Novel cryptand chromoionophores for determination of lithium ions

The syntheses and chromogenic properties of three novel chromogenic (p-nitrophenyl)azo-labeled cryptands 1-3, having inward-facing phenolic groups, are described. Cryptand chromoionophore 1 has the smallest cavity of the three cryptands and exhibits total selectivity for Li + over Na + ions in 10% aqueous diethylene glycol monoethyl ether (DEGMEE). The association constant of 3200 M -1 was obtained in 10% aqueous DEGMEE/TMA(OH) for the 1 - -Li + complex