Reversible Multichannel Detection of Cu²⁺ Using an Electropolymerized Film

The reductive co-electropolymerization of vinyl-substituted ruthenium complexes 2(PF₆) and 3(PF₆)₂ at ITO glass electrodes have afforded adherent metallopolymeric films, where complex 2(PF₆) contains a dipicolylamine (DPA) unit as the ion recognition site and 3(PF₆)₂ is a ruthenium monomer without DPA. The resulting thin films can selectively detect Cu²⁺ at the solid-liquid interface on the basis of color, absorption, and electrochemical changes. By using EDTA to remove the incorporated Cu²⁺, the polymeric film can repeatedly detect Cu²⁺ with good reversibility and film stability, as supported by XPS and TEM analyses.