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Metal complexes of Schiff base derived from different antibiotics are widely employed as biological active materials, especially as antibacterial agents. Two new metal (II) complexes with the Schiff, base (HL) derived from amoxicillin and salicylaldehyde were synthesized and investigated using elemental analysis, spectroscopic techniques (IR and UV-Vis), conductometric and magnetic measurements. The IR spectra illustrated a bidentate ligand which coordinates through phenolic oxygen atom and imino nitrogen atom from azomethine bond. UV-Vis spectrophotometry showed the characteristic adsorption bands corresponding to an octahedral geometry for both metal complexes. The general formula established from experimental data was found to be [ML 2 (H 2 O) 2 ] (M=Co(II) and Ni(II)). This composition was further confirmed by thermal analysis and their thermal stability in nitrogen atmosphere was investigated. Antibacterial study showed that the efficiency of metal complexes is higher than the one found for the free Schiff base ligand.

New [ML2(H2O)2] complexes, where M = Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base.

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