Design and synthesis of a more highly selective ammonium ionophore than nonactin and its application as an ion-sensing component for an ion-selective electrode

Koji Suzuki, Dwi Siswanta, Takeshi Otsuka, Tsuyoshi Amano, Takafumi Ikeda, Hideaki Hisamoto, Ryoko Yoshihara, Shigeru Ohba

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

A novel ammonium ionophore, which exhibits superior NH4+ selectivity compared with that of the natural antibiotic nonactin, was successfully designed and synthesized based on a 19-membered crown compound (TD19C6) having three decalino subunits in the macrocyclic system. This bulky decalino subunit is effective for (1) increasing the structural rigidity of the cyclic compound, (2) introducing the 'block-wall effect', which prevents forming a complex with a large ion, and (3) increasing the lipophilicity of the ionophore molecule. In the ammonium ionophore design, the first factor contributes to increasing the NH4+ selectivity relative to smaller ions such as Li+, Na+, or even the closest size, K+, and the second factor increases the NH4+ selectivity over larger ions such as Rb+ and Cs+. The X-ray structural analysis proved that TD19C6 forms a size-fit complex with NH4+ in its crown ring cavity. As an application of this ionophore, an ion sensor (ion-selective electrode) was prepared, which exhibited NH4+ to K+ and Na+ selectivity of 10 and 3000 times, respectively. This electrode showed a better performance compared to the electrode based on nonactin, which is the only ammonium ionophore presently used in practical applications.

Original languageEnglish
Pages (from-to)2200-2205
Number of pages6
JournalAnalytical chemistry
Volume72
Issue number10
DOIs
Publication statusPublished - 2000 May 15

ASJC Scopus subject areas

  • Analytical Chemistry

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