Tetrafunctionalized resorcinarene cavitands (4−6) have been synthesized starting from tetrakis(bromomethyl)cavitand 3. New cavitand-based cation ligands with (carbamoylmethyl)phosphonate (CMP) and -phosphine oxide (CMPO) moieties (8a,b and 9a,b) were prepared via two different routes in good (45−86%) overall yields. The ligands (8a,b and 9b) are very effective europium extractants. Ph2CMPON(Pr)-cavitand 8b has the highest extraction constant, determined with radiotracer experiments, for 1:1 complexation with Eu(picrate)3 (Kex1 = 2.7 × 1012 M-4). The steric preorganization of the four CMP(O) moieties on the resorcinarene cavitand improves the efficiency and selectivity [of Eu(III) over UO2(II) and Fe(III)] of the metal extraction processes, compared to simple CMP(O) extractants.

Novel Resorcinarene Cavitand-Based CMP(O) Cation Ligands: Synthesis and Extraction Properties.

The aqueous geochemistry of the rare-earth elements: Critical stability constants for complexes with simple car☐ylic acids at 25°C and 1 bar and their application to nuclear waste management

Citrate complexes are the dominant binding form of trivalent actinides and lanthanides in human urine at pH < 6. Hence, an accurate prediction of the speciation of these elements in the presence of citrate is crucial for the understanding of their impact on the metabolism of the human organism and the corresponding health risks. We studied the complexation of Cm(III) and Eu(III), as representatives of trivalent actinides and lanthanides, respectively, in aqueous citrate solution over a wide pH range using time-resolved laser-induced fluorescence spectroscopy. Four distinct citrate complexes were identified and their stability constants were determined, which are MHCit0, M(HCitH)HCit2−, M(HCit)23−, and M(Cit)25− (M = Cm, Eu). Additionally, there were also indications for the formation of MCit− complexes. Structural details on the EuHCit0 and EuCit− complexes were obtained with FT-IR spectroscopy in combination with density functional theory calculations. IR spectroscopic evidence for the deprotonation of the hydroxyl group of the citrate ion in the EuCit− complex is presented, which also revealed that the complexation of the Eu3+ ion takes place not only through the carboxylate groups, like in EuHCit0, but additionally via the hydroxylate group. In both EuHCit0 and EuCit− the carboxylate binding mode is mono-dentate. Under a very low metal : citrate ratio that is typical for human body fluids, the Cm(III) and Eu(III) speciation was found to be strongly pH-dependent. The Cm(III) and Eu(III) citrate complexes dominant in human urine at pH < 6 were identified to be Cm(HCitH)HCit2− and a mixture of Eu(HCitH)HCit2− and EuHCit0. The results specify our previous in vitro study using natural human urine samples (Heller et al., Chem. Res. Toxicol., 2011, 24, 193–203).

Curium(III) citrate speciation in biological systems: a europium(III) assisted spectroscopic and quantum chemical study

Nuclear data sheets for A = 149

Short-lived isotopes of lanthanum, cerium and praseodymium studied by SISAK-technique

A study of citrate complexes of several lanthanides

The separation of fission-product La, Ce, Pr, Nd and Y was performed in 4 min by electro-migration. As complexing agent, nitrilotriacetic acid was used at two concentrations of the NTA ion selected so as to optimize mutual separation of the elements. Rapid location of the zone on the paper strip reached after migration was obtained by color reaction of the carrier added to the irradiated sample. The purity of the elements thus separated was checked by γ-ray spectrometry. At the higher concentration of NTA ([[NTA]=1.0×10−2M, pH=4.1) under which all of rare earths and Y migrate toward the anode, the elements were well separated from each other, although appreciable amounts of other F.P. were also found in each fraction. On the other hand, at the lower NTA concentration ([NTA]=4.0 × 10−3M, pH=2.0) where the F.P. all migrate toward the cathode, each zone contained the isotopes of the respective element almost exclusively, except for a few small photo-peaks attributable to other elements. In each fraction, the...

Rapid Separation of Fission-Product Rare Earths and Yttrium by Electromigration

Short-lived isotopes of lanthanum, cerium and praseodymium in neutron irradiated uranium☆

A study of complexes with a polybasic acid: Am(III) citrate complexes

Rapid separation using NTA in paper electromigration was applied to the study of the γ-decay of 148Pr and 149Pr produced in the fission of 235U. The γ-ray spectrum was measured with a high-resolution Ge(Li) detector. The γ-transitions found to decay with half-lives shorter than 3 min were: 135, 162, 256, 300, 511, 614, 696, 868, 1,022 and 1,248 keV. Of these, the values of 300 keV, and of 135 and 162 keV were in fair agreement with those reported for 148Pr and 149Pr. The decay plot of the strong photopeak of 300 keV presented good linearity and the accurate half-life of 148Pr could be determined as 2.30±0.03 min, which is longer than the 1.98 min reported for 148Pr. Similar decay plots of both photopeaks at 135 and 162 keV gave a half-life of 2.9±0.1 min for 149Pr, which again is longer than the reported value of 2.3 min. Other low intensity photopeaks at 256, 696, 868 and 1,022 keV decaying with half-lives of 2.1∼2.4 min can possibly be attributed to 148Pr. The γ-transitions of 110, 578 and 742 keV repor...

Emiko Ohyoshi

Papers

A study of citrate complexes of several lanthanides

Rapid Separation of Fission-Product Rare Earths and Yttrium by Electromigration

Short-lived isotopes of lanthanum, cerium and praseodymium in neutron irradiated uranium☆

A study of complexes with a polybasic acid: Am(III) citrate complexes

Gamma-Ray Energies and Half-Lives of Praseodymium-148 and -149