Density functional theory study of the interaction between formamide and uracil

Abstract

The hydrogen bonding of complexes formed between formamide and guanine molecules has been completely investigated in the present study using density functional theory (DFT) at 6-311++G(d, p) level. For comparison, HF and MP2 methods are also utilized in this paper. Nine stable cyclic structures stabilified by two hydrogen bonds are found. One of them is a six-membered ring, five of them are seven-membered rings and the others are eight-membered rings. The eight-membered ring is preferred to the seven-membered and six-membered ones as follows from the hydrogen bond lengths and interaction energies. Structure FG4 is calculated to be the most stable one, and another cyclic structure FG5 is the most unstable because of the six-membered ring and the weakest interaction. The infrared (IR) spectrum frequencies, IR intensities and vibrational frequency shifts are also reported.