Syntheses, characterizations, crystal structures, antibacterial and SOD-like activities of nickel(II) and copper(II) complexes with 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol

<p>Three mononuclear nickel(II) and copper(II) complexes, [Ni(L)<sub>2</sub>(py)<sub>2</sub>] (<b>1</b>), [Ni(L)<sub>2</sub>(DMF)(H<sub>2</sub>O)] (<b>2</b>), and [Cu(L)<sub>2</sub>] (<b>3</b>), where HL = 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol, py = pyridine and DMF = N,N-dimethylformamide, have been synthesized and their structures determined by single crystal X-ray analysis. Complexes <b>1–3</b> crystallized in the monoclinic system of the space groups C2/c, P2<sub><i>1/n</i></sub>, and <i>P</i>2<sub><i>1/c</i></sub>, respectively. The crystal structures of <b>1</b> and <b>2</b> present an octahedral geometry at the metal center and <b>3</b> shows a square-planar geometry. The FT-IR spectra, UV–vis spectra, and magnetic susceptibility measurements agree with the observed crystal structures. EPR spectra indicate a d<sub>x2–y2</sub> ground state (g<sub>||</sub> > g<sub>⊥</sub> > 2.0023 and A<sub>||</sub> > A<sub>⊥</sub>) for <b>3</b> at RT and LNT. The results of simultaneous TG-DTA analyses of <b>1</b> and <b>3</b> showed the final degradation products are NiO for <b>1</b> and CuO for <b>3</b>. The Schiff base (HL) behaves as monobasic bidentate ligand possessing N and O donor atoms. Electrochemical properties for the complexes are similar and involve two irreversible redox processes. Complex <b>3</b> exhibits the ability to inhibit jack bean urease, although its Schiff base has no ability to inhibit urease. Complex <b>1</b> exhibits more active scavenging effects against O<sub>2</sub><sup>−</sup> than HL, <b>2</b> and <b>3</b> under the same conditions. Antibacterial screening activities of these complexes were also investigated.</p>