2)][Cu(2)(O(2)CCH(3))(4)] (4) have been synthesized starting from different metal salts. All the compounds have been fully characterized by physical and analytical methods. In addition, a single-crystal XRD analysis revealed the 3D structure of 1, which exhibits tridentate, vicinal N,N,O-coordination of two symmetry-related Hbdmpza ligands in an elongated octahedral arrangement with four equatorial nitrogen atoms and two axial oxygen atoms. The neutral carboxylic moiety acts as a hydrogen-bond donor to a HSO(4)(-) counterion. The two hydrogensulfates form a unique hydrogen-bonded pair (HSO(4)(-))(2) with very short O center dot center dot center dot O distances (2.59 angstrom) bridged between adjacent [Cu(HL)(2)](2+) coordination units. Also a short O center dot center dot center dot O contact (2.54 angstrom) is present between the C-OH and an 0 of a hydrogensulfate. A characteristic IR C=O vibration is observed at 1700 cm(-1) for 1 and 2, whereas the v(as)(O(2)C) vibration is present at 1650 cm(-1) for 3 and 4. These IR data strongly suggest the presence of Hbdmpza ligands in 1 and 2 and the deprotonated form bdmpza- in 3 and 4. A mononuclear coordination unit [CuL(2)], as proven for 1 by X-ray diffraction, is also proposed for the other compounds 2-4. In compound 4, an additional dinuclear [Cu(2)(O(2)CCH(3))(4)] neutral coordination unit is present, as deduced from the vibration bands v(as)(O(2)C) at 1600 cm(-1) and v(s)(O(2)C) at 1420 cm(-1), which are typical of a carboxylate function, and from the two-species analysis of the chi(M)T(T) curve of the magnetic susceptibility data (2J = -322 cm(-1)). Also, the EPR spectra recorded at different temperatures agree with this structure. Malden Wiley-Blackwell 2011 6 European journal of inorganic chemistry : a journal of ChemPubSoc Europe 24 3650 3655 10.1002/ejic.201100410 Institut für Chemie OPUS4-36444 Wissenschaftlicher Artikel Radziuk, Darya; Skirtach, Andre; Gessner, Andre; Kumke, Michael Uwe; Zhang, Wei; Möhwald, Helmuth; Shchukin, Dmitry Ultrasonic Approach for Formation of Erbium Oxide Nanoparticles with Variable Geometries Ultrasound (20 kHz, 29 W. cm(-2)) is employed to form three types of erbium oxide nanoparticles in the presence of multiwalled carbon nanotubes as a template material in water. The nanoparticles are (i) erbium carboxioxide nanoparticles deposited on the external walls of multiwalled carbon nanotubes and Er(2)O(3) in the bulk with (ii) hexagonal and (iii) spherical geometries. Each type of ultrasonically formed nanoparticle reveals Er(3+) photoluminescence from crystal lattice. The main advantage of the erbium carboxioxide nanoparticles on the carbon nanotubes is the electromagnetic emission in the visible region, which is new and not examined up to the present date. On the other hand, the photoluminescence of hexagonal erbium oxide nanoparticles is long-lived (mu s) and enables the higher energy transition ((4)S(3/2)-(4)I(15/2)), which is not observed for spherical nanoparticles. Our work is unique because it combines for the first time spectroscopy of Er(3+) electronic transitions in the host crystal lattices of nanoparticles with the geometry established by ultrasound in aqueous solution of carbon nanotubes employed as a template material. The work can be of great interest for "green" chemistry synthesis of photoluminescent nanoparticles in water. Washington American Chemical Society 2011 9 Langmuir 27 23 14472 14480 10.1021/la203622u Institut für Chemie OPUS4-36501 Wissenschaftlicher Artikel Wessig, Pablo; Wawrzinek, Robert; Moellnitz, Kristian; Feldbusch, Elvira; Schilde, Uwe A new class of fluorescent dyes based on 1,3-benzodioxole and [1,3]-dioxolo[4.5-f]benzodioxole We report on synthesis and photophysical properties of a new class of fluorescent dyes. They are characterized by large Stokes-shifts, long fluorescence lifetimes in organic solvents and a pronounced dependency of the fluorescence lifetime on the solvent polarity. Also worthy of note is the high bleaching stability. To provide access to biochemical and medical applications a series of derivatives were prepared, which exhibit specific reactivity towards different biologically relevant functional groups (carboxylic acids, amines, maleimides, N-hydroxysuccinimide esters). Furthermore, two alkynes were prepared, which could be used in 'Click' chemistry. Oxford Elsevier 2011 4 Tetrahedron letters 52 46 6192 6195 10.1016/j.tetlet.2011.09.058 Institut für Chemie OPUS4-36475 Wissenschaftlicher Artikel Schmidt, Bernd; Geissler, Diana Olefin-Metathesis-Based Synthesis of Furans by an RCM/Deprotonation/Phosphorylation Sequence and Their Diels-Alder Reactions Butenolides, obtained by ring-closing metathesis (RCM) of acrylates, undergo quantitative deprotonation with amide bases. Trapping of the resulting anions with electrophiles, for example, chlorophosphates, give furans. Subsequent DielsAlder reaction and acid-catalysed rearrangement of the resulting oxabicyclonorbornadienes give substituted benzenes. Weinheim Wiley-VCH 2011 8 European journal of organic chemistry 35 7140 7147 10.1002/ejoc.201101078 Institut für Chemie OPUS4-36434 Wissenschaftlicher Artikel Fechner, Mabya; Koetz, Joachim Potentiometric behavior of Polyampholytes based on N,N'-diallyl-N,N'-dimethylammonium chloride and maleamic acid derivatives Strongly alternating copolymers (PalH, PalPh, PalPhBisCarb) composed of N,N'-diallyl-N,N'-dimethyl-ammonium chloride (DADMAC) and maleamic acid derivatives (MAD) are synthesized by a water-based free radical copolymerization using 4,4-azobis(4-cyanovaleric acid) (V501) as the initiator. The structure of the copolymers is verified by 1H-NMR, elemental analysis, and thermogravimetric measurements, and the physicochemical properties are investigated by viscometric and potentiometric techniques. Potentiometric titration curves show that the acidity of the carboxylic groups strongly depends on the degree of dissociation and the ionic strength. Since all copolymers behave as polycations at low degree of dissociation, a transition from an extended chain to a coil conformation can be identified by reaching the isoelectric point (IEP). Malden Wiley-Blackwell 2011 9 Macromolecular chemistry and physics 212 24 2691 2699 10.1002/macp.201100532 Institut für Chemie OPUS4-36436 Wissenschaftlicher Artikel Kristen-Hochrein, Nora; Laschewsky, André; Miller, Reinhard; von Klitzing, Regine Stability of foam Films of oppositely charged polyelectrolyte/surfactant mixtures - effect of isoelectric point In the present paper, the influence of the surfactant concentration and the degree of charge of a polymer on foam film properties of oppositely charged polyelectrolyte/surfactant mixtures has been investigated. To verify the assumption that the position of the isoelectric point (IEP) does not change the character of the foam film stabilities, the position of the IEP of the polyelectrolyte/surfactant mixtures has been shifted in two different ways. Within the first series of experiments, the foam. film properties were studied using a fixed surfactant concentration of 3 x 10(-5) M in the mixture. Due to the low surfactant concentration, this is a rather dilute system. In the second approach, a copolymer of nonionic and ionic monomer units was Used to lower the charge density of the polymer. This gave rise to additional interactions between the polyelectrolyte and the surfactant, which makes the description of the foam film behavior more complex. In both systems, the same characteristics of the foam film stabilities were found: The foam film stability is reduced toward the IEP of the system, followed by a destabilization around the IEP., At polyelectrolyte concentrations above the IEP, foam films are very stable. However, the concentration range where unstable films were formed was rather broad, and the mechanisms leading to the destabilization had different origins. The results were compared with former findings on PAMPS/C(14)TAB mixtures with an IEP of 10(-4)M.(1) Washington American Chemical Society 2011 9 The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry 115 49 14475 14483 10.1021/jp206964k Institut für Chemie OPUS4-36439 Wissenschaftlicher Artikel Stojanovic, Milovan; Markovic, Rade; Kleinpeter, Erich; Baranac-Stojanovic, Marija Endo-Mode cyclizations of vinylogous N-acyliminium ions as a route to the synthesis of condensed thiazolidines endo-Mode cyclizations of vinylogous N-acyliminium ions incorporating heteroatom-based nucleophiles have been examined as a route to the synthesis of condensed thiazolidines. The scope of these reactions and stereochemical outcome are discussed and explained using quantum chemical calculations. Oxford Elsevier 2011 14 Tetrahedron 67 49 9541 9554 10.1016/j.tet.2011.10.011 Institut für Chemie OPUS4-36508 Wissenschaftlicher Artikel Kröner, Dominik; Krüger, Hartmut; Thesen, Manuel W. Electronic structure calculations for Hole-Transporting Triphenylamine Derivatives in Polymer Light-Emitting Diodes Hole-transporting polymers based on polyethene-triphenylamine derivatives are investigated with respect to their UV/Vis spectra. Two substituents, N-phenyl-1-naphthylamine and carbazole, are examined as their respective polymer light-emitting diodes (PLEDs) show very different luminous efficiencies. In order to identify the origin of these phenomena electronic structure calculations based on TD-DFT were performed using monomer models of the hole-transporting polymers. In experiment these hole-transporting polymers show very specific differences in their absorption and emission (fluorescence and phosphorescence) spectra. The analysis of the simulated absorption and emission spectra, the MOs as well as the ground and excited state geometries give explanations for the different optical performances of the corresponding PLEDs. Malden Wiley-Blackwell 2011 16 Macromolecular theory and simulations 20 9 790 805 10.1002/mats.201100016 Institut für Chemie OPUS4-36486 Wissenschaftlicher Artikel Nikolaus, Jörg; Czapla, Sylvia; Möllnitz, Kristian; Höfer, Chris T.; Herrmann, Andreas; Wessig, Pablo; Müller, Peter New molecular rods - Characterization of their interaction with membranes Molecular rods are synthetical molecules consisting of a hydrophobic backbone which are functionalized with varying terminal groups. Here, we report on the interaction of a recently described new class of molecular rods with lipid and biological membranes. In order to characterize this interaction, different fluorescently labeled rods were synthesized allowing for the application of fluorescence spectroscopy and microscopy based approaches. Our data show that the rods are incorporated into membranes with a perpendicular orientation to the membrane surface and enrich preferentially in liquid-disordered lipid domains. These characteristics underline that rods can be applied as stable membrane-associated anchors for functionalizing membrane surfaces. Amsterdam Elsevier 2011 8 Biochimica et biophysica acta : Biomembranes 1808 12 2781 2788 10.1016/j.bbamem.2011.08.008 Institut für