Synthesis, growth and spectral studies of S-benzyl isothiouronium nitrate by density functional methods

Abstract

S-benzyl isothiouronium nitrate (SBTN), was synthesized and characterized by X-ray diffraction, FTIR, UV–Vis and NMR spectra. The Centro-symmetric single crystal of S-benzyl isothiouronium nitrate (SBTN), which crystallizes in monoclinic crystal system with space group P21/C, exhibits second order non-linear optical (NLO) susceptibility, due to intermolecular charge transfer. S-benzyl isothiouronium ion forms well defined charge transfer (CT) salt with anion nitrate through N–H⋯O and C–H⋯O hydrogen bonds. It is to identify the direction of specific N–H⋯O hydrogen bond between the –NH2 group and O− in the anion and also sacking in the solid state responsible for NLO activity in this crystal. The SHG technique confirms the non-linear optical property of the grown crystals. Density functional theory (DFT) calculation has been carried out to study the nature of hydrogen involved in the SBTN crystal. The bond lengths and bond angles of the structure of SBTN crystal calculated using B3LYP method with 6-311+(2d,2p) basis set. These calculations are compared with experimental values to provide deep insight into its electronic structure and property of grown crystal.