Unraveling the complexation mechanism of actinide(iii) and lanthanide(iii) with a new tetradentate phenanthroline-derived phosphonate ligand

Abstract

The separation and complexation mechanisms of actinide(iii) and lanthanide(iii) with a new phenanthroline-derived phosphonate ligand were studied experimentally and theoretically.

Comparative Investigation into the Complexation and Extraction Properties of Tridentate and Tetradentate Phosphine Oxide‐Functionalized 1,10‐Phenanthroline Ligands toward Lanthanides and Actinides

“…Based on the single crystal structure of the 1 : 1 Eu III complex with L 1 (Figure 6), the 10‐coordinated 1 : 1 Eu III and Am III complexes with L 1 were optimized (Figure 9). Similar complexation modes of the 1 : 1 Eu III or Am III complexes have also been reported in other tetradentate phenanthroline derivatives [9f,10a,b,26] . For the 1 : 2 species, the 10‐coordinated Am III and Eu III complexes with L 1 were also optimized (Figure 9) on the basis of other similar 1 : 2 Eu III complexes that have been confirmed by single X‐ray crystallography in [Eu(CyMe 4 ‐BTPhen) 2 NO 3 ] 2+ and [Eu(CyMe 4 ‐BTBP) 2 NO 3 ] 2+ cations [8a,27] .…”

“…As listed in Table 1, the cumulative stability constants (log β ) for the formation of 1 : 1 and 1 : 2 complexes of NdL 3+ and NdL 2 3+ with L 1 were determined as 6.15±0.01 and 10.48±0.10, respectively, which are around one order of magnitude larger than that of the corresponding 1 : 1 and 1 : 2 Nd III complexes with L 2 (log β 1 =5.16±0.15, log β 2 =10.07±0.03), C2‐POPhen (5.15±0.01) [10a] and C4‐POPhen (5.43±0.02) [10b] under the same conditions. These results suggest that the tetradentate L 1 has stronger affinity to lanthanides than those of the tridentate L 2 or tetradentate phenanthroline‐derived phosphonate type ligands, further confirming the stronger binding ability of phosphine oxide (−P=O(R) 2 ) group than that of phosphonate (−P=O(OR) 2 ) moiety toward lanthanides.…”

“…As reported previously, [10a,b,13] NMR spectroscopy titration is a very effective method to probe the speciation and structure of organic ligands, especially those containing aromatic protons or P and F atoms, when complexing with diamagnetic metal ions in solution. Here, the 31 P NMR titrations of L 1 and L 2 with two diamagnetic lanthanides La(NO 3 ) 3 and Lu(NO 3 ) 3 , which is the first and the last lanthanide element with the biggest difference in the Ln III serial, in deuterated methanol were performed to determine the complexation species formed between two ligands and trivalent lanthanides.…”

Preorganization of N,O-hybrid phosphine oxide chelators for effective extraction of trivalent Am/Eu ions – a computational study

“…33 Recently, one class of N,O-mixed phenanthroline-derived phosphonate ligands has been developed for the extraction actinides over lanthanides. 34,35 It has been found that C2-POPhen held more extraction capability toward trivalent lanthanides and actinides than the N,N 0 -diethyl-N,N 0 -ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) ligand. 36 It is notable that the replacement of phosphonate (-PQO(OR) 2 ) with phosphine oxide (-PQO(R) 2 ) could intensify the basicity of O donors.…”

Influence of Electronic Modulation of Phenanthroline-Derived Ligands on Separation of Lanthanides and Actinides

“…The calculated protonation constants of four BTPhen ligands are presented in Table 1 . As we can see from Table 1 , the original large dipole moment of phenanthroline makes it able to coordinate with H + even with the effect of withdrawing electrons by biliteral triazine [ 32 ]. The protonation process caused the alteration of the chemical environment of H3, H4, H5, H6, H7, and H8 at the corresponding carbon C3, C4, C5, C6, C7, and C8.…”