Stracke Jonas, Weßling Patrik, Sittel Thomas, Meiners Paul, Geist Andreas, Panak Petra J
Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE) P.O. Box 3640 76021 Karlsruhe Germany
Heidelberg University, Institut für Physikalische Chemie Im Neuenheimer Feld 253 69120 Heidelberg Germany.
RSC Adv. 2024 Sep 5;14(39):28415-28422. doi: 10.1039/d4ra05630b. eCollection 2024 Sep 4.
To improve the understanding of the extraction chemistry of An(iii) and Ln(iii) with N-donor ligands 2,6-bis(5-(-butyl)-1-pyrazol-3-yl)pyridine (C4-BPP) in the presence of 2-bromohexanoic acid was investigated. Extraction studies showed an excellent separation factor of SF ≈ 200 and SF ≈ 60 in comparison with the structurally similar ligand 2,6-bis(5-neopentyl-1-pyrazol-3-yl)pyridine C5-BPP (SF ≈ 100), even though C5-BPP showed significantly higher stability constants. Time-resolved laser fluorescence spectroscopy (TRLFS) studies revealed the formation of the ternary 1 : 1 and 1 : 2 complexes [Eu(C4-BPP) (2-bromohexanoate) ] ( = 1-2) ( and ). [Eu(C4-BPP)(2-bromohexanoate) ] was the relevant complex species in solvent extraction. In contrast, Cm(iii) form stable 1 : 3 complexes. The ability of 2-bromohexanoic acid to replace C4-BPP from the inner coordination sphere of Eu(iii) but not from Cm(iii) is due to a more favorable complexation of Cm(iii) over Eu(iii) with C4-BPP. This resulted in a notably more efficient separation of An(iii) and Ln(iii) in comparison with C5-BPP.
为了增进对在2-溴己酸存在下，用氮供体配体2,6-双(5-(正丁基)-1-吡唑-3-基)吡啶(C4-BPP)萃取锕系元素(iii)和镧系元素(iii)的化学过程的理解，展开了研究。萃取研究表明，与结构相似的配体2,6-双(5-新戊基-1-吡唑-3-基)吡啶C5-BPP(SF≈100)相比，其分离因子极佳，SF≈200和SF≈60，尽管C5-BPP显示出明显更高的稳定常数。时间分辨激光荧光光谱(TRLFS)研究揭示了三元1∶1和1∶2配合物Eu(C4-BPP)(2-溴己酸根) ( 和 )的形成。[Eu(C4-BPP)(2-溴己酸根) ]是溶剂萃取中的相关配合物物种。相比之下，Cm(iii)形成稳定的1∶3配合物。2-溴己酸从Eu(iii)的内配位层取代C4-BPP但不能从Cm(iii)取代的能力，是由于Cm(iii)与C4-BPP的络合比Eu(iii)更有利。这导致与C5-BPP相比，An(iii)和Ln(iii)的分离效率显著提高。
