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)Cl-2(CN(t)butyl)(2), which has favorable energetics, Delta G(CS) approximate to -1.0 eV, for singlet electron transfer from the Ru complex to PDI. Time-resolved optical spectroscopy reveals that upon selective photoexcitation of I I PDI, ultrafast charge transfer (<150 fs) from the Ru complex to (PDI)-P-1 center dot generates the Ru(III)-PDI-center dot ion pair. The resulting experimental and computational (DFT and TDDFT) studies show that energy-preserving photodriven singlet electron transfer can vibrationally hot Ru(III)-PDI-center dot ion pair exhibits fast relaxation (tau = 3.9 ps) and charge recombination (tau(CR) = 63 ps). Our dominate in properly designed organic dye/metal complexes, making them of particular interest for use in artificial photosynthetic systems for solar fuels formation.