Photocatalytic Oxidation Of Organic Substrates In A Three Components System

Visible light-driven hydrocarbon oxidation with water as an oxygen source is of importance to artificial photosynthesis. Due to less protons and electrons are involved in photocatalytic hydrocarbon oxidation, it has been considered as a convenient approach to photo-induced hydrogen production relative to the photocatalytic water oxidation when coupled to the proton reduction half reaction.To develop sustainable and efficient photocatalytic hydrocarbon oxidation system, six ruthenium complexes (Rul-Ru6), four iron complexes (Fel-Fe4), four manganese complexes (Mnl-Mn4) and two cobalt complexes (Col-Co2) were prepared as photocatalysts. Three complexes (Ru(bpy)3Cl2, Znl and Zn2) were prepared as photosensitizers. All complexes were applied in a three components homogeneous system including catalyst, photosensitizer and sacrificial electron acceptor to improve the photocatalytic activity in the oxidation of benzyl alcohol to benzaldehyde. To our delight, photosensitizer based on non-noble metal such as Znl, showed comparable photocatlytic activity to that of ruthenium photosensitizer. Meanwhile, catalysts based on non-noble metals such as iron, cobalt and manganese showed comparable photocatlytic activities to those of ruthenium catalysts. As the most active catalyst in this study, Fe(TMC)(OTf)2(Fel) exhibited remarkable activity with a conversion of19%corresponding to a TON of48. Our results open a way of rational design of low-cost and highly efficient photocatalytic system.