@article{StrehmelSarkerLahtietal.2005,
  author    = {Strehmel, Veronika and Sarker, A. M. and Lahti, P. M. and Karasz, F. E. and Heydenreich, Matthias and Wetzel, Hendrik and Haebel, Sophie and Strehmel, Bernd},
  title     = {One- and two-photon photochemistry and photophysics of poly(arylenevinylene)s containing a biphenyl moiety},
  issn      = {1439-4235},
  year      = {2005},
  abstract  = {Photochemical and photophysical properties were investigated for poly(arylenevinylene)s containing a flexible biphenyl "hinge" unit by applying one-photon (OP) and two-photon (TP) excitation to explore excited-state properties. The poly(arylenevinylene)s were poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(4,4'-dihexyloxy-3,3'-biph enylenevinylene)] (1), poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(2,2'-dihexyloxy-3,3'-biph enylenevinylene)] (2), and poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(2,2'-biphenylene-vinylene )] (3). Effective emission quantum yields and related photonic properties were evaluated on a realistic per-chromophore basis using effective conjugation lengths based on the Strickler-Berg relationship. intramolecular photocyclization was deduced to occur in the one case where the biphenyl molecular connectivity permitted the reaction, based on matrix- assisted loser desorption/ionization time-of-flight (MALDI-TOF), heteronuclear multiple-quantum coherence (HMQC)-NMR, and gel-permeation chromatography (GPC) results. The various photoprocesses could be induced by either OP or TP excitation, though the first excited singlet state is the photoactive state. The higher excitation energy 1 of the TP excited state favors indirect population of the S, state by electronic coupling between the TP and OP excited states [lambda(max)(TPE) (nm): 726; delta (GM)([9]): 1 = 229, 2 = 215, 3 = 109). Photochemical processes occurring from the lowest OP excited state (S-1) could therefore also be indirectly induced by TP excitation},
  language  = {en}
}
@article{SzczubialkaMoczekGoliszeketal.2005,
  author    = {Szczubialka, K. and Moczek, Lukasz and Goliszek, A. and Nowakowska, M. and Kotzev, Anton and Laschewsky, Andr{\´e}},
  title     = {Characterization of hydrocarbon and fluorocarbon microdomains formed in aqueous solution of associative polymers : a molecular probe technique},
  issn      = {0022-1139},
  year      = {2005},
  abstract  = {Fluorocarbon associative polymers of the polysoap type were studied using two fluorescent probes, 1- octanoylpyrene (OcPyH) and 1-perfluorooctanoylpyrene (OcPyF). In aqueous solution the polymers formed hydrophobic domains composed of hydrocarbon, fluorocarbon or both types of polymeric side chains, which could solubilize the probes. This resulted in the appearance of new fluorescence emission bands and changes in the fluorescence polarization of the probes. The differences in the solubilization properties of the polymers are discussed. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{SchulerLipmanSteinbachetal.2005,
  author    = {Schuler, Benjamin and Lipman, Everett A. and Steinbach, P. J. and Kumke, Michael Uwe and Eaton, W. A.},
  title     = {Polyproline and the "spectroscopic ruler" revisited with single-molecule fluorescence},
  issn      = {0027-8424},
  year      = {2005},
  abstract  = {To determine whether Forster resonance energy transfer (FRET) measurements can provide quantitative distance information in single-molecule fluorescence experiments on polypeptides, we measured FRET efficiency distributions for donor and acceptor dyes attached to the ends of freely diffusing polyproline molecules of various lengths. The observed mean FRET efficiencies agree with those determined from ensemble lifetime measurements but differ considerably from the values expected from Forster theory, with polyproline treated as a rigid rod. At donor-acceptor distances much less than the Forster radius R-o, the observed efficiencies are lower than predicted, whereas at distances comparable to and greater than R-0, they are much higher. Two possible contributions to the former are incomplete orientational averaging during the donor lifetime and, because of the large size of the dyes, breakdown of the point-dipole approximation assumed in Forster theory. End-to-end distance distributions and correlation times obtained from Langevin molecular dynamics simulations suggest that the differences for the longer polyproline peptides can be explained by chain bending, which considerably shortens the donor-acceptor distances},
  language  = {en}
}
@article{SieboldKellingSchildeetal.2005,
  author    = {Siebold, M. and Kelling, Alexandra and Schilde, Uwe and Strauch, Peter},
  title     = {Heterobimetallic 3d-4-complexes with bis(1;2-dithiooxalato)nickelate(II) as planar bridging block},
  issn      = {0932-0776},
  year      = {2005},
  abstract  = {Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)(n)}(2)- {Ni(dto)(2)}(3)] (.) xH(2)O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9-12). With [{Nd(H2O)(5)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 10-12) (1) and [{Er(H2O)(4)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 9- 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P2(1)/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2)angstrom , beta = 98.907(9)degrees and Z = 2; 2, triclinic in P (1) over bar with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) angstrom, alpha = 107.899(4)degrees, beta = 91.436(4)degrees, gamma = 112.918(4)degrees and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions},
  language  = {en}
}
@article{RitschelKuntzZulicke2005,
  author    = {Ritschel, Thomas and Kuntz, Philip J. and Zulicke, Lutz},
  title     = {Structure and dynamics of cationic van-der-Waals clusters : I. Binding and structure of protonated argon clusters},
  year      = {2005},
  abstract  = {The geometric structure and bonding properties of medium-sized ArnH+ clusters (n = 2-35), in which a proton is wrapped up in a number of Ar atoms, are investigated by applying a diatomics-in-molecules (DIM) model with ab-initio input data generated by means of multi-reference configuration-interaction (MRCI) computations. For the smaller complexes, n = 2-7, cross-checking calculations employing the coupled-cluster approach (CCSD) with the same one-electron atomic basis set as for the input data calculations (aug-cc-pVTZ from Dunning), show good agreement thus justifying the extension of the DIM study to larger n. Local minima of the multi-dimensional potential-energy surfaces (PES) are determined by combining a Monte-Carlo sampling followed, for each generated point, by a steepest-descent optimization procedure. For the electronic ground state of the ArnH+ clusters, the global minimum (corresponding to the most stable structure of the cluster) as well as secondary minima are found and analyzed. The structural and energetic data obtained reveal the building-up regularities for the most stable structures and make it possible to formulate a simple increment scheme. The low-lying excited states are also calculated by the DIM approach; they all turn out to be globally repulsive},
