TY - THES A1 - Akdemir, Özgür T1 - Synthesis of novel non-viral gene carriers via atom transfer radical polymerization and click chemistry Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Award, Duhan Jawad T1 - Mixed 1,2-Dümine-1,2-Dithiolate Ligand Complexes : Structure, Proberties and EPR Spectroscopy Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Balci, Kubilay A1 - Koch, Andreas A1 - Kleinpeter, Erich T1 - A theoretical IR spectroscopic study based on DFT calculations for free mn-15S(2)O(3) maleonitrile-dithiacrown ether compound N2 - The theoretically possible stable conformers of free mn-15S2O3 maleonitrile-dithiacrown ether molecule were searched by means of a conformational study which consists of molecular dynamics and energy minimization calculations performed with MM2 force field and successive geometry optimization + frequency calculations performed first at B3LYP/3- 21G and then at B3LYP/6-31G(d) levels of theory. The obtained calculation results have clearly indicated that the free molecule in electronic ground state is very flexible and accordingly has many possible stable conformers of different conformational properties at room temperature; among them, the one having a macrocyclic ring structure in which all of the ether units oriented toward the center of the ring was determined the energetically most preferable conformer. In addition, the equilibrium geometrical parameters, vibrational normal modes and associated IR spectral data of the determined most stable three conformers of the molecule were calculated at B3LYP/6-31+G(d) and B3LYP/6-31++G(d,p) levels of theory. A successful assignment of the fundamental bands observed in the recorded experimental solid phase and solution phase IR spectra of the molecule was achieved in the light of the theoretical data obtained from these DFT calculations. To fit the calculated harmonic wavenumbers to the experimental ones, two different scaling procedures, referred to as "Scaled Quantum Mechanical Force Field (SQM FF) methodology" and "Scaling wavenumbers with empirical dual scale factors", were proceeded independently. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00222860 U6 - https://doi.org/10.1016/j.molstruc.2008.08.027 SN - 0022-2860 ER - TY - JOUR A1 - Beuermann, Sabine T1 - Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations N2 - The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding or electron pair donor/acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, k(P), may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of k(P). In contrast, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in k(P). Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/10003270 U6 - https://doi.org/10.1002/marc.200900131 SN - 1022-1336 ER - TY - JOUR A1 - Beuermann, Sabine T1 - Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations N2 - The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding, or electron pair donor / acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, kp, may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of kp. Contrary, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in kp. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117932056/issueyeargroup?year=2009 SN - 1022-1336 ER - TY - JOUR A1 - Bivigou Koumba, Achille Mayelle A1 - Kristen, Juliane A1 - Laschewsky, André A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Synthesis of symmetrical triblock copolymers of styrene and N-isopropylacrylamide using bifunctional bis(trithiocarbonate)s as RAFT agents N2 - Six new bifunctional bis(trithiocarbonate)s were explored as RAFT agents for synthesizing amphiphilic triblock copolymers ABA and BAB, with hydrophilic "A" blocks made from N-isopropylacrylamide and hydrophobic "B" blocks made from styrene. Whereas the extension of poly(N-isopropylacrylamide) by styrene was not effective, polystyrene macroRAFT agents provided the block copolymers efficiently. End group analysis by H-1 NMR spectroscopy supported molar mass analysis and revealed an unexpected side reaction for certain bis(trithiocarbonate)s, namely a fragmentation to simple trithiocarbonates while extruding ethylene-trithiocarbonate. The amphiphilic block copolymers with short polystyrene blocks are directly soluble in water and self-organize into thermo-responsive micellar aggregates. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291521-3935 U6 - https://doi.org/10.1002/macp.200800575 SN - 1022-1352 ER - TY - JOUR A1 - Boehm, Stanislav A1 - Tomašciková, Jana A1 - Imrich, Ján A1 - Danihel, Ivan A1 - Kristian, Pavol A1 - Koch, Andreas A1 - Kleinpeter, Erich A1 - Klika, Karel D. T1 - Computational study to assign structure, tautomerism, E/Z and s-cis/s-trans isomerism, pi-delocalization, partial aromaticity, and the ring size of 1,3-thiazolidin-4-ones and 1,3-thiazin-4-ones formed from thiosemicarbazides N2 - A set of structures encompassing 1-(9-acridinyl)thiosemicarbazide and its 2-methyl derivative together with their various tautomeric structures; the 5-membered ring 1,3-thiazolidin-4-one products resulting from the reaction of 1- (9-acridinyl)thiosemicarbazide and its 2-methyl derivative with dimethyl acetylenedicarboxylate (DMAD) together with the alternative 6-membered ring isomeric reaction products as well as other potential isomeric structures; and the 6- membered ring 1,3-thiazin-4-one product resulting from the reaction