Azacalixarene: A New Class in the Calixarene Family

Abstract

Calixarenes, together with crown ethers and cyclodextrins, play an important role in supramolecular chemistry. A variety of calixarene analogues involving heteroatoms as the bridging units have been reported because the substitution of the carbon bridges with heteroatoms can impart novel properties and functions to molecules. This is typified by, for example, thiacalixarenes. In recent years, nitrogen-bridged calixarene analogues have emerged as a new calixarene family. While the diversity is still limited as compared with carbon- and sulfur-bridged calixarenes, intriguing structure-property relationships based on the introduction of nitrogen atoms as the bridging units have been reported. This review summarizes the recent reports on the preparations, conformations, and inclusion properties of nitrogen-bridged calixarene analogues with a [1 _n ]metacyclophane skeleton.