Calix[4]arenes with CMPO functions at the narrow rim. Synthesis and extraction properties

Calix[6]arene‐Picolinamide Extractants for Radioactive Waste Treatment: Effect of Additional Carboxy Binding Sites in the Pyridine 6‐Positions on Complexation, Extraction Efficiency and An/Ln Separation

“…Owing to the particular extraction conditions used (solvents, synergizer and acidity) and to the stoichiometry of the complexes formed by these multicoordinate ligands [8] in homogeneous solution, a direct comparison with acyclic ligands is not feasible. However, compared with lower-rim calix [4]arene tetracarbamoylmethyldiphenylphosphane oxide derivatives, www.eurjoc.orgcalix [6]arenes 3 and 5 form 1:1 complexes in methanol of similar stabilities (log β = 4.6-6.4 vs. log β = 5.0-6.4 [34] ) and have comparable values of SF Am/Eu in extraction, [35] whereas calix [4]arenes L2 and L3 form slightly less stable complexes in methanol (log β = 5.1-5.7) but are considerably more selective in extraction (SF Am/Eu up to 11.4).…”

Antiproliferative effect on HepaRG cell cultures of new calix[4]arenes. Part II

“…4-[(5-bromopentyl)oxy]benzonitrile [52] in dry DMF and in the presence of NaH as a base gave the desired tetra alkylated calix [4]arene 6 (Scheme 3) [53][54][55]. The use of NaH in DMF ensures the formation of the calix [4]arene in the cone conformation.…”

Advanced Extraction Methods for Actinide/Lanthanide Separations

“…In previous work with Calix [4]arenes and triphenoxymethane molecule appended with CMPO arms, the extraction efficiency of the constructs was amplified by the increased flexibility of the linker between the CMPO and the base skeleton. 34,63 This trend can be attributed to the enhanced ability of ligand to satisfy the geometrical requirements of the metal center, but often, the improvement in binding affinity comes at the expense of selectivity. In 15, the DGA groups are tethered to the triphenoxymethane platform by only two carbons, and to test the effect of the length of this arm linker on the extraction ability, a new tri-substituted diglycolamide was synthesized with three carbons linking the DGA arms to the triphenoxymethane base (17).…”

“…The affinity for lanthanides in these systems varied widely across the series, with the selectivity toward some lanthanides equaling that of the actinides. 34 Additionally, the multi-CMPO ligand systems presented in the literature have thus far lacked definitive characterizations of the ligand-metal complexes formed during the extraction experiments. Such a detailed understanding of the chemical basis for the metal selectivities of these ligands is essential for creating improved metal extracting systems.…”

“…Inspired by this fact, groups in the 1990s attached multiple CMPO moieties to a variety of calixarene and calixarene-like platforms and were able to extract actinides at higher selectivities than seen in comparable experiments with mono-CMPO extractants. [32][33][34][35][36] The most extensively studied group of these ligand systems contained four CMPO moieties tethered to the narrow and wide rims of calix [4]arenes ( Figure 4). These ligand systems have shown increased actinide affinity relative to the mono-CMPO ligands, but their lanthanide selectivity has proved to be less predictable.…”