  language  = {en}
}
@article{PetersPetersKimetal.2005,
  author    = {Peters, Karl and Peters, E. M. and Kim, Boo Geun and Linker, Torsten},
  title     = {Crystal structure of ethyl (3aR,4R,5R,6R,7aR)-4,5-diacetoxy-6-acetoxymethyl-2-oxy-3a,5,6,7a-tetrahy dro-4H- pyrano[3,2-d]isoxazole-3-carboxylate, C16H21NO11},
  issn      = {1433-7266},
  year      = {2005},
  abstract  = {C16H21NO11, monoclinic, P12(1)1 (no. 4), a = 8.181(1) angstrom, b = 11.604(2) angstrom, c = 10.193(1) angstrom, beta = 101.59(1)degrees, V = 947.9 angstrom(3), Z = 2, R-gt(F) = 0.068, wR(ref)(F-2) = 0.177, T = 293 K.},
  language  = {en}
}
@article{PetersPetersLinkeretal.2005,
  author    = {Peters, Karl and Peters, E. M. and Linker, Ursula and Linker, Torsten},
  title     = {Crystal structure of 1,1,2,2-tetramethoxycarbonylethanol, C2H(CH3OCO)(4)OH},
  issn      = {1433-7266},
  year      = {2005},
  abstract  = {C10H14O9, monoclinic, C12/c1 (no. 15), a = 15.801(1) angstrom, b = 7.920(1) angstrom, c = 21.055(2) angstrom, beta = 101.31 (1)degrees, V = 2583.8 angstrom(3), Z = 8, R-gt(F) 0.044, wR(ref)(F-2) = 0.134, T = 293 K.},
  language  = {en}
}
@article{PetersPetersRebienetal.2005,
  author    = {Peters, Karl and Peters, E. M. and Rebien, F. and Linker, Torsten},
  title     = {Crystal structure of methyl (1R,2S,3R,4S)-1-phenyl-3,4-epoxi-1,2,3,4-tetrahydronaphthalene-2-carboxy late,C18H16O3},
  issn      = {1433-7266},
  year      = {2005},
  abstract  = {C18H16O3, monoclinic, P12(1)/c1 (no. 14), a = 14.954(3) angstrom, b = 8.088(2) angstrom, c = 11.973(2) angstrom, beta = 93.50(1)degrees, V = 1445.4 angstrom(3), Z = 4, R-gt(F) = 0.083, wR(ref)(F-2) = 0.249, T = 293 K.},
  language  = {en}
}
@article{RancanWieheNoebeletal.2005,
  author    = {Rancan, Fiorenza and Wiehe, Arno and N{\"o}bel, Maria and Senge, Mathias O and Al Omari, Saleh and B{\"o}hm, Fritz and John, Matthias and R{\"o}der, Beate},
  title     = {Influence of substitutions on asymmetric dihydroxychlorins with regard to intracellular uptake, subcellular localization and photosensitization of Jurkat cells},
  issn      = {1011-1344},
  year      = {2005},
  abstract  = {The search for new efficient sensitizers for photodynamic therapy (PDT) points to improve photophysical properties like absorption in the red region and singlet oxygen quantum yield as well as to control the localization of the sensitizer within the tumour cell. Depending on their physicochemical properties and their uptake mechanism, sensitizers can reach different intracellular concentrations and localize in different subcellular compartments. Moreover, the preferential localization of a sensitizer in target organelles, like mitochondria or lysosomes, could determine the cell death mechanism after PDT. This study aimed to investigate the influence of substitutions on dihydroxychlorins with regard to intracellular uptake, subcellular localization and cell death pathway. Moreover, the effect of a liposome-based delivery system was tested. The intracellular uptake was found to be strictly dependent on the sensitizer molecular structure and the means of its delivery. The most polar sensitizer in this study (compound 3) had, depending on incubation time, an intracellular concentration 2-8 times higher than the unsubstituted chlorin 1. All investigated photosensitizers localize predominantly in lysosomes but after longer incubation times weak fluorescence intensity was also detected in mitochondria and Golgi apparatus. The cell death pathway was found to be influenced by the sensitizer intracellular concentration and the applied light doses. In general, the increasing amphiphilicity of the sensitizer molecules is correlated with an increased sensitizer uptake and an increased rate of necrotic cells after irradiation. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{PeikowMaternPeteretal.2005,
  author    = {Peikow, Dirk and Matern, Christa-Maria and Peter, Martin G. and Schilde, Uwe},
  title     = {Crystal structure of (1,4,7,10,13-pentaoxacyclopentadecane-O,O ',O '',O ''')(trifluoromethanesulfonato-O,O ')sodium, Na(C10H20O5)(CF3SO3)},
  year      = {2005},
  abstract  = {C11H20F3NaO8S, monoclinic, P121/nil (no. 11), a = 7.947(1) angstrom, b = 12.056(1) angstrom, c = 9.083(1) angstrom, P = 106.01 (1)degrees, V = 836.4 angstrom(3), Z = 2, R-gt(F) = 0.043, wR(ref)(F-2) = 0.120, T = 210 K.},
  language  = {en}
}
@article{HildebrandtCharbonniereBecketal.2005,
  author    = {Hildebrandt, Niko and Charbonniere, Lo{\"i}c J. and Beck, Michael and Ziessel, Raymond F. and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {Quantum dots as efficient energy acceptors in a time-resolved fluoroimmunoassay},
  issn      = {1433-7851},
  year      = {2005},
  language  = {en}
}
@article{Loehmannsroeben2005,
  author    = {L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {Laser-induced fluorescence (LIF) spectroscopy and laser-based ion mobility (IM) spectrometry for in-situ analysis of contaminated soils},
  year      = {2005},
  language  = {en}
}
@phdthesis{Polleux2005,
  author    = {Polleux, Julien Philippe},
  title     = {Ligang-Mediated synthesis and assembly of crystalline metal oxide nanoparticles},
  address   = {Potsdam},
  pages     = {118 S. : Ill., graph. Darst.},
  year      = {2005},
  language  = {en}
}
@article{LeporattiSczechRiegleretal.2005,
  author    = {Leporatti, S. and Sczech, R. and Riegler, H. and Bruzzano, Stefano and Storsberg, J. and Loth, Fritz and Jaeger, Werner and Laschewsky, Andr{\´e} and Eichhorn, S. and Donath, E.},
  title     = {Interaction forces between cellulose microspheres and ultrathin cellulose films monitored by colloidal probe microscopy : effect of wet strength agents},
  year      = {2005},
  language  = {en}
}
@phdthesis{Ali2005,
  author    = {Ali, Abu Md. Imroz},
  title     = {Morphology control in nanoscopic composite polymer particles},
  address   = {Potsdam},
  pages     = {97, XXXV S. : Ill., graph. Darst.},
  year      = {2005},
  language  = {en}
}
@article{AlarconAldereteAguilaetal.2005,
  author    = {Alarcon, Julio and Alderete, Joel B. and Aguila, Sergio and Peter, Martin G.},
  title     = {Regio and stereoselective hydroxylation of alpha-agarofuran by biotransformation of rhizopus nigricans},
  year      = {2005},
  abstract  = {A new synthesis of 9 alpha-hydroxy-alpha-agarofuran (6 alpha) is described, using a microbiological hydroxylation alpha-agarofuran (5) as the key reaction. The stereochemistry of the biohydroxylation was determined on the basis of a NOESY-experiment and GIAO calculations at the B3LYP/cc-pVDZ level. A strong gamma-effect was observed at C15 of the agarofuran ring which was correctly predicted by the GIAO-B3LYP calculations},
  language  = {en}
}
@article{KozlevcarHumarStrauchetal.2005,
  author    = {Kozlevcar, Bojan and Humar, M. B. and Strauch, Peter and Leban, I},
  title     = {Fixation of copper(II) ions in aqueous solution to lignin model compound vanillin in an absence of the nitrogen donor ligands : structural and EPR correlation},
