Crystal structures and antimicrobial activity of zinc(II) and nickel(II) complexes of 5-bromo-(((2-(phenylamino)ethyl)imino)methyl)phenol

Abstract

Four new zinc(II) complexes, [ZnL2] (1), [ZnL(μ 2-η 1:η 1-OAc)]n (2), [Zn2L2(μ1,1-N3)(μ1,3-N3)]n (3) and [ZnL(μ 2-1,5-dca)]n (4), and a new nickel(II) complex, [Ni2L2(MeOH)2(μ 1,1-N3)2] (5), where L is the deprotonated form of 5-bromo-(((2-(phenylamino)ethyl)imino)methyl)phenol (HL), OAc is acetate and dca is dicyanamide, were synthesized and characterized by elemental analyses, infrared and electronic spectroscopy, and single crystal X-ray determination. Complex 1 is a mononuclear zinc(II) compound, with the Zn(II) in tetrahedral coordination. Complexes 2, 3 and 4 are acetate, azide and dicyanamide bridged polymeric zinc(II) compounds, respectively, with the Zn(II) in distorted trigonal bipyramidal coordination. Complex 5 is an azide bridged dinuclear nickel(II) compound, with the Ni(II) ion having octahedral coordination. The compounds were evaluated for their antibacterial activities on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens and antifungal activities on Candida albicans and Aspergillus niger. Complexes 1 and 2 showed the most effective activity against B. subtilis and E. coli, with MIC values of 1.2–4.7 μM.