Novel Calixarene-Based Metal Ion Extracting Agents

Previous work has looked at di-ionizable calixarene-crown ethers as metal ion extractants.  In most cases, the ionizable groups were attached to the lower rim of the calix[4]arene scaffold.  We have now synthesized the calix[4]arene-crown-6 ligand series shown below to determine the effect of moving the ionizable groups to the upper rim.  The metal ion extraction behavior for this ligand series is compared with those for two structurally related series of di-ionizable calix[4]arene compounds.