Tris(bipyridine)ruthenium(II)-photosensitized reduction of a CoIII–Schiff base complex in a network of gelatin hydrogel and in an aqueous gelatin solution

Abstract

The Ru(bpy)²⁺₃ photosensitized reduction of a Co^III–Schiff base complex proceeds effectively in a network of gelatin hydrogel and in an aqueous gelatin solution under anaerobic conditions. In both systems, a reduced intermediate species of the Co^III complex coordinated to a gelatin molecule, which has an absorption maximum at 450 nm (R₄₅₀), was initially generated. After irradiation had been stopped, R₄₅₀ turned slowly to the diaqua Co^II–Schiff base complex in the hydrogel system whereas it was oxidized gradually to the initial Co^III–Schiff base complex in an aqueous gelatin solution. It is suggested from the results obtained that the gelatin acts as the ligand for the Co^III complex, and both the electron donor and, probably, electron acceptor for the photosensitized reactions in both the systems.