Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

The photoexcitation of the Fc-ph-DCV at 390 nm generates the S2 state. The S2 → S1 internal conversion (IC) occurs with a time constant of ∼100 fs and generates the S1 state having a CT character. The IC process is faster than the solvation processes and is independent of solvent polarity. On the other hand, the lifetime of S1 state shows a substantial solvent dependence, changing from 50-60 ps in ACN to ∼20 ps in CHX, reflecting that the S1 state is more stabilized in more polar solvent. The up-conversion data indicate the presence of ultrafast solvation and/or vibrational relaxation in the S1 state. The present study clarified the ultrafast dynamics of the CT process following electronic relaxation of a newly synthesized donor-π-acceptor system, Fc-ph-DCV.