A Bpp-based dinuclear ruthenium photocatalyst for visible light-driven oxidation reactions

A diruthenium dyad molecule consisting of a 2,2-(1H-pyrazole-3,5-diyl)dipyridine (Hbpp) bridging ligand with the formula out-/in-[(bpy)₂Ru(bpp)Ru(L)(tpy)]ⁿ⁺ (bpy = 2,2′-bipyridine, tpy = 2,2′:6′,2′′-terpyridine, L = Cl, CF₃COO⁻, H₂O or CH₃CN and n = 2 or 3) has been prepared and fully characterised. The complex has been characterized by analytical and spectroscopic techniques and by X-ray diffraction analysis for two of the derivatives (Cl and CH₃CN). Additionally, full electrochemical characterization based on cyclic voltammetry and square wave voltammetry has been also performed. The pH dependence of the redox couples for the aqua complex has also been studied and the corresponding Pourbaix diagram drawn. Furthermore, the capacity to photo-catalytically oxidize organic substrates, such as alcohols, alkenes, and sulfides, has been carried out and the overall stability and selectivity of the catalyst has been analysed.