Abstract
A new macrocyclic multidentate Schiff-base ligand Na4L consisting of two submacrocyclic units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12]tetracosa-1(23),2,6,8,10,12(24),13,17,19,21,-decaene-23,24-disodium) and its tetranuclear metal complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) are reported. Na4L was prepared via a template approach, which is based on the condensation reaction of sodium 2,4,6-triformyl phenolate with ethylenediamine in mole ratios of 2 : 3. The tetranuclear macrocyclic-based complexes were prepared from the reaction of the corresponding metal chloride with the ligand. The mode of bonding and overall geometry of the compounds were determined through physicochemical and spectroscopic methods. These studies revealed tetrahedral geometries about Mn, Co, and Zn atoms. However, square planar geometries have been suggested for NiII and CuII complexes. Biological activity of the ligand and its metal complexes against Gram positive bacterial strain Staphylococcus aureus and Gram negative bacteria Escherichia coli revealed that the metal complexes become more potentially resistive to the microbial activities as compared to the free ligand. However, these metal complexes do not exhibit any effects on the activity of Pseudomonas aeruginosa bacteria. There is therefore no inhibition zone.
Highlights
Macrocyclic species based on transition metal compounds and multidentate ligands is an interesting field in chemistry and has been the subject of extensive research due to their potential applications in building block macrocyclic-based chemistry [1, 2] and environmental chemistry [3] and biomedical [4]
As part of our group to explore the use of multidentate Schiff-base ligands for the building blocks of macrocyclic compounds, we describe here the formation of macrocyclic species of some phenoxo-bridged tetranuclear transition metal ions with the new macrocyclic Schiff-base
The ligand was derived via a template approach in which ethylenediamine fragments facilitated the linkage of the two units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12] tetracosa-1(23),2,6,8,10, 12(24),13,17,19,21,decaene-23,24-disodium)
Summary
Macrocyclic species based on transition metal compounds and multidentate ligands is an interesting field in chemistry and has been the subject of extensive research due to their potential applications in building block macrocyclic-based chemistry [1, 2] and environmental chemistry [3] and biomedical [4]. One interesting application in the field of coordination chemistry has been to investigate the use of Schiff-base ligands to develop phenoxo-bridged binuclear complexes with homometallic and/or heterometallic centres. We reported the formation of polymeric chain assemblies of some phenoxo-bridged binuclear transition metal complexes with multidentate Schiff-base ligand, namely, sodium(E)6,60-((1E,10E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene) bis(methan-1-yl-ylidene) bis-(4-methyl-2((E)(pyridine-2-ylmethylimino)methyl)phenolate) H2L. As part of our group to explore the use of multidentate Schiff-base ligands for the building blocks of macrocyclic compounds, we describe here the formation of macrocyclic species of some phenoxo-bridged tetranuclear transition metal ions with the new macrocyclic Schiff-base. The ligand was derived via a template approach in which ethylenediamine fragments facilitated the linkage of the two units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12] tetracosa-1(23),2,6,8,10, 12(24),13,17,19,21,-decaene-23,24-disodium)
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