Lower-Rim Substituted Calixarenes and Their Applications

Abstract

This review discusses in detail “calixarenes” since their discovery as by-products of the phenol formaldehyde bakelites till the present scenario wherein calixarene has assumed a new dimension in the field of supramolecular chemistry. Extensive literature exists for calixarenes; but herein we have tried to concentrate on the different lower-rim modified calixarenes with their potential applications. An attempt has also been made to critically evaluate the synthesis procedures for different lower-rim substituted calixarenes.

Bis(spirolactam) 1,3-double-armed calix[4]arene compounds and their application as extractants for the determination of heavy metal ions

“…There are many literature reports of distal 1,3-bis(amido)-linked calix [4]arenes with a variety of ligating groups for binding to neutral, anionic and cationic guests [3][4][5][6]. In the vast majority of these cases the ligating groups have a large degree of conformational freedom.…”

“…Literature syntheses of amide linked calix [4]arenes have mainly used three different methods to create the amide linker [3][4][5][6]. Firstly, aminolysis of an ester with an amine gave good yields of the amides, but this method is restricted to the use of primary amines.…”

“…Calix [4]arenes are an important class of macrocyclic compounds which have been used extensively in supramolecular chemistry for molecular recognition [3][4][5][6]. They were first prepared by Baeyer in 1872, as by-products in the synthesis of baeklite [7].…”

“…Since Gutsche first published the synthesis of calix [4]arene-based macrocycles [11], the investigation of the complexation properties of these compounds has been of intense interest for a wide variety of ionic species and small organic guest molecules, through the formation of host-guest or supramolecular complexes. This area is subject to regular in-depth reviews [3][4][5][6].…”

“…Much of the current research into calixarenes focuses on the smallest and most rigid of the family, namely the calix [4]arenes, since the larger cavity-containing analogues are more flexible and therefore not always suited to strong binding with guest species, and are also generally less selective. Many calix [4]arene compounds have been synthesised over the last 40 years, with a variety of ligating groups to fine-tune binding to an array of ionic and neutral guests in solution and in the solid state [3][4][5][6]. Some of the functionalities attached to the calixarene scaffold are large and while they can facilitate binding can crowd the cavity and decrease the binding strength.…”