Mechanism of singlet oxygen interaction with spin trap α-phenyl- N- tert-butylnitrone

Abstract

The mechanism of singlet oxygen ( 1O 2) quenching by α-phenyl- N- tert-butylnitrone was investigated by the laser flash photolysis technique using 1,3-diphenylisobenzofuran and rubrene as 1O 2 acceptors. It was found that the quenching is substantially a reversible electron transfer process with a rate constant of (8.2 ± 0.9) × 10 6 M −1 s −1 and that the rate constant for chemical reaction is equal to (1.4 ± 0.1) × 10 5 M −1 s −1 at 20 °C. From the triplet-triplet energy transfer method the position of the lowest triplet state of nitrone was estimated to be 16 200 ± 100 cm −1.