Zinc(II), cadmium(II), mercury(II) and lead(II) semiquinone-type complexesof a new Schiff-base ligand: Antibacterial studies

A new Schiff-base ligand LH2, has been prepared by reaction of 2,9-diformyl -,10-phenanthroline with 2,3-diamino-1,4-naphthoquinone. The formation and characterization of complexes of Zn(II), Cd(II), Hg(II) and Pb(II) with the semi-oxidized ligand LH is described. The M(LH)X-2 (X = Cl, Br and AcO) ra dical species are paramagnetic and the observed EPR signals in the solid st ate at room temperature, with g values close to the electron free g value a re proof of the semiquinonic character of the ligand. The antibacterial act ivity of the ligand and the metal complexes prepared were tested against fo ur bacteria strains and compared with the activity of penicillin.