Experimental and Computational Studies of Bis(thiourea) Lead Chloride: Semi-organic Material for NLO Applications

Abstract

Non liner optical single crystals of bis(thiourea) lead chloride (BTLC), belonging to the semi-organic material category, have been prepared by a slow solvent evaporation process. The single crystal X-ray diffraction analysis indicated the orthorhombic crystal structure and non-centrosymmetric Pna21 space group of the BTLC crystal. The crystalline nature of BTLC has been verified by means of the high resolution XRD (HRXRD) method. With the aid of elemental analysis, the purity and the stoichiometry of the crystal have been validated. Etching studies have been performed on BTLC using water etchant. The nature of electronic transitions, significant optical constant values and single oscillator parameters have been identified through ultra violet transmittance studies. The laser damage threshold (LDT) value of BTLC has been determined from LDT analysis. Theoretical calculations have been performed using the density functional theory (DFT) and the values of polarizability, hyperpolarizability and dipole moment of BTLC have been elucidated. Natural bond analysis (NBO) has also been done in order to gain knowledge on the nature of donor-acceptor interactions and charge distributions existing in the BTLC crystal. The frontier orbital HOMO-LUMO gap analysis assisted in arriving at the values of important global chemical molecular reactivity descriptors.