Photoinduced Singlet Charge Transfer in a Ruthenium(II) Perylene-3,4:9,10-bis(dicarboximide) Complex

Abstract

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)Àruthenium(II) complex, bis-PDI-2,2 0 -bipyridineRu(II)Cl 2 (CN t butyl) 2 , which has favorable energetics, ΔG CS ≈ À1.0 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)ÀPDI À• ion pair. The resulting vibrationally hot Ru(III)ÀPDI À• ion pair exhibits fast relaxation (τ = 3.9 ps) and charge recombination (τ CR = 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 photosynthetic systems for solar fuels formation.

Selective photoinduced charge separation in perylenediimide-pillar[5]arene rotaxanes

“…Whilst the 1 PDI undergoes internal conversion (IC) back down to the ground state in 100 ps, the PDI •− species undergoes recombination (RC) to the ground state in 180 ps. The coexistence of a 1 PDI and charge-separated state has been observed previously by Wasielewski and co-workers 39 .…”

Merging of a Perylene Moiety Enables a RuII Photosensitizer with Long‐Lived Excited States and the Efficient Production of Singlet Oxygen

“…[44][45][46] In particular, rylene imide architectures were successfully incorporated to facilitate charge transfer transitions to or from the organic chromophore system. [47][48][49][50][51][52] Rylene radical anions or cations can be observed with characteristic absorption bands. Hence, embedding of such rylene based dyes (organic chromophores) into traditional polypyridine ligands for the preparation of improved transition metal complexes is of high interest.…”

Investigation of excited state, reductive quenching, and intramolecular electron transfer of Ru(ii)–Re(i) supramolecular photocatalysts for CO2reduction using time-resolved IR measurements

“… 28 , 35 , 36 However, they did not clearly observe formation of the one-electron reduced binuclear complex by TRIR with single-shot excitation, even in the presence of triethanolamine as a reductant, and could not determine the rate of intramolecular electron transfer from the reduced porphyrin unit to the Re-complex unit. Although a few other groups have also reported photochemical electron transfer in systems consisting of other porphyrins, 29 organic dye, 31 , 34 or polyoxometalate 37 , 38 and a Re( i )-complex unit, intramolecular electron transfer events from the reduced unit in the ground state to the Re unit were not reported.…”