Allosteric Binding of Alkali Metal Ions to a Pseudocryptand Formed by a Tripodal Heterocyclic Hexadentate Ligand and Ga(III)†
✍ Scribed by Akira Katoh; Hidenori Kudo; Ryota Saito
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 267 KB
- Volume
- 2
- Category
- Article
- ISSN
- 1472-7862
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✦ Synopsis
A new tripodal heterocyclic hexadentate ligand, in which three sets of 3-hydroxy-4(1H)-pyridinone and ethyleneoxy chain are linked to tris(carboxyethoxymethyl)ethane, was synthesized. UV-Vis spectroscopic analysis in aqueous solution indicated 1:1 stoichiometric complexation of the hexadentate ligand with iron(III) (l max 460 nm and " 5100 M À1 cm À1 ; the relative stability constant log K=32.9). Allosteric binding of alkali metal ions to a pseudocryptand formed by the tripodal hexadentate ligand and Ga(III) was examined in CDCl 3 -CD 3 CN (1:1) mixture by means of 1 H NMR spectroscopy. The pseudocryptand formed 1:1 complexes with Na + and K + ions, and the binding constant was estimated to be almost the same (K=5.9Â10 2 for Na + and 5.8Â10 2 M À1 for K + ).