ABSTRACT
Calixarenes are macrocyclic phenol-formaldehyde condensation oligomers that possess the capability for cationic, anionic, and molecular inclusion. Calixarenes were first reported by A. Zinke and E. Ziegler in 1941. During an investigation of one portion of the Bakelite process, they treated p-tert-butylphenol with formaldehyde and sodium hydroxide. Modification of the base of the calixarene framework has been found to produce a highly effective alkali metal ion complexation agent. Since much of the chemistry of cation complexation occurs in aqueous solution, the synthesis of water-soluble calixarenes has opened a new area of endeavor. This aspect of calixarene chemistry has been pioneered by Shinkai and has recently been reviewed. Studies of the calix [4] arenes may be conveniently divided into those relating to water-soluble species and those relating to hydrocarbon-soluble substances. Due to the extensive efforts of Shinkai and co-workers, the chemistry of the hydrophilic calix[6]arenes is rather more developed than that of the lipophilic ones.
