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Synthesis and Electrochemical Properties of Calix[4]arene-triester-monoquinones Weon Seok Oh,^a Taek Dong Chung,^b Jongwon Kim,^b Hee-Soo Kim,^b Hasuck Kim,^b Dongmok Hwang,^c Kimoon Kim,^cSeung Gul Rha,^a and Suk-Kyu Chang^a ^aDepartment of Chemistry, Chung-Ang University, Seoul 156-756, Korea ^bDepartment of Chemistry and Center for Molecular Catalysis, Seoul National University, Seoul 151-742, Korea ^cDepartment of Chemistry, Center for Biofunctional Molecules, Pohang University of Science and Technology, Pohang 790-784, Korea

Abstract

Calix[4]arene-based monoquinones having three efficient ligating groups of alkoxycarbomethyl ethers were prepared and their ionophoric properties were investigated by electrochemical technique. Calix[4]-triester-monoquinones 3a and 3b were prepared from calix[4]arene and p-tert-butylcalix[4]arene by selective trialkylation followed by oxidation with Tl(NO₃)₃ and Tl(CF₃CO₂)₃, respectively. X-ray crystal structural analysis revealed that the ligand 3a adopted a partial cone conformation with an inverted quinone moiety. MM+ calculations suggested that the energy difference between the two conformations is relatively small (< 3.5 kcal mole-1). Electrochemical studies also showed that the monoquinones 3a and 3b form strong complexes with Na⁺ ion, and the positive shifts in the reduction potential exceeded those of the closely related diquinones 5a and 5b.

Key Words: Calix[4]arene, Monoquinone, Na⁺ ion, Electrochemistry, Complexation.

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