Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes

A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.

ChemInform Abstract: Conformationally Mobile Wide Rim Carbamoylmethylphosphine Oxide (CMPO)-Calixarenes.

Conformationally Mobile Wide Rim Carbamoylmethylphosphine Oxide (CMPO)-Calixarenes

Six new calix[4]arene derivatives 2a–f have been synthesised, bearing CMPO-like functions (-NH–C(O)–CH2–P(O)Ph2) at their wide rim. They differ by their alkoxy groups at the narrow rim, comprising all possible combinations of methoxy and syn-propoxy groups including the conformationally mobile tetramethyl ether 2e and the tetrapropyl ether 2f fixed in the cone conformation. Their extraction behaviour for thorium(IV) and several lanthanides(III) from 1M HNO3 to dichloromethane has been studied and compared also to non cyclic calixarene analogues 6a–e. Surprisingly the best extraction results were found for the 1,2-dimethoxy-3,4-dipropoxy derivative 2c among the calixarenes and for the tetram…

Calix[4]arenes as Selective Extracting Agents. An NMR Dynamic and Conformational Investigation of the Lanthanide(III) and Thorium(IV) Complexes

The lanthanide and Th4+ complexes with calix[4]arene ligands substituted either on the narrow or at the wide rim by four coordinating groups behave totally differently as shown by an NMR investigation of the dia- and paramagnetic complexes. Solutions of complexes were prepared by reacting anhydrous metal perchlorate salts with the ligands in dry acetonitrile (CAUTION). Relaxation time T1 titrations of acetonitrile solutions of Gd3+ by calixarenes indicate that ligands subsituted on the narrow rim form stable 1:1 complexes whether they feature four amide groups (1) or four phosphine oxide functions. In contrast, a ligand substituted by four (carbamoylmethyl)-diphenylphosphine oxide moieties …

ChemInform Abstract: Tropylium Cation Capsule of Hydrogen-Bonded Tetraurea Calix[4]arene Dimers.

Separation of lanthanides and actinides using magnetic silica particles bearing covalently attached tetra-CMPO-calix[4]arenes

Calix[4]arene tetraethers in the cone conformation bearing four –NH–CO–CH2–P(O)Ph2 (= CMPO) residues on their wide rim and one, two or four ω-amino alkyl residues of various lengths at the narrow rim were synthesized. Reaction with dichlorotriazinyl (DCT) functionalized magnetic particles led to complete coverage of the available surface by covalently linked CMPO-calix[4]arenes in all cases. Magnetically assisted removal of Eu(III) and Am(III) from acidic solutions was distinctly more efficient with these particles in comparison to analogous particles bearing the same amount of analogous single-chain CMPO-functions. The best result, an increase of the extraction efficiency by a factor of 14…

Tropylium cation capsule of hydrogen-bonded tetraurea calix[4]arene dimers

The interaction between tropylium salts and tetraurea calix[4]arene derivatives (such as 1 and 2) was studied in solution using 1D, 2D, diffusion, VT NMR and UV–visible spectroscopy. It was found that tropylium salts form charge transfer complexes with both the monomers and dimers of the tetraurea calix[4]arene derivatives depending on the experimental conditions. Compound 1 increases dramatically the solubility of tropylium salts in apolar solvents such as C2D4Cl2, CDCl3 and CD2Cl2 by forming the molecular capsule 1·C7H7+·1. In contrast to the benzene capsule of 1, in 1·C7H7+·1 the hydrogen bonds in the equatorial region that hold together the two parts of the dimer change their directiona…