  year      = {2005},
  abstract  = {In order to elucidate the interactions of copper with wood, three mononuclear copper(II) coordination compounds with a vanillinate anion, cis-[Cu(C8H7O3)(2)(H2O)(2)] (1), trans-[Cu(C8H7O3)(2)(H2O)(2)].2H(2)O (2), and trans- [Cu(C8H7O3)(2)(H2O)(2)] (3), have been characterized. X-ray structure analysis of the cis isomer 1 reveals two bidentate vanillinate ions coordinated via methoxy (Cu-O1 2.260(2) angstrom) and deprotonated hydroxy oxygen atoms (Cu-O2 1.909(2) angstrom), and two water molecules (Cu-O1w 2.087(2) angstrom) in the octahedral CuO6 chromophore. Two axes O1-Cu- O1w' in the octahedron have the same length, while the third axis O2-Cu-O2' is shorter. This is in agreement with the room temperature EPR spectrum of 1, showing two signals (g(12) 2.302, g(3) 2.005), but interestingly, three signals (g(1) 2.393, g(2) 2.214, g(3) 2.010) in the 115 K spectrum were found. The same coordination atoms were found also in the trans isomer 2 (Cu-O2 1.950(2), Cu-O1w 1.994(2), Cu-O1 2.334(2) angstrom), however here, two axes of almost equal length are short (O2-Cu-O2' O1w-Cu-O1w'), while the third axis is longer (O1-Cu-O1'). On the other hand, three (rhombic) signals (g(1) 2.289, g(2) 2.163, g(3) 2.086) in the room temperature EPR spectrum of 2 suggest three different axes in the coordination octahedron. In the EPR spectrum, of the second trans complex 3, a slightly rhombically distorted elongated axial spectrum is found. The 115 K EPR spectra of the two trans complexes 2 and 3 do not differ significantly from the features observed at room temperature. These results indicate that there is not always a straightforward correlation between the results of XRD structure analysis and EPR spectroscopy. Nevertheless, both methods can act also complementarily and give a deeper insight into the nature of copper(II) chromophores},
  language  = {en}
}
@article{RickertLendleinKelchetal.2005,
  author    = {Rickert, D and Lendlein, Andreas and Kelch, S and Franke, R. P. and Moses, M. A.},
  title     = {Cell proliferation and cellular activity of primary cell cultures of the oral cavity after cell seeding on the surface of a degradable, thermoplastic block copolymer},
  year      = {2005},
  abstract  = {Using standard cell biological and biochemical methods we were able to test the ability of a degradable, thermoplastic block copolymer to support the adhesion, proliferation, and the cellular activity of primary cell cultures of the oral cavity in vitro. The delicate balance between a group of endogenous enzymes, Matrix Metalloproteinases (MMPs), and their inhibitors (Tissue Inhibitor of MMPs, TIMPs) have a decisive function in the remodeling of the extracellular matrix during processes like wound healing or the integration of biomaterials in surrounding tissues after implantation. Recently developed, biodegradable thermoplastic elastomers with shape-memory properties may be the key to develop new therapeutical options in head and neck surgery. Primary cell cultures of the oral cavity of Sprague-Dawley rats were seeded on the surface of a thermoplastic block copolymer and on a polystyrene surface as control. Conditioned media of the primary cells were analyzed for MMPs and TIMPs after different periods of cell growth. The MMP and TIMP expression was analysed by zymography and a radiometric enzyme assay. No statistically significant differences in the appearance and the kinetic of MMP-1, MMP-2, MMP-9 and TIMPs were detected between cells grown on the polymer surface compared to the control. An appropriate understanding of the molecular processes that regulate cellular growth and integration of a biomaterial in surrounding tissue is the requirement for an optimal adaptation of biodegradable, polymeric biomaterials to the physiological, anatomical, and surgical conditions in vivo to develop new therapeutic options in otolaryngology and head and neck surgery},
  language  = {en}
}
@article{LoehmannsroebenLau2005,
  author    = {L{\"o}hmannsr{\"o}ben, Hans-Gerd and Lau, Steffen},
  title     = {Isotope selectivity in environmental monitoring : NIR diode laser spectroscopy for isotope-selective sensing of soil-respired carbon dioxide},
  year      = {2005},
  language  = {en}
}
@article{EngelhardtLinker2005,
  author    = {Engelhardt, Ulrike and Linker, Torsten},
  title     = {1,4-cyclohexadienes as mechanistic probes for the Jacobsen epoxidation : evidence for radical pathways},
  year      = {2005},
  abstract  = {1,4-Cyclohexadienes allow a direct comparison of epoxidation and C - H oxidation within the same molecule and give evidence for radical pathways during the Jacobsen epoxidation},
  language  = {en}
}
@article{FudickarFeryLinker2005,
  author    = {Fudickar, Werner and Fery, Andreas and Linker, Torsten},
  title     = {Reversible light and air-driven lithography by singlet oxygen},
  issn      = {0002-7863},
  year      = {2005},
  language  = {en}
}
@article{LutzLaschewsky2005,
  author    = {Lutz, Jean-Francois and Laschewsky, Andr{\´e}},
  title     = {Multicompartment micelles : has the long-standing dream become a reality?},
  issn      = {1022-1352},
  year      = {2005},
  abstract  = {Multicompartment micelles are complex nanosized systems that possess a hydrosoluble shell and a hydrophobic core, which is characterized by segregated incompatible subdomains. With roots starting about ten years ago, the field of multi compartment micelles has evolved slowly, until recently when significant achievements have been made. The present article reviews strategies for building such micellar assemblies as well as morphological studies, highlights the future challenges, and discusses possible applications, which exploit the coexistence of differentiated nano- domains. Formation of multi compartment micelles using miktoarm stars mu-(polyethylethylene)(poly(ethylene oxide))(poly(perfluoropropylene oxide)) and a cryo-TEM image visualizing the process},
  language  = {en}
}
@article{MertogluGarnierLaschewskyetal.2005,
  author    = {Mertoglu, Murat and Garnier, Sebastien and Laschewsky, Andr{\´e} and Skrabania, Katja and Storsberg, J.},
  title     = {Stimuli responsive amphiphilic block copolymers for aqueous media synthesised via reversible addition fragmentation chain transfer polymerisation (RAFT)},
  issn      = {0032-3861},
  year      = {2005},
  abstract  = {A series of RAFT agents was synthesised, and used to prepare various ionic. non-ionic and zwitterionic water- soluble polymers, in organic as well as in aqueous media. The RAFT process proved to be a powerful method to prepare functional polymers of complex structure. such as amphiphilic diblock and triblock copolymers. This includes polymers containing one or even two stimuli-sensitive hydrophilic blocks. Switching the hydrophilic character of a single or of several blocks by changing the PH, the temperature or the salt content demonstrated the variability of the molecular designs suited for stimuli-sensitive polymeric amphiphiles, and exemplified the concept of multiple-sensitive systems. (c) 2005 Published by Elsevier Ltd},
