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

Abstract

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˙⁻ radical anion and the examined substrates showed rate constants (k_ET) in the order of 10⁹–10¹⁰ M⁻¹ s⁻¹ and the generated radical cations exhibit a broad absorption band (350–550 nm) with lifetime values in the 7–62 μs range, depending on the nature of the aromatic substituents. A satisfactory correlation between log (k_ET) and ΔG⁰_ET demonstrates that the ET process follows the Marcus model.