Ir(III)-Naphthoquinone complex as a platform for photocatalytic activity

Inspired by the primary events that take place in Photosystem II (PSII), we designed and synthesized a heteroleptic Ir(III) complex featuring an attached naphthoquinone (NQ) as an electron transfer (ET) auxiliary reminiscent of the plastoquinone electron acceptor in PSII. In this design, NQ is covalently attached to the 2,2′-bipyridyl (bpy) ligand of [Ir(dF(CF3)ppy)2(bpy)][PF6], (dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine). Following excitation of the photocatalyst ([Ir(dF(CF3)ppy)2(bpy-NQ)][PF6]), reduced NQ (NQ•‒) was observed in transient absorption spectroscopy. This novel catalyst has potential applications in oxidative and reductive photocatalytic processes.