  language  = {en}
}
@article{MertogluLaschewskySkrabaniaetal.2005,
  author    = {Mertoglu, Murat and Laschewsky, Andr{\´e} and Skrabania, Katja and Wieland, C.},
  title     = {New water soluble agents for reversible addition-fragmentation chain transfer polymerization and their application in aqueous solutions},
  issn      = {0024-9297},
  year      = {2005},
  abstract  = {A series of nonionic, anionic, and cationic water-soluble monomers bearing the (meth)acrylate, (meth)acrylamide, or styrene moiety were polymerized in water by free-radical polymerization via reversible addition- fragmentation chain transfer (RAFT). Several new water-soluble RAFT agents based on dithiobenzoate were employed that are water soluble independently of the pH. One of them bears a fluorophore, enabling unsymmetrical double end-group labeling as well as the preparation of fluorescent-labeled polymers. The temperature-dependent stability of the new RAFT agents against hydrolysis was studied. Controlled polymerization in aqueous solution was possible with styrenic, acrylic, and methacrylic monomers; molar masses increase with conversion, and polydispersities are relatively low. But RAFT polymerization failed for an anionic itaconate. Whereas polymerizations of methacrylamides were slow at temperatures below 60 degrees C, such conditions proved favorable for the RAFT polymerization of acrylates and methacrylates, to minimize hydrolysis of the dithioester end-group functionality, and to improve the preparation of block copolymers},
  language  = {en}
}
@article{MullerRatschSonnenburgetal.2005,
  author    = {Muller, K. R. and Ratsch, G. and Sonnenburg, S. and Mika, Sebastian and Grimm, M. and Heinrich, N.},
  title     = {Classifying 'drug-likeness' with kernel-based learning methods},
  issn      = {1549-9596},
  year      = {2005},
  abstract  = {In this article we report about a successful application of modern machine learning technology, namely Support Vector Machines, to the problem of assessing the 'drug-likeness' of a chemical from a given set of descriptors of the Substance. We were able to drastically improve the recent result by Byvatov et al. (2003) on this task and achieved an error rate of about 7\% on unseen compounds using Support Vector Machines. We see a very high potential of such machine learning techniques for a variety of computational chemistry problems that occur in the drug discovery and drug design process},
  language  = {en}
}
@article{LaschewskyLunkenheimerRakotoalyetal.2005,
  author    = {Laschewsky, Andr{\´e} and Lunkenheimer, K. and Rakotoaly, R. H. and Wattebled, Laurent},
  title     = {Spacer effects in dimeric cationic surfactants},
  issn      = {0303-402X},
  year      = {2005},
  abstract  = {A series of dimeric cationic surfactants (gemini surfactants), which have spacer groups of varying length and flexibility, was synthesized. The series is derived from the parent compounds dodecyltrimethylammonium chloride or benzyldodecyldimethylammonium chloride. Characteristic surfactant properties of the dimeric ammonium compounds such as surface activity, micellization, viscosity effects, foaming, and solubilization, were studied with respect to the influence of the spacer group on the surfactant. For all properties, the influence of the length of the spacer group was predominant though the chemical nature of the spacer cannot be neglected},
  language  = {en}
}
@article{LaschewskyWattebledArotcarenaetal.2005,
  author    = {Laschewsky, Andr{\´e} and Wattebled, Laurent and Arotcarena, Michel and Habib-Jiwan, Jean-Louis and Rakotoaly, R. H.},
  title     = {Synthesis and properties of cationic oligomeric surfactants},
  issn      = {0743-7463},
  year      = {2005},
  abstract  = {Three series of new oligomeric cationic surfactants were synthesized. These amphiphiles are trimeric and tetrameric oligomeric quaternary ammonium chlorides, with spacer groups of different lengths separating the individual surfactant fragments. The properties of the compounds, such as Krafft temperatures, surface activity, micellization, viscosifying effects, foaming and solubilizing capacity, are studied. The influence of the degree of oligomerization and of the spacer group on the surfactant properties is discussed, in comparison with the analogous standard monomeric and dimeric ("gemini") surfactants. Typically, the evolution of the properties observed from standard to dimeric surfactants progresses with the trimers and tetramers, resulting for instance in extremely low critical micellization concentrations},
  language  = {en}
}
@article{LemkeFernandezTrujilloLoehmannsroeben2005,
  author    = {Lemke, Matthias and Fernandez-Trujillo, R. and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {In-situ LIF analysis of biological and petroleum-based hydraulic oils on soil},
  issn      = {1424-8220},
  year      = {2005},
  abstract  = {Absorption and fluorescence properties of 4 hydraulic oils ( 3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil- containing compartments, namely a soil column and a soil bed},
  language  = {en}
}
@article{WieheShakerBrandtetal.2005,
  author    = {Wiehe, A. and Shaker, Y. M. and Brandt, J. C. and Mebs, S. and Senge, Mathias O.},
  title     = {Lead structures for applications in photodynamic therapy : Part 1: Synthesis and variation of m-THPC (Temoporfin) related amphiphilic A(2)BC-type porphyrins},
  issn      = {0040-4020},
  year      = {2005},
  abstract  = {Photodynamic therapy (PDT) is a developing modality for the treatment of certain tumorous and other diseases. Considerable progress has been made in recent years in the search for new photosensitizers, in particular elucidating the role of localization of the photosensitizer. Known successful photosensitizers of the tetrapyrrole type are amphiphilic molecules, preferably localizing in cellular membrane structures. Thus, the quest for new photosensitizers requires the synthesis of unsymmetrically Substituted (amphiphilic) tetrapyrroles. In this article. we describe strategies for the de novo synthesis of amphiphilic tetrapyrroles using a 3-hydroxyphenyl substituted tetrapyrrolic system (Temoporfin) as the lead structure. From an applied science-oriented approach, such a set of amphiphilic porphyrins is best synthesized by combining well-developed condensation methods with subsequent functionalization via organolithium compound or transition metal catalyzed coupling protocols. Starting from simple A(2)- or AB-porphyrins, the synthesis of A(2)B-, A(3)-, A(3)B-, and A(2)BC-porphyrins with a mixed hydrophilic/hydrophobic substitution pattern is described. Because of the versatility of this approach to unsymmetrically Substituted porphyrins it is also applicable to other areas where porphyryns with a tailor-made substitution patterns are needed. for example. catalysts or molecular electronic devices based on tetrapyrroles. (c) 2005 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{WanjohiYenesewMidiwoetal.2005,
