Laser Flash Photolysis Study of the Photoionisation of Chlorpromazine and Promazine in Solution

Abstract

Solutions of promazine hydrochloride and chlorpromazine hydrochloride have been flash photolysed with 25 ns pulses of 347.1 nm light from a frequency-doubled ruby laser. In addition to the excited triplet states of these molecules, the cation radicals and the solvated electron were observed. The ionisation of promazine and chlorpromazine was found to occur by a monophotonic process; a possible mechanism for this process is considered. The quantum yield for photoionisation of chlorpromazine in aqueous solution was determined to be (1.0 ± 0.2)× 10–1 and the extinction coefficient of the chlorpromazine cation radical was determined to be 9.3 × 102 m2 mol–1.