Voltammetric anion recognition by a highly cross-linked polyviologen film

Abstract

A highly cross-linked polyviologen film was prepared by reductive electropolymerization of a trifunctional monomer with three 4-cyanopyridinium moieties. The film was deposited on an ITO-deposited glass electrode at higher current efficiency than in the case of a linear polyviologen from a bifunctional monomer. The resulting polymer film shows a clear electrochromism characteristic of a viologen redox process. The film exhibits typical redox waves in a monomer-free electrolytic solution containing a smaller electrolyte anion than the anion used in electropolymerization. On the contrary, the film behaves as electrochemically inactive in a solution containing a larger electrolyte anion due to its reduced mobility through the cavity in the cross-linked polymer structure. This anion-controlled redox behavior suggested that the cavity size in the cross-linked polymer may be determined by the template effect of the electrolyte anion used in electropolymerization, called anion-imprinted electropolymerization. These features can be regarded as a new voltammetric anion recognition of the highly cross-linked polyviologen film.