Synthesis, characterization, crystal structure, superoxide dismutase and biological activities of nickel (II) complexes with bidentate ligands possessing N and O donor atoms

Two new Schiff bases 2-((E)-(4-bromo-2-chlorophenylimino)methyl)-4-bromophenol(HL1) and1-((E)-(4-bromo-2-chlorophenylimino)methyl)naphthalene-2-ol (HL2) and their new nickel (II) complexes [Ni(L-1)2]center dot DMF(1) and [Ni(L-2)(2)] (2) have been synthesized and characterized by various physico-chemical and spectroscopic methods. The solid-state structures of synthesized compounds were determined by single crystal X-ray crystallography, which revealed square planar geometry around Ni (II) ion. Infrared spectra, UV-Vis, thermal analysis and magnetic susceptibility measurements agreed with the observed crystal structures. The ligand (HL1) crystallized in the Orthorhombic system of the space group Pbca,a = 7.5485(4)angstrom, b = 11.5514(5) angstrom, c = 30.1370(14)angstrom, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees and Z = 8 degrees. Complex [Ni(L-1)(2)]center dot DMF(1) crystallized in the Triclinic system of the space group P-1, a = 8.9954(3) angstrom, b = 9.4593(4) angstrom, c = 13.2657(5) angstrom, alpha = 101.478 degrees, beta = 99.595 degrees, gamma = 117.651 degrees and Z = 2, whereas complex [Ni(L-2)(2)]center dot(2) crystallized in the Monoclinic system of the space group P2(1)/c, a = 9.301(9)angstrom, b = 12.149(8) angstrom, c =13.792(10)angstrom, alpha = 90 degrees, beta = 106.35(4)degrees, gamma = 90 degrees and Z = 2. The Schiff bases (HL(1)and HL2) behaved as monobasic bidentate ligands possessing N and O donor atoms. The SOD activities of HL1 and its Ni (II) complex[Ni(L-1)(2)]center dot DMF(1) have been measured using xanthine-xanthine oxidase as a source of super-oxide radical and NBT assay as O-2(-) scavenger. In vitro antimicrobial activities of the Ni(II) complexes (1) and (2)against Bacillus cereus and Staphylococcus aureus as Gram + ve and Salmonella typhi, ICIebsiella pneumonia and Escherichia coli as Gram-ve species have been investigated comparing with the Schiff base ligands (HL1 and HL2). (C) 2017 Elsevier B.V. All rights reserved.