Synthesis, crystal growth, optical, thermal, electrical and theoretical investigation on 1,2,3-benzotriazole 2-chloro 4-nitrobenzoic acid (BCNB) single crystal for nonlinear optical (NLO) applications

The 1,2,3-benzotriazole 2-chloro-4-nitrobenzoic acid (BCNB) single crystal was successfully grown by the slow evaporation solution technique (SEST) and using methanol as the solvent for nonlinear optical applications. The crystal system and space group of the BCNB single crystal were identified by single crystal X-ray diffraction (SXRD) analysis. The BCNB crystal was subjected to powder X-ray diffraction (PXRD) to endorse the crystalline quality of the material. The UV-Visible-NIR study exposes the transparency and cut-off wavelength of the BCNB crystal. The chemical environment of carbon and hydrogen in the proposed structure of BCNB crystal was confirmed by FT-NMR studies. The vibrational assignments and their functional groups were identified from the FT-IR and FT-Raman analysis. The thermal properties like thermal stability point, melting point, and decomposing point were examined by Thermogravimetry/Differential thermal analysis (TG-DTA). The third order NLO behaviour of BCNB crystal was investigated by the Z-scan technique. The negative photoconductive nature of BCNB crystal was confirmed by photoconductivity analysis. The surface morphology of the grown crystal was examined by chemical etching analysis. The dielectric experiment (constant & loss) was performed on BCNB crystal as a function of frequency at room temperature to measure electrical properties of the material. Density functional theory (DFT) calculations have been investigated by DFT/B3LYP/6-311++G (d,p) method. To understand the intermolecular interaction of crystal packing, the BCNB material was investigated by Hirshfeld surface analysis and it was concluded that the molecular H-H interactions are of higher value compared to other interactions of the total molecules. The Gaussian 09 W programme was used for the DFT calculations such as molecule structure optimization, natural bond orbital analysis (NBO) and HOMO-LUMO analysis. The HOMO and LUMO energy values are estimated as -7.3239 eV and -2.8958 eV respectively.