@article{WackerDahmsSengeetal.2007, author = {Wacker, Philipp and Dahms, Katja and Senge, Mathias O. and Kleinpeter, Erich}, title = {Conformational Landscape of meso-(1,3-Dithian-2-yl)porphyrins}, doi = {10.1021/Jo0708700}, year = {2007}, abstract = {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.}, language = {en} } @article{RudershausenDrexlerBansseetal.2007, author = {Rudershausen, S. and Drexler, Hans-Joachim and Banße, Wolfgang and Kelling, Alexandra and Schilde, Uwe and Holdt, Hans-Joachim}, title = {Three polymorphs of bis(5-methylthio-1,2-dithiole-3-thione)-disulfide}, doi = {10.1002/crat.200610776}, year = {2007}, abstract = {The title compound, bis(5-methylthio-1,2-dithiole-3-thione)-disulfide, was yielded for the first time as by- product of the reaction of nickel(II) and cobalt(II) ions with 5-methylthio-1,2-dithiole-3-thione-4-thiolate. The compound can be obtained directly by oxidation of the ammonium salt of the ligand. C8H6S10 forms three polymorphs: (I), which crystallizes in the orthorhombic space group P212121, (II) and (III), which crystallize in the monoclinic space groups P21/c and P21/n, respectively. The crystal and molecular structures are presented here. The determination of the absolute configuration of (I) indicated the P-helical enantiomer. In contrast to this, the crystals of (II) und (III) are racemic, containing P- and M-helical enantiomers. The polymorphs differ in the kind of skewing around the disulfide bond and of the positions of the both dithiole rings to the S-S-moiety}, language = {en} } @article{ParkinsonAharonChangetal.2007, author = {Parkinson, P. and Aharon, E. and Chang, M. H. and Dosche, Carsten and Frey, G. L. and K{\"o}hler, Anna and Herz, L. M.}, title = {Dimensionality-dependent energy transfer in polymer-intercalated SnS2 nanocomposites}, doi = {10.1103/Physrevb.75.165206}, year = {2007}, abstract = {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.}, language = {en} } @article{Kleinpeter2007, author = {Kleinpeter, Erich}, title = {Syntheses and conformational analyses of mono- and trans-1,4-dialkoxy substituted cyclohexanes : the steric substituent/skeleton interactions}, issn = {0040-4020}, doi = {10.1016/j.tet.2007.06.094}, year = {2007}, abstract = {Mono- and trans-1,4-dialkoxy substituted cyclohexanes (alkyl=Me, Et, i-Pr, t-Bu) were prepared using the solvomercuration-demercuration (SM-DM) procedure. The axialaxial and axial,axialequatorial, equatorial conformational equilibria of the products were studied by low temperature 1H and 13C NMR spectroscopy in CD2Cl2. The structures and relative energies of the participating conformers were calculated at both the B3LYP (6-311G*//6-311+G*) and MP2 (6-311+G*//6-311G*) levels of theory. In the case of DFT, good correlations of ;Gocalcd versus ;Goexptl were obtained. Both the structures and the energy differences of the conformers have been discussed with respect to established models of conformational analysis, viz. steric and hyperconjugative interactions. In addition, 1JH,C coupling constants were considered with respect to the hyperconjugation present.}, language = {en} } @article{KleinpeterKlodKoch2007, author = {Kleinpeter, Erich and Klod, Sabrina and Koch, Andreas}, title = {Visualization of through space NMR shieldings of aromatic and anti-aromatic molecules and a simple means to compare and estimate aromaticity}, issn = {0166-1280}, doi = {10.1016/j.theochem.2007.02.049}, year = {2007}, abstract = {Through space NMR shieldings of aromatic (benzene, mono-substituted and annelated benzenes, ferrocene, [14]- and [18]-annulenes, phenylenes and tetra- to heptahelicene) and anti-aromatic molecules (cyclobutadiene and pentalene) were assessed by ab initio molecular-orbital calculations. Employing the nucleus-independent chemical shifts (NICS) concept, these through space NMR shieldings were visualized as iso-chemical-shielding surfaces (ICSSs) and can be applied quantitatively to determine the stereochemistry of proximal nuclei. In addition, the distances in {\AA} at ICSS values of ±0.1 ppm in-plane and perpendicular-to-center of the aromatic ring system were employed as a simple means to compare and estimate qualitatively the aromaticity of the systems at hand.