TY - THES A1 - Stocco, Antonio T1 - Amphiphilic block copolymers at the liquid-fluid interface, invesrigated by evanescent light scattering and ellipsometry Y1 - 2007 CY - Potsdam ER - TY - JOUR A1 - Yoneda, Julliane Diniz A1 - Leal, Katia Zaccur A1 - Seidl, Peter Rudolf A1 - Azeredo, Rodrigo Bagueira de V. A1 - Kleinpeter, Erich T1 - Camphor : a good model for illustrating NMR techniques N2 - CAMPHOR: A GOOD MODEL FOR ILLUSTRATING NMR TECHNIQUES. The use of Nuclear Magnetic Resonance spectroscopy to establish the three-dimensional structures of molecules is an important component of modern Chemistry courses. The combination of techniques that can be used for this purpose is conveniently illustrated by their application to the camphor molecule. This paper presents applications of several techniques used in NMR spectral interpretation in an increasing order of complexity. The result of individual experiments is illustrated in order to familiarize the user with the way connectivity through bonds and through space is established from 1D/2D-NMR spectra and molecular stereochemistry is determined from different NMR experiments Y1 - 2007 ER - TY - JOUR A1 - Wacker, Philipp A1 - Dahms, Katja A1 - Senge, Mathias O. A1 - Kleinpeter, Erich T1 - Conformational Landscape of meso-(1,3-Dithian-2-yl)porphyrins N2 - An investigation of the conformational landscape of 1,3-dithian-2-yl bearing porphyrins and the rotational behavior of the dithianyl substituents in meso position was carried out by variable-temperature (VT) NMR spectroscopy. Additionally, theoretical results for alternative conformations and energy barriers were obtained by molecular modeling. The study revealed different NH trans tautomers with regard to the orientation of the dithianyl ligands for the free base porphyrins 1-3. Relatively ruffled porphyrin core conformations were established for the transition states of the dithianyl rotation, resulting in a lower rotational energy barrier for the nickel(II) complex 4 compared to that of the free base systems. The data obtained and the first depiction of a rotational transition state for the rotation of bulky meso-alkyl substituents illustrate the close structural interplay between meso-alkyl substituents and the macrocycle conformation in porphyrins. Y1 - 2007 UR - http://pubs.acs.org/doi/full/10.1021/jo0708700 U6 - https://doi.org/10.1021/Jo0708700 ER - TY - THES A1 - Kulkarni, Amit Narahari T1 - Degradation kinetics studies of polymers for biomedical applications Y1 - 2007 CY - Potsdam ER - TY - JOUR A1 - Neuvonen, Helmi A1 - Neuvonen, Kari A1 - Koch, Andreas A1 - Kleinpeter, Erich T1 - DFT study of the substituent cross-interaction effects on the conformation of substituted N-benzylideneanilines : Models of liquid crystal forming compounds ; use of C-13 Nmr chemcal shift of the C=N carbon as a tool to predict the conformation of the molecule N2 - The conformations of N-benzylideneani lines p-X-C6H4-CH=N-C6H4 p-Y (X, Y = NO2, CN, CF3, F, Cl, Br, H, Me, OMe, NMe2) have been studied by B3LYP density functional (DFT) hybrid method in combination with the 6-31G* or 6-311G* split valence basis set. The twist of the plane of the aniline ring with respect to the other part of the molecule (tau(2)) is systematically controlled by substituents X and Y, the effect of Y being larger. The value of the dihedral angle tau(2), correlates nicely with equation tau(2) = rho(F)(Y)(x)sigma(F)(Y)+rho(+R)(Y)(x)sigma(+)(R)(Y) + k(x) or tau(2) = rho(F)(X)(y)sigma(F)(X)+rho(-)(R)(X)(y)sigma(+)(R)(X) + k(y), respectively, when aniline or benzylidene substituent