Characterization of the transient species in the 266-nm laser photolysis of adenine and its derivatives.

Abstract

Abstract. Transient absorption spectra produced by 266‐nm ns laser flash photolysis of aqueous solutions of adenine, 2′‐deoxyadenosine, 2′‐deoxyadenosine‐5′‐phosphate, adenosine‐5′‐phosphate, 2′‐deoxyadenylyl‐(3′‐5′)‐2‐deoxyadenosine, 7‐methyladenine and 9‐methyladenine have been measured under different pH conditions. The transients observed after excitation consisted mainly of the hydrated electron, the radical cation, the radical anion and/or neutral radicals resulting from its protonation, and a minor contribution from the excited triplet state. The photoionization occurs mainly through an excited singlet state. For adenine, the cation and anion radical absorption spectra were determined using laser and pulse radiolysis techniques. The triplet state presence was established through sensitization experiments. The hydrated electron decays following a pseudo‐first‐order reaction with the neutral base.