Molecular structure, Hirshfeld surface and density functional theoretical analysis of a NLO active chalcone derivative single crystal—A quantum chemical approach

Abstract

Nonlinear optically active thienyl chalcone, with molecular formula C16H15ClO4S has been synthesized by adopting claisen-schimdt condensation reaction method. FT-IR and NMR spectral study was used to identify the functional groups present in the newly synthesized compound and confirm the molecular structure. Based on the solubility study DMF is chosen as solvent to grow single crystals of the compound using slow evaporation (solution growth) technique. The single crystal XRD study reveals that the grown crystal belongs to the orthorhombic crystal system with Pbca space group and the associated cell parameters are, a = 16.6575 (6) Å, b = 8.1147 (3) Å, c = 23.6618 (9) Å, α = β = γ = 90°. The linear optical properties were studied using UV-–visible, Photoluminescence method. The energy band gap of the material was calculated using tauc's plots. The refractive index (1.47) of the crystal was determined using Brewster's angle method. Second harmonic generation (SHG) test was carried out using Kurtz and Perry powder technique and SHG efficiency of 1.82 times that of urea was estimated. The thermal stability of the compound was tested by thermo gravimetric and differential thermal analysis. Various inter contacts present within the crystal were visualized through 3-D molecular hirshfeld surface analysis and their percentage contribution towards the total hirshfeld surface area has been quantized using 2D finger print plot method. The theoretical investigation was carried out using DFT method and HOMO-LUMO energy band gap was determined. The different global chemical reactivity descriptors (GCRDs) parameters were calculated. The molecular electrostatic potential map of the molecule was analyzed and the sites of electrophilic and nucleophilic attacks were predicted. The molecular NLO properties such as static dipole moment, mean polarizability, anisotropy of polarizability and first order hyper polarizability values were theoretically determined.