Multi-target activity of copper complexes; antibacterial, DNA binding, and molecular docking with SARS-CoV-2 receptor.

A series of pendant-armed mixed-ligand copper(II) complexes of the type [CuL(diimine)] (1-6) have been synthesized by the reaction of pendant-armed ligands N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)benzamide (HL), N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-4-nitrobenzamide (HL) and N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-3,5-dinitrobenzamide (HL) with diimine = 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) in the presence of copper(II) chloride and analyzed using various spectroscopic methods. All the spectroscopic results support that the complexes adopt a pentagonal-bipyramidal shape around the metal ions. Gram-positive and Gram-negative bacteria were used to test all the complexes for antibacterial activity and all the complexes had greater potency against gram-negative pathogens. DNA-binding experiments of complexes with calf thymus DNA revealed a major-groove binding pattern, further supported by molecular docking studies. Complexes have significantly interacted with SARS-CoV-2 receptor via π-π, π-σ, π-alkyl, π-anion, π-cation, alkyl, hydrogen bond, van der Waals, and electrostatic interactions. The estimated binding energy and inhibition constant of these complexes are higher than standard drugs, chloroquine, and molnupiravir.