Abstract

Single crystals of (E)-N'-(2,4-trimethoxybenzylidene)benzohydrazide (TMBBH) have been grown by slow evaporation technique. The active functional groups present in the synthesized compound were identified by Fourier transform infrared (FT-IR) spectroscopy. UV-Visible spectral analysis was performed to study the optical properties of the organic crystal. In this study the band gap energy between HOMO and LUMO is computed by the B3LYP/6-311++G(d,p) theory method. The HOMO and LUMO energies are predicted as -5.4175 eV and -1.5888 eV. The energy gap between HOMO and LUMO is 3.828 eV. The HOMO-LUMO energy gap value supports the optical activity of the synthesized molecule. The natural bond orbital analysis (NBO) results state that the highest energy transfer of 111.9 kJ/mol occur between the donor π (C2-C7) to acceptor π*(C1-N8) shows the hyperconjugation within the –CONH‒ group. The first hyperpolarizability value 19 ×10⁻³⁰ esu of the synthesized compound is nineteen times greater than that of urea (0.3728 ×10^-30 esu). The third order NLO properties of the crystal were studied using nonlinear refractive index (n₂=1.15×10^-9 cm²/ W), absorption coefficient (β=6.12 ×10^-5 cm/ W), and third order nonlinear susceptibility (χ³=3.38 ×10^-6 esu) of the grown crystal were determined using Z-Scan technique.

Keywords: FT-IR, Uv-Vis, NBO, Z-Scan