Cation Complexation by Calixarenes

The present survey summarizes some of the most relevant properties of calixarenes as cation ligands that strongly contributed to the success of this class of synthetic receptors in supramolecular chemistry. After a first general introduction on the synthesis and conformational properties of calixarenes we will try to point out the main features that influence selectivity in metal and ammonium ion binding, analyzing in sequence the ligands for (1) alkali and alkaline-earth ions, (2) lanthanide and actinide ions, (3) transition and posttransition metal ions, and (4) ammonium, alkylammonium, and quaternary ammonium cations. More than to be comprehensive, this article strives to transmit the reader the calixarene distinctive features which govern selectivity and efficiency in metal ion binding.