SiO₂ Sol−Gel Composite Films Containing Redox-Active, Polypyridyl−Ruthenium Polymers

The RuII-bpy derivatized, polystyrene polymers, [PS−CH2CH2NHCO−(RuII)n]Cl2n (n = 18 or 20), have been incorporated into SiO2 sol−gels and deposited as thin films on ITO (In2O3:Sn) electrodes. In these optically transparent, redox-active composite membranes, RuII can be oxidized reversibly to RuIII. With [Os(bpy)3]2+ or the [PS−CH2CH2NHCO−(OsII)20]Cl40 in an external CH3CN solution they display diffusional redox mediation and rectifying behavior. Cyclic voltammograms as a function of scan potential in the presence of [Os(bpy)3]2+ are shown at right.