Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie

Publisher: Max-Planck-Gesellschaft zur Förderung der Wissenschaften

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  • Other titles
    Zeitschrift für Naturforschung. B, Chemie, Biochemie, Biophysik, Biologie und verwandte Gebiete (Max-Planck-Gesellschaft zur Förderung der Wissenschaften: 1962), Zeitschrift für Naturforschung. Teil b, Chemie, Biochemie, Biophysik, Biologie und verwandte Gebiete, Chemie, Biochemie, Biophysik, Biologie und verwandte Gebiete
  • ISSN
    0044-3174
  • OCLC
    9321722
  • Material type
    Periodical
  • Document type
    Journal / Magazine / Newspaper

Publications in this journal

  • Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 12/2014; 69b:1375-1383.
  • Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 12/2014; 69B:1402-1418.
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    ABSTRACT: Zr2MSb3 (M: Cu, Pd) and Zr3MSb7 (M: Ni, Pd) are prepared by arc melting of the elements followed by annealing at 973 K in evacuated quartz tubes.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 11/2013;
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    ABSTRACT: The lanthanoid(III) oxide fluoride sulfides M6O2F8S3 (M = La–Nd, Sm, Gd) can be obtained by reacting the rare-earth metals, their trifluorides and sesquioxides with elemental sulfur in appropriate molar ratios at 850 °C flux-assisted by NaCl in gas-tightly sealed niobium or tantalum ampoules. All compounds are colorless, except for those containing M = Pr with green, M = Nd with lilac and M = Sm with yellow color. They form transparent single crystals as needles or rods. The M6O2F8S3 representatives crystallize in a hexagonal structure (space group: P63/m; a ≈ 1382–1326, c ≈ 398–376 pm, c/a ≈ 0.288–0.284; Z = 2) with two different crystallographic M3+ positions. The (M2)3+ cations reside in ninefold coordination of anions arranged as tricapped trigonal prisms formed by three F−, four mixed-occupied O2−/F− and two S2− anions, resembling the unique M3+ coordination sphere of the M3OF5S-type oxide fluoride sulfides. The (M1)3+ cations are surrounded by square antiprisms built of four O2−/F− and S2− anions each, which are capped by one F− anion each, again resulting in a ninefold coordination similar to that of the A-MFS-type fluoride sulfides. While the crystallographically unique S2− anions have six cationic neighbors arranged in trigonal prisms, there are four different light-anion positions. Two of them, representing only fluoride anions, are situated in a triangular environment of cations ((F1)−: planar, (F2)−: non-planar). The mixed-occupied light-anion positions (F3)−/(O3)2− and (F4)−/(O4)2− exhibit tetrahedral coordination spheres with a ratio F− : O2−= 2:1. The M6O2F8S3 arrangement is characterized by an empty hexagonal channel structure created by (F1)− anions with a potential of accommodating alkali-metal cations like Na+. All single-crystal X-ray structure investigations did not indicate any ordering of the O2− and F− anions, but MAPLE calculations revealed a slightly favored oxygen occupation for the (F4)−/(O4)2− rather than for the (F3)−/(O3)2− position. Electron-beam microanalyses gave no evidence for the incorporation of either Na+ or Cl− ions stemming from NaCl used as the flux.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 07/2013; 68:751-760.
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    ABSTRACT: Small single crystals of the Sm5Ge4-type (space group Pnma) germanides RE2Nb3Ge4 (RE = Sc, Y, Gd–Er, Lu) and Sc2Ta3Ge4 were synthesized by arc-melting of the respective elements. The samples were characterized by powder and single-crystal X-ray diffraction. In all structures, except for Sc2:04Nb2:96Ge4 and Sc2:19Ta2:81Ge4, the rare earth and niobium atoms show full ordering on the three crystallographically independent samarium sites of the Sm5Ge4 type. Two sites with coordination number 6 are occupied by niobium, while the slightly larger site with coordination number 7 is filled with the rare earth element. Small homogeneity ranges with RE=Nb and RE=Ta mixing can be expected for all compounds. The ordered substitution of two rare earth sites by niobium or tantalum has drastic effects on the coordination number and chemical bonding. This was studied for the pair Y5Ge4/Y2Nb3Ge4. Electronic structure calculations show larger charge transfer from yttrium to germanium for Y5Ge4, contrary to Y2Nb3Ge4 which shows stronger covalent bonding due to the presence of Nb replacing Y at two sites
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2013; 68:625.
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    ABSTRACT: Ethyl-Lophine, 1-ethyl-2,4,5-triphenyl-1H-imidazole, C23H20N2, was synthesized as a precursor for large organic cations in ionic liquids using an improved microwave-assisted method. The title compound and a precursor compound were characterized by NMR, IR, and DSC thermal measurements, as well as elemental analyses. The crystal structure of ethyl-lophine was determined by singlecrystal X-ray structure analysis (triclinic, P¯1, a = 10:1137(3), b = 12:4935(4), c = 14:6351(4) A° , a = 98:182(2)�, b = 90:694(2)�, g = 102:666(2)�, Z = 4, wR2 = 0:1030 for 611 refined parameters).
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2013; 68:245-249.
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    ABSTRACT: Several dihydrothiazoles (III) are obtained by the Asinger reaction and converted into novel diacyl acetals by acylation with acyl chloride (IV) followed by reaction with sodium carboxylates (V).
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2012;