Chemie OPUS4-36427 Wissenschaftlicher Artikel Zehm, Daniel; Laschewsky, André; Liang, Hua; Rabe, Jürgen P. Straightforward access to amphiphilic dual bottle brushes by combining RAFT, ATRP, and NMP polymerization in one sequence Molecular brush diblock copolymers were synthesized by the orthogonal overlay of the RAFT (reversible addition-fragmentation chain transfer), the ATRP (atom transfer radical polymerization), and the NMP (nitroxide-mediated polymerization) techniques. This unique combination enabled the synthesis of the complex amphiphilic polymers without the need of postpolymerization modifications, using a diblock copolymer intermediate made from two selectively addressable inimers and applying a sequence of four controlled free radical polymerization steps in total. The resulting polymers are composed of a thermosensitive poly(N-isopropylacrylamide) brush as hydrophilic block and a polystyrene brush as hydrophobic block, thus translating the structure of the established amphiphilic diblock copolymers known as macro surfactants to the higher size level of "giant surfactants". The dual molecular brushes and the aggregates formed on ultra flat solid substrates were visualized by scanning force microscopy (SFM). Washington American Chemical Society 2011 7 Macromolecules : a publication of the American Chemical Society 44 24 9635 9641 10.1021/ma2015613 Institut für Chemie OPUS4-36429 Wissenschaftlicher Artikel Kröner, Dominik Chiral distinction by ultrashort laser pulses electron wavepacket dynamics incorporating magnetic interactions The qualitative and quantitative distinction of enantiomers is one of the key issues in chemical analysis. In the last years, circular dichroism (CD) has been combined with laser ionization mass spectrometry (LIMS), applying resonance enhanced multiphoton ionization (REMPI) with ultrashort laser pulses. We present theoretical investigations on the CD in the populations of the first electronic excited state of the REMPI process, caused by the interaction of 3-methylcyclopentanone with either left or right circular polarized fs-laser pulses. For this we performed multistate laser driven many electron dynamics based on ab initio electronic structure calculations, namely, TD-CIS(D)/6-311++(2d,2p). For a theoretical description of these experiments, a complete description of the field-dipole correlation is mandatory, including both electric field electric dipole and magnetic field magnetic dipole interactions. The effect of various pulse parameters on the CD are analyzed and compared with experimental results to gain further understanding of the key elements for an optimal distinction of enantiomers. Washington American Chemical Society 2011 9 The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory 115 50 14510 14518 10.1021/jp207270s Institut für Chemie OPUS4-36453 Wissenschaftlicher Artikel Fudickar, Werner; Linker, Torsten Reversible Photooxygenation of Alkynylanthracenes chemical generation of singlet oxygen under very mild conditions Weinheim Wiley-VCH 2011 4 Chemistry - a European journal 17 49 13661 13664 10.1002/chem.201102230 Institut für Chemie OPUS4-36455 Wissenschaftlicher Artikel Bland-Hawthorn, Joss; Ellis, S. C.; Leon-Saval, S. G.; Haynes, R.; Roth, Martin M.; Löhmannsröben, Hans-Gerd; Horton, A. J.; Cuby, J. -G.; Birks, T. A.; Lawrence, J. S.; Gillingham, P.; Ryder, S. D.; Trinh, C. A complex multi-notch astronomical filter to suppress the bright infrared sky A long-standing and profound problem in astronomy is the difficulty in obtaining deep near-infrared observations due to the extreme brightness and variability of the night sky at these wavelengths. A solution to this problem is crucial if we are to obtain the deepest possible observations of the early Universe, as redshifted starlight from distant galaxies appears at these wavelengths. The atmospheric emission between 1,000 and 1,800 nm arises almost entirely from a forest of extremely bright, very narrow hydroxyl emission lines that varies on timescales of minutes. The astronomical community has long envisaged the prospect of selectively removing these lines, while retaining high throughput between them. Here we demonstrate such a filter for the first time, presenting results from the first on-sky tests. Its use on current 8 m telescopes and future 30 m telescopes will open up many new research avenues in the years to come. London Nature Publ. Group 2011 7 Nature Communications 2 50 10.1038/ncomms1584 Institut für Chemie OPUS4-36936 Wissenschaftlicher Artikel Kirpichenko, Svetlana V.; Kleinpeter, Erich; Ushakov, Igor A.; Shainyan, Bagrat A. Conformational Analysis of 3-Methyl-3-Silathiane and 3-Fluoro-3-Methyl-3-Silathiane The conformational equilibria of 3-methyl-3-silathiane 5, 3-fluoro-3-methyl-3-silathiane 6 and 1-fluoro-1-methyl-1- silacyclohexane 7 have been studied using low temperature C-13 NMR spectroscopy and theoretical calculations. The conformer ratio at 103 K was measured to be about 5(ax):5(eq) - 15:85, 6(ax):6(eq)-50:50 and 7(ax):7(eq)-25:75. The equatorial preference of the methyl group in 5 (0.35 kcal mol(-1)) is much less than in 3-methylthiane 9 (1.40 kcal mol(-1)) but somewhat greater than in 1-methyl-1-silacyclohexane 1 (0.23 kcal mol(-1)). Compounds 5-7 have low barriers to ring inversion: 5.65 (ax -> eq) and 6.0 kcal mol(-1) (eq -> ax) (5), 4.6 kcal mol(-1) (6), 5.1 kcal mol(-1) (Me-ax -> Me-eq), and 5.4 kcal mol(-1) (Me-eq -> Me-ax) (7). Steric effects cannot explain the observed conformational preferences, like equal population of the two conformers of 6, or different conformer ratio for 5 and 7. Actually, by employing the NBO analysis, in particular, considering the second order perturbation energies, vicinal stereoelectronic interactions between the Si-X and adjacent C-H, C-S, and C-C bonds proved responsible. Hoboken Wiley-Blackwell 2011 7 Journal of physical organic chemistry 24 4 320 326 10.1002/poc.1758 Institut für Chemie OPUS4-36940 Wissenschaftlicher Artikel Yin, Jian; Linker, Torsten Stereoselective diversity-oriented syntheses of functionalized saccharides from bicyclic carbohydrate 1,2-lactones Bicyclic carbohydrate 1,2-lactones have been synthesized in only two steps and high yields by saponification and subsequent cyclization from known malonate addition products to glycals. The gluco-configured lactone serves as an important precursor for diversity-oriented syntheses. Thus, stereoselective opening of the lactone ring was realized with various nucleophiles in the presence of Sc(OTf)(3). This enabled the introduction of different substituents at the anomeric position, to afford a broad variety of 1-functionalized carbohydrates. On the other hand, stereoselective alpha-substitution of the gluco-configured lactone with different electrophiles and subsequent ring opening gives a collection of 2-functionalized saccharides. More than 30 products have been isolated in analytically pure form, and their configurations were unequivocally established by various NMR methods. Thus, carbohydrate 1,2-lactones are attractive precursors for the stereoselective synthesis of diverse saccharides. Oxford Elsevier 2011 15 Tetrahedron 67 13 2447 2461 10.1016/j.tet.2011.01.069 Institut für Chemie OPUS4-36880 Wissenschaftlicher Artikel Vidadala, Srinivasa Rao; Pimpalpalle, Tukaram M.; Linker, Torsten; Hotha, Srinivas Gold-Catalyzed reactions of 2-C-Branched carbohydrates mild glycosidations and selective anomerizations 2-C-branched methyl glycosides react with various alcohols under gold catalysis to transglycosylated products. The method is applicable for the convenient synthesis of disaccharides. Without nucleophile a selective anomerization occurs, giving first access to alpha-configured 2-C-nitromethyl glycosides. The results are interesting for the mechanism of gold-catalyzed glycosidations. Malden Wiley-Blackwell 2011 5 European journal of organic chemistry 13 2426 2430 10.1002/ejoc.201100134 Institut für Chemie OPUS4-36898 Wissenschaftlicher Artikel Vukicevic, Radovan; Beuermann, Sabine Fullerenes decorated with poly(vinylidene fluoride) Fullerenes decorated with poly(vinylidene fluoride) (PVDF) were synthesized in a three-step procedure: Iodine transfer polymerization of vinylidene fluoride with C(6)F(12)I(2) as the chain transfer agent was carried out in supercritical carbon dioxide to synthesize iodine-terminated PVDF, which was subsequently transformed to azide-terminated polymer. Finally, azide-terminated PVDF chains were attached to a fullerene core under microwave irradiation at 160 degrees C in 1.5 h. The materials were characterized by NMR, FT-IR, UV/vis, GPC, elemental analysis, and DSC. On average, 4-5 PVDF chains are attached to one C(60) moiety. FT-IR spectra and DSC measurements indicate that the polymer end groups strongly affect the crystallinity of the material. For PVDF with azide end groups and PVDF attached to fullerenes the fraction of the beta polymorph is dominant while alpha polymorphs are almost absent. Washington American Chemical Society 2011 7 Macromolecules : a publication of the American Chemical Society 44 8 2597 2603 10.1021/ma102754c Institut für Chemie OPUS4-36902 Wissenschaftlicher Artikel Weiss, Jan; Laschewsky, André Temperature-induced self-assembly of triple-responsive triblock copolymers in aqueous solutions A series of triple-thermoresponsive triblock copolymers from poly(N-n-propylacrylamide) (PNPAM, A), poly(methoxydiethylene glycol acrylate) (PMDEGA, B), and poly(N-ethylacrylamide) (PNEAM, C) was synthesized by sequential reversible addition-fragmentation chain transfer polymerizations. Polymers of differing block sequences, ABC, BAC, and ACB, with increasing phase transition temperatures in the order A < B < C were prepared. Their aggregation behavior in dilute aqueous solution was investigated using dynamic light scattering, turbidimetry, and NMR spectroscopy. The self-organization of such polymers was found to dependent strongly on the block sequence. While polymers with a terminal low-LCST (lower critical solution temperature) block undergo aggregation above the first phase transition temperature at 20-25 degrees C, triblock copolymers with the low-LCST block in the middle show aggregation only above the second phase transition. The collapse of the middle block is not sufficient to induce aggregation but produces instead stable, unimolecular micelles with a collapsed middle block, as supported by NMR and fluorescence probe data. Continued heating of all copolymers led to two additional thermal transitions at 40-55 and 70-80 degrees C, which could be correlated to the phase transitions of the B and C blocks, respectively. All polymers show a high tendency for cluster formation, once aggregation is induced. The carrier abilities of the triple responsive triblock copolymers for hydrophobic agents were probed with the solvatochromic fluorescence dye Nile Red. With passing through the first thermal transition, the block copolymers are capable of solubilizing Nile Red. In the case of block copolymers with sequences ABC or