  author    = {Wanjohi, John M. and Yenesew, Abiy and Midiwo, Jacob O. and Heydenreich, Matthias and Peter, Martin G. and Dreyer, M. and Reichert, M. and Bringmann, Gerhard},
  title     = {Three dimeric anthracene derivatives from the fruits of Bulbine abyssinica},
  issn      = {0040-4020},
  year      = {2005},
  abstract  = {From the fruits of Bulbine abyssinica three new dimeric anthracene derivatives, (P)-8,9,1',8'- tetrahydroxy-3,3'-dimethyl[10,7'-bianthracene]-1,4,9',10'- tetraone (trivial name abyquinone A), (10R)-1,4,8,1',8-pentahydroxy-3,3'-dimethyl-[10,7'-bianthracene]9,9',10' (10H)-trione (trivial name abyquinone B), and (10R)-3,4'-dihydro-1,4,8,3',8',9'-hexahydroxy-3,3'- dimethyl-[10,7'-biant hracene]9,1'(10H,2'H)-dione (trivial name abyquinone Q were isolated. Despite their structural differences, these three compounds are connected to each other by the apparently biomimetic conversion of abyquinone C (a preanthraquinonylanthrone with two stereogenic centers) into B (an anthraquinonylanthrone with one stereogenic center) and finally into A (an axially chiral bianthraquinone) under mild conditions, involving a highly efficient center-to-axis chirality transfer. In addition, the known anthraquinones islandicin and chrysophanol were identified. The structures were determined on the basis of spectroscopical evidences, chemical transformations, and quantum chemical CD calculations. (C) 2005 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{YenesewMushibeIndulietal.2005,
  author    = {Yenesew, Abiy and Mushibe, E. K. and Induli, M. and Derese, Solomon and Midiwo, Jacob O. and Kabaru, Jacques M. and Heydenreich, Matthias and Koch, Andreas and Peter, Martin G.},
  title     = {7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoloata},
  issn      = {0031-9422},
  year      = {2005},
  abstract  = {From the acetone extract of the roots of Derris trifoliata an isollavonoid derivative, named 7a-O- methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isollavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence. Rotenone and deguelin were identified as the larvicidal principles of the acetone extract of the roots of Derris trifoliata. (c) 2005 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{YenesewDereseMidiwoetal.2005,
  author    = {Yenesew, Abiy and Derese, Solomon and Midiwo, Jacob O. and Bii, Christine C. and Heydenreich, Matthias and Peter, Martin G.},
  title     = {Antimicrobial flavonoids from the stem bark of Erythrina burttii},
  issn      = {0367-326X},
  year      = {2005},
  abstract  = {The chloroform extract of the stem bark of Erythrina burttii showed antifungal and antibacterial activities using the disk diffusion method. Flavonoids were identified as the active principles. Activities were observed against fungi and Gram(+) bacteria, but the Gram(-) bacteria Escherichia coli was resistant. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{NoteKoetzKosmellaetal.2005,
  author    = {Note, Carine and Koetz, Joachim and Kosmella, Sabine and Tiersch, Brigitte},
  title     = {Hydrophobically modified polyelectrolytes used as reducing and stabilizing agent for the formation of gold nanoparticles},
  issn      = {0303-402X},
  year      = {2005},
  abstract  = {This paper is focused on the synthesis and characterization of hydrophobically modified polyelectrolytes and their use as reducing as well as stabilizing agents for the formation of gold nanoparticles. Commercially available poly(acrylic acid) has been hydrophobically modified with various degrees of grafting of butylamine introduced randomly along the chain. Different analytical methods are performed, i.e., IR and H-1-NMR spectroscopy in combination with elemental analysis to determine the degree of grafting. The modified polymers can successfully be used for the controlled single-step synthesis and stabilization of gold nanoparticles. The process of nanoparticle formation is investigated by means of UV-vis spectroscopy. The size and shape of the particles obtained in the presence of unmodified or modified polyelectrolytes are characterized by dynamic light scattering, zeta potential measurements and transmission electron microscopy. The polyelectrolytes were involved in the crystallization process of the nanoparticles, and in the presence of hydrophobic microdomains at the particle surface, a better stabilization at higher temperature can be observed},
  language  = {en}
}
@article{RusuNgWilkeetal.2005,
  author    = {Rusu, Viorel Marin and Ng, C. H. and Wilke, Max and Tiersch, Brigitte and Fratzl, Peter and Peter, Martin G.},
  title     = {Size-controlled hydroxyapatite nanoparticles as self-organized organic-in organic composite materials},
  issn      = {0142-9612},
  year      = {2005},
  abstract  = {This paper presents some results concerning the size-controlled hydroxyapatite nanoparticles obtained in aqueous media in a biopolymer matrix from soluble precursors salts. Taking the inspiration from nature, where composite materials made of a polymer matrix and inorganic fillers are often found, e.g. bone, shell of crustaceans, shell of eggs, etc., the feasibility on making composite materials containing chitosan and nanosized hydroxyapatite was investigated. A stepwise co-precipitation approach was used to obtain different types of composites by means of different ratio between components. The synthesis of hydroxyapatite was carried out in the chitosan matrix from calcium chloride and sodium dihydrogenphosphate in alkaline solutions at moderate pH of 10-11 for 24 h. Our research is focused on studying and understanding the structure of this class of composites, aiming at the development of novel materials, controlled at the nanolevel scale. The X-ray diffraction technique was employed in order to study the kinetic of hydroxyapatite formation in the chitosan matrix as well as to determine the HAp crystallite sizes in the composite samples. The hydroxyapatite synthesized using this route was found to be nano-sized (15-50nm). Moreover, applying an original approach to analyze the (002) XRD diffraction peak profile of hydroxyapatite by using a sum of two Gauss functions, the bimodal distribution of nanosized hydroxyapatite within the chitosan matrix was revealed. Two types of size distribution domains such as cluster-like (between 200 and 400 nm), which are the habitat of "small" hydroxyapatite nanocrystallites and scattered-like, which are the habitat of "large" hydroxyapatite nanocrystallites was probed by TEM and CSLM. The structural features of composites suggest that self-assembly processes might be involved. The composites contain nanosized hydroxyapatite with structural features close to those of biological apatites that make them attractive for bone tissue engineering applications. (c) 2005 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@misc{KoetzReicheltKosmellaetal.2005,
  author    = {Koetz, Joachim and Reichelt, S. and Kosmella, Sabine and Tiersch, Brigitte},
  title     = {Recovery of nanoparticles produced in phosphatidylcholine-based template phases},
  issn      = {0021-9797},
  year      = {2005},
