A Ruthenium Complex–Porphyrin–Fullerene‐Linked Molecular Pentad as an Integrative Photosynthetic Model

A ruthenium complex, porphyrin sensitizer, fullerene acceptor molecular pentad has been synthesized and a long‐lived hole–electron pair was achieved in aqueous solution by photoinduced multistep electron transfer: Upon irradiation by visible light, the excited‐state of a zinc porphyrin (1ZnP*) was quenched by fullerene (C60) to afford a radical ion pair, 1,3(ZnP.+‐C60.−). This was followed by the subsequent electron transfer from a water oxidation catalyst unit (RuII) to ZnP.+ to give the long‐lived charge‐separated state, RuIII‐ZnP‐C60.−, with a lifetime of 14 μs. The ZnP worked as a visible‐light‐harvesting antenna, while the C60 acted as an excellent electron acceptor. As a consequence, visible‐light‐driven water oxidation by this integrated photosynthetic model compound was achieved in the presence of sacrificial oxidant and redox mediator. Pent‐up energy: A ruthenium‐based water oxidation catalyst linked to porphyrin–fullerene units in a molecular pentad has been synthesized. Transient absorption indicated the photoinduced multistep electron transfer afforded a long‐lived hole–electron pair, and photocatalytic water oxidation by the pentad was achieved in the presence of sacrificial oxidant.