ACB, which bear the low-LCST block at one terminus, notable amounts of dye are solubilized already at this stage. In contrast, the hydrophobic probe is much less efficiently incorporated by the BAC triblock copolymer, which forms unimolecular micelles. Only after the collapse of the B block, when reaching the second phase transition at about 45 degrees C, does aggregation occur and solubilization becomes efficient. In the case of ABC and ACB polymers, the hydrophobic probe seems to partition between the originally collapsed A chains and the additional hydrophobic chains formed after the collapse of the less hydrophobic B block. Washington American Chemical Society 2011 9 Langmuir 27 8 4465 4473 10.1021/la200115p Institut für Chemie OPUS4-36887 Wissenschaftlicher Artikel Idzik, Krzysztof Ryszard; Cywinski, Piotr J.; Cranfield, Charles G.; Mohr, Gerhard J.; Beckert, Rainer Molecular recognition of the antiretroviral drug abacavir towards the development of a novel carbazole-based fluorosensor Due to their optical and electro-conductive attributes, carbazole derivatives are interesting materials for a large range of biosensor applications. In this study, we present the synthesis routes and fluorescence evaluation of newly designed carbazole fluorosensors that, by modification with uracil, have a special affinity for antiretroviral drugs via either Watson-Crick or Hoogsteen base pairing. To an N-octylcarbazole-uracil compound, four different groups were attached, namely thiophene, furane, ethylenedioxythiophene, and another uracil; yielding four different derivatives. Photophysical properties of these newly obtained derivatives are described, as are their interactions with the reverse transcriptase inhibitors such as abacavir, zidovudine, lamivudine and didanosine. The influence of each analyte on biosensor fluorescence was assessed on the basis of the Stern-Volmer equation and represented by Stern-Volmer constants. Consequently we have demonstrated that these structures based on carbazole, with a uracil group, may be successfully incorporated into alternative carbazole derivatives to form biosensors for the molecular recognition of antiretroviral drugs. New York Springer 2011 10 Journal of fluorescence 21 3 1195 1204 10.1007/s10895-010-0798-7 Institut für Chemie OPUS4-36909 Wissenschaftlicher Artikel Marsat, Jean-Noel; Heydenreich, Matthias; Kleinpeter, Erich; Berlepsch, Hans V.; Boettcher, Christoph; Laschewsky, André Self-Assembly into multicompartment micelles and selective solubilization by Hydrophilic-Lipophilic-Fluorophilic block copolymers Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated. Washington American Chemical Society 2011 14 Macromolecules : a publication of the American Chemical Society 44 7 2092 2105 10.1021/ma200032j Institut für Chemie OPUS4-36911 Wissenschaftlicher Artikel Kleinpeter, Erich; Laemmermann, Anica; Kühn, Heiner Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions. Oxford Elsevier 2011 9 Tetrahedron 67 14 2596 2604 10.1016/j.tet.2011.02.012 Institut für Chemie OPUS4-36961 Wissenschaftlicher Artikel Reznichenko, Alexander L.; Emge, Thomas J.; Audoersch, Stephan; Klauber, Eric G.; Hultzsch, Kai C.; Schmidt, Bernd Group 5 metal binaphtholate complexes for catalytic asymmetric hydroaminoalkylation and hydroamination/cyclization 3,3'-Silylated binaphtholate tantalum and niobium complexes were shown to be efficient catalysts for the asymmetric hydroaminoalkylation of N-methylaniline derivatives and N-benzylmethylamine with simple alkenes in enantioselectivities of up to 80% ee. No hydroaminoalkylation was observed with aminoalkenes; rather, exclusive asymmetric hydroamination/cyclization took place in up to 81% ee. Washington American Chemical Society 2011 4 Organometallics 30 5 921 924 10.1021/om1011006 Institut für Chemie OPUS4-36654 Wissenschaftlicher Artikel Thuenemann, Andreas F.; Klobes, Peter; Wieland, Christoph; Bruzzano, Stefano On the nanostructure of micrometer-sized cellulose beads The analysis of the porosity of materials is an important and challenging field in analytical chemistry. The gas adsorption and mercury intrusion methods are the most established techniques for quantification of specific surface areas, but unfortunately, dry materials are mandatory for their applicability. All porous materials that contain water and other solvents in their functional state must be dried before analysis. In this process, care has to be taken since the removal of solvent bears the risk of an incalculable alteration of the pore structure, especially for soft materials. In the present paper, we report on the use of small-angle X-ray scattering (SAXS) as an alternative analysis method for the investigation of the micro and mesopores within cellulose beads in their native, i.e., water-swollen state; in this context, they represent a typical soft material. We show that even gentle removal of the bound water reduces the specific surface area dramatically from 161 to 109 m(2) g(-1) in cellulose bead sample type MT50 and from 417 to 220 m(2) g(-1) in MT100. Simulation of the SAXS curves with a bimodal pore size distribution model reveals that the smallest pores with radii up to 10 nm are greatly affected by drying, whereas pores with sizes in the range of 10 to 70 nm are barely affected. The SAXS results were compared with Brunauer-Emmett-Teller results from nitrogen sorption measurements and with mercury intrusion experiments. Heidelberg Springer 2011 8 Analytical & bioanalytical chemistry 401 4 1101 1108 10.1007/s00216-011-5176-z Institut für Chemie OPUS4-36610 Wissenschaftlicher Artikel Moskalik, Mikail Yu.; Shainyan, Bagrat A.; Schilde, Uwe Reaction of trifluoromethanesulfonamide with alkenes and cycloocta-1,5-diene under oxidative conditions direct assembly of 9-heterobicyclo[4.2.1]nonanes Reactions of trifluoromethanesulfonamide with alpha-methylstyrene, 2-methylpent-1-ene, and cycloocta-1,5-diene in the system t-BuOCl-NaI were studied. In the reaction with alpha-methylstyrene 1-iodo-2-phenylpropan-2-ol was the only isolated product. The reaction with 2-methylpent-1-ene gave a mixture of N,N'-(2-methylpentane-1,2-diyl)bis(trifluoromethanesulfonamide), trifluoro-N-(2-hydroxy-2-methylpentyl)-methanesulfonamide, and N,N'-[oxybis(2-methylpentan-2,1-diyl)]bis(trifluoromethanesulfonamide). Trifluoromethanesulfonamide reacted with cycloocta-1,5-diene to produce a mixture of 2,5-diiodo-9-(trifluoromethylsulfonyl)-9-azabicyclo[4.2.1]nonane and 2,5-diiodo-9-oxabicyclo[4.2.1]nonane; this reaction may be regarded as the first example of direct assembly of bicyclononane skeleton. New York Pleiades Publ. 2011 7 Russian journal of organic chemistry 47 9 1271 1277 10.1134/S1070428011090016 Institut für Chemie OPUS4-36634 Wissenschaftlicher Artikel Kreye, Oliver; Toth, Tommy; Meier, Michael A. R. Copolymers derived from rapeseed derivatives via ADMET and thiol-ene addition Novel (co)polymers were synthesized from substances obtained from rapeseed via ADMET and thiol-ene additions. alpha,omega-Dienes derived from oleic and erucic acid were copolymerized with a ferulic acid derivative, a representative phenolic acid (p-hydroxycinnamic acid) present, for instance, in rapeseed cake. Copolymers with different ratios of these monomers were prepared via two different routes (ADMET and thiol-ene) and studied in detail. Both monomer and polymer synthesis were optimized in order to achieve high yielding synthetic procedures that meet the requirements of green chemistry. Some thermal properties of the resulting copolymer series were then studied and correlated to the co-monomer composition. Oxford Elsevier 2011 13 European polymer journal 47 9 1804 1816 10.1016/j.eurpolymj.2011.06.012 Institut für Chemie OPUS4-36638 Wissenschaftlicher Artikel Kienzler, Andrea; Flehr, Roman; Kramer, Rolf A.; Gehne, Soeren; Kumke, Michael Uwe; Bannwarth, Willi Novel Three-Color FRET Tool Box for Advanced Protein and DNA Analysis We report on a new three-color FRET system which we were able to verify in peptides as well as in synthetic DNA. All three chromophores could be introduced by a building block approach avoiding postsynthetic labeling. Additional features are robustness, matching spectroscopic properties, high-energy transfer, and sensitivity. The system was investigated in detail on a set of peptides as well as an array of tailored oligonucleotides. The detailed analysis of the experimental data and comparison with theoretical considerations were in excellent agreement. It is shown that in the case of polypeptides specific interaction with the fluorescence probes has to be considered. In contrast with DNA, the fluorescence probes did not show any indications of such interactions. The novel three-color FRET toolbox revealed the potential for applications studying fundamental processes of three interacting molecules in life science applications. Washington American Chemical Society 2011 12 Bioconjugate chemistry 22 9 1852 1863 10.1021/bc2002659 Institut für Chemie OPUS4-36642 Wissenschaftlicher Artikel Kramer, Markus; Kleinpeter, Erich A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings The conformational analyses of six non-rigid N-acetyl glucosamine (NAG) derivatives employing residual dipolar couplings (RDCs) and NOEs together with molecular dynamics (MD) simulations are presented. Due to internal dynamics we had to consider different conformer ratios existing in solution. The good quality of the correlation between theoretically and experimentally obtained RDCs show the correctness of the calculated conformers even if the ratios derived from the MD simulations do not exactly meet the experimental data. If possible, the results were compared to former published data and commented. San Diego Elsevier 2011 12 Journal of magnetic resonance 212 1 174 185 10.1016/j.jmr.2011.06.029 Institut für Chemie OPUS4-36687 Wissenschaftlicher Artikel Kleinpeter, Erich; Koch, Andreas The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl substituents are consequently positioned either above the fluorene moiety or in-plane with it; thus, the methyl protons are either shielded or deshielded, respectively, due to the ring current effect of the fluorene moiety. This anisotropic effect on the H-1 chemical shifts of the methyl protons has been quantified on the basis of through-space NMR shieldings (TSNMRS) and subsequently Delta delta(calcd) compared with the experimentally observed chemical shift differences, Delta delta(exp). In this context, the experimental anisotropic effects of functional groups in the H-1 NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between Delta delta(calcd) and Delta delta(exp) were, for the first time, also quantified as arising from steric compression. Oxford Elsevier 2011 4 Tetrahedron 67 32 5740 5743 10.1016/j.tet.2011.06.005 Institut für Chemie OPUS4-36688 Wissenschaftlicher Artikel Wessig, Pablo; Pick, Charlotte; Schilde, Uwe First example of an atropselective dehydro-Diels-Alder (ADDA) reaction A new concept of a stereoselective synthesis of axially chiral biaryls, formed