ИСТИНА

We present here the results of our research on the novel calix[4]arene-based heteroditopic host for ion-pair recognition. The hosts of general type 1 are functionalized calixtubes, which are easily available due to the use of 3-R-1- adamantylcalix[4]arenes at the step of bis-calixarene preparation. The well established cation binding site (especially for K+) formed by eight calixtube oxygens is completed with two of four urea groups for anion binging thus providing the heteroditopic action of hosts 1. Calix[4]arenes bearing one, two or four carboxymethyl groups at narrow rim reacted with tryptamine or tryptophane methyl ester to give the heteroditopic hosts through amide formation: the cation binging site is formed by amide oxygens while the anion binding occurs at the indole NHs. The calixarenes with one or two distal indole functionalities at narrow rim undergo inter/intramolecular dimerization when kept in trufluoroacetic acid and then oxidized, thus giving the 2,2’-bisindole-bridged calix[4]arenes 2 and bis-calix[4]arenes 3. The hosts of type 2 possess the more rigid cation binding site if compared to their non-dimerized precursors and also the bisindole fluorophore site for anion recognition.