Calix arene amide groups

Upper rim calix[4]arenes functionalized with two and four ruthenium(II) bi-pyridyl amide groups (136 and 137) have very recently been prepared (258). These receptors also sense the presence of dihydrogen phosphate anions selectively. 

By arranging two amide groups in a parallel arrangement in space, Cameron and Loeb developed a set of receptors that are selective for Y-shaped carboxylate anions over tetrahedral or pseudotetrahedral OxO-anions. Calix[4]arenes 15.16,and 17 were synthesized by reaction of the upper-rim calix[4]arene h/.s-amine with mono-, di-. or trichloroacetyl chloride. Receptor 16 proved to have the highest affinity for anionic guests. For example, receptor... 

As we have seen. calix[4]arenes offer an organic scaffold upon which receptors may be constructed. Gale. Loeb, and coworkers also used a platinum tetrapyridine complex as an inorganic scaffold with which to arrange amide groups in space. The square planar Pt(II)... 

The polymers 12a, 12b and 12c exhibit high absorption capacities towards soft cations, such as Ag and Hg, in comparison with that hard cations (Na, K ). These results are in accordance with the characteristic amide group, which is easily to bind soft cations but difficult to hard cations. On the other hand, it can be noticed that the absorption capacities towards cations show the selectivity order of polymers 12a > 12b > 12c, which indicates that the cavities of calix[6]arene play important role in cations bindings. 

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