Influence of a Pre-organized N-Donor Group on the Coordination of Trivalent Actinides and Lanthanides by an Aminopolycarboxylate Complexant

Colt R. Heathman, Travis S. Grimes, Santa Jansone-Popova, Santanu Roy, Vyacheslav S. Bryantsev, Peter R. Zalupski

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The thermodynamic influence of a pre-organized N-donor group on the coordination of trivalent actinides and lanthanides by an aqueous aminopolycarboxylate complexant has been investigated. The synthesized reagent, N-2-methylpicolinate-ethylenediamine-N,N′,N′-triacetic acid (EDTA-Mpic), resembles ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) with a single acetate pendant arm replaced by a 6-carboxypyridin-2-ylmethyl group. The rigid N-donor picolinate functionality has a profound impact on ligand protonation and trivalent f element complexation equilibria, as demonstrated by potentiometric, spectroscopic, and liquid/liquid metal-partitioning studies as well as by molecular dynamics calculations. Relative to diethylenetriamine-N,N,N′,N′′,N′′-pentaacetic acid (DTPA), the ability to preferentially bind trivalent actinides over trivalent lanthanides was moderately lowered due to the presence of the N-(6-carboxypyridin-2-ylmethyl) substituent. The structural modification substantially amplifies the total ligand acidity of EDTA-Mpic. As a result the complexant sustains the metal complexation and efficient An 3+ /Ln 3+ differentiation in aqueous mixtures of unprecedented acidity for this class of reagents.

Original languageEnglish
Pages (from-to)2545-2555
Number of pages11
JournalChemistry - A European Journal
Volume25
Issue number10
DOIs
StatePublished - Feb 18 2019

Funding

The experimental work conducted by T.S.G., C.R.H., and P.R.Z. at the Idaho National Laboratory was supported by the Nuclear Technology Research and Development Program, Office of Nuclear Energy, DOE Idaho Operations Office under contract DE-AC07-05ID14517. The synthetic work by S.J.-P. and computational studies by S.R. and V.S.B. were supported by the Nuclear Technology Research and Development Program, Office of Nuclear Energy, US Department of Energy. This research used the resources of the Oak Ridge Leadership Computing Facility and, in part, of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, supported by the Office of Science of the US Department of Energy under contracts No. DE-AC05-00OR22725 and DE-AC05-00OR22725, respectively.

Keywords

  • actinides
  • coordination modes
  • density functional calculations
  • lanthanides
  • molecular dynamics
  • thermodynamics

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