A structurally diverse Ru(II),Pt(II) tetrametallic motif for photoinitiated electron collection and photocatalytic hydrogen production.

Coupling a reactive metal to light absorbers affords molecular devices for photoinitiated electron collection and photocatalytic conversion of substrates to fuels. A new Ru(II),Pt(II) tetrametallic supramolecule, {(phen)(2)Ru(dpp)}(2)Ru(dpq)PtCl(2)(6), and the trimetallic precursors, {(phen)(2)Ru(dpp)}(2)RuCl(2)(4) and {(phen)(2)Ru(dpp)}(2)Ru(dpq)(6), have been synthesized, and their redox, spectroscopic, spectroelectrochemical, photophysical and photocatalytic properties studied. They efficiently absorb UV and visible light. The electrochemistry of {(phen)(2)Ru(dpp)}(2)Ru(dpq)PtCl(2)(6) suggests a lowest-lying terminal Ru→dpq charge-separated state that quenches the emission of the parent complex with non-unity population of the emissive (3)MLCT excited state. Photolysis of {(phen)(2)Ru(dpp)}(2)Ru(dpq)PtCl(2) at 470 nm with DMA gives multielectron reduction, storing electrons in a new manner on the central (dpp)(2)Ru(II)(dpq) moiety. Addition of H(2)O to the photolysis system produces 21 μmol of H(2) in 5 h, with 115 turnovers of the tetrametallic photocatalyst.