Sung Ok Kang

Urea derivative of calix[4]diquinone: HSO4− ion selective receptor

Abstract Urea derivative of calix[4]diquinone 3 has been synthesized in two steps via urea formation and oxidation of 1 . Anion-ligand interactions were studied by 1 H NMR and electrochemical analysis and showed a good affinity between receptor 3 and HSO 4 − .

Electrochemistry of a urea-functionalized calix[4]diquinone sulfate-anion selective receptor

Abstract A new class of neutral ligands is synthesized and studied for the binding properties with anions by electrochemical methods. The binding of calix[4]diquinone 1 with HSO 4 − causes a large negative shift of the electrode potentials of the calix[4]diquinone. This novel neutral anion receptor 1 binds anions through hydrogen-bonding and shows high selectivity for HSO 4 − over H 2 PO 4 − , Cl − , and CH 3 CO 2 − . The selectivity of HSO 4 − over H 2 PO 4 − , Cl − , and CH 3 CO 2 − may be attributed to the stronger hydrogen-bonding with the urea moiety, and also with the quinone moiety of 1 receptor, and also the greater compatibility of the cavity of 1 with tetrahedral HSO 4 − .

Anion Recognition by Urea Derivatives of Anthraquinone: Dihydrogen Phosphate Ion Selective Neutral Receptors

Three urea derivatives of anthraquinone were synthesized and they showed a high selectivity for dihydrogen phosphate ions.

Synthesis and Conformational Studies of Lower Rim Cyanomethyl Substituted Calix[4]arenes

The conformational inversion characteristics of calix[4]arenes carrying cyanomethyl groups on the lower rim have been investigated. Complete conversion from a 1,3-alternate to a partial cone conformation was observed for the 1,3-dicyanomethyl ether of calix[4]arene at room temperature, while at higher temperatures further inversion to a 1:1 mixture of partial cone and cone conformers occurred.

Synthesis and Ion Binding Properties of Cesium Selective Quadruply Bridged Calix[6]arenes

Several quadruply bridged calix[6]arenes were prepared in high yield by the reaction of various 1,4-di-O-alkylated calix[6]arenes with 1,2,4,5-tetrakis-(bromomethyl)benzene in the presence of Cs2CO3. The alkali metal extraction study established that this compound shows the high selectivity toward Cs+ among alkali metal cations. The cesium binding characteristics were investigated with 1H NMR and UV spectroscopy.