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Physico-Chemical Characterization, Opto Electronic Investigation and Vibrational Analysis on Coordinate Covalent Complex; Bis (Thiourea) Nickel Bromide (BTNB) Using Experimental and Computational Tools

Anand S, Sundararajan RS, Ramachandraraja C, Ramalingam S and Durga R

In this work, a thorough spectroscopic investigation is made on the molecule; Bis (thiourea) Nickel Bromide (BTNB) by recording FT-IR, FT-Raman and UV Visible spectra. The computational calculations were carried out by HF and DFT methods with 6-31++G(d, p) and 6-311++G(d, p) basis sets and the optimized geometrical parameters, vibrational fundamentals, natural bond orbitals, Frontier molecular orbital energies and NMR chemical shift have been calculated and presented in the table. The cause of change of physical and chemical properties by coordination covalent bond between metal and organic atoms has been discussed in detail. Hence, the Non Linear Optical properties of the present molecule have been studied by calculating average Polarizability and diagonal hyperpolarizability. The enhancements of physical and chemical properties of the coordination complex due to the Vander Waals bond have been interpreted. The thermodynamical parameters were calculated and these values are obtained from NIST thermodynamical program. The variation of specific heat capacity, entropy and enthalpy with respect to different temperature are displayed in the graph and are discussed. A new semiorganic nonlinear optical crystal of Bis (thiourea) Nickel Bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectrum is recorded to determine symmetries of molecular vibrations. The recording of Optical absorbance spectrum revealed that this crystal has good transparency in the visible region. The nonlinear nature of the present crystal has been confirmed by the SHG test. The BTNB crystal was analyzed by a differential thermal analysis and thermo gravimetric analysis (DTA-TGA) to obtain its thermal stability. Vickers micro-hardness test has done on the crystal and this shows that the crystal has greater physical strength.