Homo pair formations of thiobarbituric acid: DFT calculations and QTAIM analysis

Abstract

Homo pair formations of thiobarbituric acid (TBA) were investigated in this work by performing density functional theory (DFT) calculations and the quantum theory of atoms in molecule (QTAIM) analysis. Different types of interactions including N–H . . . O, N–H . . . S, C–H . . . O, and C–H . . . S were involved in formations of five models of homo pair of TBA. In this regard, the results of energy strength and QTAIM features indicated that the model with two N–H . . . O interacting bond (D1) was placed at the highest stability and the model with one N–H . . . O and one C–H . . . S interacting bonds (D5) was placed at the lowest stability. Existence of hydrogen bond (HB) interactions in the models were confirmed based on the obtained results. As a consequence, self-interaction of TBA, as an initiator of pharmaceutical compounds production, was investigated in this work in addition to recognition of existence of different types of interactions.