Syntheses, Characterization, Antimicrobial Activity and Extraction Studies of Tetraaza Macrocyclic/Linear Schiff Bases Derived from Benzene-1,4-Dicarboxaldehyde and Their Coordination Compounds

Non-template [2 + 2] condensation of benzene-1,4-dicarboxaldehyde with two diamines: ethane-1,2-diamine and propane-1,2-diamine was carried out to give Ligands 1 and 2. Additionally, template [1 + 2] condensation of benzene-1,4-dicarboxaldehyde with ethane-1,2-diamine and propane-1,2-diamine were also carried out to give Ligands 3 and 4. These were characterized using 1H and 13C NMR, UV-Vis and infra-red spectroscopy and mass spectrometry. Coordination compounds of each ligand were further synthesized using Ni(II) and Cu(II) ions. They were characterized by Uv-vis, infrared spectroscopy, mass spectrometry, magnetic susceptibility and energy dispersion X-ray spectroscopy EDX. The ligands and complexes were further analyzed for their antimicrobial activities and extraction efficiency. The results obtained suggested that tetraaza macrocyclic and linear compounds were obtained for [2 + 2] and [1 + 2] condensation reactions respectively. Coordination compounds of the macrocyclic ligand yielded octahedral geometry for Ni(II) and Cu(II) complexes of Ligand 1 and square planar geometry for Ni(II) and Cu(II) complexes of Ligand 2. On the other hand square planar geometry was proposed for coordination compounds of Ligand 3 and 4 exception for the Ni(II) complex of Ligand 3. All ligands coordinated to the metal ion in a tetradentate fashion. In some cases chelation enhanced the antimicrobial activity of some of the ligands. The results further showed that Ligands 1-4 effectively extracted cadmium(II). zinc(II) and lead(II) ions in solution.