Bestimmung des Cantharidins in den spanischen Fliegen und verwandten Insekten

Ohne Zusammenfassung     

Massenspektrometrie isomerer Diazaphenanthrene—I

The mass spectra of five diazaphenanthrenes formed by photochemical cyclodehydrogenation of styryl diazines are investigated. It is shown that fragmentation of these compounds starts almost exclusively at the heterocyclic part of the molecule and proceeds by competitive α-cleavage. From the intensity ratios of the ions [M ? H˙]⁺, [M ? HCN]⁺˙, [M ? N₂]⁺˙ and [M ? 2 HCN]⁺˙ generated in this way, each isomer can unequivocally be identified.     

Ein neues Kupfercobaltboratoxid mit isolierten B2O5-Baugruppen: Cu2Co(B2O5)O

On a New Copper Cobalt Borate Oxide with Isolated B₂O₅ Units: Cu₂Co(B₂O₅)O Single crystals of a new compound with the empirical formula Cu₂CoB₂O₆ were obtained by using a B₂O₃ flux technique. X-ray single crystal technique led to a new structure type. Cu₂CoB₂O₆ crystallizes monoclinic, space group C-P2₁/c (No. 14); a = 3.2250(6); b = 14.847(1); c = 9.1171(6) Å; β = 93.67°; Z = 4. All metal sites are octahedrally coordinated and form a two dimensional framework consisting of edge sharing octahedra ribbons. In addition one observes isolated B₂O₅-units and oxygen which is not coordinated to boron. The far relation to the crystal structure of the mineral Warwickite is illustrated.     

In situ spectroscopic study of the oxidation and reduction of Pd(111)

Using a photoemission spectroscometer that operates close to ambient conditions of pressure and temperature we have determined the Pd-O phase diagram and the kinetic parameters of phase transformations. We found that on the (111) surface oxidation proceeds by formation of stable and metastable structures. As the chemical potential of O2 increases chemisorbed oxygen forms followed by a thin surface oxide. Bulk oxidation is a two-step process that starts with the metastable growth of the surface oxide into the bulk, followed by a first-order transformation to PdO.     

Darstellung und Charakterisierung von Halogeno(diethyldithiocarbamato) (triethyl- und triphenylphosphin)palladium(II)-Komplexen

The Complexes [Pd(PEt ₃)₂ dtc]X (1) and Pd(PR ₃)Xdtc (2, 3) (dtc=S₂CNEt ₃;X=Cl, Br, I;R=Et, Ph) have been prepared. Conductivity, susceptibility, UV and IR measurements show that the cations [Pd(PEt ₃)₂ dtc]⁺ of1 and the complexes2, 3 have square-planar structure.

     

Benzo[h]cinnolin

The synthesis of benzo[h]cinnolin ( 3 ) is reported. Its spectroscopic properties (uv, luminescence, pmr, ms) are similar to the other diazaphenanthrenes containing a diazine ring. The lowering of the basicity of 3 compared with a monoazaphenanthrene like other diaza-aromatic compounds appears to be due to an electrostatic field effect and not to an inductive effect.     

Corynebactin and enterobactin: related siderophores of opposite chirality

Most species of bacteria employ siderophores to acquire iron. The chirality of the ferric siderophore complex plays an important role in cell recognition, uptake, and utilization. Corynebactin, isolated from Gram-positive bacteria, is structurally similar to enterobactin, a well known siderophore isolated from Gram-negative bacteria, but contains L-theronine instead of L-serine in the trilactone backbone. Corynebactin also contains a glycine spacer unit in each of the chelating arms. A hybrid analogue (serine-corynebactin) has been synthesized. The chirality and relative conformational stability of the three ferric complexes of enterobactin, corynebactin, and the hybrid has been investigated. In contrast to enterobactin, corynebactin assumes a Lambda configuration. However, the ferric serine-corynebactin hybrid forms a racemic mixture, only slightly favoring the Lambda conformation.     

Ozone‐Induced Band Bending on Metal‐Oxide Surfaces Studied under Environmental Conditions

Ozone adsorption and decomposition on metal oxides is of wide interest in technology and in atmospheric chemistry. Here, ozone‐adsorption‐induced band bending is observed on Ti‐ and Fe‐oxide model surfaces under dry and humid conditions. Photoelectron spectroscopic studies indicate the effect of charge transfer to O₃, which limits the surface coverage of the precursor to decomposition reactions. This is also consistent with the negative pressure dependence observed in previous studies. These results contribute to our fundamental understanding of ozone adsorption and decomposition mechanisms on metal oxides of environmental and technological relevance.     

Validation of a coupled FE-model for the simulation of methane oxidation via thermal imaging

To simulate the processes of methane oxidation in landfill cover layers, a new computational model was created. The purpose of the model is to allow a forecast on the performance of methanotrophic activity in landfill cover layers under changing environmental conditions. Therefore, a thermodynamic consistent model based on the well-known Theory of Porous Media (TPM) combined with the mixture theory was developed, which analyzes the relevant gas productions of methane, oxygen and carbon dioxide. Diffusion, advection and conversion processes are considered as well as the energy production during methane oxidation. With the help of the thermal imaging technique a new experimental setup was developed in order to validate the coupled model in terms of the heat generation. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)