Effect of p-tert-Butylcalix[4]arene Fitted with Phosphinoyl Pendant Arms as Synergistic Agent in the Solvent Extraction and Separation of Some Trivalent Lanthanoids with 4-Benzoyl-3-methyl-1-phenyl-5-pyrazolone

Assessment of the Equilibrium Constants of Mixed Complexes of Rare Earth Elements with Acidic (Chelating) and Organophosphorus Ligands

A survey of the experimental equilibrium constants in solution for the mixed complexes of 4f ions with acidic (chelating) and O-donor organophosphorus ligands published in the period between 1954 and 2022 is presented. These data are widely used in both analytical and solvent extraction chemistry. Important data evaluation criteria involved the specification of the essential reactions, process conditions and the correctness of techniques and calculations used, as well as appropriate equilibrium analysis of experimental data. Higher-quality data have been evaluated, compiled and presented herein, providing a synoptic view of the unifying theme in this area of research, i.e., synergism.

Synergism as a phenomenon in solvent extraction of 4f-elements with calixarenes

The objective of the review is to provide an overview on the synergistic solvent extraction of lanthanoids: β-diketone/calixarene mixtures.

Are fancy acidic or neutral ligands really needed for synergism in ionic liquids? A comparative study of lanthanoid extraction in CHCl3 and an ionic liquid

Five lanthanoid ions were extracted with 3-methyl-1-phenyl-4-(4-phenylbenzoyl)-pyrazol-5-one in combination with calix[4]arene as a synergistic agent using CHCl₃ or 1-butyl-3-methylimidazolium-bis(trifluoromethanesulfonyl)imide as solvent.

Comparing extraction, synergism and separation of lanthanoids using acidic and neutral compounds in chloroform and one ionic liquid: is the latter always “better”?

Five lanthanoid ions were extracted with 3-methyl-1-phenyl-4-(4-trifluoromethylbenzoyl)-pyrazol-5-one alone and in combination with partially substituted calix[4]arenes as synergistic agents using CHCl₃ and one IL.

Uranyl complexes formed with a para-t-butylcalix[4]arene bearing phosphinoyl pendant arms on the lower rim. Solid and solution studies

The current interest in functionalized calixarenes with phosphorylated pendant arms resides in their coordination ability towards f elements and capability towards actinide/rare earth separation. Uranyl cation forms 1:1 and 1:2 (M:L) complexes with a tetra-phosphinoylated p-tert-butylcalix[4]arene, B4bL4: UO2(NO3)2(B4bL4) n · xH2O (n = 1, x = 2, 1; n = 2, x = 6, 2). Spectroscopic data point to the inner coordination sphere of 1 containing one monodentate nitrate anion, one water molecule and the four phosphinoylated arms bound to UO2 2+ while in 2, uranyl is only coordinated to calixarene ligands. In both cases the U(VI) ion is 8-coordinate. Uranyl complexes display enhanced metal-centred luminescence due to energy transfer from the calixarene ligands; the luminescence decays are bi-exponential with associated lifetimes in the ranges 220 μs <τ s <250 μs and 630 μs <τ L < 640 μs, pointing to the presence of two species with differently coordinated calixarene, as substantiated by a XPS study of U(4f 5/2,7/2), O(1s) and P(2p) levels on solid state samples. The extraction study of UO2 2+ cation and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B4bL4 in chloroform shows the uranyl cation being much more extracted than rare earths.