  abstract  = {This paper focuses on the characterization and use of polymer-modified phosphatidylcholine (PC)/sodium dodecyl sulfate (SDS)-based inverse microemulsions as a template phase for BaSO4 nanoparticle formation. The area of the optically clear inverse microemulsion phase in the isooctane/hexanol/water/PC/SDS system is not significantly changed by adding polyelectrolytes, i.e., poly(diallyldimethylammonium chloride) (PDADMAC), or amphoteric copolymers of diallyldimethylammonium chloride and maleamid acid to the SDS-modified inverse microemulsion. Shear experiments show non- Newtonian flow behavior and oscillation experiments show a frequency-dependent viscosity increase (dilatant behavior) of the microemulsions. Small amounts of bulk water were identified by means of differential scanning calorimetry. One can conclude that the macromolecules are incorporated into the individual droplets, and polymer-filled microemulsions are formed. The polymer-filled microemulsions were used as a template phase for the synthesis of BaSO4 nanoparticles. After solvent evaporation the nanoparticles were redispersed in water and isooctane, respectively. The polymers incorporated into the microemulsion are involved in the redispersion process and influence the size and shape of the redispersed BaSO4 particles in a specific way. The crystallization process mainly depends on the type of solvent and the polymer component added. In the presence of the cationic polyelectrolyte PDADMAC the crystallization to larger cubic crystals is inhibited, and layers consisting of polymer-stabilized spherical nanoparticles of BaSO4 (6 nm in size) will be observed. (c) 2004 Elsevier Inc. All rights reserved},
  language  = {en}
}
@article{KubowiczBaussardLutzetal.2005,
  author    = {Kubowicz, Stephan and Baussard, Jean-Francois and Lutz, Jean-Francois and Th{\"u}nemann, Andreas F. and von Berlepsch, Hans and Laschewsky, Andr{\´e}},
  title     = {Multicompartment micelles formed by self-assembly of linear ABC triblock copolymers in aqueous medium},
  year      = {2005},
  language  = {en}
}
@article{ZhangSpitzAntoniettietal.2005,
  author    = {Zhang, T. and Spitz, Christian and Antonietti, Markus and Faul, C. F.},
  title     = {Highly photoluminescent polyoxometaloeuropate-surfactant complexes by ionic self-assembly},
  year      = {2005},
  abstract  = {Facile organization of the inorganic sandwiched heteropolytungstomolybdate K-13[Eu(SiW9Mo2O39)(2)] (E) into highly ordered supramolecular nanostructured materials by complexation with a series of cationic surfactants is achieved by the ionic self-assembly (ISA) route. The structure and phase behavior of the complexes were examined by IR spectroscopy, differential scanning calorimetry, optical microscopy, and small- and wide-angle X-ray scattering. This class of materials shows a number of interesting physicochemical properties, namely liquid-crystalline phases (both thermotropic and lyotropic) and strong photoluminescence. The photophysical behavior (fluorescence spectra, fluorescence lifetimes, fluorescence quantum yield) of the complexes differs widely in solid powders, films, and solutions. The amphiphilic cationic surfactants not only play a structural role but also have a strong influence on the photophysical properties of E. The photophysical behavior of E can in this way be easily modified by its organizational motifs},
  language  = {en}
}
@article{KrauseKlamrothSaalfrank2005,
  author    = {Krause, Pascal and Klamroth, Tillmann and Saalfrank, Peter},
  title     = {Time-dependent configuration-interaction calculations of laser-pulse-driven many-electron dynamics : Controlled dipole switching in lithium cyanide},
  issn      = {0021-9606},
  year      = {2005},
  abstract  = {We report simulations of laser-driven many-electron dynamics by means of the time-dependent configuration interaction singles (doubles) approach. The method accounts for the correlation of ground and excited states, is capable of describing explicitly time-dependent, nonlinear phenomena, and is systematically improvable. Lithium cyanide serves as a molecular test system in which the charge distribution and hence the dipole moment are shown to be switchable, in a controlled fashion, by (a series of) laser pulses which induce selective, state-to-state electronic transitions. One focus of our time-dependent calculations is the question of how fast the transition from the ionic ground state to a specific excited state that is embedded in a multitude of other states can be made, without creating an electronic wave packet. (c) 2005 American Institute of Physics},
  language  = {en}
}
@article{SaalfrankKlamrothHuberetal.2005,
  author    = {Saalfrank, Peter and Klamroth, Tillmann and Huber, C. and Krause, Pascal},
  title     = {Laser-driven electron dynamics at interfaces},
  issn      = {0021-2148},
  year      = {2005},
  abstract  = {In this paper we present time-dependent, quantum-dynamical simulations of photoinduced processes at solid surfaces involving nonadiabatic transitions of electrons to and from short-lived intermediate excited states. In particular, two-photon photoemission (2PPE) spectra of naked metal surfaces and free-standing metal films are considered. One major problem in both cases is the presence of electron-electron scattering, which is treated here in various ways. The first way is to adopt an open-system density matrix approach, in which a single electron is weakly coupled to a "bath" of other electrons. The second approach is based on a many-electron Schrodinger equation, which is solved with the help of a time-dependent configuration interactions singles (TD-CIS) method},
  language  = {en}
}
@article{NestKlamrothSaalfrank2005,
  author    = {Nest, Mathias and Klamroth, Tillmann and Saalfrank, Peter},
  title     = {The multiconfiguration time-dependent Hartree-Fock method for quantum chemical calculations},
  issn      = {0021-9606},
  year      = {2005},
  abstract  = {We apply the multiconfiguration time-dependent Hartree-Fock method to electronic structure calculations and show that quantum chemical information can be obtained with this explicitly time-dependent approach. Different equations of motion are discussed, as well as the numerical cost. The two-electron integrals are calculated using a natural potential expansion, of which we describe the convergence behavior in detail},
  language  = {en}
}
@article{KlamrothKronerSaalfrank2005,
  author    = {Klamroth, Tillmann and Kroner, Dominic and Saalfrank, Peter},
  title     = {Laser-driven coupled electron-nuclear dynamics : Quantum mechanical simulation of molecular photodesorption from metal films},
  issn      = {1098-0121},
  year      = {2005},
