Formation of macrocyclic complexes with bis(dithiocarbamate) ligand; synthesis, spectral characterisation and bacterial activity

The preparation and characterisation of dithiocarbamate (DTC) ligand and its binuclear metal(II) dithiocarbamatebased macrocyclic complexes are reported. The free ligand was prepared from the reaction of a bis-secondary amine, CS2 and KOH. The macrocyclic bis(dithiocarbamate) complexes were synthesised using two approaches; (i) from the reaction of the free ligand with a metal ion, and (ii) via a one-pot reaction. In the free ligand approach, complexes were prepared by the reaction of potassium dithiocarbamate salt with the metal ions; MnII, CoII, and CuII. In the one-pot reaction, the complexes were prepared using a bis-secondary amine, CS2, KOH and metal(II) chloride. Ligand and its complexes were fully characterised by elemental analysis, thermal analysis, FTIR, UV-Vis, mass spectroscopy, magnetic susceptibility, conductance, melting points, and 1H, 13C- NMR spectroscopy. These studies revealed the formation of binuclear macrocyclic complexes of the general formula [M(Ln)]2 with tetrahedral geometries for MnII, CoII, and square planar geometry with CuII complex. Bacterial activity of the ligands and their metal complexes were screened for their antibacterial activity against four bacterial species (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus stubtilis), which revealed that the complexes are potentially more active against these bacterial strains, compared with the free ligand.

Author(s): Enaam I. Yousif, Hasan A. Hasan, Riyadh M. Ahmed and Mohamad J. Al-Jeboori

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