Comparative study of mono- and di-substituted 14-crown-4 derivatives as lithium ionophores

Abstract

14-Crown-4 derivatives bearing either one or two methoxy, methoxycarbonylmethyl or carbamoylalkyl substituents have been prepared in an attempt to obtain selective ionophores for lithium ions. Complexation with lithium has been monitored by IR and 13C NMR spectroscopy and solvent polymeric membranes have been fabricated and evaluated using the fixed interference method. The highest selectivity for lithium with respect to sodium is observed for a diamide derivative (630 : 1).