The voltammetric behavior of transition metal complexes of 2,2′-bipyridine, [MII(bpy)3](ClO4)2 (MII = CoII, FeII, or RuII, in toluene/acetonitrile mixtures has been studied by cyclic voltammetry. In solutions with a low acetonitrile-to-toluene ratio and tetra(n-butyl)ammonium perchlorate as supporting electrolyte, oxidation of [MII(bpy)3](ClO4)2 leads to the precipitation of a solid, electrochemically inactive phase of [MIII(bpy)3](ClO4)3 (M = Co or Fe) on the electrode. Electrodes modified by this solid phase are shown to display catalytic waves that result from chemical reduction of the film by soluble species: [M(bpy)3]+ when no other electroactive species is present or [C60]- when C60 is also present in the solution. The redox behavior of C60 on an electrode covered by a [CoIII(bpy)3](ClO4)3 layer was extensively investigated. The catalytic current associated with the reduction of C60 at a [CoIII(bpy)3](ClO4)3 modified electrode can be used for the quantitative determination of fullerene concentration in solution. The reduction current associated with square wave voltammetric experiments increased linearly with the concentration of C60 in the range of 0.25-20 μM. The detection limit is 0.1 μM. This method of fullerene quantitative determination exhibits good reproducibility, simplicity, and is relatively fast. Electrochemical oxidation of [RuII(bpy)3](ClO4)2 does not produce an analogous redox inactive layer of [RuIII(bpy)3](ClO4)3.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry