ABSTRACT
This chapter reviews the application of crown compounds to neutral carrier-type ion-selective electrodes. It deals with monocyclic and bicyclic crown ethers, and other cyclic crown ether analogs, but not with noncyclic analogs. Emphasis is placed on highly ion-selective crown ethers for the neutral carriers of membrane electrodes. The electrochemical membranes for neutral carrier-type ion-selective electrodes should be essentially liquid membranes. Coated-wire electrodes are compact and handy as ion-selective electrodes, and the typical construction is as illustrated. There are some crown ether analogs that have potential as neutral carriers of ion-selective membrane electrodes. Design of crown compounds or their analogs as neutral carriers for ion-selective electrodes is important to attain high performance of the resulting electrodes. A great number of highly ion-selective crown compounds are still expected to be designed. Inevitably, crown ether derivatives have been great candidates for the neutral carriers of ion-selective electrodes, since they can complex selectively cations such as alkali and alkaline earth metal ions.
