Photoinduced singlet charge transfer in a ruthenium(II) perylene-3,4: 9,10-bis(dicarboximide) complex

Elucidation of photoinduced charge transfer behavior in organic dye/metal hybrids is important for developing photocatalytic systems for solar energy conversion. We report the synthesis and photophysical characterization of a perylene-3,4:9,10-bis(dicarboximide) (PDI)–ruthenium(II) complex, bis-PDI-2,2′-bipyridineRu(II)Cl2(CNtbutyl)2, which has favorable energetics, ΔGCS ≈ −1.0 eV, for singlet electron transfer from the Ru complex to PDI. Time-resolved optical spectroscopy reveals that upon selective photoexcitation of PDI, ultrafast charge transfer (<150 fs) from the Ru complex to 1*PDI generates the Ru(III)–PDI–• ion pair. The resulting vibrationally hot Ru(III)–PDI–• ion pair exhibits fast relaxation (τ = 3.9 ps) and charge recombination (τCR = 63 ps). Our experimental and computational (DFT and TDDFT) studies show that energy-preserving photodriven singlet electron transfer can dominate in properly designed organic dye/metal complexes, making them of particular interest for use in artificial photosynt...