CALIXCROWNS AND RELATED MOLECULES

The synthesis of 1,2- and 1,3-calix[4]-bis-crowns, double calix[4]aren es and double calixcrowns have been shown to depend on the reaction co nditions (nature of the base, structure of the ditosylates, and the st oichiometry of the reactants). The 1,3-alternate conformation of the 1 ,3-calix[4]-bis-crowns was shown to be favourable to the selective com plexation of cesium cation. The observed Na+/Cs+ selectivity was explo ited in separation processes using them as carriers in transport throu gh supported liquid membranes (SLMs). The best Na+/Cs+ selectivity (1/ 45 000) was observed far the naphthyl derivative 7. Calix(aza)crowns a nd 1,3-calix[4]-bis-(aza)-crowns were also produced through the prelim inary formation of the Schiff base-calixarenes, which were further hyd rogenated. The syntheses consisted of the 1,3-selective alkylation of calixarenes followed by cyclization into a 1,3-bridged calixarene or b y the direct 1,3-capping of the calixarene with appropriate ditosylate s. Soft metal complexation by these ligands is also presented.