Effect of counter-anions on the adsorption of trivalent actinides and lanthanides on tertiary pyridine resin in alcoholic chloride and nitrate solutions

Ikeda, Atsushi; Itoh, K.; Suzuki, Tatsuya; Aida, Masao; Fujii, Yasuhiko; Mitsugashira, Toshiaki; Hara, Mitsuo; Ozawa, Masaki

doi:10.1016/j.jallcom.2004.11.096

Cited by 11 publications

(13 citation statements)

References 29 publications

(35 reference statements)

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“…Nitrate is known to be a better counter ion for lanthanide ions than chloride. (27-29) Lastly, for all the complexes the amount of the free metal ion determined by uv/vis spectroscopic method was 0.002% (0.2uM/10 mM) of the total. (30) Indeed, if one examines the synthesis of the DTPA[Gd(III)] complex directly from DTPA and Gd 2 O 3 , this route produces a diprotonated complex that requires the addition of two equivalents of base to make this complex physiologically acceptable.…”

Section: Resultsmentioning

confidence: 94%

A New Approach in the Preparation of Dendrimer-Based Bifunctional Diethylenetriaminepentaacetic Acid MR Contrast Agent Derivatives

Nwe

Regino

et al. 2009

Bioconjugate Chem.

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In this paper we report a new method to prepare and characterize a contrast agent based on a fourthgeneration (G4) polyamidoamine (PAMAM) dendrimer conjugated to the gadolinium complex of the bifunctional diethylenetriamine pentaacetic acid derivative (1B4M-DTPA). The method involves pre-forming the metal-ligand chelate in alcohol prior to conjugation to the dendrimer. The dendrimerbased agent was purified by a Sephadex® G-25 column and characterized by elemental analysis. The analysis and SEHPLC data gave a chelate to dendrimer ratio of 30:1 suggesting conjugation at approximately every other amine terminal on the dendrimer. Molar relaxivity of the agent measured at pH 7.4 displayed a higher value than that of the analogous G4 dendrimer based agent prepared by the post-metal incorporation method (r 1 = 26.9 vs. 13.9 mM -1 s -1 at 3T and 22°C). This is hypothesized to be due to the higher hydrophobicity of this conjugate, and the lack of available charged carboxylate groups from non-complexed free ligands that might coordinate to the metal and thus also reduce water exchange sites. Additionally, the distribution populations of compounds that result from the post-metal incorporation route are eliminated from the current product simplifying characterization as quality control issues pertaining to the production of such agents for clinical use as MR contrast agents. In vivo imaging in mice showed a reasonably fast clearance (t 1/2 = 24 min) suggesting a viable agent for use in clinical application.

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Section: Resultsmentioning

confidence: 94%

A New Approach in the Preparation of Dendrimer-Based Bifunctional Diethylenetriaminepentaacetic Acid MR Contrast Agent Derivatives

Nwe

Regino

et al. 2009

Bioconjugate Chem.

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“…Nitrogen-donating ligands are softer than oxygen and often are incorporated into an aromatic ring. The pyridine resin (Figure ) has been used in the separation of rare-earth ions. ,,− The unprotonated resin has a higher affinity for actinides and lanthanides than the protonated form, which supports the hypothesis that the ions bind to the free nitrogen . Time-resolved laser-induced fluorescence spectroscopy was used to study the coordination states of Eu(III) in the pyridine resin. , It has a higher affinity for actinides than lanthanides from aqueous methanol solutions that contain either HCl or LiCl, because of the modest enhancement of covalency involving actinide s or p orbitals.…”

Section: Polymer-supported Reagents For Trivalent Lanthanide and Acti...mentioning

confidence: 96%

Affinity of Polymer-Supported Reagents for Lanthanides as a Function of Donor Atom Polarizability

Yang

Alexandratos

2009

Ind. Eng. Chem. Res.

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This review correlates lanthanide-ion affinities with the polarizability of the donor atoms on immobilized ligands to gain an insight into the design of lanthanide-selective polymer-supported reagents. Comparison with the affinities for actinide ions clarifies the correlation. Polymers with different ligands are classified into four categories, based on an increasing order of donor atom polarizability: oxygen, oxygen and nitrogen, nitrogen, and sulfur. Hard−soft acid−base theory is an important determinant of ion−ligand affinities. Additional factors that affect complexation levels include counterion coordination to the metal, protonation of the ligand, and hydration. Selectivity for the lanthanide ions may be engineered into polymer-supported reagents by introducing phosphonic acid ligands.

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“…Unlike a trend that is monotonic, this bell-shaped trend is not explained by any single property used to characterize the lanthanides: ionic radius, third ionization energy, ionization potential, electronegativity, or hydration energy (Table ). A continuously increasing or decreasing trend along the series has been reported with polymer-supported complexants with pyridine and sulfonic acid ligands …”

Section: Discussionmentioning

confidence: 86%

Mechanism of Ionic Recognition by Polymer-Supported Reagents: Immobilized Tetramethylmalonamide and the Complexation of Lanthanide Ions

Yang

Alexandratos

2010

Inorg. Chem.

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The mechanism of ionic recognition by polymer-supported reagents is probed with cross-linked polystyrene modified with tetramethylmalonamide (TMMA) ligands. The substrates are lanthanide ions in 0.001-8 M HCl and HNO(3) solutions. The results fall into three regions of acid concentration: low, mid, and high. In HCl, distribution coefficients are low in 0.001 to 2 M, increase in 4 and 6 M, and then decrease in 8 M HCl. In the low-acid region, the metal ion remains with its waters of hydration and does not coordinate to the carbonyl oxygens. As the acid concentration exceeds 2 M, protonation of the amide occurs to form an iminium moiety, electrostatically attracting the anionic lanthanide complex through ion-exchange and releasing waters of hydration. At high acid concentration, the apparent affinity decreases due to competition by the large excess of chloride ions for the ion-exchange sites. The affinity sequence in 6 M HCl is Tb > Dy > Eu > Gd > Ho > Sm > Er > Tm > Yb > Lu > Nd > Ce > La. The TMMA-Ln interaction is due to recognition since there is a point of maximum affinity across the series rather than a monotonic trend. The trends are comparable in HNO(3). A comparison of the distribution coefficients at the maxima (6 M HCl and 4 M HNO(3)) shows nitrate to have greater values than chloride due to a hydration effect, as also indicated by results from H(2)SO(4).

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Effect of counter-anions on the adsorption of trivalent actinides and lanthanides on tertiary pyridine resin in alcoholic chloride and nitrate solutions

Cited by 11 publications

References 29 publications

A New Approach in the Preparation of Dendrimer-Based Bifunctional Diethylenetriaminepentaacetic Acid MR Contrast Agent Derivatives

A New Approach in the Preparation of Dendrimer-Based Bifunctional Diethylenetriaminepentaacetic Acid MR Contrast Agent Derivatives

Affinity of Polymer-Supported Reagents for Lanthanides as a Function of Donor Atom Polarizability

Mechanism of Ionic Recognition by Polymer-Supported Reagents: Immobilized Tetramethylmalonamide and the Complexation of Lanthanide Ions

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