Synthese und Eigenschaften von Polyacetylen

Polyacetylene is important because it can be transferred into metallic conducting phases by treatment with strong oxidizing or reducing agents (“doping”). The influence of the reaction conditions, especially of the polymerization catalyst, are investigated. The polymers obtained under normal conditions are always crosslinked. The morphology is independent of the polymerization method and can be described as an aggregation of lamellar particles with typical dimensions of a few 100 Å. The polymer chains are oriented perpendicular to the surface and chain folding is observed. The crystal structures of cis and trans polyacetylene are given. The consequences of the morphology on the mechanism of doping and charge transport are discussed using general structural principles.     

Synthese von porösen Kohlenstoffmonolithen unter Verwendung von Porenbeton als Templat. Teil II: Untersuchungen mechanischer Eigenschaften

Monolithic forms are particularly suitable when using porous carbon materials in flow through apparatus. One method to synthesize these materials is the template‐assisted synthesis. Porous carbon monoliths have been prepared using porous concrete as a template. Systematic investigations of the mechanical stability have shown the potential of these materials for technical applications. It could be proven that the monoliths are stable against compressive stress and flow‐through of water, respectively.     

Synthese von porösen Kohlenstoffmonolithen unter Verwendung von Porenbeton als Templat

Porous carbon monoliths have been prepared by template assisted routes using porous concrete as the template. Due to its good workability, porous concrete is a suitable template to produce carbon monoliths with defined shape. The pore widths of the obtained monoliths are distributed over a broad range from the micropore to the macropore region. Such materials are a promising base for developing construction components which can be applied in adsorption devices or catalytic systems.     

Synthese und Komplexchemische Eigenschaften eines neuen Chelon-Mikrosphären-Dextrangels

The covalent anchoring of chelating groups on a spherical dextran gel by the simultaneous action of alkali dextran, 2,3-dibrompropionic acid, and iminodiacetic acid under various conditions was investigated. The formation of stable metalchelate complexes of the resulting spherical polymer is demonstrated by means of neutralization curves for bivalent metallic ions with the succession of selectivity corresponding with the course for N-donator atoms. The presence of functional α,β-alanine-N,N-diacetic acid groups and weakly acidic carboxylic groups is inferred from the different stabilities and capacities in dependence on pH for In³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ca²⁺, in comparison with the N-content on spherical dextran derivate capacity of a competing ligand in solution.     

Eine neue Synthese zur Darstellung von organischen Tellurverbindungen unter Verwendung von elektrochemisch erzeugten Polytelluriden

A Novel Synthesis of Organic Tellurium Compounds by the Use of Electrochemically Generated Polytelluride-ions The cathodic polarisation of a tellurium electrode in aprotic solutions gives rise to polytelluride anions, which react with alkylhalides to the corresponding disubstituted ditellurides. By this method of electrosynthesis a number of organic ditellurides can be simply prepared and without danger. Dialkylditellurides of the general formula R-Te-Te-R ( 2a – r ) can be produced with high yields. The reaction with α,ω-dihalides gives heterocycles, which involve one or two tellurium atoms in the ring ( 5a – d , 6 – 8 ). The electrochemical reduction of tellurium in the presence of methyliodid yields trimethyltelluroniumiodid ( 9 ).     

Untersuchungen zur Synthese und den Eigenschaften von amphiphilen Polymeren

Investigations of the Synthesis and Properties of Amphiphilic Polymers By reaction of propylene/maleic anhydride copolymers with the sodium salt of α-dodecyl-ω-hydroxy-trioxyethylene ionic polymers with different shares of long aliphatic side chains were prepared. The properties of these amphiphilic polymers were studied. Like micelles they are able to solubilize nonpolar probe molecules (N,N-dimethyl-aminoazobenzene). Viscosity measurements show the dependence of the conformation of the polymeric chain in solution on the share of aliphatic side chain and the degree of protonation. The polymers from micelle-like aggregates. It is supposed that the polymer with a high share of aliphatic side chains froms several local aggregates per polymer chain, while the polymer containing only few side chains seems to form intermolecular aggregates between different polymer chains. These investigations were performed with pyrene as probe molecule. Pyrene was also used to examine the micropolarity of the aggregates. Like polyelectrolytes the amiphilic polymers are able to cause the aggregation of opposite charged dyes (thionine).     

Synthese,Struktur und photophysikalische Eigenschaften von polyarylierten Imidazolen und Oxazolen

Synthesis, Structure, and Photophysical Properties of Polyarylated Imidazoles and Oxazoles 23 tetraphenylimidazoles 1,2 and 11 triphenyloxazoles 4,5 with amino, nitro, methoxy, hydroxy, or halogeno substituents chiefly in the para position were prepared. The absorption and fluorescence emission properties were investigated in ethanolic solution. The effects of the substituents in 1,2 on the spectral shifts show that the arrangement of the phenyl rings in 1 position is not coplanar in relation to the heterocycle whereas the phenyl rings in 2 position are more coplanar. The spectral changes of compound 2a in solvents of various polarity (dielectric constants 2,02–47,24) are almost negligible. The Stokes shift is moderately increased. A remarkable increase in the fluorescence quantum yield is observed by chlorine substitution in phenyl ring 2.     

Synthese und Eigenschaften von Trimethincyaninen mit verbrückten Ketten

Synthesis and Properties of Trimethinecyanines with Bridged Chains The effects of meso-substituents (H, morpholino, ethoxy) and hydrocarbon bridges, on the light absorption and the electrochemical properties of trimethinecyanine dyes ( 4a--f , 8a–c 10a–f ) are investigated. The results are in a good agreement with the predictions of the perturbation theory. Methods for the preparation of the dyes involving reaction of methylthio quaternary salts ( 1a , b ) with enamines ( 2a , b ) are described.     

Synthese,Struktur und Eigenschaften von hochtemperaturbeständigen Faserpolymeren

Thermomechanically stable fiberpolymers are formed by aromatic molecule segments. In the course of the synthesis of dicarbonic acid dichlorides and diamines in the solvent dimethyl acetamide acetic acid chloride is formed, which causes chainbreaking. X-ray-structure of poly-m-phenylene-isophthalicamide shows, that the hydrogenbond forming carbonamide groups are vertically arranged to the aromatic planes. With this structure model it is possible to explain thermal and mechanical data of aromatic polyamides.