Ferrocenasymmetrie, 5. Mitt.: Die Anwendung eines halbempirischen Rechenverfahrens auf optisch aktive Ferrocenderivate

The procedure ofBrewster was employed in the calculation of the molecular rotation of optically active derivatives of 1,2-tetramethylene-ferrocene, which (in addition to ferrocene asymmetry) contain asymmetric (chiral) centers in the cyclohexene part of the molecule. Satisfactory agreement between the calculated and observed values for the rotations was obtained throughout. In one case, the calculation of the absolute configuration of the planarasymmetric part was successful; it was found to be in agreement with the results of an independent (experimental) method employed earlier. The absolute conformation of some of the ferrocene derivatives is discussed with the aid of optical circular dichroism.     

Photolysis of polyesters: Poly(propylene-1,2-maleate) and poly(propylene-1,2-ortho-phthalate)

A spectroscopic study of the photo-oxidation of poly(propylene-1,2-maleate), poly(propylene-1,2-o-phthalate) and poly(propylene-1,2-maleate-o-phthalate) under 280–480 nm radiation was investigated in detail. Results obtained indicate that, during photolysis of these polyesters, the primary photoreactions involve excitation of conjugated structures: carbonyl groups (in ester groups)—double bonds or carbonyl groups-phenylene rings. The secondary reactions occur by complicated mechanisms resulting in oxidation, scission, radical termination and cross-linking of structures present in the photolysed polyesters. Light of wavelength 280–480 nm causes deterioration in the polyesters in the early stages of irradiation. Singlet oxygen does not react with these polyesters even during long periods of exposure. Photo-oxidation mechanism occurs by free radical mechanism.     

A comprehensive two-dimensional map of cytosolic proteins of Bacillus subtilis

Proteomics relying on two-dimensional (2-D) gel electrophoresis of proteins followed by spot identification with mass spectrometry is an excellent experimental tool for physiological studies opening a new perspective for understanding overall cell physiology. This is the intriguing outcome of a method introduced by Klose and O'Farrell independently 25 years ago. Physiological proteomics requires a 2-D reference map on which most of the main proteins were identified. In this paper, we present such a reference map with more than 300 entries for Bacillus subtilis proteins with an isoelectric point (pI) between 4 and 7. The most abundant proteins of exponentially growing cells were compiled and shown to perform mainly housekeeping functions in glycolysis, tricarboxylic acid cycle (TCC), amino acid biosynthesis and translation as well as protein quality control. Furthermore, putative post-translational modifications were shown at a large scale, with 47 proteins in total forming more than one spot. In a few selected cases evidence for phosphorylation of these proteins is presented. The proteome analysis in the standard pI range was complemented by either stretching the most crowded regions in a narrow pH gradient 4.5-5.5, or by adding other fractions of the total B. subtilis proteome such as alkaline proteins as well as extracellular proteins. A big challenge for future studies is to provide an experimental protocol covering the fraction of intrinsic membrane proteins that almost totally escaped detection by the experimental procedure used in this study.     

Consequences of the ‘Pedersen papers’ on crown type chemistry at Würzburg and Bonn Universities: From heteroaromatic crowns and podands to large molecular and crystalline cavities including multisite receptors,cascade molecules,chromoionophores, siderophores,surfactant-type,and extreme ligands

We thank the editors of this issue for the opportunity to present the historic development of crown chemistry at the Universities of Wurzburg and Bonn in memory of C. J. Pedersen, the originator of the crown ethers. His legacy of science has tremendously stimulated research at both universities.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Simultaneous determination of60Co,131I and137Cs in model radioactive waste water by reverse radiometric flow injection analysis with the aid of a multichannel analyzer

Reverse radiometric flow injection analysis was used for the simultaneous determination of⁶⁰Co,¹³¹I and¹³⁷Cs in model radioactive waste water. A NaI (Tl) scintillation detector coupled to a Canberra MCA was used for measuring the activity of¹³⁷Cs at 662 keV,⁶⁰Co at 1173 keV and 1332 keV, and¹³¹I at 364 keV.     

