Photoinduced electron transfer from chloropromazine and promethazine to chloroalkanes accompanied by cleavage of C–Cl bond

Electron transfer from two phenothiazine derivatives namely promethazine and chloropromazine to chloroalkanes namely carbontetrachloride and chloroform has been studied by steady state fluorescence and transient absorption techniques. These phenothiazine derivatives also form weak charge transfer complexes with the above two chloroalkanes. Picosecond transient absorption studies provide direct evidence for two processes: (1) charge separation in the charge transfer complex and (2) electron transfer from the excited state of phenothiazines to chloroalkanes. A modified Marcus electron transfer theory proposed by Saveant [J. Am. Chem. Soc. 109 (1987) 6788], which incorporates the bond cleavage, has been used to explain the observed experimental results.