}, language = {en} } @article{HaebelBahrkePeter2007, author = {Haebel, Sophie and Bahrke, Sven and Peter, Martin G.}, title = {Quantitative sequencing of complex mixtures of heterochitooligosaccharides by vMALDI-linear ion trap mass spectrometry}, issn = {0003-2700}, doi = {10.1021/Ac062254u}, year = {2007}, abstract = {Heterochitooligosaccharides possess interesting biol. properties. Isobaric mixts. of such linear heterochitooligosaccharides can be obtained by chem. or enzymic degrdn. of chitosan. However, the sepn. of such mixts. is a challenging anal. problem which is so far unresolved. It is shown that these isobaric mixts. can be sequenced and quantified simultaneously using std. derivatization and multistage tandem mass spectrometric techniques. A linear ion trap mass spectrometer equipped with a vacuum matrix-assisted laser desorption ionization (vMALDI) source is used to perform MS2 as well as MS3 expts. [on SciFinder (R)].}, language = {en} } @article{DoscheMicklerLoehmannsroebenetal.2007, author = {Dosche, Carsten and Mickler, Wulfhard and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Agenet, Nicolas and Vollhardt, K. Peter C.}, title = {Photoinduced electron transfer in [N]phenylenes}, issn = {1010-6030}, doi = {10.1016/j.jphotochem.2006.12.038}, year = {2007}, abstract = {First studies of electron transfer in [N]phenylenes were performed in bimolecular quenching reactions of angular [3]- and triangular [4]phenylene with various electron acceptors. The relation between the quenching rate constants k(q) and the free energy change of the electron transfer (Delta G(CS)(0)) could be described by the Rehm- Weller equation. From the experimental results, a reorganization energy lambda of 0.7 eV was derived. Intramolecular electron transfer reactions were studied in an [N]phenylene bichomophore and a corresponding reference compound. Fluorescence lifetime and quantum yield of the bichromophor display a characteristic dependence on the solvent polarity, whereas the corresponding values of the reference compound remain constant. From the results, a nearly isoenergonic charge separation process can be determined. As the triplet quantum yield is nearly independent of the polarity, charge recombination leads to the population of the triplet state.}, language = {en} } @article{SchwarzeMuellerDoscheetal.2007, author = {Schwarze, Thomas and Mueller, Holger and Dosche, Carsten and Klamroth, Tillmann and Mickler, Wulfhard and Kelling, Alexandra}, title = {Luminescence detection of open-shell transition-metal ions by photoinduced electron transfer controlled by internal charge transfer of a receptor}, doi = {10.1002/anie.200603992}, year = {2007}, language = {en} } @article{WackerKleinpeter2007, author = {Wacker, Philipp and Kleinpeter, Erich}, title = {Stoichiometry, complex stability, molecular size and conformational variations of metal ion crown ether complexes subject to diffusion coefficients in nonaqueous solutions}, doi = {10.1007/s10847-007-9332-1}, year = {2007}, abstract = {Both the stoichiometry and complex stability constants of crown ether complexes with metal ions have been determined by examining gradual changes in their diffusional behavior in nonaqueous solution. Diffusion coefficients, D, were evaluated by pulsed field gradient (PFG) NMR titration experiments whilst complex stability constants were determined by nonlinear curve-fitting procedures, D versus csol., which also allow the treatment of multiple complexation equilibria (1:1 to 1:2 stoichiometries). Differences in the diffusion coefficients of the various free crown ethers with respect to their metal ion complexes indicate great sensitivity to both conformational changes and changes in molecular size upon complexation.