No abstract

Regioregular Head-to-tail (HT)-type polythiophene was synthesized by deprotonative nickel-catalyzed cross-coupling polymerization of 2-chlorothiophene bearing neopentyl benzenesulfonate group at the 3-position. The obtained HT-regioregular polymer was found dissolved in chloroform or THF, while it turned to water soluble upon heating the polymer 2 at 185 °C for 10 min by the liberation of the protected neopentyl group. The thin-film of the polymer showed remarkable improvement of the conductivity ca. 10 3 times before/after heating suggesting thermally-induced intramolecular doping polythiophene by the formed sulfonic acid at the side chain. The related doping was also observed in a poly(phenylacetylene) derivative, which was synthesized by rhodium-catalyzed polymerization. Copolymerization of such thiophene and acetylene bearing neopentyl sulfonate with 3-alkylthiophene and phenylacetylene produced the corresponding statistical copolymers, respectively, demonstrating the formal self-doping of poly(3-alkylthiophene) and poly(phenylacetylene).

No abstract

A simple and ubiquitous nickel(II) complex NiCl 2 (PPh 3) 2 catalyzes polymerization of oligothiophenes. Treatment of chlorobithiophene with chloromagnesium 2,2,6,6-tetramethylpiperidin-1-yl lithium chloride salt (TMPMgCl¢LiCl) followed by addition of 2.0 mol % NiCl 2 (PPh 3) 2 undergoes deprotonative polymerization leading to poly(3-hexylthiophene) (P3HT) with M n = 13000 and M w /M n = 1.67 (74% yield). The related terthiophene and quaterthiophene also polymerize to afford the corresponding polythiophene while little polymerization takes place with 2-chloro-3-hexylthiophene under similar conditions.

Deprotonative metalation of 2-chloro-3-substituted thiophene at the 5-position of the thiophene ring is performed by a bulky magnesium amide 2,2,6,6-tetramethylpiperidin-1-yl magnesium chloride lithium chloride salt (TMPMgCl•LiCl). The obtained metallic species reacts with bromothiophene to afford the regioregular head-to-tail-type chlorobithiophene, which is subjected to further end functionalization by the coupling reaction with C-Cl bond. Deprotonative C-H coupling polycondensation of differently-substituted chlorobithiophene gives polythiophene of the formal alternating copolymer.