Abstract
A series of biologically active complexes of cobalt(II), copper(II) and nickel(II) with nicotinoylhydrazine derived compounds having the same metal ion but different anions, such as sulphate, nitrate, oxalate and acetate, have been synthesised and characterised on the basis of their physical, analytical and spectral data. In order to understand the possible role of anions on the antibacterial properties, these synthesised compounds and their metal complexes with various anions have been screened against the bacterial species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. These title studies have indicated a decisive role of anions in increasing the antibacterial properties.