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

ABSTRACT: A new series of lanthanide (1-5) and uranyl (6) complexes with a tetra-substituted bifunctional calixarene ligand H₂ L is described. The coordination environment for the Ln³⁺ and UO₂ ²⁺ 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: La³⁺ , Pr³⁺ ; intermediate: Eu³⁺ and Gd³⁺ ; and heavy: Yb³⁺ ), as well as the uranyl cation (UO₂ ²⁺ ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2 : 2 M : L, [Ln₂ (L)₂ (H₂ O)]²⁺ (1-5), in solution, whereas uranyl formed a 1 : 1 M : L complex [UO₂ (L)(MeOH)]_∞ (6) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H₂ L was found to be an effective extracting agent for UO₂ ²⁺ over La³⁺ and Yb³⁺ cations. The separation factors at pH 6.0 are: β_UO 22+ _/La 3+ =121.0 and β_UO 22+ _/Yb 3+ =70.0.

SUBMITTER: Glasneck F 

PROVIDER: S-EPMC9306641 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature