ABSTRACT
Chromoionophores are colored ionophores, a family of compounds in which a chromophore and an ionophore structure are combined. The chromophore may be introduced at any place within the ionophore molecule. Chromoionophores, like ordinary ionophores, are classified into two types according to their molecular charge when they complex with metal ions, i.e., neutral and anionic chromoionophores. Chromoionophores, of course, are connected to the former type, and many interesting aspects of complexation and lipophilization of alkali and alkaline earth metal ions were disclosed by studying the absorption behavior of built-in chromophoric groups. The development of chromoionophores has been limited to those interacting with cationic species. Construction of chromoionophores capable of interacting with anions would be an interesting challenge in the future, particularly in designing the molecular mechanisms by which anionic entity is recognized and the binding signal is transformed into optical signals. A chromoionophore molecule is provided with an optically sensing function in addition to an ion-binding ability.
