CHROMOGENIC LITHIUM CRYPTAHEMISPHERAPLEXES FOR DETERMINATION OF SODIUM IN AQUEOUS-SOLUTIONS

Three new lithium cryptahemispheraplexes for selective complexation of sodium in aqueous solutions were synthesized. Combining diaza-12-crown-4 or diaza-14-crown-4 with the rigid trianisyl concave produced hosts with two different cavity sizes. These compounds, having the [1.1] cavity, incorporate 2,4-dinitro-6-(trifluoromethyl)anilino (2 and 5) and 2,6-dinitro-4-(trifluoromethyl)anilino (4) chromophoric groups for generating a chromogenic and kinetic response to sodium ion. For comparison, the end product of sodium complexation with compound 2 (cryptahemispheraplex 3) was isolated and characterized.