Photo-oxidation of tris(2,2′-bipyridine)ruthenium(II) by para-substituted benzene diazonium salts in acetonitrile. Two-compartment photoelectrochemical cell applications
Abstract
The photo-oxidation of tris(2,2′-bipyridine)ruthenium(II)[Ru(bpy)2+3] by substituted benzene diazonium salts (p-RC6H4N+2) has been studied in acetonitrile. Quenching of the excited state [Ru(bpy)2+*3] by p-RC6H4N+2 takes place at diffusional rates (kq 1.6 × 1010 dm3 mol–1 s–1) and leads to the effective build-up of the oxidized species Ru(bpy)3+3 with a high quantum yield (ϕ > 0.12). ϕ depends on the nature of the substituent R. This Ru(bpy)2+*3/p-RC6H4N+2 system has been applied in some two-compartment photoelectrochemical cells. The photogenerated Ru(bpy)3+3 oxidizes an electron donor D in the dark compartment. Features of this cell are reported, especially the influence of D on the open-circuit photovoltage and the photocurrent passing through a 1000 Ω resistor. The performance of this cell has been improved by the use of a second irradiation compartment where D is photogenerated as the reduced form of the 1,1′-dimethyl-4,4′-bipyridinium dication.