Hergen Breitzke

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In the last fifteen years several novel porous silica materials, which are periodically structured on the mesoscopic length scale, have been synthesized. They are of broad interest for fundamental studies of surface-substrate interactions, for studies of the dynamics of guest molecules in confinement and for studies of the effect of confinement on the(More)
A program for iterative fitting procedures to determine the NMR parameters from (51)V solid-state MAS NMR spectra was developed. It contains options to use genetic algorithms and downhill-simplex optimizing procedures to extract the optimal parameter sets, which describe our spectra. As computational kernel the SIMPSON program is employed. Other kernels(More)
For the first time, the existence of a substrate adduct of a nickel superoxide dismutase (NiSOD) model, based on the first nine residues from the N terminus of the active form of Streptomyces coelicolor NiSOD, has been proven and the adduct has been isolated. This adduct is based on the cyanide anion (CN(-)), as a substrate analogue of the superoxide anion(More)
Amorphous SiHfBCN ceramics were prepared from a commercial polysilazane (HTT 1800, AZ-EM), which was modified upon reactions with Hf(NEt2)4 and BH3·SMe2, and subsequently cross-linked and pyrolyzed. The prepared materials were investigated with respect to their chemical and phase composition, by means of spectroscopy techniques (Fourier transform infrared(More)
A novel heterogeneous dirhodium catalyst has been synthesized. This stable catalyst is constructed from dirhodium acetate dimer (Rh2(OAc)4) units, which are covalently linked to amine- and carboxyl-bifunctionalized mesoporous silica (SBA-15-NH2-COOH). It shows good efficiency in catalyzing the cyclopropanation reaction of styrene and ethyl diazoacetate(More)
The successful synthesis and solid state NMR characterization of silica-based organic-inorganic hybrid materials is presented. For this, collagen-like peptides are immobilized on carboxylate functionalized mesoporous silica (COOH/SiOx) materials. A pre-activation of the silica material with TSTU (O-(N-Succinimidyl)-N,N,N',N'-tetramethyluronium(More)
Para-hydrogen induced polarization (PHIP) is observed in an organic solvent-free homogeneous catalyst/substrate system using ionic liquids. The hydrogenation reactions are performed employing a Rh-catalyst/ionic liquid system without further organic solvents. The PHIP phenomenon is demonstrated for the ethyl acrylate system. Small amounts of ionic liquids(More)
The macrocyclic ligand [13]aneN 4 ( L1, 1,4,7,10-tetra-azacyclotridecane) was reacted with Zn(II) perchlorate and CO 2 in an alkaline methanol solution. It was found that, by means of subtle changes in reaction conditions, two types of complexes can be obtained: (a) the mu 3 carbonate complex 1, {[Zn( L1)] 3(mu 3-CO 3)}(ClO 4) 4, rhombohedral crystals,(More)
The parameters describing the quadrupolar and CSA interactions of 51V solid-state MAS NMR investigations of model complexes mimicking vanadoenzymes as well as vanadium containing catalysts and enzyme complexes are interpreted with respect to the chemical structure. The interpretation is based on the data of 15 vanadium complexes including two new complexes(More)