Uracil anion radical in aqueous solution: thermodynamics versus spectroscopy.

ESR experimental data combined with quantum mechanical calculations and first-principle molecular dynamics simulations have allowed the unequivocal identification and characterization of the canonical form of the uracil anion radical as the prevalent tautomer in aqueous solution, contrary to both gas-phase results and recently reported results in solution based on thermodynamic analyses. The present study confirms the effectiveness of spectroscopic/theoretical investigations of short lived molecular species in different environments.