One-electron reduction of 2-aminopurine in the aqueous phase. A DFT and pulse radiolysis study

Abstract

The electron affinity and the subsequent proton affinity of the electron adducts of 2-aminopurine (abbreviated 2AP) and adenine (A) are calculated with density functional theory (DFT). According to these calculations 2AP˙⁻ and A˙⁻ have similar thermochemical parameters leading to the conclusion that their reaction pathways should be close to analogous. Using the pulse radiolysis technique 2AP˙⁻ is formed by reaction with the hydrated electron (e⁻_aq) and the resulting transient absorption spectrum is assigned to 2AP(NH)˙. Additionally, it was found, employing the laser flash photolysis technique, that the excited singlet state of 2AP is incapable of oxidizing guanine in the aqueous phase. However, the one-electron oxidized 2AP (2AP˙⁺) has sufficient energy to ionize guanine according to the DFT results in agreement with experimental data from the literature.