Silver Ion-Selective Electrodes Using π-Coordinate Calix[4]arene Derivatives as Soft Neutral Carriers

Abstract

Calix[4]arene derivatives incorporating π-coordinate substituents such as allyl, benzyl, and propargyl groups were designed as soft neutral carriers for silver ion sensors. Most of all, tert-butylcalix[4]arene tetra(allyl ether) is an excellent neutral carrier for plasticized poly(vinyl chloride)-membrane silver ion-selective electrodes. The ion sensors showed high silver ion selectivity over alkali metal ions and also good selectivity against other soft metal ions such as lead and mercury(II) ions. The electrode potential response was as rapid as that for neutral-carrier-type alkali metal ion electrodes due to the soft interaction between π-coordinate substituents and silver ion, which was elucidated by ¹H NMR spectroscopy.