Orbital Analysis of Natural Bonds, Calculations of the Functional Theory of Density Time-Dependent and Absorption Spectral of a Series of Rhodanine Derivatives

Abstract

In this work, the density functional theory (DFT) method at the B3LYP/6-31 + G (d, p) level has used to determine the optimization of five rhodanine derivatives. The stability of the derivatives (7a-7e) of 5-arylidene rhodanine, the hyperconjugative interactions, the delocalization of the atomic charges was analyzed with the analysis of the Natural Bond Orbital (NBO). The electronic structures were discussed and the relocation of electronic density was determined. Molecular Electrostatic Potential (MEP), local density functional descriptors, border molecular orbitals and absorption spectrum were studied. Through the local Fukui reactivity indices, the carbon of the carbonyl group (C = O) is the preferential site of the nucleophilic attack and the sulfur atom linked to the trigonal carbon (C = S) is the preferential site of electrophile attack. Analysis of the global descriptors revealed that compound 7c is the most reactive with an energy difference between the frontier orbitals of ΔEgap = 3.305 eV. Furthermore, this compound 7c is the less stable, the softest and has the greatest electronic exchange capacity of all studied compounds. The intramolecular electronic transitions which stabilize these compounds are LP → π * for 7a and 7d and σ → σ * for 7b, 7c and 7e. The rhodanine derivatives are more reactive and more soluble in polar solvents.