New Potassium- and Cesium-selective Ionophoric Bis(crown ether)s Derived from Xanthene-4,5-dicarboxylic Acid |
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Authors: | Yeon Hee Cho Seung Gul Rha Suk-Kyu Chang Taek Dong Chung Keunchang Cho Hasuck Kim |
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Institution: | (1) Department of Chemistry, Chung-Ang University, Seoul, 156-756, Korea;(2) Department of Chemistry and Center for Molecular Catalysis, Seoul National University, Seoul, 151-742, Korea |
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Abstract: | A series of bis(crown ether)sbased-upon a xanthene-4,5-dicarboxylic acid skeletonwas prepared and their ionophoric properties towardalkali metal cations were investigated. Bis(crownether)s bearing 15-crown-5 and 18-crown-6 moietiesexhibited pronounced extraction efficiencies towardK+ and Cs+ ions, respectively, and theextraction constant estimated by solvent extractionstudies was as high as 109 for the 2-K+ and 3-Cs+ systems. Using UVtitration of potassium picrate with 2 in THF, thecomplex was found to have a structure of a completelyencapsulated guest in the host. In transportexperiments, the bis(crown ether)s showed nosignificant selectivity pattern compared withextraction results, again implying the strongcomplexation of bis(crown ether)s. Ion-selectiveelectrode studies also demonstrated that the selectiveionophoric properties of 2 toward K+ werereminiscent of the natural antibiotic valinomycinexcept for a somewhat slow response. |
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Keywords: | potassium-selective ionophore bis(crown ether) ion selective electrode solvent extraction |
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