Studies on some biologically active Metal(II) chelates: Spectral, thermal, biological and molecular modelling approaches

Abstract

A new quinoxaline based Schiff base ligand, 3-((2-methoxyphenylimino)methyl)quinoxalin-2(1H)-one (MMQ), was synthesised via the simple condensation reaction between 3-hydroxyquinoxaline-2-carboxaldehyde and o-anisidine in a 1:1 molar ratio. The newly prepared ligand was characterised by the help of analytical and spectral techniques. Using MMQ, the coordination behaviour of a series of transition metal(II) ions was studied. The coordination pattern, nature, and geometries of the new coordination compounds had been inferred from elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV–Vis., 1H & 13C NMR, ESR spectroscopy and mass spectrometry results. The ligand to metal ratio is found as 2:1. The thermal stability of MMQ and its coordination complexes were established by thermogravimetric analysis. The analytical and spectral data tell that MMQ is neutral and behaves as a bidentate ligand. It binds the metal(II) ions through the azomethine nitrogen atom and phenolic oxygen atom through deprotonation. The electrochemical actions of the new coordination compounds were confirmed by cyclic voltammetry. The newly prepared ligand and the metal chelates were extensively studied for their biological activities (DNA cleavage and anticancer activity). The compounds were also subjected to some theoretical studies viz. DFT, molecular docking, etc., to rationalise the obtained results.