Abstract
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.
Highlights
Schiff bases are a growing class of compounds with varying chemistry
The absence of the aldehydic protons, which existed in benzene-1,4-dicarboxaldehyde, in this spectrum suggests the formation of the imine
Corroborating this was the signal observed at 5.42 ppm, consistent with a methine proton [34] [35]. This serves as evidence that a Schiff base was obtained
Summary
Schiff bases are a growing class of compounds with varying chemistry. They have often been in use as chelating agents in coordination chemistry [1] [2] [3] [4]. As a result of the versatility of their donor atoms, they are regarded as privileged ligands [5]. They have been reported to exhibit a number of important biological activities which include anti-bacterial, -fungal, -diabetic and -tumor [6]-[14]. The physical and chemical properties of these bases may be tuned by varying their peripheral functionalities and their template agent [16] [19] [20] [21]
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