Electrochemical and UV–Vis/ESR spectroelectrochemical properties of thienylenevinylenes substituted by a 4-cyanostyryl group

The π-electron delocalisation in conjugated thienylenevinylenes bearing arylethenyl chromophores, makes those materials interesting candidates for electro-optic applications. In this study, we report the results of electrochemical and UV–Vis/ESR spectroelectrochemical studies of a pair of thienylenevinylenes substituted by the 4-cyanostyryl group, bearing either a hydrogen, or methyl group terminated α carbons at the peripheral thiophene rings. The reactivity of various functional segments of investigated molecules was assessed by comparing the reactivity of the protected and unprotected counterparts and the behaviour of their electrooxidation products. For the capped derivative, two irreversible anodic redox processes giving electrochemically inactive products were observed, while the uncapped molecule yields electroactive materials already upon its first oxidation step.

► Electropolymerisation of the cyanostyryl substituted thienylenevinylene derivative affords a polymer having an optical band gap of ca. 1.8 eV, supplemented by soluble oligomers.
► Vinyl bonds of the thienylenevinylene derivative were found unstable upon electrooxidation of the molecule to a radical cation.
► Two groups of spins of the radical cation of the thienylenevinylene derivative have been identified.