Preparation and oxidative doping studies of dithienyl polyenes stabilized by alkyl group substitution

Abstract

Dithienyl polyenes with up to 10 double bonds have been synthesized by Wittig condensation. The thienyl end groups were substituted in the β and β′ positions with butyl groups, resulting in greatly enhanced polyene solubility in common solvents. Oxidative doping of the polyene series with SbCl₅ in methylene dichloride solution produced extremely stable bipolaron-like dications. Preliminary evaluation of the third-order optical nonlinearity of both the neutral and doped species by degenerate four-wave mixing confirms previous predictions of bipolaronic enhancement of χ⁽³⁾, the third-order susceptibility.