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The synthesis of polyvinyl polymers by radical polymerization of α-vinyl-ω-alkyl-terminated thiophene and bi-, ter-, and quaterthiophenes is reported. The photoluminescence properties of the polymers in solution and in thin film are described. In thin film, self-assembly-induced white photoluminescence was observed for poly(5-vinyl-5‘ ‘‘-hexylquaterthiophene). For this polymer, single crystals with rectangular shape and micrometer size were obtained by drop casting from CS2. MM3 calculations on model diads and triads indicate that, on increasing the size of the side groups, van der Waals interactions promote the stacking of the pendants on the same side of the polyvinyl chain.

A new class of thiophene-based polymers characterized by the presence of one nonaromatic thienyl S,S-dioxide moiety (O) to every two, four, and six aromatic thienyl units (T) was prepared from the newly synthesized precursors TOT, TTOTT, and TTTOTTT, and electrochemically characterized. The polymers displayed remarkably greater electron affinities than that of polythiophene and could be reversibly n-doped at moderate potentials, while still maintaining the property of also being p-doped at moderate potential values. All polymers were characterized by good p-doping/undoping cyclability, while at least four aromatic units to every nonaromatic one were needed to ensure good n-doping/undoping cyclability. ZINDO/S//PM3 calculations on TOT, TTOTT, and TTTOTTT and on (TOT)3 and (TTOTT)3, as models for the corresponding polymers, showed that the presence of the nonaromatic units does not affect the π,π* character of the frontier orbitals but decreases their energy, in particular that of the LUMO. The calculations allow the cyclability properties of the polymers in the p- and n-doping domains to be rationalized in terms of delocalization of the electronic charge of p- and n-type charge carriers over the aromatic units.

The trend of variation of sulfur and oxygen shieldings of X-SO2-Y and X-SO-Y substrates is rationalized in terms of the joint effects of n -> σ* conjugative interactions and ligands electronegativity. The relative weight of these effects is different in the two classes of compounds, the former being dominant in the series X-SO2-Y and the latter in the series X-SO-Y.

Summary Solid particles for nuclear fuel fabrication can be produced by gel-supported precipitation. Process by-products are aqueous wastes containing organic materials, ammonium nitrate and ammonia that can be decomposed into nitrogen compounds. A differential pulse polarographic determination of nitrate- and nitrite-nitrogen in such mixtures is described.

It is shown by carbon-13 NMR that the only product of the imidazole ring-opening of 7-methyl-guanosine at physiological pH is 2-amino-6-hydroxy-5-N-methylformamido-4-(N-β-ribofurano-sylamino)pyrimidine and that, contrary to previous results, the hydrolysis of the glycosylic bond at pH=7.2 is a much slower process than the ring opening. The ring opened formamidopyrimidine derivative is a very mobile molecule existing under different conformations depending on the solvent, and in water it is capable of giving different kinds of aggregates. Possible biochemical implications of these results are discussed.

New conjugated polymers containing variable amounts of thienyl and thienyl-S,S-dioxide units have been prepared by chemical or electrochemical polymerization of the appropriate substrates. The presence of the thienyl S,S-dioxide units leads to the decrease of the LUMO energies with respect to those of the ‘all thienyl’ counterparts. Electrochemical and spectro electrochemical data of n-doping of these materials are reported.

Regiospecifically methyl substituted α-conjugated thiophene oligomers have been synthesized and their structural and conformational properties investigated by 13C NMR, X-ray and force field MMP2 calculations. The use of these molecules as 'monomers' for electropolymerization affords poly(3-methylthiophenes) showing spectroelectrochemical properties which depend on the size and the substitution pattern of the starting oligorners.

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.