Laser flash photolysis study on the quenching reaction of the excited triplet state of acenaphthenequinone by antioxidant vitamin C

The photo-induced reactions of acenaphthenequinone (ACQ) as well as ACQ and vitamin C (VC) in ACN–H2O (v/v, 4:1) mixed solvent have been investigated by means of laser flash photolysis technique. The reaction intermediates have been identified and the reaction mechanism has been analyzed. The self-quenching rate constant of 3ACQ* by ground state ACQ and the quenching rate constant of 3ACQ* by biological antioxidant VC have also been measured. The results indicate that there is a hydrogen transfer from VC to 3ACQ* during the laser photolysis. VC is an effective quencher to 3ACQ* and the quenching rate constant is 4.0 × 108 L mol−1 s−1.