Calixarenes for metal cations extraction

The synthesis of a series of chromogenic calix [4]arenes derivatives is described. Different chelating agents as ester, amide, bipyridyl and bithiazolyl moieties were grafted on the lower rim of p-phenylazocalix [4]arenes. In addition, a calixarene bearing two beta-ketoimine groups has been synthesized. Their extraction properties were studied by liquid-liquid extraction. The results show that the ester/amide azocalix [4]arene derivatives have an affinity for alkali metal ions whereas beta-ketoimine calix [4]arene exhibits a good affinity and selectivity towards Pb2+. In the case of biheterocyclic calixarenes, bipyridyl and bithiazolyl derivatives have a similar behavior with a slight affinity for Cu2+ and Ag+. Their homologous thiacalix [4]arene derivatives give the best extraction percentages and have the best efficiency for the extraction Of Cu2+ and Ag+. (c) 2005 Academie des sciences. Published by Elsevier SAS. All rights reserved.