Synthesis of Azacalixarenes and Development of Their Properties.

Hiroyuki Takemura

doi:10.3390/molecules26164885

Abstract

This review focuses on the synthesis, structure, and interactions of metal ions, the detection of some weak interactions using the structure, and the construction of supramolecules of azacalixarenes that have been reported to date. Azacalixarenes are characterized by the presence of shallow or deep cavities, the simultaneous presence of a basic nitrogen atom and an acidic phenolic hydroxyl group, and the ability to introduce various side chains into the cyclic skeleton. These molecules can be given many functions by substituting groups on the benzene ring, modifying phenolic hydroxyl groups, and converting side chains. The author discusses the evidence of azacalixarene utilizing these characteristics.

Highlights

Calix[n]arenes are cyclic compounds consisting of alternating p-substituted phenol and methylene chains
Compounds with similar structures have appeared one after another, and a number of cyclic compounds bearing the name calixarene have been reported to date
Thiacalixarenes, in which the methylene of the calixarene is replaced by a sulfur atom [4,5,6,7,8]; azacalixarenes, in which the methylene is replaced by a nitrogen atom [9,10,11,12,13,14,15,16,17,18,19]; and homoxacalixarenes, in which a -CH2O- unit is inserted [20,21], have been widely studied

Summary

General Concepts of the Azacalixarenes and Related Compounds

Calix[n]arenes are cyclic compounds consisting of alternating p-substituted phenol and methylene chains. As they are easy to synthesize and obtain in sufficient quantities for laboratory use, their structures are unique, and various applications are possible by modifying the molecules; research on them was, at one time, widely conducted worldwide, and all kinds of research, from basic to applied, was carried out [1,2]. Thiacalixarenes, in which the methylene of the calixarene is replaced by a sulfur atom [4,5,6,7,8]; azacalixarenes, in which the methylene is replaced by a nitrogen atom [9,10,11,12,13,14,15,16,17,18,19]; and homoxacalixarenes, in which a -CH2O- unit is inserted [20,21], have been widely studied. In this review, only homoazacalixarenes are considered, referred to as azacalixarene, not homoazacalixarene, unless it is necessary

The Birth of Azacalixarene

Complex Formation with Metal Ions

Linkage of Azacalixarenes by Metal Coordination Bonds