Calixarenes for metal cations extraction

Abstract

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 β-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 β-ketoimine calix [4]arene exhibits a good affinity and selectivity towards Pb 2+ . In the case of biheterocyclic calixarenes, bipyridyl and bithiazolyl derivatives have a similar behavior with a slight affinity for Cu 2+ and Ag + . Their homologous thiacalix [4]arene derivatives give the best extraction percentages and have the best efficiency for the extraction of Cu 2+ and Ag + . .