in the course of the dehydro-Diels-Alder (DDA) reaction, has been disclosed. It is based on asymmetric induction of the newly formed chirality axis by a chirality center, which is present in the two synthesized DDA reactants. Depending on the different length of the linkers joining the alkyne moieties the DDA reaction may be triggered photochemically or thermally, where only the thermal variant was stereoselective. Oxford Elsevier 2011 3 Tetrahedron letters 52 32 4221 4223 10.1016/j.tetlet.2011.06.024 Institut für Chemie OPUS4-36631 Wissenschaftlicher Artikel Schmidt, Bernd; Geissler, Diana Ru- and Pd-Catalysed Synthesis of 2-Arylfurans by One-Flask Heck Arylation/Oxidation 2,5-Disubstituted furans were synthesized by one-flask Heck arylation/oxidation sequences. The starting materials are 2-substituted 2,3-dihydrofurans, conveniently available by RCM/isomerization sequences, and arenediazonium salts. These react in ligand-free Heck reactions to afford 2,5-disub-stituted 2,5-dihydrofurans, which are oxidized to the corresponding furans without isolation or intermediate workup. The oxidation is conveniently achieved with chloranil or DDQ, depending on the substrate. Weinheim Wiley-VCH 2011 9 European journal of organic chemistry 25 4814 4822 10.1002/ejoc.201100549 Institut für Chemie OPUS4-37003 Wissenschaftlicher Artikel Schmidt, Bernd; Staude, Lucia; Kelling, Alexandra; Schilde, Uwe A Cross-Metathesis-Conjugate addition route to enantiopure gamma-Butyrolactams and gamma-Lactones from a C-2-Symmetric Precursor A protected derivative of (3R, 4R)-hexa-1,5-diene-3,4-diol, a conveniently accessible C-2-symmetric building block, undergoes single or double cross metathesis with methyl acryl-ate. The cross metathesis products are amenable to stereoselective conjugate addition reactions and can be converted into either gamma-butyrolactones or gamma-lactams. Malden Wiley-Blackwell 2011 7 European journal of organic chemistry 9 1721 1727 10.1002/ejoc.201001528 Institut für Chemie OPUS4-36984 Wissenschaftlicher Artikel Vijayakrishnan, Balakumar; Issaree, Arisara; Corilo, Yuri E.; Ferreira, Christina Ramires; Eberlin, Marcos N.; Peter, Martin G. MSn of the six isomers of (GlcN)(2)(GlcNAc)(2) aminoglucan tetrasaccharides (diacetylchitotetraoses) rules of fragmentation for the sodiated molecules and application to sequence analysis of hetero-chitooligosaccharides The six possible isomers of di-N-acetylchitotetraoses [AADD, ADDA, ADAD, DADA, DAAD, and DDAA, where D stands for 2-amino-2-deoxy-3-D-glucose (GlcN) and A for 2-acetamido-2-deoxy-beta-D-glucose (GlcNAc)] were analyzed by ESI(+)-MSn. Collision induced dissociation via MSn experiments were performed for the sodiated molecules of m/z 769 [M+Na](+) for each isomer, and fragments were generated mainly by glycosidic bond and cross-ring cleavages. Rules of fragmentation were then established. A reducing end D residue yields the (O.2)A(4) cross-ring [M-59+Na](+) fragment of m/z 710 as the most abundant, whereas isomers containing a reducing end A prefer to lose water to form the [M-18+Na](+) ion of m/z 751, as well as abundant (O.2)A(4) cross-ring [M-101+Na](+) fragments of m/z 668 and B-3 [M-221+Na](+) ions of m/z 548. MS3 of C- and Y-type ions shows analogous fragmentation behaviour that allows identification of the reducing end next-neighbour residue. Due to gas-phase anchimeric assistance, B-type cleavage between the glycosidic oxygen and the anomeric carbon atom is favoured when the glycon is an A residue. Relative ion abundances are generally in the order B >> C > Y, but may vary depending on the next neighbour towards the non-reducing end. These fragmentation rules were used for partial sequence analysis of hetero-chitooligosaccharides of the composition D(2)A(3), D(3)A(3), D(2)A(4), D(4)A(3), and D(3)A(4). Oxford Elsevier 2011 14 Carbohydrate polymers : an international journal devoted to scientific and technological aspects of industrially important polysaccharides 84 2 713 726 10.1016/j.carbpol.2010.04.041 Institut für Chemie OPUS4-36985 Wissenschaftlicher Artikel Mengibar, M.; Ganan, M.; Miralles, B.; Carrascosa, A. V.; Martinez-Rodriguez, Adolfo J.; Peter, Martin G.; Heras, A. Antibacterial activity of products of depolymerization of chitosans with lysozyme and chitosanase against Campylobacter jejuni Chitosan has several biological properties useful for the food industry, but the most attractive is its potential use as a food preservative of natural origin due to its antimicrobial activity against a wide range of food-borne microorganisms. Among food-borne pathogens, Campylobacter jejuni and related species are recognised as the most common causes of bacterial food-borne diarrhoeal disease throughout the world. Recently, it has been demonstrated that campylobacters are highly sensitive to chitosan. Even though chitosan is known to have important functional activities, poor solubility makes them difficult to use in food and biomedical applications. Unlike chitosan, the low viscosity and good solubility of chitosan oligosaccharides (COS) make them especially attractive in an important number of useful applications. In the present work, the effect of different COS on C. jejuni was investigated. Variables such as the physicochemical characteristics of chitosan and the enzyme used in COS preparation were studied. The COS had been fractioned using ultrafiltration membranes and each fraction was characterized regarding its FA and molecular weight distribution. It has been demonstrated that the biological properties of COS on Campylobacter depend on the composition of the fraction analysed. COS prepared by enzymatic hydrolysis with chitosanase were more active against Campylobacter that lysozyme-derived COS, and this behaviour seems to be related with the acetylation of the chains. On the other hand. the 10-30 kDa fraction was the most active COS fraction, independently of the enzyme used for the hydrolysis. These results have shown that COS could be useful as antimicrobial in the control of C. jejuni. Oxford Elsevier 2011 5 Carbohydrate polymers : an international journal devoted to scientific and technological aspects of industrially important polysaccharides 84 2 844 848 10.1016/j.carbpol.2010.04.042 Institut für Chemie OPUS4-36967 Wissenschaftlicher Artikel Wessig, Pablo; Matthes, Annika Preparation of Strained Axially Chiral (1,5)Naphthalenophanes by Photo-dehydro-Diels-Alder Reaction The preparation of 10 (1,5)naphthalenophanes (10a-j) by photo-dehydro-Diels-Alder (PDDA) reaction is described. Owing to hindered rotation around the biaryl axis, compounds 10 are axially chiral and the separation of enantiomers by chiral HPLC was demonstrated in three cases (10a,b,e). The absolute configuration of the isolated enantiomers could be unambiguously determined by comparison of calculated and measured circular dichroism (CD) spectra. Furthermore, we analyzed ring strain phenomena of (1,5)naphthalenophanes 10. Depending on the length of the linker units, one can distinguish three classes of naphthalenophanes. Compounds 10a-c are highly strained (E-STR = 7-31 kcal/mol), and the strain is caused by small bond angles in the linker unit and deformation of the naphthalene moiety. Another type of strain is observed if the linker unit becomes relatively long (10g,h) originating from transannular interactions and is comparable with the well-known strain of medium sized rings. The naphthalenophanes 10d-f with a linker length of 10-14 atoms are only marginally strained. To clearly discriminate the different sources of strain, we defined two geometrical parameters (average central dihedral angle delta(C) and naphthalene thickness D-N) and demonstrated that they are well-suited to indicate naphthalene deformation of our naphthalenophanes 10 as well as of ten model naphthalenophanes (I-X) with different linker lengths and linking positions. Washington American Chemical Society 2011 9 Journal of the American Chemical Society 133 8 2642 2650 10.1021/ja109118m Institut für Chemie OPUS4-36971 Wissenschaftlicher Artikel Neumann, Mike; Noeske, Robert; Bach, Grete; Glaubauf, Thomas; Bartoszek, Michael; Strauch, Peter A procedure for rapid determination of the silicon content in plant materials An efficient, reliable and low-cost procedure to determine the silicon content in plant material is presented which allows to monitor the agricultural aspects like growth and yield. The presented procedure consists of a hydrochloric acid pre-treatment and a subsequent thermal oxidation. The method is compared to other processes like dissolution in hydrofluoric acid combined with ICP OES, energy-dispersive X-ray fluorescence spectroscopy (EDXRF) or aqua regia treatment. Tübingen De Gruyter 2011 6 Zeitschrift für Naturforschung : B, Chemical sciences 66 3 289 294 Institut für Chemie OPUS4-37016 Wissenschaftlicher Artikel Kreye, Oliver; Toth, Tommy; Meier, Michael A. R. Introducing multicomponent reactions to polymer science passerini reactions of renewable monomers Combination of the Passerini three component-reaction (3CR) and olefin metathesis led to the formation of poly[1-(alkyl carbamoyl)alkyl alkanoates], a new class of polyesters with amide moieties in their side chain, from renewable resources. Two different approaches were studied and compared to each other. First, monomers were synthesized by the Passerini-3CR and then polymerized via acyclic diene metathesis. Alternatively, bifunctional monomers were synthesized by self-metathesis and then polymerized by Passerini-3CR. Both approaches led to the formation of high-molecular-weight polymers. Moreover, Passerini-3CRs were shown to be a versatile grafting-onto method. The results clearly demonstrate that the Passerini-3CR offers an interesting new access to monomers and polymers and thus broadens the synthetic portfolio of polymer science. Washington American Chemical Society 2011 3 Journal of the American Chemical Society 133 6 1790 1792 10.1021/ja1113003 Institut für Chemie OPUS4-37020 Wissenschaftlicher Artikel Huber, Christian; Klamroth, Tillmann Explicitly time-dependent coupled cluster singles doubles calculations of laser-driven many-electron dynamics We report explicitly time-dependent coupled cluster singles doubles (TD-CCSD) calculations, which simulate the laser-driven correlated many-electron dynamics in molecular systems. Small molecules, i.e., HF, H(2)O, NH(3), and CH(4), are treated mostly with polarized valence double zeta basis sets. We determine the coupled cluster ground states by imaginary time propagation for these molecules. Excited state energies are obtained from the Fourier transform of the time-dependent dipole moment after an ultrashort, broadband laser excitation. The time-dependent expectation values are calculated from the complex cluster amplitudes using the corresponding configuration interaction singles doubles wave functions. Also resonant laser excitations of these excited states are simulated, in order to explore the limits for the numerical stability of our current TD-CCSD implementation, which