Synthesis and Evaluation of a Bis(crown ether) Ionophore with a Conformationally Constrained Bridge in Ion-Selective Electrodes

Zhiren Xia, Ibrahim H.A. Badr, Shawn L. Plummer, Lawrence Cullen, Leonidas G. Bachas

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19 Scopus citations


A new bis(crown ether) ionophore containing two benzo-15-crown-5 moieties connected with each other via a conformationally constrained bridge attached to a C 18 -lipophilic side chain was designed and synthesized. The bridge consisted of an isophthalic acid derivative, which was selected in order to enhance potassium over sodium binding. Liquid-polymeric membrane ion-selective electrodes (ISEs) based on this ionophore were prepared using different plasticizers and mole ratios of lipophilic ionic additives. Membrane electrodes with optimum composition (using o-nitrophenyloctyl ether or bis(1-butylpentyl)adipate as plasticizer and 60 mol% lipophilic borate additive) show Nernstian responses toward potassium (57 and 58 mV/decade, respectively) over a wide concentration range with a micromolar detection limit. These ISEs exhibit enhanced potassium over sodium selectivity (K K+,Na+ pot =6×10 -4 ). In addition, the electrodes show selectivities for potassium over Cs + and NH 4 + that are better than those of valinomycin-based ISEs.

Original languageEnglish (US)
Pages (from-to)169-173
Number of pages5
JournalAnalytical Sciences
Issue number1
StatePublished - Jan 1 1998
Externally publishedYes



  • Bis(crown ether)
  • Cation sensor
  • Ion-selective electrode
  • Lipophilic salt
  • Liquid-polymeric membrane
  • Neutral carrier

ASJC Scopus subject areas

  • Analytical Chemistry

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