SYNTHESIS, CHARACTERISATION AND ANTIMICROBIAL ACTIVITY OF MIXED-LIGAND NICKEL(II) AND COPPER(II) COMPLEXES OF SALICYLALDEHYDE WITH 2,2′-BIPYRIDINE, 1,10-PHENANTHROLINE AND ETHYLENEDIAMINE

Abstract

Nickel(II) and copper(II) mixed-ligand complexes of Salicylaldehyde with 2,2′-bipyridine, 1,10-phenanthroline and ethylenediamine were synthesised and characterised by molar conductance, spectroscopic measurement, room temperature magnetic measurement and antimicrobial activity. The complexes showed different shades of colour and were non-electrolyte. The infrared spectra of the complexes confirmed the coordination through the lone pair of the carbonyl oxygen of the Salicylaldehyde. The electronic transitions were consistent with the adoption of five-coordinate geometry for the copper complexes and six-coordinate geometry for the nickel complexes. The microbial susceptibility testing showed that the copper complexes had stronger antifungal activity than the antibacterial activity. The antifungal activity was more pronounced at 12.5 – 100 mg/mL, while the antibacterial activity was generally restricted to 100 mg/mL. Notably, [Cu(Sal)2(bipy)] showed no antifungal activity while [Cu(Sal)2(en)] showed neither antifungal nor antibacterial activity. Among the nickel complexes only [Ni(Sal)2(phen)] had both antifungal (except Fusarium) and antibacterial activity. [Ni(Sal)2(en)] was neither antifungal nor antibacterial.