uses time-independent molecular orbitals to form excited configurations. Melville American Institute of Physics 2011 8 The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr 134 5 10.1063/1.3530807 Institut für Chemie OPUS4-37022 Wissenschaftlicher Artikel Havelius, Kajsa G. V.; Reschke, Stefan; Horn, Sebastian; Doerlng, Alexander; Niks, Dimitri; Hille, Russ; Schulzke, Carola; Leimkühler, Silke; Haumann, Michael Structure of the molybdenum site in YedY, a sulfite oxidase homologue from escherichia coli YedY from Escherichia coil is a new member of the sulfite oxidase family of molybdenum cofactor (Moco)-containing oxidoreductases. We investigated the atomic structure of the molybdenum site in YedY by X-ray absorption spectroscopy, in comparison to human sulfite oxidase (hSO) and to a Mo(IV) model complex. The K-edge energy was indicative of Mo(V) in YedY, in agreement with X- and Q-band electron paramagnetic resonance results, whereas the hSO protein contained Mo(VI). In YedY and hSO, molybdenum is coordinated by two sulfur ligands from the molybdopterin ligand of the Moco, one thiolate sulfur of a cysteine (average Mo-S bond length of similar to 2.4 angstrom), and one (axial) oxo ligand (Mo=O, similar to 1.7 angstrom). hSO contained a second oxo group at Mo as expected, but in YedY, two species in about a 1:1 ratio were found at the active site, corresponding to an equatorial Mo-OH bond (similar to 2.1 angstrom) or possibly to a shorter M-O(-) bond. Yet another oxygen (or nitrogen) at a similar to 2.6 angstrom distance to Mo in YedY was identified, which could originate from a water molecule in the substrate binding cavity or from an amino acid residue close to the molybdenum site, i.e., Glu104, that is replaced by a glycine in hSO, or Asn45. The addition of the poor substrate dimethyl sulfoxide to YedY left the molybdenum coordination unchanged at high pH. In contrast, we found indications that the better substrate trimethylamine N-oxide and the substrate analogue acetone were bound at a similar to 2.6 angstrom distance to the molybdenum, presumably replacing the equatorial oxygen ligand. These findings were used to interpret the recent crystal structure of YedY and bear implications for its catalytic mechanism. Washington American Chemical Society 2011 8 Inorganic chemistry 50 3 741 748 10.1021/ic101291j Institut für Chemie OPUS4-37000 Wissenschaftlicher Artikel Neuvonen, Kari; Neuvonen, Helmi; Koch, Andreas; Kleinpeter, Erich NBO analysis of polar and steric effect using the axial-equatorial equilibrium of cyclohexyl acetates as a probe The proportion of the axial conformer increases in the ax reversible arrow eq equilibrium of cyclohexyl acetates (RCOOC(6)H(11), R reversible arrow Me, Et, iPr, tBu, CH(2)Cl, CHCl(2), CO(3). CH(2)Br, CHBr(2), CBr(3)) with the increasing size of the acyloxy substitution. The nature of this unexpected steric substituent effect, which is opposite to general stereochemical concepts, was studied by means of ab kiln MO method, accompanied by NBO and isodesmic calculations. NBO parameters seem to be good descriptors for quantitative prediction of the experimental Delta G degrees value of the title conformational equilibrium. The origin and propagation of the substituent effect of the polar substitutions (CH(2)Cl, CHCl(2), CCl(3), CH(2)Br, CHBr(2), CBr(3)) differ, however, from those of the pure alkyl (Me, Et, iPr, tBu) substitutions. The Delta G degrees value of the polar derivatives depends on the qC8 charges, on the occupation of the sigma(center dot)(C1-07) orbital and on the hyperconjugative pi(center dot)(c=O) -> sigma(center dot)(C10-X) and sigma(center dot)(C10-X) -> pi(center dot)(c=O) interactions. The substituent sensitivity of these NBC parameters for the two conformers differ to the effect that the ax reversible arrow eq equilibrium is shifted to the left side with increasing electron withdrawing character of the acyloxy group. The Delta G degrees values of the alkyl derivatives are interpreted in terms of the calculated dipole moments. The destabilization in the non-polar medium (the experimental Delta G degrees values used were measured in CD(2)Cl(2)) due to the enhanced dipolar character is more prominent in the case of the equatorial alkyl conformers. As the consequence, the ax reversible arrow eq equilibrium is shifted to the left despite the increasing size of the R group when going from Me to tBu substitution. Amsterdam Elsevier 2011 9 Computational and theoretical chemistry 964 1-3 234 242 10.1016/j.comptc.2010.12.033 Institut für Chemie OPUS4-37002 Wissenschaftlicher Artikel Yarman, Aysu; Nagel, Thomas; Gajovic-Eichelmann, Nenad; Fischer, Anna; Wollenberger, Ursula; Scheller, Frieder W. Bioelectrocatalysis by Microperoxidase-11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles We report on the redox behaviour of the microperoxidase-11 (MP-11) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. MP-11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP-11 at high scan rate is between 350+/-50 pmol cm(-2), which reflects a multilayer process. The formal potential (E degrees') of MP-11 in the gold nanoparticles-chitosan film was estimated to be -(267.7+/-2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (k(s)) starts at 1.21 s(-1) and levels off at 6.45 s(-1) in the scan rate range from 0.1 to 2.0 V s(-1). Oxidation and reduction of MP-11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP-11. Malden Wiley-Blackwell 2011 8 Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis 23 3 611 618 10.1002/elan.201000535 Institut für Chemie OPUS4-37175 Wissenschaftlicher Artikel Kreye, Oliver; Toth, Tommy; Meier, Michael A. R. Poly-alpha,beta-unsaturated aldehydes derived from castor oil via ADMET polymerization 10-Undecenal, derived by pyrolysis and reduction from castor oil, was almost quantitatively transformed into the corresponding aldol condensation product under basic conditions. This alpha,omega-diene monomer was polymerized using acyclic diene metathesis (ADMET) polymerization. In a catalyst screening, four of nine different ruthenium-based metathesis catalysts showed good reactivity under neat conditions at 80 degrees C in the presence of 1,4-benzoquinone and polymers with molecular weights up to 11 kDa were formed. Furthermore, the (1)H NMR spectra showed that the metathesis catalysts tolerate the alpha,beta-unsaturated aldehyde function and due to the addition of benzoquinone, the degree of double bond isomerization was low. Further experiments investigating reduced catalyst amounts (down to 0.2 mol%) and the temperature dependence of these ADMET polymerizations gave also satisfying results for the formation of poly-alpha,beta-unsaturated aldehydes. Moreover, ADMET polymerizations with different amounts of methyl 10-undecenoate as chain-stopper were performed and the integrals of the corresponding (1)H NMR spectra allowed the determination of an absolute degree of polymerization. Finally, a reduction of a poly-alpha,beta-unsaturated aldehyde with sodium borohydride was accomplished. The resulting poly-(allyl alcohol) could be a useful compound in the generation of polymer networks like polyesters, polyurethanes, and polycarbonates and thus be of high interest in materials research. Weinheim Wiley-VCH 2011 8 European journal of lipid science and technology 113 1 31 38 10.1002/ejlt.201000108 Institut für Chemie OPUS4-37176 Wissenschaftlicher Artikel Biermann, Ursula; Meier, Michael A. R.; Butte, Werner; Metzger, Jürgen O. Cross-metathesis of unsaturated triglycerides with methyl acrylate synthesis of a dimeric metathesis product Highly functionalized dimeric triglycerides, such as compound 2, are obtained as minor products besides branched macromolecules from the acyclic triene metathesis (ATMET) polymerization of unsaturated triglycerides such as glyceryl triundec-10-enoate 1 and methyl acrylate (MA) in the presence of the second generation Hoveyda-Grubbs catalyst. The formed amount of interesting products of lower molecular weight during the ATMET reaction depends on the ratio of MA and triglyceride, reaction time, and temperature. We isolated the dimeric metathesis product 2 and synthesized the respective partially hydrogenated dimer 3 regioselectivly in a seven step reaction sequence starting from 10-undecenoic acid 7 and glycerol. Product 3 was unambiguously characterized by (13)C and (1)H NMR and MS as well as the further intermediate products of the seven step reaction including 10,11 bromo-undecanoic acid 8, the respective brominated 1,3-diglyceride 9, the brominated 1,3-triglyceride 6, and the self-metathesis products 4 and 5 which were isolated and purified. Weinheim Wiley-VCH 2011 7 European journal of lipid science and technology 113 1 39 45 10.1002/ejlt.201000109 Institut für Chemie OPUS4-37218 Wissenschaftlicher Artikel Schmidt, Bernd; Hölter, Frank Suzuki-Miyaura cross coupling reactions with Phenoldiazonium salts The Suzuki-Miyaura coupling of phenol diazonium salts and aryl trifluoroborates yields 4-hydroxybiaryls in a protecting group-free synthesis. Cambridge Royal Society of Chemistry 2011 7 Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry 9 13 4914 4920 10.1039/c1ob05256j Institut für Chemie OPUS4-37219 Wissenschaftlicher Artikel Wessig, Pablo; Matthes, Annika; Pick, Charlotte The photo-dehydro-Diels-Alder (PDDA) reaction The photo-dehydro-Diels-Alder (PDDA) reaction is a valuable extension of the classical Diels-Alder (DA) reaction. The PDDA reaction differs from the DA reaction by the replacement of one of the C-C-double bonds of the diene moiety by a C-C triple bond and by the photochemical triggering of the reaction. This entails that, in contrast to the DA reaction, the PDDA reaction proceeds according to a multistage mechanism with biradicals and cycloallenes as intermediates. The PDDA reaction provides access to a considerable variety of compound classes. For example, 1-phenylnaphthlenes, 1,1'-binaphthyls, N-heterocyclic biaryls, and naphthalenophanes could be obtained by this reaction. Cambridge Royal Society of Chemistry 2011 7 Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry 9 22 7599 7605 10.1039/c1ob06066j Institut für Chemie OPUS4-37224 Wissenschaftlicher Artikel Horsch, Philipp; Urbasch, Gunter; Weitzel, Karl-Michael; Kroener, Dominik Circular dichroism in ion yields employing femtosecond laser ionization-the role of laser pulse duration The circular dichroism (CD) induced by femtosecond laser pulse excitation of 3-methylcyclopentanone has been investigated by means of experiment and theory as a function of the laser pulse duration. In the experiment the CD in ion yields is measured by femtosecond laser ionization via a one-photon resonant excited state. In the theoretical part the CD is calculated by solving laser driven quantum electron dynamics for the same resonant excitation based on ab initio electronic structure calculations employing a complete description of the electric field-electric dipole and magnetic field-magnetic dipole interactions. Both the experimentally