European Journal of Biomedical and Pharmaceutical Sciences

COMPUTATIONAL STUDIES OF STABILITY AND MOLECULAR DESCRIPTORS OF 2-PYRIDONE AND 2-PYRIDINETHIONE TAUTOMERS BY DENSITY FUNCTIONAL THEORY (DFT)

N. Surendra Babu*, Isaac Onoka and Vinod Kumar Tappa

ABSTRACT

Density functional theory (DFT) calculations were carried out to investigate the relative energies, thermodynamic properties, equilibrium constants and molecular descriptors of 2-pyridone and 2-pyridinethione tautomers in the gas phase. All possible tautomers are optimized with B3LYP/6- 311++G (d,p) basis set. It can be seen from the results that two are keto (P43HO & P34HO) and (P43HT & P34HT) tautomers have highest energy, with relative energy about 28-33 kcal mol-1. From the HOMO and LUMO orbital energies, in order to determine, the global reactivity descriptors namely, the chemical hardness (ɳ), chemical potential (μ), electrophilicity index (ω), softness (S), nucleofugality(ΔEn), and electrofugality(ΔEe), values for the prediction of the reactivity of the tautomers. From the electrophilicity index (ω) results, the tautomer P34HT is a good electrophile and P43HO is good nucleophile in gas phase.

Keywords: Molecular descriptors, 2-pyridone and 2-pyridinethione tautomers, HOMO-LUMO energies and DFT calculations.