Regulation of film electrochemistry and CO binding of a diruthenium complex embedded in artificial lipids on an electrode

Film electrochemistry of Ru 2(2-CH 3ap) 4Cl ( 1), where 2-CH 3ap is 2-(2-methylanilino)pyridinate anion, and their carbon monoxide (CO) binding ability were electrochemically investigated in three different cationic matrices at a basal plane pyrolytic graphite (BPG) electrode immersed in 0.5 M aqueous KCl solution under CO atmosphere. The matrices employed in this study were tetra- n-octylphosphonium bromide (4C 8P +Br −), tetra- n-octylammonium bromide (4C 8N +Br −), or tetra- n-heptylammonium bromide (4C 7N +Br −). The complex 1 at the lipids modified electrodes was able to bind CO molecules in the Ru 2 4+, Ru 2 3+ and Ru 2 2+ reduced forms. Regulation of CO binding reaction of the complex 1 was also examined in a cast film of an artificial lipid, di- n-hexadecyldimethylammonium poly(styrene sulfonate), 2C 16N +PSS −, which has a phase transition between the crystalline and the liquid crystalline phase at 26.6 °C. Here, the Ru 2 5+/Ru 2 4+ and Ru 2 4+/Ru 2 3+ reactions under CO atmosphere showed a strong phase transition temperature dependence, suggesting the possibility of a temperature-driven regulation for the electrochemistry of complex 1 upon CO binding.