Anion‐Templated Calix[4]arene‐Based Pseudorotaxanes and Catenanes

Abstract

We present the rational design and anion-binding properties of the first anion-templated pseudorotaxanes and catenanes in which the "wheel" component is provided by a calix[4]arene macrobicyclic unit. The designs and syntheses of two new calix[4]arene macrobicycles, 2 and 3, are presented, and the abilities of these new species both to bind anions and to undergo anion-dependent pseudorotaxane formation are demonstrated. Furthermore, it is shown that performing ring-closing metathesis reactions on some of these pseudorotaxane assemblies gives novel catenane species 14 and 15, in which the yield of interlocked molecule obtained is critically dependent on the presence of a suitable anion template, namely, chloride. Exchange of the chloride anion in catenane 14 a for hexafluorophosphate gives catenane 14 d, which contains a unique anion-binding domain defined by the permanently interlocked hydrogen-bond-donating calix[4]arene macrobicycle and pyridinium macrocycle fragments. The anion-binding properties of this domain are presented, and shown to differ from non-interlocked components.

Calix[4]arene‐Based Rotaxane Host Systems for Anion Recognition

“…Macrocycle precursor 1 [12] and axle component 2·Cl [16] were prepared according to literature procedures. The synthesis of the new axle component 3·Cl is outlined in Scheme 2.…”

“…[17,18] Through suitable modification of this heteroditopic receptor design, together with exploitation of a strategic anion templation methodology, calix [4]arene functionalised [2]catenane anion receptors were assembled. [11,12] Herein we describe the preparation of the first calix [4]arene-based [2]rotaxane anion host systems, which consist of a calix [4]arene functionalised macrocycle wheel and pyridinium axle components, through adaptation of a new synthetic pathway that involves anion templation in combination with favourable p-p stacking interactions. [15] Anion binding investigations reveal the more preorganised rotaxane exhibits an impressive high affinity for chloride Abstract: The synthesis, structure and anion binding properties of the first calix [4]arene-based [2]rotaxane anion host systems are described.…”

“…[8] They have also recently begun to be incorporated into interlocked structures including rotaxanes [9,10] and catenanes. [11][12][13] We have undertaken a research programme with the objective of exploiting the unique topological cavities of rotaxanes and catenanes in anion host-guest chemistry. [10][11][12][14][15][16] We have previously reported the synthesis of heteroditopic calix [4]arene receptors which exhibit unprecedented cooperative and ion-pair binding behaviour.…”

“…[11][12][13] We have undertaken a research programme with the objective of exploiting the unique topological cavities of rotaxanes and catenanes in anion host-guest chemistry. [10][11][12][14][15][16] We have previously reported the synthesis of heteroditopic calix [4]arene receptors which exhibit unprecedented cooperative and ion-pair binding behaviour. [17,18] Through suitable modification of this heteroditopic receptor design, together with exploitation of a strategic anion templation methodology, calix [4]arene functionalised [2]catenane anion receptors were assembled.…”

Development of [2]-Catenane with Orthogonal Binding Chloride Template

“…Beer and co-workers reported more advanced design of the anion template from the fact which the electron deficient and electron rich components are arranged so that π-π stacking is possible. [8][9][10] Although catenanes were synthesized using other types of anion templates, still more research needs to be developed.…”