Tetra-Substituted p-Tert-Butylcalix[4]Arene with Phosphoryl and Salicylamide Functional Groups: Synthesis, Complexation and Selective Extraction of f-Element Cations.

A new series of lanthanide (1-5) and uranyl (6) complexes with a tetra-substituted bifunctional calixarene ligand H L is described. The coordination environment for the Ln and UO ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert-butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La , Pr ; intermediate: Eu and Gd ; and heavy: Yb ), as well as the uranyl cation (UO ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry.