Electrochemical synthesis and characterization of copolyviologen films

Abstract

Two cyanopyridine-based monomers were synthesized and utilized for the cathodic electropolymerization of polyviologen (BPV) and copolyviologen (CoPV) films onto glassy carbon (GC) electrodes. One of the monomer material is branched (BCP) whereas the other one has a linear structure (LCP) the former bearing three the latter two polymerizable cyanopyridinium groups. The electrochemical synthesis of the polyviologen and copolyviologen films were made in aqueous solutions and the film properties were characterized by electrochemical and spectroscopic techniques. Atomic force microscopy was used in order to study the surface morphologies of the films. The BPV and CoPV films undergo a two-step reduction reaction and show redox properties typical for viologen derivatives in monomer free electrolyte solutions. In comparison to the polyviologen film, electrochemically synthesized from the branched monomer (BCP), the redox property of the copolymer was changed. The results from in situ UV–vis spectra show that the copolyviologen film has good stability and undergoes reversible electron transfer reactions successfully. The structure of the copolyviologen film was characterized by FTIR spectroscopy, confirming successful polymerization of both monomer materials. The copolymerization therefore opens up a direct electrochemical method to form viologen films with large cavities. This feature gives a potential to apply the partly conjugated copolyviologen film with redox properties as a conducting host material for immobilization of macromolecules.