Photogenerated aryl mesylate and aryl diethyl phosphate radical cations: a time-resolved spectroscopy investigation

The monoelectronic oxidation of aryl mesylates and aryl diethylphosphates in an organic/aqueous mixture in the presence of ammonium persulfate was investigated by means of time-resolved spectroscopy. The photoinduced electron transfer (ET) between the photogenerated SO4 center dot- radical anion and the examined substrates showed rate constants (k(ET)) in the order of 10(9)-10(10) M-1 s(-1) and the generated radical cations exhibit a broad absorption band (350-550 nm) with lifetime values in the 7-62 mu s range, depending on the nature of the aromatic substituents. A satisfactory correlation between log (k(ET)) and Delta G(ET)(0) demonstrates that the ET process follows the Marcus model.