EXTRACTIVE PROPERTIES TOWARDS RARE-EARTH METAL IONS OF CALIX[ 4] ARENES SUBSTITUTED AT THE NARROW RIM BY PHOSPHORYL AND AMIDE GROUPS

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Abstract
The extractive properties of the cone and partial-cone isomers of 5,11,17,23-tetra-?ert-butyl-25,27-bis( diethylcarbamoylmethoxy)-26,28-bisi( diphenylphospninoylmethoxy) calyx[ 4] arene ( cone-1 and partial-cone -1) in 1,2-dichloroethane towards rare-earth metal ions in nitrate media at 25 ° C were investigated. The analysis of the extraction equilibrium obtained from a mixture of four rare-earths ( La, Eu, Er and Y) revealed that the extracted species have a 1 1 metal/ ligand ratio for both ligands. The intra-group separation efficiercies of the ligandls have been evaluated in a competitive extraction process of 11 rare-earth metal ions ( La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y). Significantly higher extractive properties were found for cone-1 with respect to partial-cone-1, suggesting the crucial role of the phosphoryl groups in the complexation of the rare-earth ions. These findings were