Solid-state binding of dimethyl sulphoxide involving carboxylic host molecules. X-ray crystal structures of four inclusion species

The crystal structures of four dimethyl sulphoxide (DMSO) inclusion compounds with different carboxylic acid hosts,1–4, have been studied by single crystal X-ray analysis. Crystals of thetrans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid inclusion compound (1a), [1 · DMSO (1: 1)] show monoclinic (P2₁/n) symmetry with the unit cell dimensionsa = 11.522(4),b = 18.658(2),c = 8.709(1) Å and = 98.92(2)°. The clathrate of the 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (2a), [2 · DMSO (1: 2)] is triclinic (P) with the cell dimensionsa = 15.043(7),b =9.657(4),c = 8.118(7) Å, = 101.81(5), = 96.05(4) and = 100.04(4)°. Triclinic (P) symmetry is shown also by the inclusion compound of 9,10-dihydro-9,10-ethanoanthracene-11-monocarboxylic acid (3a) [3 · DMSO (1:1)] with the cell dimensionsa=6.3132(1),b=7.9846(2),c=17.5314(4) Å, = 96.46(2), = 87.08(2) and = 106.02(2)°. The 9,9-bianthryl-2-monocarboxylic acid clathrate (4a) [4 · DMSO (1:1)] is monoclinic (P2₁/n) and the cell dimensions area = 19.625(18),b = 8.817(1),c = 14.076(8) Å and = 97.92(6)°. In all these structures, the hosts show the same basic recognition pattern for the DMSO guest, involving a strong O-H ... O bond from the COON to the S=O group, and a possible C-H ... O type interaction between the carbonyl O atom of the host and a CH₃ group of the guest. The crystals consist of discrete host-guest aggregates which are mainly held together by weak intermolecular interactions of the Van der Waals' type. The stoichiometries of the aggregates are, however, different.     

Ternary tungsten oxides with the Mo5O14 structure

Following the discovery of a ternary GeW oxide with the Mo₅O₁₄ structure, a large number of ternary MWO systems were surveyed to investigate the frequency of occurrence of this structure type. Samples were prepared by heating tungsten oxides and the appropriate ternary element or a suitable compound of the ternary element in evacuated silica ampoules at 1373°K for 1 week. The compositions investigated were close to M_0.02W_0.98O_2.80. Oxides with the Mo₅O₁₄ structure were found in many systems across the whole of the periodic table, from Li to Bi. Some aspects of the formation of these phases and the way in which they could affect the course of reduction of WO₃ to W metal are discussed.     

Numerical solution of hydraulic models based on the axially-dispersed plug flow model by Laplace transforms

The problem of solving hydraulic models based on the axially-dispersed plug flow model which are applicable for the mathematical modelling of different flow-through systems both in chemical analysis (e.g., chromatography, flow injection analysis) and chemical industry (e.g., different tubular reactors) is discussed. Methods for numerical inversion of the model solution in the Laplace domain by expanding it into series of orthogonal functions are compared. Best results with respect to precision and consumption of computation time are given by the methods employing Chebyshov polynomials of the first kind and Fourier sine series. These methods were found to be better in these respects than some other frequently used numerical inversion methods.     

Corrosion Protection by Self-Assembly

The inhibition effect and properties of adsorption layers formed by molecule series ,-diphosphono-alkane on iron surface are investigated. A significant difference is obtained in inhibition effect between compounds having alkyl chains with odd and even numbers of carbon atoms; better protection can be achieved by use of diphosphonates containing odd numbers of methylene groups. The best corrosion inhibition could be attained with 1,7-diphosphono-heptane (1,7-DPH). It is found that a certain threshold concentration of the diphosphonate (c > 4 × 10^–4 M) is necessary to ensure sufficient inhibition. The influence of solution concentration on inhibition effect can be interpreted with the layer formation properties and the surfactant nature of molecules. A significant effect of the diphosphonate is appeared on the kinetic of anodic iron dissolution process. Diphosphonates act as anodic inhibitors, the inhibitor layer formation results in a passivation of the metal surface. Well-ordered self-assembled layer with high corrosion protection effect is obtained in aqueous solution of ,-diphosphonic acids. The self-assembly process takes a longer time, few days are necessary to reach the optimal organization of adsorbed organic layer. It is found that aqueous conditions are preferred for the protective layer formation. It is supposed that with simple chemical surface modification, i.e. with immersion of iron into the solution of alkane-diphosphonates, a new surface pre-treatment could be developed.