Calixarenes triple

Macrocycles containing isoxazoline or isoxazole ring systems, potential receptors in host—guest chemistry, have been prepared by multiple (double, triple or quadruple) 1,3-dipolar cycloadditions of nitrile oxides, (prepared in situ from hydroxamoyl chlorides) to bifunctional calixarenes, ethylene glycols, or silanes containing unsaturated ester or alkene moieties (453). This one-pot synthetic method has been readily extended to the preparation of different types of macrocycles such as cyclophanes, bis-calix[4]arenes and sila-macrocycles. The ring size of macrocycles can be controlled by appropriate choices of the nitrile oxide precursors and the bifunctional dipolarophiles. Multiple cycloadditive macrocy-clization is a potentially useful method for the synthesis of macrocycles. 

A new convenient strategy for the synthesis of calixarenes via a triple annulation of Fischer carbene complexes, V. Gopalsamuthiram and W. D. Wulff, J. Am. Chem. Soc.,... 

Fig. 13A-C. Topological switching of supramolecular structures by oxidation and reduction on metal ions. A The translocation of an Fe2+/3+ ion within a triple helical structure. B The conformation change of a calixarene in response to the oxidation state of an Fe2+/3+ ion. C The translocation of a cyclophane upon the change in oxidation state of a Cu+/2+ ion...

Since 1991 we have developed the synthesis of macropolycycles containing in their molecular structure the monocyclic structure of calixarenes and crown ether elements. This combination gives a close coupling of the hydrophobic cavity of the calixarenes able to include organic substrates and the metal cation complexing sites of the crown ether, with potential interactions between them. We have already demonstrated evidence of such cation-substrate contact during a triple inclusion by a calixarene [10]. The crystal structure of the Eu(III) complex of his-(homooxa)-p-rerr-butylcalix[4]arene showed the Eu(in) to be coordinated to a DMSO molecule included in the hydrophobic cavity of the calixarene [10]. 

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