Paolo Costa Bizzarri

Solvatochromic properties of poly[3-(6-methoxyhexyl)-2,5-thienylene] in different solvent mixtures

Abstract Two samples of poly[3-(6-methoxyhexyl)-2,5-thienylene] with a slight difference in regioregularity and a greater difference in molecular weights were obtained by chemical oxidation with FeCl3. The solvatochromism of the two polymers was investigated in mixtures of various solvents (dioxane, dimethylpropyleneurea, methylene chloride, tetrahydrofuran, chloroform and toluene) with different non-solvent (methanol) molar fractions, at constant polymer concentration and temperature. Some solvent/non-solvent couples were able to distinguish between the two samples, giving a different solvatochromic effect. This can be considered a very useful tool to characterize polymers with configurational and molecular weight differences.

Ester-functionalized poly(3-alkylthienylene)s: substituent effects on the polymerization with FeCl3

Abstract Ester-functionalized poly(3-alkylthienylene)s were obtained by chemical oxidation with FeCl3. Substituents with both different total length and different distance of the ester group from the thiophene ring were examined. The main reaction solvent studied was chloroform which gave polymers with high molecular weight and incomplete conversion of the monomer. Some polymers were synthesized with a new procedure involving the precipitation of FeCl3 from a saturated nitromethane solution by a tetrachloride solution of the monomer. In this way, lower molecular weights and complete monomer conversion were obtained. The effect of different substituent groups on the polymer microstructure was examined using 1H NMR spectroscopy. With both polymerization procedures, the regioregularity and absorption maximum in the visible spectrum increase with increasing length of the oligomethylenic spacer between thiophene ring and ester group.

Organic Metals: N,N'-Dicyano-1,4-benzoquinonediimines as Acceptors in Charge-Transfer Complexes

Abstract The synthesis of the title compounds is reported, together with the crystal structure of the parent system (1a): charge transfer complexes obtained therefrom show conductivities in the range of semiconductors.

Regiochemistry characterization of poly(3-hexanoyloxyethyl-2,5-thienylene) through proton and carbon nuclear magnetic resonance spectroscopy

Abstract The poly(3-hexanoyloxyethyl-2,5-thienylene) was studied by means of mono- and bidimensional nuclear magnetic resonance spectroscopy. The regiochemistry of the polymer is assigned on the basis of the 13 C chemical shifts, which are easily obtained through inverse detection experiments, utilizing a triad-based model.

Characterization of poly(3-hexanoyloxyethyl-2,5-thienylene) synthesized under different conditions: a comparative study

Poly(3-hexanoyloxyethyl-2,5-thienylene) has been chemically synthesized with FeCl3 in both nitromethane and chloroform using different conditions. A complete homopolymeric structure is obtained in chloroform as confirmed mainly by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The homopolymer shows a higher molar mass by gelpermeation chromatography and a higher thermal stability under nitrogen by thermogravimetry. The microstructure of the polymeric chains has been investigated by NMR and a low regioregularity, independent from the polymerization conditions, is found. The electronic spectra suggest low conjugation lengths. The conductivities of the oxidized polymers, ca. 10–3 S cm–1, are reported.

Synthesis and Conductivity of Thianthrene-Type Polymers

Abstract Different methods to obtain oligoriieric sulfur derivatives of thianthrene-type with cyclic chain structure are described. The pristine compounds are insulators. Values in the semiconductors range can be achived by doping the samples with SbCl5. The conductivity increases up to about 10−5 S/cm.

Electrical and Infrared Properties of a Polyheterocycle Structurally Related to Poly(p-Phenylene Sulfide)

Abstract A comparison between a thianthrenic polymer and the parent poly(p-phenylene sulfide) is presented on the basis of electrical and infrared properties. Evidence that the polyheterocycle has a higher conductivity after doping with different amounts of SbCl5 is reported. In this doped polymer significant spectral modifications are also observed, mostly around 1100 cm−1. On the contrary the spectral profile of poly(p-phenylene sulfide) remains nearly unchanged at all doping concentrations.