A homogeneous polypyridine-based manganese catalytic system: Reducing CO2 to CO under visible light

Abstract

To study the effects of substituent electron - donor on the efficiency of manganese - based photocatalyst, four different Mn(II) complexes have been used as catalysts, the ligands including phenanthroline with methyl and phenanthroline without methyl, bipyridine with methyl and bipyridine without methyl. [Ru(bpy)₃]²⁺ ([Ru]) has been used as a photosensitizer with triethanolamine (TEOA) in CH₃CN solution for the photochemical reduction of CO₂ to CO under visible light irradiation. The turnover numbers of the four catalysts are found to be 99, 717, 167, and 1038, respectively. The experiments have revealed that the catalytic effects of phenanthroline-type complexes are superior to the dipyridyl-type complexes, which has no methyl groups on their ligand. For both phenanthroline-type and dipyridyl-type complexes, the catalysts with a methyl group on the ligand shows good performance than those without a methyl group. The phenanthroline-type complexes with methyl groups has displayed the best catalytic activity among these four catalysts.