Spectroelectrochemical and electrochemical investigation of a highly conjugated all-thiophene polyazomethine

Electrochemical studies of a highly conjugated all-thiophene polyazomethine (1) revealed that it could be pseudo-reversibly oxidized. Electrochemical and chemical oxidation of 1 generated the same intermediate that absorbed at 820 nm and was bathochromically shifted by 135 nm from the neutral polymer. This intermediate was transparent in the visible spectrum and was assigned to the radical cation by the Randles–Sevcik and Job methods. Meanwhile, the chemically generated radical cation produced with FeCl3 could be reduced with hydrazine hydrate to regenerate the neutral 1, which was colored blue. The conjugated polymer was found to undergo reversible color change between the visible and NIR spectral windows with both electrochemical and chemical doping, illustrating the potential usefulness of this polymer in electrochromic devices.