Azacalixarene: An Ever-Growing class in the calixarene family

Abstract

The chemistry of azacalixarenes, in which the aromatic rings are linked by nitrogen bridges, has been growing steadily and attracting much attention as a new class in the calixarene family ever since our previous review of azacalixarenes was published in 2008. In the years that have followed, an increasing variety of azacalixarene derivatives have been reported to date. Although the diversity is still limited as compared to carbon- and sulfur-bridged calixarenes, the intriguing chemistry of azacalixarenes on the basis of the introduction of nitrogen atoms as the bridging units has thus far been disclosed. Particularly encouraging progress in the azacalixarene chemistry since 2008 has been made in the synthetic chemistry as well as the host-guest chemistry in the solid state, as revealed by recent studies. This review covers the papers published in the last 6 years, especially concentrating on the preparations and complexation properties of this new calixarene family.