Visible-light photoexcitation of pyridine surface complex, leading to selective dehydrogenative cross-coupling with cyclohexane

Abstract

Upon photoirradiation with visible light, a pyridine molecule adsorbed on a TiO₂ surface can be photoexcited to give a pyridine radical cation via ligand-to-metal charge transfer (LMCT) between pyridine and titanium. This leads to dehydrogenative cross-coupling (DCC) between pyridine and cyclohexane with concomitant hydrogen evolution. Since the radical cation can selectively oxidize cyclohexane to a cyclohexyl radical, the cross-coupling between pyridine and cyclohexane proceeds with higher selectivity compared with that in photocatalysis by TiO₂ under UV irradiation.