}, language = {en} } @article{LaschewskyPoundSkrabaniaetal.2007, author = {Laschewsky, Andr{\´e} and Pound, Gwenaelle and Skrabania, Katja and Holdt, Hans-Joachim and Teller, Joachim}, title = {Unsymmetrical bifunctional trithiocarbonate as unexpected by-product in the synthesis of a dithioester RAFT agent}, issn = {0303-402X}, doi = {10.1007/s.00396-007-1653-5}, year = {2007}, abstract = {The trithiocarbonate 2-(benzylsulfanylthiocarbonylsulfanyl) propanoic acid is formed as minor by-product in the synthesis of the dithioester 2-((2-phenylthioacetyl)sulfanyl) propanoic acid via the Grignard route. The mechanism for this side reaction is not clear. The isolated trithiocarbonate may act as unsymmetrical but bifunctional RAFT agent in the aqueous polymerization of N,N-dimethyl acrylamide. Therefore, it is important to separate it completely from the dithioester before engaging the latter in controlled free radical polymerization to guarantee a maximum control.}, language = {en} } @article{ShainyanUshakovMeshcheryakovetal.2007, author = {Shainyan, Bagrat A. and Ushakov, Igor A. and Meshcheryakov, Vladimir I. and Schilde, Uwe and Koch, Andreas and Kleinpeter, Erich}, title = {The stereodynamics of 3,5-bis(trifluoromethylsulfonyl)-1,3,5-oxadiazinane and 1,3,5- tris(trifluoromethylsulfonyl)-1,3,5-triazinane- an experimental and theoretical study}, doi = {10.1016/j.tet.2007.09.041}, year = {2007}, abstract = {Multinuclear dynamic NMR spectroscopy of 3,5-bis(trifluoromethylsulfonyl)-1,3,5-oxadiazinane (3) revealed the existence of two conformers with differently oriented CF3 groups with respect to the ring, and two dynamic processes: ring inversion and restricted rotation about the N-S bond. Two transition states connecting the two conformers and corresponding to clockwise and counterclockwise rotations about the N-S bond were found; the calculated activation barriers of about 12 kcal/mol are in excellent agreement with those measured experimentally for the related molecule 1,3,5-tris(trifluoromethylsulfonyl)-1,3,5-triazinane (1). X-ray analysis proved the existence of the symmetric isomer of 3, which is the minor isomer in solutions but the only one in the crystal due to packing effects. The normal Perlin effect (JCHax < JCHeq)observed for 2(6)-CH2 in 3, whereas the reversed Perlin effect was found for the 4-CH2 group in 3 as well as for all CH2 groups in 1 both experimentally and theoretically. The latter effect in compounds 1, 3, and 1- (methylsulfonyl)-3,5-bis(trifluoromethylsulfonyl)-1,3,5-triazinane (2) can be considered as a genuine reverse Perlin effect since larger values of 1JCH are observed for longer C-H bonds.}, language = {en} } @article{NeuvonenNeuvonenKochetal.2007, author = {Neuvonen, Helmi and Neuvonen, Kari and Koch, Andreas and Kleinpeter, Erich}, title = {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}, doi = {10.1016/j.theochem.2007.03.023}, year = {2007}, abstract = {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.}, language = {en} } @article{RasovicSteelKleinpeteretal.2007, author = {Rasovic, Aleksandar and Steel, Peter J. and Kleinpeter, Erich and Markovic, Rade}, title = {Regioselective synthesis of 1,3-thiazines by sequential 4-oxothiazolidine to 1,2-dithiole to 1,3-thiazine transformations : role of intramolecular non-bonded S...O interactions}, doi = {10.1016/j.tet.2006.12.075}, year = {2007}, abstract = {A new synthetic approach to 2,3-dihydro-4H-1,3-thiazine derivatives based upon reductive rearrangement of 1,2- dithiole-3-ylidene thiones has been developed. In turn, the 1,2-dithiole derivatives were prepared by an efficient ring- opening-closing process of 2-alkylidene-4-oxothiazolidines, induced in the presence of Lawesson's reagent by intramolecular non-bonded 1,5-type S...O interactions in the 4-oxothiazolidine precursors.