Antimicrobial activities of the metal complexes of N′-(5-(4-chlorophenyl)diazenyl)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide

A new series of metal complexes of N'-(5-(4-chlorophenyl)diazenyl)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) have been synthesized and characterized by elemental, H-1-NMR, IR, UV-Vis., ESR, magnetic, thermal analyses (TG) and conductivity measurements. The spectral data show that the ligand behaves as a neutral bidentate, (2) and (4-7), monobasic bidentate, (3), (12), (13), and (15-17), or dibasic tridentate (8-11) and (14). The ligands coordinate metal ions with the carbonyl oxygen atom in ketonic or enolic forms, azomethine nitrogen atom and/or deprotonated phenolic hydroxyl oxygen atom. The ESR spectra of solid vanadyl(II) complex (2), copper(H) complexes (4), (5) and (8) and manganese(II) complex (11) show an isotropic type while the copper(I) complexes (3), (6) and (7) show an axial symmetry type with g(parallel to)>g(perpendicular to)>g(e) indicating a covalent bond character. The biological results show that the ligand is biologically inactive but the metal complexes have a mild effect on Gram positive bacterium (Bacillus subtilis), and Gram negative bacterium (Escherichia coli). The Cu(II), Zn(II), Cd(II), and UO(II) complexes have a mild effect on Fungus (Aspergillus niger) while Hg(II) shows higher effect on fungus than standard drug (Nystatin). Comparing to previous results, the metal complexes of this type of hydrazone have mild effect on microorganisms studied may be due to the presence of the azo group.