Synthesis, Characterisation and Antimicrobial Activity of Dimeric and Monomeric Copper(II)-Schiff base Complexes

Novel copper(II)-Schiff base derivatives were prepared in 1:1 and 1:2 (M:L) molar ratio reaction in ethanol. These compounds were characterized by infrared, UV-VIS, conductivity measurements, elemental analysis and melting point (decomposition). Dimers of general formula [Cu(L)(H2O)]2.H2O {L = 3-hmp (1) or 4-hmp (3)} and [Cu(hmyp)Cl2]2 (4) were prepared and a monomer of [Cu(3-hmp)2(H2O)Cl2].H2O (2). These chemicals are non-electrolytes and have the chloride ions bonded to the metal in terminal, bridging and trans position to the metal, performing geometric patterns of a square planar and square pyramidal arrangements. The UV-VIS of these complexes showed electronic transitions of molar extinction coefficients () between 10 and 10 3 L mol -1 cm -1 related to Metal-to-Ligand Charge Transfer (MLCT) bands and d-d transitions. The bioassay of the ligands and the metal derivatives were screened against Gram-positive (Staphylococcus aureus and Bacillus subtillis), and Gram-negative (Escherichia coli and Salmonella typhimurium) microorganisms. Complex-4 and the ligands hmyp and 4-hmp showed minimum inhibition concentration (MIC) in the range of 190 to 1020 M (40 to 350 g mL) against these microorganisms but complex-1, 2 and 3 were not active.