Volker Kahlenberg

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Five phase-pure modifications of the antipsychotic drug aripiprazole were prepared and characterized by thermal analysis, vibrational spectroscopy and X-ray diffractometry. All modifications can be produced from solvents, form I additionally by heating of form X degrees to approximately 120 degrees C (solid-solid transformation) and form III by(More)
Morphine, codeine, and ethylmorphine are important drug compounds whose free bases and hydrochloride salts form stable hydrates. These compounds were used to systematically investigate the influence of the type of functional groups, the role of water molecules, and the Cl(-) counterion on molecular aggregation and solid state properties. Five new crystal(More)
A co-crystal of two polymorphic active pharmaceutical ingredients (APIs), first reported and patented in 1937, has been prepared and thoroughly characterised, including crystal structure analysis. The existence of four crystal forms of one of the APIs, the sedative and hypnotic active pharmaceutical ingredient 3,3-diethyl-2,4(1H,3H)-pyridinedione,(More)
We established a murine model of phosphate nephropathy with secondary hyperparathyroidism. db/db mice, which develop obesity and type 2 diabetes mellitus, were uninephrectomized at the age of 6 weeks and were fed either standard chow or a phosphorus-rich diet during the next 8 weeks. Thereafter, renal cryosections showed abundant tubular casts with a strong(More)
Five new 5,5'-azotetrazolate salts (amminsilver, trimethylsulfonium, tetramethyl-phosphonium, trimethylsulfoxonium, 2-(hydroxyethyl)trimethylammonium) were prepared and characterized. The crystal structures were determined by X-ray diffraction. Interactions between the ions are identified and discussed. The sensitivities of the highly energetic silver salt(More)
Four (57)Fe-labeled tetrachloroferrates(III) of organic cations (1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1-methyl-1-propylpyrrolidinium, tetraphenylphosphonium) were examined by temperature-dependent Mössbauer spectroscopy. The hyperfine and dynamic parameters of the iron(III) site were determined. Single crystal X-ray diffraction data of(More)
The solvent formation of phenobarbital, an important drug compound with an unusually complex polymorphic behavior, was studied in detail. Monosolvates with acetonitrile, nitromethane, dichloromethane, and 1,4-dioxane were produced and characterized by single-crystal and powder X-ray diffraction, thermoanalytical methods, FT-IR, Raman, and solid-state NMR(More)
An improved synthesis of the Cholesteryl Ester Transfer Protein inhibitor dalcetrapib is reported. The precursor disulfide was reduced (a) by Mg/MeOH or (b) by EtSH/DBU/THF. The resulting thiol was acylated (a) by a known procedure or (b) in a one-pot process. Impurities were removed (a) by dithiothreitol (DTT) or (b) by oxidation using H 2 O 2. Dalcetrapib(More)
The crystal structures of four salts of 1,4-diazabicyclo[2.2.2]octane (DABCO) and 5-aminotetrazole are described. Anhydrous 1:1 (Pbca, R gt = 0.041) and 1:2 (P 1 , R gt = 0.038) salts form hydrogen-bonded layers of anions and cations. The monohydrate of the 1:1 compound (P2 1 /c, R gt = 0.038) shows infinite chains of DABCO cations and an undulated layer of(More)