measured CD in ion yields and the calculated CD in excited state populations exhibit a marked increase of the CD for pulse duration increasing from 50 fs to about 200 fs. Beyond 200 fs pulse duration the CD levels off. The combination of experimental and theoretical evidences indicates that the CD decreases with increasing laser intensity connected to the increased coupling between the excited states. Cambridge Royal Society of Chemistry 2011 9 Physical chemistry, chemical physics : a journal of European Chemical Societies 13 6 2378 2386 10.1039/c0cp01903h Institut für Chemie OPUS4-37228 Wissenschaftlicher Artikel Dodoo, S.; Steitz, R.; Laschewsky, André; von Klitzing, Regine Effect of ionic strength and type of ions on the structure of water swollen polyelectrolyte multilayers This study addresses the effect of ionic strength and type of ions on the structure and water content of polyelectrolyte multilayers. Polyelectrolyte multilayers of poly(sodium-4-styrene sulfonate) (PSS) and poly(diallyl dimethyl ammonium chloride) (PDADMAC) prepared at different NaF, NaCl and NaBr concentrations have been investigated by neutron reflectometry against vacuum, H2O and D2O. Both thickness and water content of the multilayers increase with increasing ionic strength and increasing ion size. Two types of water were identified, "void water" which fills the voids of the multilayers and does not contribute to swelling but to a change in scattering length density and "swelling water" which directly contributes to swelling of the multilayers. The amount of void water decreases with increasing salt concentration and anion radius while the amount of swelling water increases with salt concentration and anion radius. This is interpreted as a denser structure in the dry state and larger ability to swell in water (sponge) for multilayers prepared from high ionic strengths and/or salt solution of large anions. No exchange of hydration water or replacement of H by D was detected even after eight hours incubation time in water of opposing isotopic composition. Cambridge Royal Society of Chemistry 2011 8 Physical chemistry, chemical physics : a journal of European Chemical Societies 13 21 10318 10325 10.1039/c0cp01357a Institut für Chemie OPUS4-37231 Wissenschaftlicher Artikel Tiseanu, Carmen; Parvulescu, Vasile I.; Boutonnet, Magali; Cojocaru, Bogdan; Primus, Philipp A.; Teodorescu, Cristian M.; Solans, Conchita; Sanchez Dominguez, Margarita Surface versus volume effects in luminescent ceria nanocrystals synthesized by an oil-in-water microemulsion method Pure and europium (Eu3+) doped cerium dioxide (CeO2) nanocrystals have been synthesized by a novel oil-in-water microemulsion reaction method under soft conditions. In-situ X-ray diffraction and RAMAN spectroscopy, high-resolution transmission electron microscopy, UV/Vis diffuse-reflectance and Fourier transform infrared spectroscopy as well as time-resolved photoluminescence spectroscopy were used to characterize the nanaocrystals. The as-synthesized powders are nanocrystalline and have a narrow size distribution centered on 3 nm and high surface area of similar to 250 m(2) g(-1). Only a small fraction of the europium ions substitutes for the bulk, cubic Ce4+ sites in the europium-doped ceria nanocrystals. Upon calcination up to 1000 degrees C, a remarkable high surface area of similar to 120 m(2) g (-1) is preserved whereas an enrichment of the surface Ce4+ relative to Ce3+ ions and relative strong europium emission with a lifetime of similar to 1.8 ms and FWHM as narrow as 10 cm(-1) are measured. Under excitation into the UV and visible spectral range, the europium doped ceria nanocrystals display a variable emission spanning the orange-red wavelengths. The tunable emission is explained by the heterogeneous distribution of the europium dopants within the ceria nanocrystals coupled with the progressive diffusion of the europium ions from the surface to the inner ceria sites and the selective participation of the ceria host to the emission sensitization. Effects of the bulk-doping and impregnation with europium on the ceria host structure and optical properties are also discussed. Cambridge Royal Society of Chemistry 2011 11 Physical chemistry, chemical physics : a journal of European Chemical Societies 13 38 17135 17145 10.1039/c1cp21135h Institut für Chemie OPUS4-37232 Wissenschaftlicher Artikel Kleinpeter, Erich; Koch, Andreas Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS) The spatial magnetic properties (through space NMR shieldings-TSNMRS) of metal complexes (with ligands such as acetylacetone, 3-hydroxy-pyran(4) one) and "metallobenzenes" have been calculated by the GIAO perturbation method and visualized as Iso-Chemical-Shielding Surfaces (ICSS) of various sizes and directions. The TSNMRS values, thus obtained, can be successfully employed to quantify and visualize partial aromaticity of the metallocyclic ring by comparison with the spatial magnetic properties of the corresponding non-complexed ligands in comparable structural and electronic situations, and benzene, respectively. Because anisotropy/ring current effects in H-1 NMR spectra proved to be the molecular response property of TSNMRS, the results obtained concerning partial "chelatoaromaticity" are experimentally ensured. Cambridge Royal Society of Chemistry 2011 9 Physical chemistry, chemical physics : a journal of European Chemical Societies 13 46 20593 20601 10.1039/c1cp21942a Institut für Chemie OPUS4-37154 Wissenschaftlicher Artikel Schmidt, Bernd; Krehl, Stefan A single precatalyst tandem RCM-allylic oxidation sequence Ring closing metathesis of allyloxy styrenes and a subsequent Ru-catalyzed allylic oxidation can be combined to a tandem sequence that makes coumarins accessible using less active but more conveniently available first generation catalysts. Cambridge Royal Society of Chemistry 2011 3 Chemical communications 47 20 5879 5881 10.1039/c1cc11347j Institut für Chemie OPUS4-37155 Wissenschaftlicher Artikel Pimpalpalle, Tukaram M.; Vidadala, Srinivasa Rao; Hotha, Srinivas; Linker, Torsten Lewis acid-catalyzed stereoselective lactonization and subsequent glycosidation of 2-C-malonyl carbohydrates Gold(III) bromide is a suitable catalyst for the stereoselective cyclization of 2-C-malonyl carbohydrates to the anomeric center under retention of one ester group. Reopening of the lactones with alcohols in the presence of TMSOTf affords allyl, propargyl and benzyl glycosides with high alpha-selectivity. Cambridge Royal Society of Chemistry 2011 3 Chemical communications 47 37 10434 10436 10.1039/c1cc13425f Institut für Chemie OPUS4-36531 Wissenschaftlicher Artikel Licausi, Francesco; Giorgi, Federico Manuel; Schmaelzlin, Elmar; Usadel, Björn; Perata, Pierdomenico; van Dongen, Joost Thomas; Geigenberger, Peter HRE-Type Genes are regulated by Growth-Related Changes in internal Oxygen Concentrations During the normal development of Potato (Solanum tuberosum) Tubers The occurrence of hypoxic conditions in plants not only represents a stress condition but is also associated with the normal development and growth of many organs, leading to adaptive changes in metabolism and growth to prevent internal anoxia. Internal oxygen concentrations decrease inside growing potato tubers, due to their active metabolism and increased resistance to gas diffusion as tubers grow. In the present work, we identified three hypoxia-responsive ERF (StHRE) genes whose expression is regulated by the gradual decrease in oxygen tensions that occur when potato tubers grow larger. Increasing the external oxygen concentration counteracted the modification of StHRE expression during tuber growth, supporting the idea that the actual oxygen levels inside the organs, rather than development itself, are responsible for the regulation of StHRE genes. We identified several sugar metabolism-related genes co-regulated with StHRE genes during tuber development and possibly involved in starch accumulation. All together, our data suggest a possible role for low oxygen in the regulation of sugar metabolism in the potato tuber, similar to what happens in storage tissues during seed development. Oxford Oxford Univ. Press 2011 16 Plant & cell physiology 52 11 1957 1972 10.1093/pcp/pcr128 Institut für Chemie OPUS4-36513 Wissenschaftlicher Artikel Senge, Mathias O.; Ryppa, Claudia; Fazekas, Marijana; Zawadzka, Monika; Dahms, Katja 5,10-A2B2-Type meso-Substituted PorphyrinsuA Unique Class of Porphyrins with a Realigned Dipole Moment Current applications in porphyrin chemistry require the use of unsymmetrically substituted porphyrins. Many current industrial interests in optics and biomedicine require systems with either pushpull (electron-donating and -withdrawing groups) or amphiphilic systems (hydrophobic and hydrophilic groups). In this context we present the class of 5,10-A2B2-type porphyrins for which two different substituents are positioned in diagonally opposite meso positions. Thus, the intramolecular dipole moment in these tetrapyrroles is positioned along a beta-beta vector passing through two pyrrole rings. This is opposite to the situation of the frequently used 5,15-A2BC porphyrins for which the dipole moment is oriented along a mesomeso axis. We have elaborated syntheses of the 5,10-A2B2 porphyrins by using transition-metal-catalyzed transformations of 5,10-A2 porphyrins or direct substitutions reactions thereof; this gives the target molecules in 2277% overall yields. The compounds exhibit interesting structural, spectroscopic, and optical features and can serve as building blocks for new porphyrin arrays and applications. Weinheim Wiley-VCH 2011 12 Chemistry - a European journal 17 48 13562 13573 10.1002/chem.201101934 Institut für Chemie OPUS4-36559 Wissenschaftlicher Artikel Riebe, Daniel; Zühlke, Martin; Zenichowski, Karl; Beitz, Toralf; Dosche, Carsten; Löhmannsröben, Hans-Gerd Characterization of rhodamine 6G release in electrospray ionization by means of spatially resolved fluorescence spectroscopy In the present work, the density distribution of rhodamine 6G ions (R6G) in the gas phase and the droplets of an electrospray plume was studied by spatial and spectral imaging. The intention is to contribute to the fundamental understanding of the release mechanism of gaseous R6G in the electrospray ionization (ESI) process. Furthermore, the influence of ESI-parameters on the release efficiency of R6G, e. g. solvent flow, R6G and salt concentration were examined via direct fluorescence imaging of R6G. A solvent-shift of the fluorescence maximum,lambda(max) = 555 nm in methanolic solution and lambda(max) = 505 nm in gas phase, allows the discrimination between solvated and gaseous R6G. Two experimental setups were used for our measurements. In the first experiment, the R6G fluorescence and the light scattered from the spray plume were imaged in two spatial dimensions using a tunable wavelength filter. The second experiment was designed for obtaining 1-dimensional spatially resolved emission spectra of the spray. Here, the intensity