Molecular orbital, spectroscopic, first order hyperpolarizability and NBO analysis of aryl-substituted 5-(benzylidine) thiazolidine-2,4-diones

Abstract

In this study, the structure of three 5-(4-subs/3, 4- di substituted benzylidene) thiazolidine-2,4-diones has been studied by using density functional theory (DFT) at 6-31G(d,p) level basis set. Detailed interpretations of the vibrational spectra of these compounds have been made on the basis of the calculated potential energy distribution (PED). The ¹H and ¹³C NMR spectra have been recorded and the chemical shifts have been calculated using the gauge- independent atomic orbital method (GIAO). The values of frontier orbital energy gap (-3.64 eV) and dipole moment (4.7012 D) show that the compound 3b is less reactive and less polar, hence the most stable among the three molecules. The significantly higher value (131.96×10^-30 esu) of total hyperpolarizability for compound 3c indicates the better use of this molecule as NLO material. The calculated local reactivity descriptors for 3(a-c) indicate that C2 is the most reactive site for nucleophilic attack whereas the oxygen attached to this C is more prone to electrophilic attack. Hyperconjugative interactions have been studied with the help of natural bond orbital analysis. The electronic properties and thermodynamic properties have also been performed.