  abstract  = {In this paper we report dynamical simulations of laser-driven, coupled nuclear-electron dynamics for a molecule- surface system. Specifically, the laser desorption of a small molecule (NO) from a metal slab (Pt) in the so-called DIET limit (Desorption Induced by Electronic Transitions), is studied. The excitation of the metal electrons by a laser pulse followed by the formation of a negative ion resonance, its subsequent decay, and the simultaneous desorption of the molecule are all treated within a single quantum mechanical model. This model is based on an earlier theory of Harris and others [S. M. Harris, S. Holloway, and G. R. Darling, J. Chem. Phys. 102, 8235 (1995)], according to which a nuclear degree of freedom is coupled to an electronic one, both propagated on a single non-Born-Oppenheimer potential energy surface. The goals of the present contribution are (i) to make a conceptual connection of this model to the frequently adopted nonadiabatic "multi-state" models of photodesorption, (ii) to understand details of the desorption mechanism, (iii) to explicitly account for the laser pulse, and (iv) to study the photodesorption as a function of the thickness of the metal film, and the laser parameters. As an important methodological aspect we also present a highly efficient numerical scheme to propagate the wave packet in a problem-adapted diabatic basis},
  language  = {en}
}
@article{ThomasKleinpeter2005,
  author    = {Thomas, Steffen and Kleinpeter, Erich},
  title     = {A novel empirical approach for the structure elucidation of disilanes by empirical estimation of their Si-29 chemical shifts},
  issn      = {0022-2860},
  year      = {2005},
  abstract  = {In C-13 NMR spectroscopy, there are many empirical methods for fast and exact computation of C-13 chemical shifts; comparable procedures for Si-29 NMR chemical shifts are not existing or are older than 20 years. On basis of the largest database of Si-29 chemical shifts available, along this paper a relatively simple procedure for the similarly exact calculation of the Si-29 chemical shifts of disilanes (average margin of error ca. 3.7 ppm) is given. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{NeuvonenFulopNeuvonenetal.2005,
  author    = {Neuvonen, Kari and Fulop, Ferenc and Neuvonen, Helmi and Koch, Andreas and Kleinpeter, Erich and Pihlaja, Kalevi},
  title     = {Propagation of polar substituent effects in 1-(substituted phenyl)-6,7-dimethoxy-3,4-dihydro- and -1,2,3,4- tetrahydroisoquinolines as explained by resonance polarization concept},
  year      = {2005},
  abstract  = {Propagation of inductive and resonance effects of phenyl substituents within 1-(substituted phenyl)-6,7- dimethoxy-3,4-dihydro- and -1,2,3,4-tetrahydroisoquinolines were studied with the aid of C-13 and N-15 NMR chemical shifts and ab initio calculations. The substituent-induced changes in the chemical shift (SCS) were correlated with a dual substituent parameter equation. The contributions of conjugative (rho(R)) and nonconjugative effects (rho(F)) were analyzed, and mapping of the substituent-induced changes is given over the entire isoquinoline moiety for both series. The experimental results can be rationalized with the aid of the resonance polarization concept. This means the consideration of the substituent-sensitive balance of different resonance structures, i.e., electron delocalization, and the effect of the aromatic ring substituents on their relative contributions. With tetrahydroisoquinolines, the delocalization of the nitrogen lone pair (stereoelectronic effect) particularly contributes. Correlation analysis of the Mulliken atomic charges for the dihydroisoquinoline derivatives was also performed. The results support the concept of the substituent-sensitive polarization of the isoquinoline moiety even if the polarization pattern achieved via the NMR approach is not quite the same as that predicted by the computational charges. Previously the concepts of localized pi- polarization and extended polarization have been used to explain polar substituent effects within aromatic side-chain derivatives. We consider that the resonance polarization model effectively contributes to the understanding of the polar substituent effects},
  language  = {en}
}
@article{KlinkaImrichDaniheletal.2005,
  author    = {Klinka, Karel D. and Imrich, Jan and Danihel, I. and Bohm, Stanislav and Kristian, Pavol and Harnul'akova, S. and Pihlaja, Kalevi and Koch, Andreas and Kleinpeter, Erich},
  title     = {Configuration and E/Z interconversion mechanism of O(S)-allyl-S(O)-methyl-N-(acridin-9-yl)iminothiocarbonate},
  issn      = {0749-1581},
  year      = {2005},
  abstract  = {The configuration and dynamic behavior of O-allyl-S-methyl-N-(acridin-9-yl)iminothiocarbonate (1) and its S- allyl-O-methyl regioisomer (2) were studied using quantum chemical calculations and by applying a novel graphical method to scatter maps obtained from MD simulations for evaluation of an NOE-weighted internuclear distance (r(NOE)). Energy calculations indicated that the Z configuration was predominant for each compound and, further, this was supported both by the calculated chemical shifts and the rNOE. Both N-inversion- and rotation-type transition-state structures were also calculated for the E/Z isomerization process, the results indicating that the preferred interconversion mechanism for 1 is N-inversion, but contrastingly, interconversion via rotation is equally as probable as N-inversion for 2. This supports the notion that one or the other or both pathways can be active and each system needs to be assessed on a case- by-case basis. Copyright (c) 2005 John Wiley \& Sons, Ltd},
  language  = {en}
}
@article{HeydenreichKochSarodnicketal.2005,
  author    = {Heydenreich, Matthias and Koch, Andreas and Sarodnick, Gerhard and Kleinpeter, Erich},
  title     = {Quinoxalines XIV : Synthesis, H-1, C-13, N-15 NMR spectroscopic, and quantum chemical study of 1H-pyrazolo[3,4- b]quinoxalines (flavazoles)},
  issn      = {0040-4020},
  year      = {2005},
  abstract  = {The synthesis of a series of 1H-pyrazolo[3,4-b]quinoxalines (flavazoles) by acylation, alkylation, halogenation, and aminomethylation of the parent compound is reported and their structure is investigated by H-1, C-13 and N-15 NMR spectroscopy. The restricted rotation about the partial C, N double bond of the N-acyl derivatives 7-10 is studied by dynamic NMR spectroscopy and the barriers to rotation are determined. In order to assign unequivocally the 15 N chemical shifts of N-4 and N-9, in case of 3-substituted flavazoles, exemplary the H-1, C-13, and N-15 NMR chemical shifts of 34, 35, and 39 are also theoretically calculated by quantum chemical methods [ab initio at different levels of theory (HF/6-3G* and B3LYP/6-31G*)]. (C) 2005 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{MarkovicBaranacStojanovicSteeletal.2005,
  author    = {Markovic, Rade and Baranac-Stojanovic, Marija and Steel, Peter J. and Kleinpeter, Erich},
  title     = {Stereocontrolled synthesis of new tetrahydrofuro[2,3-d]thiazole derivatives via activated vinylogous iminium ions},
  issn      = {0385-5414},
  year      = {2005},
  abstract  = {Heterocyclization of (Z)-5-(2-hydroxyethyl)-3-methyl-4-oxothiazolidines, bearing electron-withdrawing groups conjugated to an exocyclic double bond at C(2)-position, afforded under reductive conditions, cis-tetrahydroftiro[2,3- d]thiazole derivatives. The reactions of these functionalized push-pull beta-enamines occur in a stereocontrolled fashion via activated vinylogous N-methyliminium ions, which are trapped by an internal hydroxyethyl group},
