Structural insights into some sterically demanding heterocyclic β-diketones: Optimized molecular structure, optimized energy, stability and Mulliken charge distribution based on DFT analysis

Abstract

Density functional theory is a quantum chemical theory based computational tool for theoretical analysis of molecular structures and electronic properties of organic compounds and new materials. The present synergistic investigation between experimental spectroscopic data and theoretical data is focused to gain structural insights and to study the optimized molecular structures, optimized energies, stabilities and Mulliken charge distribution based on DFT analysis of some sterically demanding heterocyclic β-diketones. The B3LYP functionals with 6-31G* basis set was used for calculations in gas phase as well as in polar and nonpolar solvents. The experimental spectroscopic data (1H and 13C NMR) of sterically demanding heterocyclic β-diketones were compared with the corresponding theoretical data (in gas phase and polar solvent). There was a synergy between experimental spectroscopic data and theoretical data of these organic compounds. The atomic charges at all the atoms were calculated to ascertain the electrophilic and nucleophilic centres in these compounds. Global reactivity descriptors have also been calculated from the energies of frontier molecular orbitals (HOMO-LUMO energy values). The presence of various groups such as -CH3, -CH2CH3, - C6H5 and p-ClC6H4- in these compounds provided an opportunity to examine the steric and electronic effects of these groups on the stability, optimized energy, Mulliken charge distribution and spectroscopic properties of these sterically demanding heterocyclic β-diketones.