11Synthesis, crystal structures, electrochemistry and biological evaluation of tris(quinolin-8-olato) Mn(III) and Co(III) complexes methanol solvate

Abstract

Mn(III) and Co(III) complexes of 8-hydroxyquinoline (8-HQ) formulated as [Mn(8-HQ)3]·CH3OH (1) and [Co(8-HQ)3]·CH3OH (2) have been synthesized and characterized by spectroscopic techniques and single crystal X-ray crystallography. The molecular structures of the compounds revealed distorted octahedral geometry in which the metal ions coordinate three quinolin-8-olato. Cyclic and square wave voltammograms of 1 reveals two one-electron processes assignable to the redox couple Mn(III)/Mn(IV) and Mn(IV)/Mn(V). The compounds [Mn(8-HQ)3]·CH3OH (1) and [Co(8-HQ)3]·CH3OH (2) exhibited better activity than the standard against DPPH (260.18, 77.04 μg/mL respectively) and hydroxyl radicals (445.42, 484.78 μg/mL respectively) going by half-maximal inhibitory concentrations, however, [Mn(8-HQ)3]·CH3OH (1) further exhibited excellent ABTS radical scavenging and metal chelating effects than the control. Both compounds showed effective activities against alpha-amylase and alpha-glucosidase enzymes than acarbose (standard). The results showed that the compounds possess good antioxidant and antihyperglycaemic potentials.