From easily oxidized to easily reduced thiophene-based materials

We report here a new strategy towards functionalization of oligothiophenes that consists of the chemical transformation of thienyl sulfurs into the corresponding S,S-dioxides. We show that this kind of functionalization, which implies the dearomatization of the thiophene rings, leads to very stable oligomers with increased electron delocalization and has also a dramatic effect on their electron affinity as deduced from their electrochemical reduction potential. It is worth mentioning that the synthesis and the characterization of unsubstituted thiophene S,S-dioxide has been reported only very recently and that only S,S-dioxides derived from polysubstituted thiophene are stable at room temperature. So far, no electrochemical data on this kind of compound have yet been published.