Synthesis and Structural Characterization of Pyridine-based Mn(III), Fe(III), and Co(III) Complexes as SOD Mimics and BSA Binding Studies

Interaction of 2-picolylamine (2-PA) with Mn(II), Fe(III) and Co(II) chlorides in an ethanolic solution yields two types of metal chelates. The analytical data, thermal analysis (TGA and DTG), molar conductance, electrochemical, magnetic studies and spectral (IR, UV-Vis, NMR and ESR) results supported the binuclear bridging mu-peroxo formulation of the brown (Mn-III) and yellow (Co-III) products such as [(ML2Cl)(2)(O-2)]Cl-2. Hexacoordinated distorted octahedral structure is proven for the mononuclear iron(III) complex [FeL2Cl2]Cl. PXRD data along with Expo 2014's structural solution software were used for structure determination of the current metal chelates. The structural analysis results reveal that the bis-coordination system of the two bidentate N-2 donor ligands in a trans-fashion provides a square planer set of nitrogens and access for axial donors above and below the equatorial plane in the octahedron stereochemistry. Ligand substitution studies were conducted in order to correlate the lability character and the catalytic activities of the present metal chelates as SOD-mimics. The SOD mimetic catalytic activity was evaluated by both IC50 and the rate constant k(c) for the catalytic dismutation of O-2(-) . Electrochemical data were used to determine the driving force (Delta G degrees) for the catalytic disproportionation reactions of O-2(-) . Thermodynamics, kinetic and catalytic considerations of the catalytic scavenging reactions of O-2(-) were discussed. Absorption and fluorescence spectroscopy techniques were used in addition to fluorescence lifetime measurements to study the interaction between [FeL2Cl2]Cl and bovine serum albumin (BSA). The apparent binding constant, number of the binding sites and the fluorescence quenching mechanism were determined. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The interaction of 2-picolylamine with Mn(II), Fe(III) and Co(II) chlorides in an ethanolic solution forms two types of metal chelates. Structural analysis reveals the molecular structure of these metal chelates, and ligand substitution studies suggest their catalytic activity as SOD mimics. The ability of these metal chelates to scavenge superoxide anions was confirmed through kinetic studies and thermodynamic considerations.