Formation of Macrocycles Containing Metal Ions as Ring Atoms through Chelation of a Noncyclic Di-Imidazolylazo Ligand
✍ Scribed by J.H. Suh; S.H. Lee; Y.D. Lee; Y.A. Bae
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 290 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0045-2068
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✦ Synopsis
As a first step toward design of biomimetic functional molecules based on macrocycles containing metal ions as ring atoms, metal complexation by a noncyclic ligand containing distant chelating sites was undertaken. For this purpose, tetradentate ligand (N, N^{\prime})-di[3-(2imidazolylazo)phenyl]- (N, N^{\prime})-dimethyl-isophthalimide (1) and bidentate ligand (N)-[3-(2-imidazolylazo)phenyl]- (N)-methylbenzamide (2) were prepared. The (K_{\mathrm{f}}) values of the (\mathrm{Cu}() II) or (\mathrm{Ni(II)} \mathrm{complex} \mathrm{of} 1) in water, in (40 %) (v/v) dimethyl sulfoxide (DMSO), in (95 %) (v/v) DMSO. or in (95 %(\mathrm{v} / \mathrm{v}) \mathrm{CH}{3} \mathrm{CN}) were (10^{4}-10^{10}), whereas those of the corresponding complex of 2 were (10^{2}-10^{3}). Spectral titration showed the formation of 1: 1-type metal complexes for 1 in the complexation process represented by the (K{\mathrm{f}}) values. The results indicate that highly efficient binding of metal ions by (\mathbf{1}) is due to macrochelation by the two imidazolylazo moieties with the formation of 16-membered rings. The macrocylce formed by metal complexation of 1 contains a metal ion as a ring atom as well as three benzene moieties on the ring, and, therefore, may be considered as a new type of cyclophanes. 1993 Academic Press, Inc.