Crystal growth, structural, vibrational, spectroscopic studies of novelly synthesized NLO active melaminium sulfamate single crystal: Experimental and theoretical approach

Abstract

Semi-organic nonlinear optical (NLO) melaminium sulfamate (MASA) single crystals were synthesized by slow evaporation method and analyzed by using X-ray diffraction, UV–vis, FT-IR and FT-Raman experiments. Single crystal X-ray diffraction (SXRD) analysis confirms that MASA crystal belongs to triclinic system with centrosymmetric space group P-1. The quantum chemical calculation were carried out using density functional theory (DFT) with B3LYP/6-31+G(d) basis set. The intermolecular interactions were deeply analyzed by NBO analysis. The molecule with intermolecular N-H⋯N and N-H⋯O hydrogen bonds show notable vibrational effect. The optical property of MASA was evaluated by UV–vis optical transmittance spectrum. Thermal stability of the grown crystal was performed by using TG-DTA analysis. The frontier molecular orbital analysis illustrates the charge transferred from sulfamate anion to melaminium cation. Hirshfeld and 2D fingerprint plot reveals the intermolecular N-H⋯O and N-H⋯N contacts of MASA molecule. The existence of various functional groups and vibrational modes are affirmed by Fourier transform infrared (FT-IR) and FT-Raman spectral analysis. Additionally, the molecular electrostatic potential (MESP) and topological analysis such as electron localization function (ELF), reduced density gradient(RDG), localized orbital locator(LOL) and atoms in molecule(AIM) have been used to predict the intermolecular interaction, especially the hydrogen bonds. The hydrogen atom from sulphamic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The outcome of SXRD, UV–visible, TG/DTA, HOMO–LUMO, NLO and Z-Scan values were compared with earlier reported compounds and amongst the analyzed compound MASA shows good NLO activity. The NLO activity of MASA was analyzed theoretically and experimentally by DFT and Z-scan method.