Abstract
AbstractDensity functional theory (DFT) calculations have been used to explore electron attachment to the purines adenine and guanine and their hydrogen atom loss. Calculations show that the dehydrogenation at the N9 site in the adenine and guanine transient anions is the lowest‐cost channel of hydrogen loss, and the N9H bond scission has Gibbs free energies of dissociation ΔG° of 8.8 kcal mol−1 for the anionic adenine and 13.9 kcal mol−1 for the anionic guanine. The relatively high feasibility of low‐energy electron (LEE)‐induced N9H bond cleavage in the purine nucleobases arises from high electron affinities of their H‐deleted counterparts. Unlike adenine, other NH bond dissociations are competitive with the N9H bond fission in the anionic guanine. The replacement of hydrogen in the ring of purine has a significant effect on the N9H bond fragmentation. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
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