NEW SMALL-CAVITY CRYPTAND CHROMOIONOPHORES FOR COMPLEXATION OF LITHIUM AND SODIUM-IONS

Two new chromoionophores based on small-cavity cryptands with inward-f acing phenolic groups have been synthesized. Both compounds incorporat e a diaza-12-crown-4 moiety and bear a p-nitrophenylazo chromogenic gr oup attached to the cryptand phenol framework, para to the phenolic gr oup. Chromogenic cryptand 3 exhibits selectivity for Li+ ions in the e xtraction mode but shows very little cation response in homogeneous aq ueous media. A larger analog, chromogenic cryptand 4, acts as a sodium scavenger and cannot be obtained in a sodium-free form.