}, language = {en} } @phdthesis{Nest2007, author = {Nest, Mathias}, title = {Quantum dynamics for large systems: System-bath type situations and correlated dynamics of many electrons}, address = {Potsdam}, pages = {176 S., I-V, graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Alahverdjieva2007, author = {Alahverdjieva, Veneta}, title = {Experimental study of mixed protein/surfactant systems at the aqueous solution/air interface}, address = {Potsdam}, pages = {XIV, 146 S., X : graph. Darst.}, year = {2007}, language = {en} } @article{YonedaLealSeidletal.2007, author = {Yoneda, Julliane Diniz and Leal, Katia Zaccur and Seidl, Peter Rudolf and Azeredo, Rodrigo Bagueira de V. and Kleinpeter, Erich}, title = {Camphor : a good model for illustrating NMR techniques}, year = {2007}, abstract = {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}, language = {en} } @article{ModarresiAlamKhamooshiRostamizadehetal.2007, author = {Modarresi-Alam, Ali Reza and Khamooshi, Ferydoon and Rostamizadeh, Mohsen and Keykha, Hossein and Nasrollahzahdeh, Mahmoud and Bijanzadeh, Hamid-Reza and Kleinpeter, Erich}, title = {Dynamic 1H NMR spectroscopic study of the restricted S-N rotation in aryl-N-(arylsulfonyl)-N- (triphenylphosphoranylidene)imidocarbamates}, year = {2007}, abstract = {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 N{\`u}S bond and these barriers show very little solvent dependence.}, language = {en} } @article{ModarresiNajafiRostamizadehetal.2007, author = {Modarresi, Ali Reza and Najafi, Parisa and Rostamizadeh, Mohsen and Keykha, Hossein and Bijanzadeh, Hamid-Reza and Kleinpeter, Erich}, title = {Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence}, year = {2007}, abstract = {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.}, language = {en} } @phdthesis{Kaper2007, author = {Kaper, Helenea}, title = {Structure control of nanoscaled inorganic matter by ionic liquids}, address = {Potsdam}, pages = {138 S. : Ill., graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Kulkarni2007, author = {Kulkarni, Amit Narahari}, title = {Degradation kinetics studies of polymers for biomedical applications}, address = {Potsdam}, pages = {vi, 144, viii S. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{EntrialgoCastano2007, author = {Entrialgo Castano, Maria}, title = {Hydrolytic degradation of aliphatic polyester: molecular modeling and quantum mechanical investigations}, address = {Potsdam}, pages = {141 S. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Stocco2007, author = {Stocco, Antonio}, title = {Amphiphilic block copolymers at the liquid-fluid interface, invesrigated by evanescent light scattering and ellipsometry}, address = {Potsdam}, pages = {iii, 108 S. : Ill., graph. Darst.}, year = {2007}, language = {en} } @phdthesis{You2007, author = {You, Liangchen}, title = {Synthesis and characterization of novel glycopolymers}, address = {Potsdam}, pages = {116 S. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Sel2007, author = {Sel, {\"O}zlem}, title = {Hierarchical meso- and macropore architectures by liquid crystalline and polymer colloid templating}, address = {Potsdam}, pages = {105, VXI S. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Frankovitch2007, author = {Frankovitch, Christine Marie}, title = {Optical methods for monitoring biological parameters of phototropic microorganisms during cultivation}, address = {Potsdam}, pages = {iii, 95 S. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Krause2007, author = {Krause, Pascal}, title = {Many-electron dynamics in molecules by means of time-dependent configuration interaction methods}, address = {Potsdam}, pages = {III, 107 S. : graph. Darst.}, year = {2007}, language = {en} } @book{KoetzKosmella2007, author = {Koetz, Joachim and Kosmella, Sabine}, title = {Polyelectrolytes and nanoparticles}, series = {Springer laboratory manuals in polymer science}, journal = {Springer laboratory manuals in polymer science}, publisher = {Springer-Verlag}, address = {Heidelberg}, isbn = {3-540-46381-X}, pages = {105 S.}, year = {2007}, language = {en} }