Calixarenes anion binding

As with cation binding hosts, it is also possible to use calixarene frameworks (Section 3.14) to organise anion binding moieties. Addition of a cobaltocinium bis(amide) moiety to the upper rim of a calix[4]arene with p-toluenesulfonate functionalities to enhance solubility results in a rigid host 4.64... 

The related monodentate ligands 5.33 and 5.34 form MT4 type complexes with the relatively inert platinum(II). The complex [Pt(5.33)4]2+ adopts a 1,2-alternate conformation (by analogy with the calixarenes, Section 3.14) giving two anion-binding pockets that can bind planar anions such as nitrate and acetate in a 1 2 ratio. Acetate displays a positive allosteric effect with Kn being more than twice Ku. Tetrahedral anions are bound in a 1 1 ratio, however, and it is likely the complex can adopt a variety of conformations in solution. Related to [Pt(5.33)4]2+ is [Pt(5.34)4]2+. Like the complex with 5.33, X-ray diffraction results show that the chloride complex adopts a 1,2-alternate conformation with a... 

Calixarenes and their derivatives (Scheme 9.3) are among the most widely used scaffolds in anion-binding chemistry. Strategies for their functionalization have been reviewed recently [36,37]. The popularity of calixarenes reflects to a large extent the ease with which the cores themselves can be modified as well as the fact that they... 

Usually, receptors designed for ion-pair complexation are molecules comprising weU-known anion-binding motifs, for example, Lewis-acidic centers, and familiar cationbinding motifs, such as crown ethers, calixarenes. The distance occurring between these sites classifies receptors as follows ... 

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