CALIXCROWNS AND RELATED MOLECULES

The synthesis of 1,2- and 1,3-calix[4]-bis-crowns, double calix[4]aren es and double-calix-crowns have been shown to depend on the reaction c onditions (nature of the base, structure of the ditosylates, and the s toichiometry of the reactants). The 1,3-alternate conformation of the 1,3-calix[4]-bis-crowns was shown to be favourable to the selective co mplexation of cesium cation. The observed Na+/Cs+ selectivity was expl oited in separation processes using them as carriers in transport thro ught supported liquid membranes (SLMs). The best Na+/Cs+ selectivity ( 1/49000) was observed for the naphtyl derivative ($) under bar 7. Cali x(aza)crowns and 1,3-calix[4]-bis-(aza)-crowns were also produced thro ught the preliminary formation of the Schiff-base-calixarenes which we re further hydrogenated. The syntheses consisted or via the 1,3-select ive alkylation of calixarenes followed by cyclization into a 1,3-bridg e either the direct 1,3-capping of the calixarene with appropriate dit osylates. Soft metal complexation by these ligands is also presented.