Charge propagation in nickel 6,6′-bis(2′-hydroxyphenyl)-2,2′-bipyridine polymer film doped with perchlorate anions

Charge transport in the polymer film formed by anodic oxidation of Ni(dobpy) (dobpy=6,6′-bis(2′-hydroxyphenyl)-2,2′-bipyridine dianion) in acetonitrile with tetrabutylammonium perchlorate as supporting electrolyte was investigated. Oxidation of the poly[Ni(dobpy)] film is accompanied by movement of perchlorate ions into the film to main electroneutrality. The charge transfer characteristics of the film at different electrolyte concentrations, applied potentials and film thickness obtained from a.c. impedance analysis suggested that the charge propagation is controlled by the migration of ions through the polymer film. In situ FTIR spectroelectrochemical studies indicated that the absorption bands of the phenoxy rings are enhanced when the polymer film is oxidized, implying that electron diffusion occurs via the Ph–Ph–O–Ni–O–Ph–Ph bridge in the conjugated polymer backbone during film oxidation.