Structural analysis and physico-chemical characterization of mononuclear manganese(II) and polynuclear copper(II) complexes with pyridine-based alcohol

Abstract

Two novel manganese(II) and copper(II) complexes, mononuclear [Mn(H2O)2(2-(CH2)2OHpy)2](NO3)2 (1) and polynuclear [Cu(SO4)(2-(CH2)2OHpy)2]n (2), based on 2-(hydroxyethyl)pyridine (2-(CH2)2OHpy) were synthesised and fully characterised using X-ray structure analysis as well as spectroscopic, magnetic and thermal methods. Both central metal ions Mn(1) and Cu(1) are coordinated by two N,O-donor 2-(CH2)2OHpy ligands and possess an almost perfect octahedral geometry (a chromophore of {MN2O4} type). The coordination sphere of Mn(II) is completed by two molecules of water, whereas, in polynuclear complex 2, Cu(II) atoms are linked along the a crystallographic direction by bridging sulfate ligands in a μ2-κ2 binding mode to form chains. The intermolecular interactions in 1 and 2 have been interpreted in view of the 3D Hirshfeld surface analysis and associated 2D fingerprint plots. Furthermore, the complexes have been tested with ABTS+ assay in order to assess their antioxidant activity. In addition, the IC50 values calculated for 1 and 2 revealed that the complexes show a higher antioxidant activity than corresponding ligand.