A study on the laser flash photolysis of phenothiazine and its N-alkyl derivatives

Abstract

Photophysical and photochemical properties of phenothiazine and N-alkylphenothiazines (alkyl ≡ methyl, ethyl, isobutyl, phenyl, benzyl) in acetonitrile were studied by means of nanosecond laser flash photolysis. Transient absorption measurements showed that the excited triplet state, radical cation, neutral radical, dimeric radical cation and dimeric dication were formed during the photolysis. The kinetics of the formation and conversion of the transient species was investigated. The deprotonation of the phenothiazine radical cation (PTH-+ ) to give the neutral radical PT+ was prevented by the presence of tetracyanoethylene (TCNE). The mechanism of the interaction of phenothiazines and TCNE is discussed.