is varied. ED substituents X diminish the sensitivity of tau(2) to the aniline substituent Y[rho(F)(Y)(x) and rho(+)(R)(Y)(x)] while ED substituents Y increase the sensitivity Of T2 to the benzylidene substituent X[rho(F)(X)(y) and rho(+)(R)(X)(y)]. There seems to be two competitive conjugative interactions for the aniline ring n electrons: one with the nitrogen lone pair and one with the C=N unit. Substituents X and Y adjust the extent of these interactions and therefore the conformation of the molecule. A good correlation is observed between the dihedral angle tau(2) and the experimental C-13 NMR chemical shift of the C=N carbon of N-benzylideneanilines in CDCl3 (C) 2007 Elsevier B.V. All rights reserved. Y1 - 2007 U6 - https://doi.org/10.1016/j.theochem.2007.03.023 ER - TY - JOUR A1 - Parkinson, P. A1 - Aharon, E. A1 - Chang, M. H. A1 - Dosche, Carsten A1 - Frey, G. L. A1 - Köhler, Anna A1 - Herz, L. M. T1 - Dimensionality-dependent energy transfer in polymer-intercalated SnS2 nanocomposites N2 - We have investigated the influence of dimensionality on the excitation-transfer dynamics in a conjugated polymer blend. Using time-resolved photoluminescence spectroscopy, we have measured the transfer transients for both a three-dimensional blend film and for quasi-two-dimensional monolayers formed through intercalation of the polymer blend between the crystal planes of an inorganic SnS2 matrix. We compare the experimental data with a simple, dimensionality- dependent model based on electronic coupling between electronic transition moments taken to be point dipoles. Within this approximation, the energy-transfer dynamics is found to adopt a three-dimensional character in the solid film and a two-dimensional nature in the monolayers present in the SnS2-polymer nanocomposite. Y1 - 2007 UR - http://prb.aps.org/toc/PRB/v75/i16 U6 - https://doi.org/10.1103/Physrevb.75.165206 ER - TY - JOUR A1 - Modarresi-Alam, Ali Reza A1 - Khamooshi, Ferydoon A1 - Rostamizadeh, Mohsen A1 - Keykha, Hossein A1 - Nasrollahzahdeh, Mahmoud A1 - Bijanzadeh, Hamid-Reza A1 - Kleinpeter, Erich T1 - Dynamic 1H NMR spectroscopic study of the restricted S-N rotation in aryl-N-(arylsulfonyl)-N- (triphenylphosphoranylidene)imidocarbamates N2 - Dynamic 1H NMR (500 MHz) investigation of aryl-N-(arylsulfonyl)-N-(triphenylphosphoranylidene)imidocarbamates in CDCl3, CD3COCD3, and CD3OD at the temperature range of 183-298 K is reported. The observed free energy barriers (almost 12 kcal mol;1) are attributed to conformational isomerization about the NùS bond and these barriers show very little solvent dependence. Y1 - 2007 ER - TY - JOUR A1 - Modarresi, Ali Reza A1 - Najafi, Parisa A1 - Rostamizadeh, Mohsen A1 - Keykha, Hossein A1 - Bijanzadeh, Hamid-Reza A1 - Kleinpeter, Erich T1 - Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence N2 - The dynamic 1H NMR study of some primary carbamates in the solvents CDCl3 and CD3COCD3 between 183 and 298 K is reported. The free energies of activation, thus obtained (12.4 to 14.3 kcal mol-1), were attributed to the conformational isomerization about the N-C bond. These barriers to rotation show solvent dependence in contrast to the tertiary analogues and are lower in free energy by ca. 2-3 kcal mol-1. Y1 - 2007 ER - TY - THES A1 - Alahverdjieva, Veneta T1 - Experimental study of mixed protein/surfactant systems at the aqueous solution/air interface Y1 - 2007 CY - Potsdam ER - TY - THES A1 - Sel, Özlem T1 - Hierarchical meso- and macropore architectures by liquid crystalline and polymer colloid templating Y1 - 2007 CY - Potsdam ER -