New Ni(II) and Cu(II) Schiff base coordination complexes derived from 5-Bromo-salicylaldehyde and 3-picoyl amine/ethylenediamine: Synthesis, structure, Hirshfeld surface and molecular docking study with SARS-CoV-2 7EFP-main protease

Abstract

Two co-ordination compounds, one nickel(II) complex [Ni(L1)(Phen)2]ClO4(1) and one copper(II) complex [Cu(L2)] (2), were synthesized using Schiff base ligands derived from the condensation reaction of 5-Bromo-salicylaldehyde with 3-picoyl amine (L1H)(L1H = (E)-4-Bromo-2-(((pyridin-3-ylmethylene)amino) methyl) phenol) and ethylenediamine (L2H2), respectively(L2H2 = 2,2′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene))bis(methanelylidene))bis (4-bromophenol)). The newly synthesized complexes were fully characterized, including X-ray crystallography. The crystal structure of both the complexes was determined using Single Crystal structure analysis. The electrochemical properties of (1) were studied using cyclic voltammetry. DFT calculations were done for the newly synthesized co-ordination complexes to have a relevant and reasonably accurate calculation of their molecular and electronic behavior. The Hirshfeld surface (HS) analysis was also performed using the crystallographic data for investigating the nature and quantitative contribution of all possible non-covalent intermolecular interactions within the crystal lattice. To explore potential SARS-CoV-2 drug candidates, both the co-ordination compounds were subjected to molecular docking calculations with the SARS-CoV-2 virus (PDB ID: 7EFP). The molecular docking calculations of Ni(II) complex (1) into the 7EFP-main protease of SARS-CoV-2 virus revealed the binding energy of −11.5 kcal/mol, while Cu(II) complex (2) exhibited the binding energy of −8.5 kcal/mol at the inhibition binding site of the receptor protein.