title: Excited-state relaxation paths of oxo/hydroxy and N9H/N7H tautomers of guanine: a CC2 theoretical study.
abstract: We performed a theoretical investigation, at the CC2/aug-cc-pVDZ level, of the ring-deformation mechanisms of four guanine tautomers (oxo, hydroxy, N9H, and N7H). The study showed that the optimized conical intersections S₀/S₁ are accessible through the (1)ππ* excited states of tautomers. The optimized conical intersections S0/S1, which show deformation at the pyrimidine ring, have high energies. This means that the relaxations of the (1)ππ* excited states via internal conversion are disfavored. For two tautomers we found crossing points (1)ππ*/(1)πσ* of the excited-state reaction paths, revealing the possibility of a population of the (1)πσ* excited state by the (1)ππ* excited state.
authors: Department of Physical Chemistry, University of Plovdiv, Tzar Assen 24 Str., 4000 Plovdiv, Bulgaria. vdelchev@uni-plovdiv.net
authors: Vassil B
authors: VB
authors: Delchev
mesh_terms: D000465:Algorithms; D006147:Guanine / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D013816:Thermodynamics
chemical_list: D006147:Guanine
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