Exploring electronic effects on the partitioning of actinides(iii) from lanthanides(iii) using functionalised bis-triazinyl phenanthroline ligands

Abstract

The first examples of 4,7-disubstituted 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzo-triazin-3-yl)-1,10-phenanthroline (CyMe-BTPhen) ligands are reported herein. Evaluating the kinetics, selectivity and stoichiometry of actinide(iii) and lanthanide(iii) radiotracer extractions has provided a mechanistic insight into the extraction process. For the first time, it has been demonstrated that metal ion extraction kinetics can be modulated by backbone functionalisation and a promising new CHON compliant candidate ligand with enhanced metal ion extraction kinetics has been identified. The effects of 4,7-functionalisation on the equilibrium metal ion distribution ratios are far more pronounced than those of 5,6-functionalisation. The complexation of Cm(iii) with two of the functionalised ligands was investigated by TRLFS and, at equilibrium, species of 1 : 2 [M : L] stoichiometry were observed exclusively. A direct correlation between the E-E energy gap and metal ion extraction potential is reported, with DFT studies reaffirming experimental findings.

Efficient Separation of Light Lanthanides(III) by Using Bis‐Lactam Phenanthroline Ligands

“…Only ah andful of neutral ligandst hat exhibit high selectivity for light lanthanides in solvent extraction systems have been previously described. [5][6][7][8] Them ajorityo ft he known ligandse xhibit the reverse trend, that is, by being more selectivet owardsh eavy lanthanides.E xamples include acidic compounds, such as bis(2-ethylhexyl) phosphoric acid (D2EHPA), [9] am ixture of phosphinica nd phosphonic acids (Cyanex572) [10] and bis(2ethylhexyl)phosphinic acid, [11] and neutral compounds, [12] such as N,N,N',N'-tetraoctyldiglycolamide (TODGA), [13][14][15] trialkylphosphine oxides( e.g.,C yanex9 23) [16] and bis-triazinylpyridine, [17][18][19] to mention but afew.…”

New Insights into the Recovery of Strategic and Critical Metals by Solvent Extraction

“…The effect of electronic variation of BTPhen on the extraction of An/Ln was studied (Figure 4, right) and showed order-of-magnitude differences in distribution ratios while maintaining a high separation factor (SFAm/Eu ca. 110) [22]. The extraction mechanism was studied for Cm(III) by time-resolved laser-induced fluorescence spectroscopy (TRLFS).…”

Direct Selective Extraction of Trivalent Americium from PUREX Raffinate Using a Combination of CyMe4BTPhen and TEDGA—A Feasibility Study

“…Only distribution ratios of lanthanides(III) have been reported. [23,[37][38] Higginson et al reported on the application of CyMe 4 BTPhen as extractant in a liquid-liquid extraction process for nuclear forensics application from chloride media [39] and in an immobilized form as Me 4 BTPhen for the same application. [40] They found Cd(II) to be co-extracted by CyMe 4 BTPhen, but didn't test all the fission and activation products present in used nuclear fuel.…”