Bis (thiourea) strontium chloride as promising NLO material: An experimental and theoretical study

摘要

Single crystals of pure bis (thiourea) strontium chloride (BTSC) have been grown from aqueous solution by slow evaporation method. The results from single crystal X-ray diffraction studies indicated the orthorhombic structure and Pna2 1 space group of the crystals. 77% transmittance measured by the Ultra violet transmittance studies and a band gap of 4.7?eV indicated the high optical transparency. From Kurtz and Perry powder method, the second Harmonic Generation (SHG) efficiency of the BTSC has been found to be 1.54 times as that of KDP and the phase matching nature of the crystal has been confirmed. Hyper polarizability studies showed that the synthesized BTSC crystal has higher polarisability and dipole values and hence can be used as potential NLO material. The frontier orbital HOMO-LUMO gap has been determined to understand the chemical reactivity and kinetic stability of the title crystal. The values of various global chemical molecular reactivity descriptors like chemical hardness (η) and electrophilicity index (ω) have been calculated. Natural bond orbital (NBO) analysis has been carried out to study the charge distribution and to understand various donor–acceptor interactions taking place in the BTSC crystal.