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Published August 15, 2001 | public
Journal Article

Self-Assembled Monolayer of a Redox-Active Calix[4]arene: Voltammetric Recognition of the Ba^(2+) Ion in Aqueous Media

Abstract

The Redox-active monolayer of a novel calix[4]arene recognizing redox-inactive ionic species by voltammetry is reported. Calix[4]arene-disulfide-diquinone, which is not only redox-active but is also a highly selective ionophore for the Ba^(2+) ion, spontaneously forms a stable and dense monolayer film on gold. The redox-active calixarene monolayer selectively recognizes Ba^(2+) ion in aqueous media, and the voltammetric signals are proportional to the ionic concentration. A new voltammetric peak can be detected by square-wave voltammetry upon adding a dilute solution containing Ba^(2+) ion having a concentration as low as 1.0 x 10^(-6) M. The Langmuir plot (1/i_(p) vs 1/[Ba^(2+)]) shows a linear slope in the range from 1.0 x 10^(-6) M to 1.0 x 10^(-4) M. This modified electrode does not show any significant interference from alkali and alkaline earth metal ions except for Sr^(2+) and Ca^(2+). Only 100- and 500-fold concentrations of Sr^(2+) and Ca^(2+) ions, respectively, can lead to voltammetric responses comparable to that of Ba^(2+).

Additional Information

© 2001 American Chemical Society. Received 5 September 2000; accepted 7 May 2001; published online 11 July 2001; published in print 15 August 2001. Financial support from KOSEF (1999-2-121-001-5, H.K.), KRF (1999-015-DI0068, S.C.), and the Center for Molecular Catalysis, Seoul National University, is greatly appreciated. We also thank the Interuniversity Center for Natural Science Research Facilities, Seoul National University, for NMR and mass spectrometry services.

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023