Visible light-driven photocatalytic duet reaction catalyzed by the B₁₂-rhodium-titanium oxide hybrid catalyst

The hybrid catalyst composed of the B₁₂ complex and rhodium ion (Rh³⁺) modified titanium oxide was synthesized for the visible light-driven B₁₂ inspired catalytic reaction. The hybrid catalyst contains 4.93 × 10⁻⁶ molg⁻¹ of the B₁₂ complex and 5.43 × 10⁻⁵ molg⁻¹ of the Rh(III) ion on the surface of titanium oxide. Visible light irradiation (λ ≧ 420 nm) of the hybrid catalyst in the presence of triethylamine (Et₃N) as a sacrificial reagent showed absorption at 390 nm, typical for the Co(I) state of the B₁₂ complex monitored by diffuse reflectance UV–vis analysis, which imply that electron transfer from the titanium oxide to Co(III) center of the B₁₂ complex occurred by the visible light irradiation. Benzotrichloride was converted to N,N-diethylbenzamide by the visible light irradiation catalyzed by the hybrid catalyst in air at room temperature. Both the conduction band electron and valence band hole of the catalyst were utilized for the reaction to form the amide product. The reaction mechanism of the duet reaction was proposed.