Printed in Great Britain. (B 1995 IUPAC

ABSTRACT: The synthesis of 1,2- and 1,3-calix[4]-bzs-crowns, double calix[4]arenes and double-calix-crowns have been shown to depend on the reaction conditions (nature of the base, structure of the ditosylates, and the stoichiometry of the reactants). The 1,3-alternate conformation of the 1,3-calix[4]-bis-crowns was shown to be favourable to the selective complexation of cesium cation. The observed Na+/Cs+ selectivity was exploited in separation processes using them as carriers in transport throught supported liquid membranes (SLMs). The best Na+/Cs+ selectivity (1/49000) was observed for the naphtyl derivative 2. Calix(aza)crowns and 1,3-~alix[4]-bZs-(aza)-crowns were also produced throught the preliminary formation of the Schiff-base-calixarenes which were hrther hydrogenated. The syntheses consisted or via the 1,3-selective alkylation of calixarenes followed by cyclization into a 1,3-bridge either the direct 1,3-capping of the calixarene with appropriate ditosylates. Soft metal complexation by these ligands is also presented