Synthesis, X-ray, spectroscopy, molecular docking and DFT calculations of (E)-N'-(2,4-dichlorobenzylidene)-5-phenyl-1H-pyrazole-3-carbohydrazide

Abstract (E)-N'-(2,4-dichlorobenzylidene)-5-phenyl-1H-pyrazole-3-carbohydrazide (E-DPPC) has been synthesized and characterized by FT-IR, 1H-NMR, ESI-MS, and single-crystal X-ray diffraction. The structures and properties of this new pyrazole-3-carbohydrazide derivative were studied in gas phase and aqueous solution by using Functional hybrid B3LYP/6-311++G** calculations in gas phase and in aqueous solution to study. Two stable structures (C1 and C2) with similar energies were found in the PES. C2 evidence a higher dipole moment and a volume contraction in solution attributed to the presence of donors and acceptors H bonds. Besides, the changes in orientation and direction of dipole moment vector in solution are attributed to the hydration of E-DPPC with water molecules. The repulsion existent between the negative MK, Mulliken and NPA charges on the N12 and O15 atoms explain the diminishing of N12-C14-O15 angle from 123.77 ° in gas phase to 123.03 ° in solution. Nucleophilic sites are visibly observed on the acceptor H bonds groups (N10, O15 and N22 atoms) while on the N18-H21, N12-H13, C11-H23, C2-H3, C17-H20 bonds characteristics electrophilic sites were found, being the N18-H21 bond the most labile donor of H bond with the lowest MEP and bond order values. NBO calculations suggest that C2 is clearly most stable in solution than in gas phase. AIM studies show that C2 is stable in both media due to new H bonds formed. Harmonic force fields in both media were calculated together with the scaled force constants while the 102 vibration normal modes expected for C2 were completely assigned. The comparisons of experimental NMR and UV-visible spectra with the corresponding predicted evidence reasonable correlations. Docking results also displayed that E-DPPC possessed good binding profile against receptor molecule and interacted with core residues of target protein.