Vibrational, NMR and UV–visible spectroscopic investigation and NLO studies on benzaldehyde thiosemicarbazone using computational calculations

In order to investigate the vibrational, electronic and NLO characteristics of the compound; benzaldehyde thiosemicarbazone (BTSC), the XRD, FT-IR, FT-Raman, NMR and UV–visible spectra were recorded and were analysed with the calculated spectra by using HF and B3LYP methods with 6-311++G(d,p) basis set. The XRD results revealed that the stabilized molecular systems were confined in orthorhombic unit cell system. The cause for the change of chemical and physical properties behind the compound has been discussed makes use of Mulliken charge levels and NBO in detail. The shift of molecular vibrational pattern by the fusing of ligand; thiosemicarbazone group with benzaldehyde has been keenly observed. The occurrence of in phase and out of phase molecular interaction over the frontier molecular orbitals was determined to evaluate the degeneracy of the electronic energy levels. The thermodynamical studies of the temperature region 100–1000K to detect the thermal stabilization of the crystal phase of the compound were investigated. The NLO properties were evaluated by the determination of the polarizability and hyperpolarizability of the compound in crystal phase. The physical stabilization of the geometry of the compound has been explained by geometry deformation analysis. Generally, the evaluation of UV/Vis spectrum is providing the information regarding the structure of organic molecules and whether the optical and NLO properties were enabled or not. The calculated energy gap of the molecule was found to be 3.87 eV and their excitation was also assigned to n→π* transition and belongs to ultraviolet region. This observation; from gas to solvent, the electronic transitions transferred from visible to ultraviolet region. This view indicated that, the compound under study was Visible and UV active and it was capable of having rich optoelectronic properties. In addition to that, the calculated optical band gap 2.103eV which also ensure that the present compound possessing good NLO properties. In this present compound, due to the presence thiosemicarbazone groups, the NLO mechanism of molecule was improved. [Display omitted] •The NLO impact found on the structure of Benzaldehyde–thiosemicarbazone.•The existence of electronic and NLO properties found.•The optical band gap of the compound was found to be 2.103eV.•The first and second order polarizabilities showed high degree of NLO activity.