Molecular structures and electronic properties of isonicotinic acid (3-methoxy-4-hydroxy-benzylidene)-hydrazide: Ab initio and DFT calculation

Abstract

The molecular structure and conformational analysis of isonicotinic acid (3-methoxy-4-hydroxy-benzylidene)- hydrazide were investigated by Ab initio and density functional theory DFT/B3LYP levels of theory with complete relaxation in the potential energy surface using varied basis set. The four stable conformers of the studied molecule (C1, C2, C3 and C4) were computed. The computational results diagnose the most stable conformer of (3-methoxy-4-hydroxy-benzylidene)-hydrazide as the C1 form. Molecular structure, dipole moment, polarizability and first static hyperpolarizability of the four stable conformers have been calculated by using 6-311++G (d, p) basis set for both models. Besides, EHOMO (the highest occupied molecular orbital energy), ELUMO (the lowest unoccupied molecular orbital energy) and HOMO-LUMO energy gap (ΔEg) are investigated. The dipole moment for C1, C2, C3 and C4 conformers are calculated at 2.44, 7.74, 7.75 and 6.58 with DFT/B3LYP level of the theory 6-311++G (d, p) basis set and at the HF/6-311++ G (d, p) 2.60, 7.42, 7.41 and 6.36 Debye, respectively. The structural parameters of the studied molecule compared with data in the literature.