  language  = {en}
}
@article{KleinpeterSeidl2005,
  author    = {Kleinpeter, Erich and Seidl, Peter Rudolf},
  title     = {The gamma- and the delta-effects in C-13 NMR spectroscopy in terms of nuclear chemical shielding (NCS) analysis},
  issn      = {0894-3230},
  year      = {2005},
  language  = {en}
}
@article{KleinpeterSchulenburgZugetal.2005,
  author    = {Kleinpeter, Erich and Schulenburg, Anja and Zug, Ines and Hartmann, Horst},
  title     = {The interplay of thio(seleno)amide/vinylogous thio(seleno)amide "Resonance" and the anisotropic effect of thiocarbonyl and selenocarbonyl functional groups},
  issn      = {0022-3263},
  year      = {2005},
  abstract  = {[GRAPHICS] Amino-substituted thio(seleno)acrylamides 1-4 were synthesized and their H-1 and C-13 NMR spectra assigned. Both the NMR data and the results of theoretical calculations at the ab initio level of theory were employed to elucidate the adopted structures of the compounds in terms of E/Z isomerism and s-cis/s-trans configuration. In the case of the asymmetrically N(Me)Ph-substituted compounds, ab initio GIAO-calculated ring current effects of the N-phenyl group were applied to successfully determine the preferred conformer bias. The restricted rotations about the two C-N partial double bonds were studied by DNMR and the barriers to rotation (Delta G(c)(double dagger)) determined at the coalescence temperatures, and these were discussed with respect to the structural differences between the compounds. The barriers to rotation were also calculated at the ab initio level of theory where the best results (R-2 = 0.8746) were obtained only with inclusion of the solvent at the SCIPCMHF/6-31G* level of theory. The calculations also provided means of assessing structural influences which were not available due to inaccessible rotation barriers. By means of natural bond orbital (NBO) analysis of 1-4, the occupation numbers of nitrogen lone pairs and bonding/antibonding pi/pi* orbitals were shown to quantitatively describe thio(seleno)amide/vinylogous thio(seleno)amide "resonance". Finally, the thio(seleno)carbonyl anisotropic effect was quantitatively calculated by the GIRO method and visualized by isochemical shielding surfaces (ICSS). Only marginal differences between the two anisotropic effects were calculated and are therefore of questionable utility for previous and future applications with respect to stereochemical assignments},
  language  = {en}
}
@article{NeuvonenNeuvonenKochetal.2005,
  author    = {Neuvonen, Helmi and Neuvonen, Kari and Koch, Andreas and Kleinpeter, Erich},
  title     = {Ab initio study of the substituent effects on the relative stability of the E and Z conformers of phenyl esters : Stereoelectronic effects on the reactivity of the carbonyl group},
  issn      = {1089-5639},
  year      = {2005},
  abstract  = {Equilibria between the Z (tau(1) = 0 degrees) and E (tau(1) = 180 degrees) conformers of p-substituted phenyl acetates 4 and trifluoroacetates 5 (X = OMe, Me, H, Cl, CN, NO2) were studied by ab initio calculations at the HF/6-31G* and MP2/6-31G* levels of theory. The preference for the Z conformer, Delta E(HF), was calculated to be 5.36 kcal mol(-1) and 7.50 kcal mot(-1) for phenyl acetate and phenyl trifluoroacetate (i.e., with X = H), respectively. The increasing electron-withdrawing ability of the phenyl substituent X increases the preference of the Z conformer. An excellent correlation with a negative slope was observed for both series between Delta E of the E-Z equilibrium and the Hammett sigma constant. By using an appropriate isodesmic reaction, it was shown that electron-withdrawing substituents decrease the stability of both conformers, but the effect is higher with the E conformer. Electron-withdrawing phenyl substituents decrease the delocalization of the lone pair of the ether oxygen to the C=O antibonding orbital (n(O) -> pi*(C=O)) in both the E and Z forms and in both series studied; this effect is higher in the E conformer than in the Z conformer. The n(O) -> pi*(C=O) electron donation has a minimum value with tau(1) = 90 degrees and a maximum value with tau(1) = 90 degrees (the Z conformer), the value with tau(1) = 180 degrees (the E conformer) being between these two values, obviously due to steric hindrance. The effects of the phenyl substituents on the reactivity of the esters studied are discussed in terms of molecular orbital interactions. ED/EW substituents adjust the availability of the pi*(C=O) antibonding orbital to interact with the lone pair orbital of the attacking nucleophile and therefore affect the reactivity: EW substituents increase and ED substituents decrease it. Excellent correlations were observed between the rate coefficients of nucleophilic acyl substitutions and pi*(C=O) occupancies of the ester series 4 and},
  language  = {en}
}
@article{RyppaSengeHatscheretal.2005,
  author    = {Ryppa, C. and Senge, Mathias O. and Hatscher, S. S. and Kleinpeter, Erich and Wacker, Philipp and Schilde, Uwe and Wiehe, A.},
  title     = {Synthesis of mono- and disubstituted porphyrins : A- and 5,10-A(2)-type systems},
  issn      = {0947-6539},
  year      = {2005},
  abstract  = {General syntheses have been developed for meso-substituted porphyrins with one or two substituents in the 5,10- positions and no beta substituents. 5-Substituted porphyrins with only one meso substituent are easily prepared by an acid-catalyzed condensation of dipyrromethane, pyrrole-2-carbaldehyde. and an appropriate aldehyde using a "[2+1+1]" approach. Similarly, 5,10-disubstituted porphyrins are accessible by simple condensation of unsubstituted tripyrrane with pyrrole and various aldehydes using a "[3+1]" approach. The yields for these reactions are low to moderate and additional formation of either di- or mono-substituted porphyrins due to scrambling of the intermediates is observed. However, the reactions can be performed quite easily and the desired target compounds are easily removed due to large differences in solubility. A complementary and more selective synthesis involves the use of organolithium reagents for SNAr reactions. Reaction of in situ generated porphyrin (porphine) with 1.1-8 equivalents of RLi gave the monosubstituted porphyrins, while reaction with 3-6 equivalents of RLi gave the 5,10-disubstituted porphyrins in yields ranging from 43 to 90\%. These hitherto almost inaccessible compounds complete the series of different homologues of A-, 5,15-A(2)-, 5,10-A(2)-, A(3)-, and A(4)-type porphyrin's and allow an investigation of the gradual influence of type, number, and regiochemical arrangement of substituents on the properties of meso-substituted porphyrins. They also present important starting materials for the synthesis of ABCD porphyrins and are potential synthons for supramolecular materials requiring specific substituent orientations},
  language  = {en}
}