120th General Meeting of the KCS

Type Poster Presentation
Area Organic Chemistry
Room No. Exhibition Hall 2+3
Time 10월 20일 (금요일) 13:00~14:30
Code ORGN.P-277
Subject A Diazo-coupled calix[4]arene-Strapped Calix[4]pyrrole: a Colorimetric Sensor for Specific Ion Pairs
Authors Kim Seung Hyeon, Sung Kuk Kim*
Department of Chemistry, Gyeongsang National University, Korea
Abstract A chromogenic ion pair receptor was synthesized on the basis of a diazocalix[4]arene and calix[4]pyrrole hybrid compound. In this case, the calix[4]arene subunit was locked in the con conformation whereas the calix[4]pyrrole constituent are conformationally flexible. It was found by UV/vis and 1H NMR spectroscopic analyses that the ion pair receptor is highly selective for calcium and fluoride ion. For example, upon the addition of these ions to the solution of the receptor, drastic color change was observed presumably as the result of formation of the ion complexes by the receptor. In these ion complexes, the fluoride anions were bound to the calix[4]pyrrole via hydrogen bonding interactions with the pyrrolic NHs whereas the calcium cation was complexed with the oxygen and nitrogen atoms of the calix[4]arene and the triazole group, respectively. Especially, the color change of the receptor solution from red to orange is ascribable to the calcium ion bound to the oxygen atoms of the phenolic groups of the calix[4]arene linked to the diazo groups. By contrast, the color change by the fluoride anion form yellow to blue is presumably attributed to deprotonation of the phenolic OH the calix[4]arene by the basic fluoride anion.
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