Ab initio and DFT theory studies of interaction of thymine with formaldehyde

In this article, the interaction of formaldehyde (FA) with thymine is theoretically investigated by computational chemistry methods. The optimization geometries and vibrational frequencies of FA, thymine and three complexes between thymine and FA have been calculated by using the density functional theory and ab initio methods at the B3LYP/6-311G(d, p) and MP2/6-311G(d, p) levels. The NBO and AIM methods are used to analyse interaction as well. Conformers (A), (B) and (C) are cyclic structures with C-H***O and N-H***O hydrogen bonds on a common plane. The corrected complex interaction energies of cyclic structures (A), (B) and (C) at MP2/6-311G(d, p) levels are -38.41, -26.94 and -26.01 kJ/mol, respectively. The order of stability is (A) > (B) > (C).