Synthesis, Physicochemical, and Biological Properties of Nickel(II), Copper(II), and Zinc(II) Complexes of an Unsymmetrical Tetradentate Schiff Base and Their Adducts

Abstract

Nickel(II), copper(II) and zinc(II) complexes of unsymmetrical Schiff base derived from 2-hydroxy-1-naphthaldehyde, 2,4-pentanedione and p-phenylenediamine of the general formula [M(C10H6OCH:N(C6H4)N:C(CH3)CH:C(CH3)O)], [ML], and their adducts with 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) have been synthesized and characterized by elemental analyses, conductance, room temperature magnetic susceptibility, and infrared and electronic spectral measurements. The ligand is tetradentate, coordinating via the imine N and enolic O atoms. The magnetic moments and electronic spectra corroborate octahedral geometry for Ni(II) and Cu(II) complexes whereas the Zn(II) Schiff base complex analyzed 4-coordinate and the adduct 6-coordinate. The Ni(II) and Cu(II) complexes incorporated two water molecules each. The antimicrobial properties of the ligand and compounds against Staphylococcus aureus, Streptococcus faecalis, Bacillus sp, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Klebsiella pneumoniae, Acinetobacter sp, Flavobacterium sp, Enterococcus faecalis and Candida albicans are reported. The compounds generally exhibited good activity against the selected organisms. The compound [CuLphen] has comparable activity to gentamycin. The minimum inhibitory concentrations (MICs) of the sensitive compounds are between 1.0–12.0 mg/mL.