distribution of solvated and gaseous R6G as well as scattered light (lambda = 355 nm) were measured simultaneously. The results show the distribution of gaseous R6G in the plane, orthogonal to the ESI capillary, decreasing slightly towards the spray center and showing maxima at the cone margins. The distribution of gaseous R6G confirms the preferred release of gaseous ions from nano-droplets, indicating the ion evaporation model (IEM) to be the dominating release mechanism. Up to now, only a few fluorescence spectra of ionic compounds in the gas phase were published because the measurement of emission spectra of mass-selected ions in an ion trap is experimentally challenging. The fluorescence spectrum of gaseous lucigenin at atmospheric pressure is reported for the first time. This spectrum of lucigenin in the gas phase exhibits a blue shift of about Delta lambda = 10 nm in comparison to the corresponding spectrum in methanol. München De Gruyter Oldenbourg 2011 18 Zeitschrift für physikalische Chemie : international journal of research in physical chemistry and chemical physics 225 9-10 1055 1072 10.1524/zpch.2011.0149 Institut für Chemie OPUS4-37236 Wissenschaftlicher Artikel Zehm, Daniel; Laschewsky, André; Heunemann, Peggy; Gradzielski, Michael; Prevost, Sylvain; Liang, Hua; Rabe, Jürgen P.; Lutz, Jean-Francois Synthesis and self-assembly of amphiphilic semi-brush and dual brush block copolymers in solution and on surfaces The combination of two techniques of controlled free radical polymerization, namely the reversible addition fragmentation chain transfer (RAFT) and the atom transfer radical polymerization (ATRP) techniques, together with the use of a macromonomer allowed the synthesis of symmetrical triblock copolymers, designed as amphiphilic dual brushes. One type of brush was made of poly(n-butyl acrylate) as soft hydrophobic block, i.e. characterized by a low glass transition temperature, while the other one was made of hydrophilic poly(ethylene glycol) (PEG). The new triblock polymers represent "giant surfactants" according to their molecular architecture. The hydrophobic and hydrophilic blocks microphase separate in the bulk. In aqueous solution, they aggregate into globular micellar aggregates, their size being determined by the length of the stretched polymer molecules. As determined by the combination of various scattering techniques for the dual brush copolymer, a rather compact structure is formed, which is dominated by the large hydrophobic poly(n-butyl acrylate) block. The aggregation number for the dual brush is about 10 times larger than for the "semi-brush" precursor copolymer, due to the packing requirements for the much bulkier hydrophobic core. On mica surfaces the triblock copolymers adsorb with worm-like backbones and stretched out side chains. Cambridge Royal Society of Chemistry 2011 11 Polymer Chemistry 2 1 137 147 10.1039/c0py00200c Institut für Chemie OPUS4-37237 Wissenschaftlicher Artikel Buller, Jens; Laschewsky, André; Lutz, Jean-Francois; Wischerhoff, Erik Tuning the lower critical solution temperature of thermoresponsive polymers by biospecific recognition A thermosensitive statistical copolymer based on oligo(ethylene glycol) methacrylates incorporating biotin was synthesized by free radical copolymerisation. The influence of added avidin on its thermoresponsive behaviour was investigated. The specific binding of avidin to the biotinylated copolymers provoked a marked increase of the lower critical solution temperature. Cambridge Royal Society of Chemistry 2011 4 Polymer Chemistry 2 7 1486 1489 10.1039/c1py00001b Institut für Chemie OPUS4-37255 Wissenschaftlicher Artikel Weiss, Jan; Böttcher, Christoph; Laschewsky, André Self-assembly of double thermoresponsive block copolymers end-capped with complementary trimethylsilyl groups A set of double thermoresponsive diblock copolymers poly(N-n-propylacrylamide)-block-poly(N-ethylacrylamide) (PNPAM-b-PNEAM) was synthesised by sequential reversible addition-fragmentation chain transfer (RAFT) polymerisations. Using a twofold trimethylsilyl (TMS)-labeled RAFT-agent, the relative size of the two blocks was varied. While soluble as unimers below 15 degrees C, all copolymers exhibited thermally induced two-step self-assembly in water, due to distinct lower critical solution temperature (LCST) phase transitions of PNPAM (around 20 degrees C) and PNEAM (around 70 degrees C). Their temperature-dependent self-organisation in dilute aqueous solution was studied by turbidimetry, dynamic light scattering, transmission electron microscopy, and (1)H NMR spectroscopy. The copolymers show distinct, two-step self-organisation behaviour with respect to transition temperatures, aggregate type and size, which can be correlated to the relative lengths of the low and high LCST blocks. For polymers having short blocks with low LCST, the first thermal transition induces the formation of individual micelles. Further heating above the second thermal transition results reversibly either in a shrink of the micelle size or in aggregation of the micelles, with hydrodynamic diameters below 250 nm. In contrast in the case of polymers having a long block with low LCST, the first thermal transition already leads to clusters of micelles, while the second thermal transition makes the clusters shrink. Noteworthy, the twofold TMS-labeled end groups report not only on the molar masses of the polymers, but can simultaneously serve as NMR-probes for the self-assembly process. The signal of the TMS-aryl end group displays a reversible temperature dependent, two-step splitting that is indicative of the self-organisation of the block copolymers. Cambridge Royal Society of Chemistry 2011 10 Soft matter 7 2 483 492 10.1039/c0sm00531b Institut für Chemie OPUS4-37259 Wissenschaftlicher Artikel David Coy, Ericsson; Enrique Cuca, Luis; Sefkow, Michael Pd-NHC catalyzed biaryl coupling by direct C-H Activation-A Novel strategy for the synthesis of dibenzocyclooctane lignans Cross-coupling reactions, such as Buchwald-Hartwig arylamination and direct intramolecular biaryl coupling by C-H activation, were carried out using various Palladium-N-heterocyclic carbenes (Pd-NHC) as catalysts. The yields were good to excellent. The latter strategy was adopted to transform two dibenzylbutane lignans, isolated from the leaves of Ocotea macrophylla (Lauraceae), into the corresponding dibenzocyclooctane lignans in good overall yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) to view the free supplemental file. Philadelphia Taylor & Francis Group 2011 11 Synthetic communications : an international journal for rapid communication of synthetic organic chemistry 41 1 41 51 10.1080/00397910903531755 Institut für Chemie OPUS4-37247 Wissenschaftlicher Artikel Antoniou, Stella; Pashalidis, I.; Gessner, Andre; Kumke, Michael Uwe The effect of humic acid on the formation and solubility of secondary solid phases (Nd(OH)CO3 and Sm(OH)CO3) The formation of secondary Ln(III) solid phases (e.g. Nd(OH)CO3 and Sm(OH)CO3) has been studied as a function of the humic acid (HA) concentration in 0.1 M NaClO4 aqueous solution and their solubility has been investigated in the neutral pH range (6.5-8) under normal atmospheric conditions. Nd(III) and Sm(III) were selected as analogues for trivalent lanthanide and actinide ions. The solid phases under investigation have been prepared by alkaline precipitation and characterized by TGA, ATR-FTIR, XRD, TRLFS, DR-UV-Vis and Raman spectroscopy, and solubility measurements. The spectroscopic data obtained indicate that Nd(OH)CO3 and Sm(OH)CO3 are stable and remain the solubility limiting solid phases even in the presence of increased HA concentration (0.5 g/L) in solution. Upon base addition in the Ln(III)-HA system decomplexation of the previously formed Ln(III)-humate complexes and precipitation of two distinct phases occurs, the inorganic (Ln(OH)CO3) and the organic phase (HA), which is adsorbed on the particle surface of the former. Nevertheless, HA affects the particle size of the solid phases. Increasing HA concentration results in decreasing crystallite size of the Nd(OH)CO3 and increasing crystallite size of the Sm(OH)CO3 solid phase, and affects inversely the solubility of the solid phases. However, this impact on the solid phase properties is expected to be of minor relevance regarding the chemical behavior and migration of trivalent lanthanides and actinides in the geosphere. Berlin De Gruyter 2011 7 Radiochimica acta : international journal for chemical aspects of nuclear science and technology 99 4 217 223 10.1524/ract.2011.1812 Institut für Chemie OPUS4-37274 Wissenschaftlicher Artikel Wessig, Pablo; Möllnitz, Kristian; Kelling, Alexandra; Schilde, Uwe Crystal structure of 1r,2c,3c,4t,5t,6t-1,2,3,4,5,6-hexakis-trimethylsilanyloxy-cyclohexane, C24H60O6Si6 C24H60O6Si6, triclinic, P (1) over bar (no. 2), a = 11.307(2) angstrom, b = 12.159(2) angstrom, = 16.576(2) angstrom, alpha = 109.47(1)degrees, beta = 94.64(1)degrees, gamma = 111.65(1)degrees, V = 1942.3 angstrom(3), Z = 2, R-gt(F) = 0.043, wR(ref)(F-2) = 0.118, T = 210 K. München De Gruyter Oldenbourg 2011 3 Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures 226 2 228 230 10.1524/ncrs.2011.0105 Institut für Chemie OPUS4-37130 Wissenschaftlicher Artikel Kupstat, Annette; Kumke, Michael Uwe; Hildebrandt, Niko Toward sensitive, quantitative point-of-care testing (POCT) of protein markers miniaturization of a homogeneous time-resolved fluoroimmunoassay for prostate-specific antigen detection Point-of-care testing (POCT) systems which allow for a sensitive, quantitative detection of protein markers are extremely useful for the early detection and therapy progress monitoring of cancer. However, currently commercially available POCT devices are mainly limited to the qualitative detection of protein markers. In this study we demonstrate the successive miniaturization of a sensitive and fast assay for the quantitative detection of prostate-specific antigen (PSA) using a well established and clinically approved homogeneous time-resolved fluoroimmunoassay technology (TRACE (R)) on a commercial plate-reader system (KRYPTOR (R)). Regarding the initial requirements for the development of POCT devices we applied a 30-fold assay volume reduction (150 mu L to 5 mu L) to achieve a reasonable lab-on-a-chip volume and a 24-fold and 120-fold excitation pulse energy reduction to achieve reasonable pulse energies for low-cost miniature excitation sources. Due to highly efficient optimization of key POCT parameters our miniaturized PSA assay achieved a 30% increased sensitivity and a 2-fold improved limit of detection compared to the standard plate-reader method. Our results demonstrate the successful implementation of key parameters for a significant miniaturization and for cost reduction in the clinically approved KRYPTOR (R) platform for protein detection. The technological alterations required are easy-to-implement and can be immediately adapted for more than 30 diagnostic protein markers already