Polysulfonium as a new electrode-modifying polyelectrolyte

A new type of cationic polyelectrolyte, poly(methylsulfonio-1,4-phenylenethio-1,4-phenylene trifluoromethanesulfonate), that adheres to a glassy carbon electrode surface has been employed to bind a ferricyanide anion to the electrode surface from electrolyte solutions. The complex incorporated by the polyelectrolyte shows significant shifts in formal potential to less positive values due to the stronger binding of ferricyanide by the polycation coating than that of ferrocyanide. The apparent formal potential for the incorporated ferricyanide/ferrocyanide redox couple changes as the concentration of supporting electrolyte is varied. The polycation coating is anion-permselective when a methanesulfonate is used as a supporting electrolyte.