Synthesis, structural, molecular docking and spectroscopic studies of (E)-N'-(4-methoxybenzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide

Abstract (E)-N'-4-methoxybenzylidene-5-methyl-1H-pyrazole-3-carbohydrazide (E-MBPC) has been synthesized and characterized by FT-IR, 1H & 13C NMR and ESI-MS spectroscopic methods. The (E)-configuration of hydrazonoic group was confirmed by single-crystal X-ray diffraction. Theoretical structures of E-MBPC in both gas phase and aqueous solution have been optimized by using hybrid B3LYP/6-311++G** calculations. Calculations in solution have shown that dipole moment increases from 7.97 D in the gas phase to 13.68 D in solution with solvation energy of -131.34 kJ/mol. Atomic charges have evidenced that the protonation of E-MBPC in solution could occur only in the N28 atom because those charges on this atom show negative values. Mapped MEP surfaces show that the nucleophilic sites is located on the O21 and N28 atoms including the N16 atom while the electrophilic sites are observed on the N24-H27 and N18-H19 bonds. NBO calculations support the high stability of E-MBPC in solution while frontier orbitals studies suggest low reactivity of E-MBPC in both media, as compared with the (E)-N'-(4-(dimethylamino)benzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide derivative. The vibrational assignments of 93 vibration modes expected for E-MBPC were reported together with the corresponding force fields and force constants in both media. The predicted Raman and Ultraviolet-visible spectra were also reported for E-MBPC at the same level of theory. Good correlations were obtained between the predicted 1H- and 13C-NMR spectra and the corresponding experimental ones. In addition, molecular docking studies between the title ligand and 4AMJ protein were performed. Docking results revealed that the title compound can be designed as a potential anti-diabetic agent.