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@INPROCEEDINGS{Sauerwein:1017129,
      author       = {Sauerwein, Fynn Sören and Sittel, Thomas and Grieser,
                      Fabian and Wilden, Andreas and Modolo, Giuseppe},
      title        = {{C}haracterization of f-element complexes with
                      soft-donorligands (f-{C}har)},
      reportid     = {FZJ-2023-03950},
      year         = {2023},
      abstract     = {The German research project f-Char, funded by the German
                      Federal Ministry of Education and Research (BMBF),
                      contributes to a better understanding of the coordination
                      chemistry of ac-tinide (An) and lanthanide (Ln) ions with
                      ligands coordinating via soft donor atoms, e.g., N donor
                      atoms. Since recycling of minor actinides from PUREX
                      raffinate solution is a decisive step towards closing the
                      nuclear fuel cycle, current research focuses on the
                      challenging sepa-ration of Am(III) from Cm(III) and other
                      trivalent fission lanthanides. The Americium Selective
                      (AmSel) process[1] was designed for this task combining the
                      water-soluble tetradentate N-do-nor ligand SO3-Ph-BTBP
                      (tetrasodium-3,3',3'',3'''-([2,2'-bipyridine]-6,6'-diylbis(1,2,4-triazine-3,5,6-triyl))tetrabenzenesulfonate)
                      with the well-known An(III)/Ln(III) coextracting agent TODGA
                      (N,N,N',N'-tetra-n-octyl diglycolamide). While the
                      separation of Am from Cm and the light Ln (La-Gd) is
                      possible, a significant drop in distribution ratios of the
                      heavy Ln (Tb-Lu) can be observed for ≥ 1 mol L-1 HNO3.
                      This unusual behavior was further investigated looking at
                      the complexation of SO3-Ph-BTBP with different Ln using
                      different spectroscopic methods (UV/Vis, NMR). While
                      SO3-Ph-BTBP complexation at low nitric acid concentration
                      (10-3 mol L-1 HNO3) is observed for all lanthanides (Nd, Sm,
                      Ho, Lu), complex formation at high nitric acid concentration
                      (3 mol L-1 HNO3) is only observed for heavy Ln (Ho, Lu).
                      Regardless of the nitric acid concentration, NMR spectra
                      always show the same SO3-Ph-BTBP complex speciation with Ln.
                      Interestingly, the complexation equilibrium for heavy Ln in
                      3 mol L-1 nitric acid solution is established very slowly (6
                      – 22 h). This effect was also confirmed by kinetic batch
                      extraction studies and is presumably caused by the
                      kinetically inhibited (de)complexation of the
                      [Ln(SO3-Ph-BTBP)x] complexes. However, the mechanism is not
                      yet understood and requires further studies.Furthermore, the
                      two new N-donor ligands MTB
                      (6-(6-methyl-1,2,4,5-tetrazin-3-yl)-2,2'-bipyr-idine) and
                      PPTMP
                      ((4-(6-(1,10-phenanthrolin-2-yl)pyridin-2-yl)-1H-1,2,3-triazol-1-yl)methyl
                      pivalate) were tested as alternative extractants for the
                      An(III)/Ln(III) separation. Both extract-ants were able to
                      achieve good extraction efficiency into different diluents
                      (tert-butylbenzene, toluene, nitrobenzene) at low nitric
                      acid concentrations < 0.1 mol L-1 HNO3 and in presence of
                      the lipophilic anion source 2-bromodecanoic acid.[1] C.
                      Wagner et al., Solvent Extr. Ion Exch., 2016. 34 (2): p.
                      103-113, DOI: 10.1080/07366299.2015.1129192.},
      organization  = {IEK-6 Institutsseminar, Jülich
                       (Germany)},
      subtyp        = {Other},
      cin          = {IEK-6},
      cid          = {I:(DE-Juel1)IEK-6-20101013},
      pnm          = {1412 - Predisposal (POF4-141) / Verbundprojekt f-Char:
                      Spektroskopische Charakterisierung von f-Element-Komplexen
                      mit soft donor-Liganden, Teilprojekt D (02NUK059D)},
      pid          = {G:(DE-HGF)POF4-1412 / G:(BMBF)02NUK059D},
      typ          = {PUB:(DE-HGF)31},
      url          = {https://juser.fz-juelich.de/record/1017129},
}