Study on electron transfer of fluorescent probe lumichrome and nucleic acid by laser flash photolysis

Abstract

Laser flash photolysis (LFP) of lumichrome (LC) has been studied upon laser excitation at 355 nm. The transient absorption spectra of LC in aqueous solution displayed two bands at 380 nm and 540–700 nm for the triplet 3LC, and a wide band at 430–530 nm for the radical anion LC.. The triplet-state lifetime was measured up to 12 µs. It was found that the self-quenching of 3LC by the ground state of LC occurred to produce LC. during LFP. The transient spectra of LC in the presence of electron-donating triphenylamine (TPA), nucleosides and nucleic acids showed that the absorbance of 3LC was strongly quenched by these substrates and the formation of LC. was enhanced in a great extent simultaneously. The bimolecular quenching kinetics were studied and the rate constants of 3LC by a series of quenchers, including TPA, LC, nucleosides and nucleic acids were determined to be 108–109 M−1 s−1. The photo-induced electron-transfer mechanism for these processes involving the triplet 3LC was proposed.