Heteroatom-Bridged Calixarenes

Abstract

Macrocycles have always played an important role in supramolecular chemistry. Macrocycles with rigid subunits, known as calixarenes, are an important subclass of these compounds. While carbon-bridged calixarenes have been studied intensively and are used for practical applications, [a]

Recent Developments in Synthesis and Applications of Triptycene and Pentiptycene Derivatives

“…Heterocalixarenes, [67,70] in which the carbon linkages between the aromatic units are replaced by heteroatoms, have attracted much interest in recent years owing to their ready availability, tunable cavities, and potential applications in supramolecular chemistry. Oxacalixarenes and azacalixarenes, two important classes of heterocalixarenes, have shown rapid growth in calixarene chemistry as a result of increasing efforts devoted to their synthesis and conformational investigation.…”

Synthesis and inclusion properties of boroncalix[3]arene compounds obtained by self‐assembly of 3‐aminophenylboronic acid and salicylaldehyde derivatives

“…Heteroatom‐bridged calix(het)arenes, also known as heterocalixaromatics, have gained considerable attention in recent years, because of their easy accessibility, tunable conformational structures, and versatile molecular recognition properties . Although combinations of diverse aromatic rings and heteroatoms can generate in theory numerous macrocyclic compounds, most studies have been focused on calix[4]arenes macrocycles which contain four aromatic rings bridged by heteroatoms . The smallest macrocycles in the family are the less investigated heterocalix[3]arenes, most of them having a C 3 ‐symmetry, which are also attractive compounds for use in host‐guest and supramolecular chemistry …”

Methylazacalixpyridines: Remarkable Bridging Nitrogen‐Tuned Conformations and Cavities with Unique Recognition Properties

“…Since Gutsche's milestone work in the 1970s,1 calixarene chemistry has developed to become an indispensable part of supramolecular chemistry 2. Whilst efforts in derivatizing the basic calixarene skeletons are proliferating,3 one of the more recent developments in this field is the construction of new calixarenes by replacing their phenol units with other heteroarene species, in order to tune their cavities and therefore to alter and improve their selectivities towards recognition of various guest molecules 4. This has in fact resulted in a few intriguing macrocycles such as calixpyrroles,5 calixpyridines,6 and other calixheteroaromatics 7.…”

“…In particular, calixpyrroles have been shown by Sessler5 to be powerful anion receptors. In contrast with these preparations of coarsely tuned macrocyclic molecules, construction of calixarenes with finely tunable cavities, through substitution of their methylene bridges with heteroatoms, has until recently remained largely unexplored4 because of synthetic obstacles, except in the case of tetrathiacalix[4]arenes 8. Nevertheless, treatment of 1,3‐dichloro‐4,6‐dinitrobenzene with resorcinol, for example, gave a 13 % yield of a tetranitro‐substituted tetraoxocalix[4]arene,9 whilst both the Pd II ‐catalyzed cyclic oligomerization of 3‐bromo‐ N ‐methylaniline10 and the Pd 0 ‐catalyzed condensation of benzene‐1,3‐diamine and 1,3‐dibromobenzene derivatives11 produced mixtures of azacalix[ n ]arenes ( n = 3–8) in very low yields.…”

“…Nevertheless, treatment of 1,3‐dichloro‐4,6‐dinitrobenzene with resorcinol, for example, gave a 13 % yield of a tetranitro‐substituted tetraoxocalix[4]arene,9 whilst both the Pd II ‐catalyzed cyclic oligomerization of 3‐bromo‐ N ‐methylaniline10 and the Pd 0 ‐catalyzed condensation of benzene‐1,3‐diamine and 1,3‐dibromobenzene derivatives11 produced mixtures of azacalix[ n ]arenes ( n = 3–8) in very low yields. Silicon‐bridged calixarenes have been synthesized by coupling of phenol or 1,3‐dibromobenzene with dichlorodimethylsilane in 16 % or 12 % yields, respectively,12 and a few heteroatom‐bridged calixheteroaromatics have also been prepared by incorporating further heteroatoms into heteroaromatics 4. Among these, silicon‐bridged calix[ n ]phosphaarenes are notable because they act as ligands with strong π‐acceptor properties 13.…”