Spectral, structural, and superoxide dismutase activity of some octahedral nickel(II) complexes with tri-tetradentate ligands

Abstract

Three nickel(II) complexes, [Ni(L¹)₂] ⋅ 3H₂O (1), [Ni(L²)₂](ClO₄)₂ (2), and [Ni(L³)(bipy)](ClO₄)₂ (3), where L¹ = N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide, L² = 2,6-bis[N,N′-(4-methoxyphenyl)ethanimidoyl]pyridine, and L³ = N-(methoxy-phenyl-pyridin-2-yl-methyl)-N-(phenyl-pyridin-2-yl-methylene)-ethane-1,2-diamine, have been synthesized and characterized by physico-chemical and spectroscopic methods. The solid-state structures of 1–3 were determined by single crystal X-ray crystallography, which revealed distorted octahedral geometry. In solid-state structure, 3 is self-assembled via intermolecular π ··· π stacking and intramolecular CH(methyl) ··· π(phenyl) non-covalent interactions. Infrared spectra, ligand-field spectra, and magnetic susceptibility measurements agree with the observed crystal structures. These complexes have also been revealed to catalyze effectively the dismutation of superoxide () in alkaline dimethyl superoxide-nitro blue tetrazolium assay.

Keywords:

• Nickel(II) complexes
• Single crystal X-ray analysis
• Electrochemistry
• Magnetic susceptibility

Acknowledgments

Our grateful thanks are due to the National Diffraction Facility, X-ray Division, IIT Mumbai and IACT-CSIC Armilla (Granada) Spain for single crystal data collection. The Head RSIC, Central Drug Research Institute, Lucknow is also thankfully acknowledged for providing analytical and spectral facilities. Financial assistance from CSIR [Scheme No. 01(2094)\07\EMR-II] and UGC [Scheme No. 36-28/2008 (SR)] New Delhi are also thankfully acknowledged.