Recent Topics on Functionalization and Recognition Ability of Calixarenes: The ‘Third Host Molecule’

This review article covers recent topics of a calixarene family concerning their stereochemistry, complexation with metal ions and organic guests, and other topics. As stereochemistry of calixarenes, the restriction of flipping motions of the composed benzene units of calix[4]-, [5]-, [6]arenes is summarized. In Recognition of Calixarenes, the selective recognition of alkali metal cations utilizing calixcrowns is a main subject in metal cation recognition. Concerning with recognition of metal cations and organic molecules, the ‘reading-out’ systems of recognition phenomena are summarized. The complexation of calix[8]arene with fullerene, which was discovered as serendipity and will be very useful as a new fullerene purification method is also reported.