Extraction and complexation of americium(III) and europium(III) by a N-donor ligand of 3,5-bis(2-pyridyl)pyrazole

Ionic Liquid as a N,O-Donor Ligand-Based Extraction System Modifier: Establishing the Mechanism of Am(III)-Selectivity Increasing

In this work, we studied the extraction systems for the separation f-elements based on the tetradentate N,O-donor ligand di(N-ethyl-4-ethylanilide) 2,2'-dipyridyl-6,6'-dicarboxylic acid (L). The organic phase of these systems was perspective fluorine-containing organic solvents-metanitrobenzotrifluoride (F-3), ionic liquid C4mimNTf2 (IL), and their mixture. The increase of Am(III) selectivity in the presence of Ln(III) in cases of the diluent mixture was shown. The mechanism of the f-element complexation leading to the improved properties of the extraction systems was studied by UV-visible, Raman-spectroscopy, XRD-study, and density functional theory calculations.

A metal-organic framework-supported dinuclear iron catalyst for hydroboration of carbonyl compounds

Preparation of catalytically active dinuclear transition metal complexes with an open coordination sphere is a challenging task because the metal sites tend to be "saturated" with excess donor atoms around during synthesis. By isolating the binding scaffolds with the metal-organic framework (MOF) skeleton and installing metal sites through post-synthetic modification, we succeed in constructing a MOF-supported metal catalyst, namely FICN-7-Fe2, with dinuclear Fe₂ sites. FICN-7-Fe2 effectively catalyses the hydroboration of a broad range of ketone, aldehyde, and imine substrates with a low loading of 0.05 mol%. Remarkably, kinetic measurements showed that FICN-7-Fe2 is 15 times more active than its mononuclear counterpart FICN-7-Fe1, indicating that cooperative substrate activation on the two Fe centres significantly enhances the catalysis.

High-valent iron-oxo species on pyridine-containing MWCNTs generated in a solar-induced H2O2 activation system for the removal of antimicrobials

The overuse of antimicrobials has resulted in serious damage to the ecosystem and human health. Therefore, the development of an efficient, stable, and reusable catalyst to eliminate antimicrobials under mild conditions is highly desired. Drawing inspiration from the metabolism of drugs by the enzymes in the human body, such as heme catalase, we developed a simulated enzyme catalyst, perchloride iron phthalocyanine (FePcCl₁₆), immobilized on pyridine-modified multiwalled carbon nanotubes (FePcCl₁₆-Py-MWCNTs). In the catalyst, FePcCl₁₆ worked as the active site, and the axial fifth ligand, 4-aminopyridine, was introduced to cleave H₂O₂ heterolytically. Inspired by the reaction mechanism of heme catalase and H₂O₂, the catalytic system was designed based on FePcCl₁₆-Py-MWCNTs for oxidizing 4-chloro-3,5-dimethylphenol (PCMX) by H₂O₂ activation. The results showed that the catalytic activity of the system was significantly increased under simulated solar light irradiation, which can promote electron transfer for heterolytic cleavage of H₂O₂. The enzyme-like catalyst achieved much higher catalytic activity than the Fenton reaction when the pH was close to neutral. It turned out that the main active species was high-valent iron-oxo (Fe(Ⅳ) = O) rather than hydroxyl radial (•OH) or superoxide radical (•O₂^-), different from most mechanisms. Ultraperformance liquid chromatography-high-definition mass spectrometry showed that the substrate was degraded to small molecule acids by Fe(Ⅳ) = O active species and further mineralization indicated by total organic carbon. The catalytic system exhibited highly efficient, stable, recyclable catalytic performance under mild conditions and did not cause secondary pollution to the environment. This study of a simulated enzyme catalytic system offers important insight into sewage treatment.

Tailoring the selectivity of phenanthroline derivatives for the partitioning of trivalent Am/Eu ions – a relativistic DFT study

Preferential binding of actinides over lanthanides using tailored phenanthroline derivative ligands through relativistic DFT calculations.

Selective Separation and Coordination of Europium(III) and Americium(III) by Bisdiglycolamide Ligands: Solvent Extraction, Spectroscopy, and DFT Calculations

Diglycolamide-based ligands have recently received increased attention due to their outstanding affinity for trivalent actinides and lanthanides. The structure optimization of the ligands, however, still remains a hot topic to achieve better extraction performance. In this work, we prepare and investigate three multidentate diglycolamide ligands for the selective separation of Eu(III) over Am(III) from a nitric acid solution to explore the effect on the extraction of alkyl groups on the nitrogen atoms in the center of the BisDGA ligands. The introduction of ethyl or isopropyl groups on the central nitrogen atoms greatly increased the distribution ratios of trivalent metal ions and enhanced the separation factor of Eu(III) over Am(III). The complexation behaviors of Eu(III) and Am(III) ions were studied by slope analyses, electrospray ionization mass spectrometry (ESI-MS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. The results indicated that the trivalent metal ions were extracted as 1:2 and 1:3 complexes for all three BisDGA ligands during the extraction. Density functional theory (DFT) calculations verified the relevant experimental conclusion that the selectivity of THEE-BisDGA for Eu(III) is better than that for Am(III). The metal-DGA bonds in the ML₃(NO₃)₃ complexes seem to be stronger than those in ML₂(NO₃)₃ complexes.