Density functional theory (DFT) calculations using numerical basis sets were employed to predict the solvation energies, Gibbs free energies and pKa values of a series of 5-substituted uracil derivatives. Obtained results show that solvation energies are not significantly different between DFT methods using the numerical (DNP) and Gaussian basis set (aug-cc-pVTZ). It is noteworthy that the independent and suitable solvation energy of proton of -258.6 kcal/mol has been proposed for the

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... of pKa values in conjunction with the numerical basis set. In addition, the calculated pKa values suggest that the anti-conformation of 5-formyluracil is the most stable form in the aqueous solution.