Investigation of hydrogen bonding in small nucleobases using DFT, AIM, NCI and NBO technique

In this work hydrogen bonded base pairing properties of two adenine analogue nucleobases and thymine were investigated. wB97XD/6-311++G(2d,2p) level of theory was employed to optimize the monomers and the base pairs in different orientations. Atoms In Molecule, AIM analysis was carried out to analyse the individual hydrogen bonds in the studied complexes. NH...N and OH...N were found to be major contributors to the overall interaction energy than O...HC and N...HC bonds. Non Covalent Interaction, NCI and Reduced Density Gradient, RDG plots revealed that interactions are mainly weak and intermediate in nature. Finally Natural Bond Orbital, NBO calculations were performed to calculate the second order perturbation energy E(2) which helped to understand the interaction between electron donor and acceptors in the individual complexes.

Automated summary

This study investigated the hydrogen bonded base pairing properties of two adenine analogue nucleobases and thymine. The monomers and base pairs were optimized using the wB97XD/6-311++G(2d,2p) level of theory. Analysis of the individual hydrogen bonds in the studied complexes was carried out using Atoms In Molecule (AIM) analysis. The results showed that NH...N and OH...N bonds were major contributors to the overall interaction energy.