Synthesis and X-Ray Crystal Structures of Trinuclear Nickel(II) Complexes Derived from Schiff Bases and Acetate Ligands with Biological Activity

Jin-Long Hou,Wei Chen,Cheng-Bin Sun,Hong-Yuan Wu,Ye Bi

doi:10.17344/acsi.2020.5824

Abstract

The reactions of Ni(OAc)2 2H2O with Schiff base ligands 5-bromo-2-((cyclopentylimino)methyl)phenol (HL1) and 5-bromo-2-(((2-(isopropylamino)ethyl)imino)methyl)phenol (HL2) in methanol afforded two discrete trinuclear com-plexes [Ni3(L1)2(?2-?1:?1-OAc)2(DMF)2(BrSal)2] (1) and [Ni3(L2)2(?2-?1:?1-OAc)2(?2-?2:?1-OAc)2] (2), where BrSal is the monoanionic form of 4-bromosalicylaldehyde. The complexes were characterized by elemental analysis, IR and UV-Vis spectroscopy. The crystal structures of the complexes have been determined by X-ray crystallography. In both com-plexes, the nickel atoms are in octahedral coordination geometries. The L1 ligand coordinates to the nickel atoms through the phenolate O and imino N atoms, and the L2 ligand coordinates to the nickel atoms through the phenolate O, imino N and amino N atoms. The antimicrobial activities of the complexes were assayed.

Highlights

Studies on supramolecular interaction and the self-assembly resulting from them have attracted remarkable attention in recent years
Both complexes were readily prepared by reacting nickel acetate tetrahydrate with Schiff base ligands
The complexes are soluble in common organic solvents like dimethyl sulphoxide, dimethylformamide, methanol, and ethanol

Summary

Introduction

Studies on supramolecular interaction and the self-assembly resulting from them have attracted remarkable attention in recent years Schiff bases and their metal complexes exhibit biological activity as antibiotics, antiviral, antibacterial and antitumour agents because of their specific structures.[1] Among Schiff bases, those derived from the mono-condensation of organic amines with carbonyl compounds, are a group of classical NO or NNO donor ligands.[2] These ligands react readily with nickel salts to occupy its equatorial coordination sites whereas several anionic or neutral ligands can be coordinated to the fourth coordination site of the square plane to yield different type of complexes.[3] Among the co-ligands, acetate has received remarkable attention because it can coordinate to the metal centers through versatile modes, such as monodentate, chelating, bidentate bridging, monoatomic bridging, chelating bridging, etc (Scheme 1).[4] To combine Schiff bases and acetate ligands together in the complexes, a number of nickel complexes have been prepared.

Experimental Section

Results and Discussion

Conclusion