Solubilization of NaX Salts in Chloroform by Bifunctional Receptors

Abstract

First the cation, then the anion. This describes the complexation of alkali metal halides with bifunctional receptors like that on the right (R = n-octyl) based on calix[4]arenes. The uncomplexed ligand has a strong intramolecular hydrogen bond between the urea moieties, which is disrupted by the conformational change induced by complexation of a Na+ ion. Only then is an anion like Cl− bound in the upper portion of the calixarene.