New bis hydrazone: Synthesis, X-ray crystal structure, DFT computations, conformational study and in silico study of the inhibition activity of SARS-CoV-2

The aim of this work was to synthesize new bis hydrazone derived from benzil in good yield, namely: (1Z,2Z)-1,2-bis (3-Chlorophenyl Hydrazino) Benzil, encoded by 3-Cl BHB. The benzil (or 1,2-diphenyl ethanedione) reacts with 3-Cl phenyl hydrazine by reflux method using ethanol as solvent to obtain the target compound. The obtained product is depicted by UV–Vis, IR spectroscopy and XRD-crystals analysis. All various contacts intra and intermolecular found in 3-Cl BHB were determined by the X-ray diffraction technique performed on single crystals. On the other hand, the optimized geometric structure of 3-Cl BHB was computed by the DFT/B3LYP method with 6–31 G (d, p) level. So, the bond lengths and angles, frontier molecular orbitals (FMO), surface electrostatic potential of the molecule (MEP), global reactivity descriptors, Mulliken atomic charges, computed vibrational analysis and electronic absorption spectrum were determined to get a good understanding of the electronic properties and the active sites of 3-Cl BHB, then to compare them with experimental data. Additionally, a conformational study was carried out using the same method (DFT). The structure-activity relationships established through molecular docking studies showed that 3-Cl BHB structure strongly binds to the receptors M(pro) (-8.90 Kcal/mol) and RdRp (-8.60 Kcal/mol) which confirm its inhibition activity against COVID-19.