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Chelation and stabilization of berkelium in oxidation state+IV

  • Author(s): Deblonde, GJP
  • Sturzbecher-Hoehne, M
  • Rupert, PB
  • An, DD
  • Illy, MC
  • Ralston, CY
  • Brabec, J
  • De Jong, WA
  • Strong, RK
  • Abergel, RJ
  • et al.
Abstract

Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin - a mammalian metal transporter - in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

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