Synthesis, spectroscopic characterization, optical, second harmonic generation and DFT analysis of 4-isopropylbenzaldehyde derived hydrazone

Abstract In this work, a new hydrazone (E)-N'-(4-isopropylbenzylidene)-4-methoxybenzohydrazide (IBMB) was synthesized via condensation of 1:1 molar ratio of 4-isopropylbenzaldehyde and 4-methoxybenzohydrazide in ethanol. The molecular structure, composition and thermal property of IBMB were analyzed using FT-IR, NMR (1H and 13C), GC-MS, powder XRD, elemental analysis and TG/DTA techniques. The structure was elucidated by single crystal XRD analysis and the crystals belong to orthorhombic system with noncentrosymmetric space group P212121, resulting in highly translucent and nonlinear optical properties. The direct and indirect bandgap energies were evaluated by utilizing Kubelka–Munk algorithm. The efficiency of IBMB in terms of nonlinear optical (NLO) activity was verified and the hydrazone displayed higher NLO activity compared to that of reference materials, as determined by second harmonic generation and molecular hyperpolarizability measurements. Computational studies using density functional theory (DFT) at B3LYP/6-31G(d,p) level of theory were performed for elucidation of the structural parameters, Mulliken population analysis, frontier molecular orbital analysis, UV-Vis absorption spectra and NLO properties of IBMB. Consequently, a good concurrence between the experimental and the DFT results was achieved. Global reactivity parameters were determined using the frontier molecular orbital energies and revealed that IBMB was reasonably stable and more reactive. Mulliken population, Hirshfeld surfaces and fingerprint plot analyses confirmed the presence of inter and intramolecular interactions, contributing superior nonlinearity of crystals.