Growth, hyperpolarizability, characterization and theoretical studies of NLO active tris(allylthiourea)mercury(II) chloride

Abstract

Single crystals of tris(allylthiourea)mercury(II) chloride (TATMC) have been grown by slow evaporation solution growth technique. It belongs to the trigonal system with noncentrosymmetric space group R3c and the cell parameters are, a=b=11.4443(3)Å, c=28.1142(6)Å, V=3188.85(14)Å3, α=β=90°, γ=120° and Z=6. Powder X-ray diffraction pattern reveals the crystallinity of the as-grown specimen and it closely resembles the simulated one from the single crystal XRD data. Good reflectance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka–Munk algorithm. The functional groups are identified by Fourier transform infrared spectral analysis and compared with theoretical spectrum. The crystal is stable up to the melting point and the mechanistic behavior is ascertained by microhardness studies. The second harmonic generation efficiency of TATMC is estimated by Kurtz and Perry powder technique. The first-order molecular hyperpolarizabilities of some tris(allylthiourea) complexes have been evaluated using density functional theory (DFT) employing B3LYP functional, LanL2DZ as basis set and results rationalized. The optimized geometry closely resembles the ORTEP. The Hirshfeld surface analysis is carried out using HF method with 3-21G as basis set. Investigation of the intermolecular interactions and crystal packing via Hirshfeld surface analysis, derived by single crystal XRD data, reveals the close contacts associated with strong interactions.