Exploration of key electronic and optical nonlinearity properties of synthesized salicylaldehyde based compounds via quantum chemical approach

Thiosemicarbazones are considered as emerging scaffolds for various research domains due to their diverse applications. Herein, novel thiosemicarbazone based compounds 1–5 were derived from the condensation reaction between salicylaldehyde and differently substituted thiosemicarbazides with an excellent yield. The structures of yielded chromophores have been confirmed by UV–Vis, vibrational (IR) and NMR spectral techniques. Besides this, DFT study was also accomplished to elucidate the electronic properties of 1–5 chromophores at M06/6-311G(d,p) level. Different kind of investigation: natural bond orbital (NBO), natural population analysis (NPA), frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) and global reactivity parameters (GRPs) were determined to explore the NLO assets of chromophores. The NBO analysis elucidated that the intramolecular interactions, electron delocalization and hyper conjugative interactions played a significant role in stabilizing the compounds. The NPA and MEP analyses were performed for predicting the charge distributions for the atoms and chemical reactivity regions of studied compounds. The GRPs were calculated utilizing FMOs energies and compound 1 was found as soft, less stable, more reactive molecule from other compounds The non-linear optical (NLO) findings exploited that 1–5 compounds showed 40.6, 34.2, 34.6, 35.4 and 29.1 times greater hyperpolarizability than the urea and can be utilized as efficient optoelectronic materials.