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    ABSTRACT: The reaction behavior of HF-HNO 3-H 2O etching mixtures, which are frequently used for texturing silicon surfaces, is significantly influenced by the addition of sulfuric acid. For high concentrations of sulfuric acid, nitronium ions NO 2 + ions have been detected by means of 14N NMR spectroscopy, and results of Raman spectroscopic investigation have allowed the quantification of the nitronium ions. Maximum etching rates of 4000 - 5000 nm s -1 are reached for HF (40 %)-HNO 3 (65%)-H2SO 4 (97%) mixtures with w (40%-HF)/w (65%-HNO 3) ratios of 2 to 4 and w (97%-H 2SO 4)<0.3. For higher concentrations of sulfuric acid, H 2SO 4 can be considered as a diluent. In order to investigate the influence of the sulfuric acid at constant HF and HNO 3 quantities, fuming HNO 3 (100 %) was used and the water in the mixtures successively replaced by H 2SO 4. A sudden increase of etching rates was found for sulfuric acid concentrations around 6 mol L?1 correlating with the characteristic color of the etching solutions. Decreased reaction rates at > 7 molL 1 H 2SO 4 are attributed to high solution viscosities and the formation of fluorosulfuric acid. Generally, in HF-HNO 3-H 2SO 4/H 2O etching mixtures a reduced dissociation of nitric acid, the formation of nitronium ions, the solubility of neutral nitrogen intermediates (e. g. NO 2, N 2O 3), as well as other effects influence the attack of silicon surfaces. The structure of etched silicon surfaces was investigated by means of scanning electron (SEM) and laser scanning microscopy (LSM). The morphologies are influenced most significantly by the relative amounts of sulfuric acid. Unexpectedly, in nitronium ion-containing mixtures rough surfaces with pore-like etching pits are generated.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 02/2011; 66(2):155.
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    ABSTRACT: The bisoxazoles 1a – 1c that feature structures with two oxazole moieties connected to a 2,6-pyridylene central linker and contain different aryl substituents in 4- and 5-positions of the oxazole rings have been synthesized. Single-crystal X-ray structure determinations of the free ligand 1a, containing the NiCl2 complex of 1c as the CH3COOH solvate as well as the 1,4-dioxane-solvated diester intermediate 2a are reported, which show specific molecular conformations and packings in the crystals. The conformation of 1a is syn with reference to the oxazole nitrogen atoms and anti with reference to the oxazole and pyridine nitrogen atoms. In the Ni2+ complex, the metal ion is in an octahedral coordination environment with the nitrogens of 1c and an oxygen of an acetic acid molecule in the basal plane, while two chloride ions occupy the axial positions. Of three additional acetic acid molecules one is hydrogen-bonded to a chloride and two form a carboxylic dimer, thus giving rise to a 1 : 1 : 4 (1c : NiCl2 : HOAc) stoichiometric ratio. The crystalline 1 : 1 inclusion compound of 2a with 1,4-dioxane suggests a typical clathrate owing to the bulkyness of the host molecule.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2011; 66:197-204.
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    ABSTRACT: via two consecutive Henry nitroaldol reactions
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2011; 66b:611-623.
  • Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2009; 64b:784-792.
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    ABSTRACT: The first total synthesis of annomuricatin B (8) is described via coupling of the tripeptide Boc-L-asparaginyl(benzhydryl)-L-alanyl-L-tryptophan-OH and the tetrapeptide L-leucyl-glycyl-L-thryl-L-proline-OMe followed by cyclization of the linear heptapeptide fragment. On pharmacological investigation, it was observed that the cycloheptapeptide 8 displays moderate cytotoxicity against Dalton’s lymphoma ascites and Ehrlich’s ascites carcinoma cell lines with cytotoxic inhibitory concentration (50 %) values of 11.6 and 14.1 μM, in addition to potent antidermatophyte activity against Trichophyton mentagrophytes and Microsporum audouinii with a minimum inhibitory concentration of 6 μg/mL. Moreover, Gram-negative bacteria and Candida albicans were found to be moderately sensitive towards the newly synthesized peptide.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2009; 64:237-244.
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    ABSTRACT: Solutions consisting of HF - NOHSO4 - H2SO 4 exhibit a strong reactivity towards crystalline silicon which is controlled by the concentrations of the reactive species HF and NO+. Selective isotropic and anisotropic wet chemical etching with these solutions allows to generate a wide range of silicon surface morphology patterns. Traces of Ag+ ions stimulate the reactivity and lead to the formation of planarized (polished) silicon surfaces. Analyses of the silicon surface, the etching solution and the gas phase were performed with scanning electron microscopy (SEM), DR/FT-IR (diffusive reflection Fourier transform infra-red), FT-IR, Raman and NMR spectroscopy, respectively. It was found that the resulting silicon surface is hydrogen-terminated. The gas phase contains predominantly SiF4, NO and N2O. Furthermore, NH4+ is produced in solution. The study has confirmed the crucial role of nitrosyl ions for isotropic wet chemical etching processes. The novel etching system is proposed as an effective new way for selective surface texturing of multi- and monocrystalline silicon. A high etching bath service lifetime, besides a low contamination of the etching solution with reaction products, provides ecological and economical advantages for the semiconductor and solar industry.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 11/2007; 62(11):1411.
  • Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2007;
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    ABSTRACT: DFT-calculations (RB3LYP/LANL2DZp) show that the migration of a proton inside [1.1.1]- and [2.2.2]-cryptand from one nitrogen atom to the other follows different paths. While the proton in [H⊂1.1.1]-cryptand moves via an ether oxygen atom (activation energy: 19.2 kcal/mol), the proton in [H⊂2.2.2]-cryptand moves directly from one nitrogenatom to the other (activation energy: 16.1 kcal/mol). Our calculations rule out the application of doubly protonated [2.2.2]-cryptands as anion hosts.
    Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2006; 61b:1327 – 1334.
  • Zeitschrift für Naturforschung. Teil B. Anorganische Chemie, organische Chemie, Biochemie, Biophysik, Biologie 01/2004; 2004(59b):406-413.