Synthesis, characterization, and biological activity of nickel(II) complexes with a tridentate Schiff base derived from heterocyclic aldehyde

Abstract

A series of nickel(II) complexes, namely [Ni(L)₂] (1), [Ni(L)(HL)](ClO₄)(H₂O) (2), [Ni(HL)(bipy)(H₂O)](NO₃)(ClO₄)(H₂O) (3), and [Ni(HL)(dien)](ClO₄)₂(H₂O) (4) have been synthesized with Schiff base (L) derived from 2-pyridinecarboxaldehyde and benzoylhydrazine. The elemental analyses of the complexes indicate stoichiometry ML₂ and M(L)(B), where L = N-[(1)-pyridin-2-ylmethylidene]benzohydrazide, B = diethylenetriamine/2,2′-bipyridine. L is a deprotonated as well as neutral tridentate ligand. Single-crystal X-ray structures of 1–4 reveal distorted octahedral geometry in the complexes. The molecules are connected by various hydrogen-bonding interactions. Magnetic susceptibility measurements at room temperature were 2.79–2.91 MB. The electrochemical behavior, superoxide dismutase, and antibacterial activities of these complexes were made by cyclic voltammetry, the alkaline DMSO-nitro blue tetrazolium chloride assay, and the paper disc diffusion method, respectively.

Keywords:

• Hydrogen bonds
• Crystal engineering
• Cyclic voltammetry

Acknowledgments

Our grateful thanks are due to the National Diffraction Facility, X-ray Division, and RSIC (SAIF), IIT Mumbai for single-crystal data collection and EPR measurements, respectively. The Head RSIC (SAIF), Central Drug Research Institute, Lucknow is also gratefully acknowledged for providing analytical and spectral facilities. Financial assistance from UGC [Scheme no. 36–28/2008 (SR)] and CSIR [Scheme no. 01(2451)/11/EMR-II] New Delhi are also gratefully acknowledged.