of 2-methyl-1-(9-acridinyl)thiosemicarbazide with methyl propiolate (MP) together with the alternative 5-membered ring isomeric reaction product were all extensively studied by molecular modeling calculations using DFT at the B3LYP/6-31G(d,p) level of theory. The ring-chain tautomerism of the thiosemicarbazides, the regio- and stereoselectivity of the reactions, the adopted conformations and E/Z configurations of the products, the prototropic tautomerism of all the compounds, and the reasons for the predominance of the s-cis conformation of the Z configuration of the 1,3-thiazolidin-4-one product in particular were all extensively analyzed. Comparison of the modeled structures were also made to the 1,3-thiazolidin-4-one and 1,3-thiazin-4-one structures of the methyl derivative as well as 1-(9-acridinyl)thiosemicarbazide available from X-ray crystallographic analysis. Tactics utilizing spectroscopic methods {1R frequencies (nu) and NMR chemical shifts (delta), scalar coupling constants (J), and NOEs (eta)} in conjunction with molecular modeling calculations of the spectral parameters (frequency calculations (v) and NMR 6 using the GIAO method and J by calculation of the Fermi contact term) were evaluated in terms of proving 5- or 6-membered ring formation. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/01661280 U6 - https://doi.org/10.1016/j.theochem.2009.09.019 SN - 0166-1280 ER - TY - JOUR A1 - Breininger, Eugenia A1 - Imran-ul-haq, Muhammad A1 - Tuerk, Michael A1 - Beuermann, Sabine T1 - Effect of polymer properties on poly(vinylidene fluoride) particles produced by rapid expansion of CO2 + polymer mixtures N2 - The generation of nanoscale primary poly(vinylidene fluoride) (PVDF) particles by rapid expansion of supercritical solutions (RESS) is reported. The experimental results show that RESS enables the formation of PVDF particles with median particle diameters ranging from 56 to 226 nm and that the size of PVDF particles can be influenced by polymer properties. The particle size can be decreased either by increasing molar mass, in case of identical polymer end groups, or by increasing the degree of crystallinity, in case of similar molar mass and different end groups. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/08968446 U6 - https://doi.org/10.1016/j.supflu.2008.09.016 SN - 0896-8446 ER - TY - JOUR A1 - Brown, Lauren E. A1 - Landaverry, Yakira R. A1 - Davies, James R. A1 - Milinkevich, Kristin A. A1 - Ast, Sandra A1 - Carlson, Joseph S. A1 - Oliver, Allen G. A1 - Konopelski, Joseph P. T1 - Progress toward the total synthesis of Psymberin/Irciniastatin A N2 - In this paper, we describe our synthesis of four key building blocks for the total synthesis of psymberin (1) and its C4 epimer (2). Despite early difficulties in processing material to the advanced intermediate stage, we have been successful in developing high-yielding syntheses for the pyran core, natural side chain, 4-epi side chain, and aryl fragments of the molecule. Our findings from the optimization process are presented herein. Y1 - 2009 UR - http://pubs.acs.org/journal/joceah U6 - https://doi.org/10.1021/Jo9009003 SN - 0022-3263 ER - TY - JOUR A1 - Böhm, Stanislav A1 - Tomaszciková, Jana A1 - Imrich, Ján A1 - Danihel, Ivan A1 - Kristian, Pavol A1 - Koch, Andreas A1 - Kleinpeter, Erich A1 - Klika, Karel D. T1 - Computational study to assign structure, tautomerism, E/Z and s-cis/s-trans isomerism, pi-delocalization, partial aromaticity, and the ring size of 1,3-thiazolidin-4-ones and 1,3-thiazin-4-ones formed from thiosemicarbazides N2 - A set of structures encompassing 1-(9-acridinyl)thiosemicarbazide and its 2-methyl derivative together with their various tautomeric structures; the 5-membered ring 1,3-thiazolidin-4-one products resulting from the reaction of 1- (9-acridinyl)thiosemicarbazide and its 2-methyl derivative with dimethyl acetylenedicarboxylate (DMAD) together with the alternative 6-membered ring isomeric reaction products as well as other potential isomeric structures; and the 6- membered ring 1,3-thiazin-4-one product resulting from the reaction of 2-methyl-1-(9-acridinyl)thiosemicarbazide with methyl propiolate (MP) together with the alternative 5-membered ring isomeric reaction product were all extensively studied by molecular modeling calculations using DFT at the B3LYP/6-31G(d,p) level of theory. The ring-chain tautomerism of the thiosemicarbazides, the regio- and stereoselectivity of the reactions, the adopted conformations and E/Z configurations of the products, the prototropic tautomerism of all the compounds, and the reasons for the predominance of the s-cis conformation of the Z configuration of the 1,3-thiazolidin-4-one product in particular were all extensively analyzed. Comparison of the modeled structures were also made to the 1,3-thiazolidin-4-one and 1,3-thiazin-4-one structures of the methyl derivative as well as 1-(9-acridinyl)thiosemicarbazide available from X-ray crystallographic analysis. Tactics utilizing spectroscopic methods {IR frequencies (;) and NMR chemical shifts (;), scalar coupling constants (J), and NOEs (;)} in conjunction with molecular modeling calculations of the spectral parameters {frequency calculations (;) and NMR ; using the GIAO method and J by calculation of the Fermi contact term} were evaluated in terms of proving 5- or 6-membered ring formation. Y1 - 2009 SN - 0166-1280 ER -