Potassium ion-selective membrane electrodes based on 1,3-alternate calix[4]crown-5-azacrown-5.

A series of 1,3-alternate calix[4]azacrown ethers for which the monoaza and unsymmetrical crowned-azacrown with different side arms were examined as an ionophore for ion-selective polymeric membrane electrode toward potassium ion. Among them, the electrode based on calix[4]crown-5-azacrown-5 with a phenyl group exhibited near Nernstian response for K(+) ions over a wide concentration range (1x10(-5) to 1x10(-1) M) with a limit of detection of 2x10(-6) M. It has a fast response time of approximately 2-3 s and can be used for at least 2 months without observing any major deterioration.

Molecular taekwondo. 2. A new calix[4]azacrown bearing two different binding sites as a new fluorescent ionophore.

Synthesis and binding studies of a new calixarene-based fluoroionophore were made. Calix[4]azacrown having an anthracenyl unit displayed large chelation-enhanced fluorescence effects with Cs(+), Rb(+), and K(+) over other metal ion tested. Interesting "molecular taekwondo" processes between Cs(+)-Cu(2+) and Cs(+)-Ag(+) pairs were monitored via fluorescent changes.