available for the KRYPTOR (R) platform. These features strongly recommend our assay format to be utilized in innovative, sensitive, quantitative POCT of protein markers. Cambridge Royal Society of Chemistry 2011 7 The analyst : the analytical journal of the Royal Society of Chemistry 136 5 1029 1035 10.1039/c0an00684j Institut für Chemie OPUS4-37131 Wissenschaftlicher Artikel Cywinski, Piotr J.; Moro, Artur J.; Ritschel, Thomas; Hildebrandt, Niko; Löhmannsröben, Hans-Gerd Sensitive and selective fluorescence detection of guanosine nucleotides by nanoparticles conjugated with a naphthyridine receptor Novel fluorescent nanosensors, based on a naphthyridine receptor, have been developed for the detection of guanosine nucleotides, and both their sensitivity and selectivity to various nucleotides were evaluated. The nanosensors were constructed from polystyrene nanoparticles functionalized by (N-(7-((3-aminophenyl) ethynyl)-1,8-naphthyridin- 2-yl) acetamide) via carbodiimide ester activation. We show that this naphthyridine nanosensor binds guanosine nucleotides preferentially over adenine, cytosine, and thymidine nucleotides. Upon interaction with nucleotides, the fluorescence of the nanosensor is gradually quenched yielding Stern-Volmer constants in the range of 2.1 to 35.9mM(-1). For all the studied quenchers, limits of detection (LOD) and tolerance levels for the nanosensors were also determined. The lowest (3 sigma) LOD was found for guanosine 3',5'-cyclic monophosphate (cGMP) and it was as low as 150 ng/ml. In addition, we demonstrated that the spatial arrangement of bound analytes on the nanosensors' surfaces is what is responsible for their selectivity to different guanosine nucleotides. We found a correlation between the changes of the fluorescence signal and the number of phosphate groups of a nucleotide. Results of molecular modeling and zeta-potential measurements confirm that the arrangement of analytes on the surface provides for the selectivity of the nanosensors. These fluorescent nanosensors have the potential to be applied in multi-analyte, array-based detection platforms, as well as in multiplexed microfluidic systems. Heidelberg Springer 2011 8 Analytical & bioanalytical chemistry 399 3 1215 1222 10.1007/s00216-010-4420-2 Institut für Chemie OPUS4-37074 Wissenschaftlicher Artikel Awad, Duha Jawad; Schilde, Uwe; Strauch, Peter 4,4 '-Bis(tert-butyl)-2,2 '-bipyridinedichlorometal(II) - Synthesis, structure and EPR spectroscopy Due to the better solubility of the 4,4'-substituted bipyridine ligand a series of 4,4'0-bis(tert-butyl)-2,2'-bipyridinedichlorometal(II) complexes, [M(tbbpy)Cl(2)], with M = Cu, Ni, Zn, Pd, Pt was synthesised and characterised. The blue copper complex 4,4'-bis(tert-butyl)-2,2'-bipyridinedichlorocopper(II) was isolated in two different polymorphic forms, as prisms 1 with a solvent inclusion and solvent-free as needles 2. Both structures were determined by X-ray structure analysis. They crystallise in the monoclinic space group P2(1)/c with four molecules in the unit cell, but with different unit cells and packing motifs. Whereas in the prisms 1, with the unit cell parameters a = 12.1613(12), b = 10.6363(7), c = 16.3074(15) angstrom, eta = 94.446(8)degrees, the packing is dominated by intra-and intermolecular hydrogen bonds, in the needles 2, with a = 7.738(1), b = 18. 333(2), c = 13.291(3) angstrom, beta = 97.512(15)degrees, only intramolecular hydrogen bonds appear and the complex molecules are arranged in columns which are stabilised by p-p-stacking interactions. In both complexes the copper has a tetrahedrally distorted coordination sphere. These copper complexes were also studied by EPR spectroscopy in solution, as frozen glass and diamagnetically diluted powder with the analogue [Pd(tbbpy)Cl(2)] as host lattice. Lausanne Elsevier 2011 6 Inorganica chimica acta : the international inorganic chemistry journal 365 1 127 132 10.1016/j.ica.2010.08.035 Institut für Chemie OPUS4-37080 Wissenschaftlicher Artikel Möller, Eleonore; Beuermann, Sabine Homogeneous phase copolymerizations of vinylidene fluoride and hexafluoropropene in supercritical carbon dioxide Copolymerizations of vinylidene fluoride (VDF) and hexafluoropropene (HFP) were carried out in homogeneous phase with supercritical carbon dioxide up to complete VDF conversion using conventional peroxide initiators. The HFP monomer feed ratios, f(HFP), were varied between 0.65 and 0.20. Depending on f(HFP) amorphous or semi-crystalline copolymers were obtained. f(HFP) also determines the minimum pressure required to allow for homogeneous phase reactions. For example, HFP-rich copolymerizations in 70 wt.-% CO(2) at 100 degrees C require a pressure of around 500 bar. Further, bulk copolymerizations in homogenous phase were feasible for f(HFP) 0.65 at 900 bar up to complete VDF conversion. Copolymerizations in the presence of perfluorinated hexyl iodide carried out at 75 degrees C gave access to low dispersity polymers. Due to homogeneous phase conditions the use of any surfactants or fluorinated cosolvent is avoided. Weinheim Wiley-VCH 2011 14 Macromolecular reaction engineering 5 1 8 21 10.1002/mren.201000031 Institut für Chemie OPUS4-37067 Wissenschaftlicher Artikel Glatzel, Stefan; Laschewsky, André; Lutz, Jean-Francois Well-Defined uncharged polymers with a sharp UCST in water and in physiological milieu Washington American Chemical Society 2011 3 Macromolecules : a publication of the American Chemical Society 44 2 413 415 10.1021/ma102677k Institut für Chemie OPUS4-37070 Wissenschaftlicher Artikel Prevost, Sylvain; Wattebled, Laurent; Laschewsky, André; Gradzielski, Michael Formation of monodisperse charged vesicles in mixtures of cationic gemini surfactants and anionic SDS The aggregation behavior of catanionics formed by the mixture of cationic geminis derived from dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecylsulfate (SDS) was studied by means of phase studies and comprehensive small-angle neutron scattering (SANS) experiments at 25 degrees C and 50 mM overall concentration. The results are compared to those for the previously studied SDS + DTAC system. Various gemini spacers of different natures and geometries were used, but all of them had similar lengths: an ethoxy bridge, a double bond, and an aromatic ring binding the two DTACs in three different substitutions (ortho, meta, and para). SANS and SAXS data analysis indicates that the spacer has no large effect on the spheroidal micelles of pure surfactants formed at low concentration in water; however, specific effects appear with the addition of electrolytes. Microstructures formed in the catanionic mixtures are rather strongly dependent on the nature of the spacer. The most important finding is that for the hydrophilic, flexible ethoxy bridge, monodisperse vesicles with a fixed anionic/cationic charge ratio (depending only on the surfactant in excess) are formed. Furthermore, the composition of these vesicles shows that strongly charged aggregates are formed. This study therefore provides new opportunities for developing tailor-made gemini surfactants that allow for the fine tuning of catanionic structures. Washington American Chemical Society 2011 10 Langmuir 27 2 582 591 10.1021/la103976p Institut für Chemie OPUS4-37071 Wissenschaftlicher Artikel Schreiber, Ulrike; Hosemann, Benjamin; Beuermann, Sabine 1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP Block copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (AC8) were obtained from ARGET ATRP. To obtain block copolymers of low dispersity the PAC8 block was synthesized in anisole with a CuBr(2)/PMDETA catalyst in the presence of tin(II) 2-ethylhexanoate as a reducing agent. The PAC8 block was subsequently used as macroinitiator for copolymerization with butyl and tert-butyl acrylate carried out in scCO(2). To achieve catalyst solubility in CO(2) two fluorinated ligands were employed. The formation of block copolymers was confirmed by size exclusion chromatography and DSC. Weinheim Wiley-VCH 2011 12 Macromolecular chemistry and physics 212 2 168 179 10.1002/macp.201000307 Institut für Chemie OPUS4-37105 Wissenschaftlicher Artikel Ahnert, Karsten; Abel, Markus; Kollosche, Matthias; Jorgensen, Per Jorgen; Kofod, Guggi Soft capacitors for wave energy harvesting Wave energy harvesting could be a substantial renewable energy source without impact on the global climate and ecology, yet practical attempts have struggled with the problems of wear and catastrophic failure. An innovative technology for ocean wave energy harvesting was recently proposed, based on the use of soft capacitors. This study presents a realistic theoretical and numerical model for the quantitative characterization of this harvesting method. Parameter regions with optimal behavior are found, and novel material descriptors are determined, which dramatically simplify analysis. The characteristics of currently available materials are evaluated, and found to merit a very conservative estimate of 10 years for raw material cost recovery. Cambridge Royal Society of Chemistry 2011 6 Journal of materials chemistry 21 38 14492 14497 10.1039/c1jm12454d Institut für Chemie OPUS4-37109 Wissenschaftlicher Artikel Skrabania, Katja; Miasnikova, Anna; Bivigou Koumba, Achille Mayelle; Zehm, Daniel; Laschewsky, André Examining the UV-vis absorption of RAFT chain transfer agents and their use for polymer analysis The absorption characteristics of a large set of thiocarbonyl based chain transfer agents (CTAs) were studied by UV-vis spectroscopy in order to identify appropriate conditions for exploiting their absorbance bands in end-group analysis of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerisation. Substitution pattern and solvent polarity were found to affect notably the wavelengths and intensities of the pi-pi*- and n-pi*-transition of the thiocarbonyl bond of dithioester and trithiocarbonate RAFT agents. Therefore, it is advisable to refer in end group analysis to the spectral parameters of low molar mass analogues of the active polymer chain ends, rather than to rely on the specific RAFT agent engaged in the polymerisation. When using appropriate conditions, the quantification of the thiocarbonyl end-groups via the pi-pi* band of the thiocarbonyl moiety around 300-310 nm allows a facile, sensitive and surprisingly precise estimation of the number average molar mass of the polymers produced, without the need of particular end group labels. Moreover, when additional methods for absolute molar mass determination can be applied, the quantification of the thiocarbonyl end-groups by UV-spectroscopy provides a good estimate of the degree of active end group for a given polymer sample. Cambridge Royal Society of Chemistry 2011 10 Polymer Chemistry 2 9 2074 2083 10.1039/c1py00173f Institut für Chemie OPUS4-34064 Wissenschaftlicher Artikel Csütörtöki, Renáta; Szatmári, István; Koch, Andreas; Heydenreich, Matthias; Kleinpeter, Erich; Fulop, Ferenc Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives 2011 Institut für Chemie