Synthesis, characterization, ab initio quantum chemical calculations and molecular docking studies of Se bearing phenoxo-bridged bimetallic Ni(II) complexes

Abstract

In this paper, we report the reactivity of Ni(dppe)Cl2; dppe = bis(diphenylphosphino)ethane, with phenol based selenium bearing macroacyclic Schiff bases, 2,6-bis({N-[2-(phenylselenato)ethyl]} benzimidoyl)-4-methylphenol and 2,6-bis({N-[3-(phenylselenato)propyl]}benzimidoyl)-4-methylphenol. The reaction of Ni(dppe)Cl2 with these Se2N2O ligands in 1:1 M ratio yield [{(PhC = NCH2CH2SePh)(C6H2(O)(4-CH3)(PhCO)}2Ni2Cl2], 1 and [{(PhC = NCH2CH2CH2SePh) (C6H2(O)(4-CH3)(PhCO)}2Ni2Cl2], 2 as suggested by analytical and spectroscopic data of respective complexes and supported by single crystal X-ray crystallography of phenylseleno(ethyl)amine hydrochloride. In both of these bimetallic complexes, one arm of the ligand undergoes hydrolysis at the CN bond and the 1,2-bis(diphenylphosphenoethane) moiety of 1,2-bis(diphenylphosphino)ethanenickel(II) chloride is displaced by stronger chelating donors; nitrogen and oxygen of the ligands. Two molecules of the partially hydrolyzed ligand coordinate to two Ni(II) through azomethine nitrogen, benzoyl oxygen and the phenolic oxygen. The phenolic oxygen bridges the two Ni(II) ions. Each nickel is bonded to one chloride. Nickel adopts square pyramidal coordination geometry with trans-NiNO3Cl core as evaluated by spectroscopic data and ab initio quantum chemical calculations at Hartree-Fock level. The cyclic voltammograms of complex 1 and 2 show metal centered two electron quasi-reversible redox processes. Molecular docking study of the ligands L1H and L2H and complexes 1 and 2 with DNA revealed non-covalent interaction and bind at active sites of B-DNA. The minimum calculated binding energy is −6.44 kcal/mol in complex 2.