Highly Efficient Extraction of Trivalent f-Cations Using Several N-Pivot Tripodal Diglycolamide Ligands in an Ionic Liquid: The Role of Ligand Structure on Metal Ion Complexation

Seraj A. Ansari, Prasanta K. Mohapatra*, Parveen K. Verma, Andrea Leoncini, Ashok K. Yadav, Shambhu N. Jha, Dibyendu Bhattacharyya, Jurriaan Huskens, Willem Verboom*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

Complexation of trivalent lanthanides and actinides was studied in a room temperature ionic liquid (RTIL) using five N-pivot tripodal diglycolamide ligands (LI–LV) having different structural features, viz. spacer lengths and substituents. The nature of the metal/Ligand complex changed with the substitution of N atom near the tripodal platform from ML with LIII and LIV to ML2 with LI, LII and LV (where M = Eu3+/Nd3+/Am3+). With 0.2 mmol/L ligands, the distribution ratio of Am3+ at 1 m HNO3 followed the order: LI (210) > LII (42) > LIII (2.1) > LV (0.7) > LIV (0.2). The formation constants between Nd3+ and the ligands (log βML,ML2) followed an identical order, viz. LI > LII > LIII > LV > LIV. The extraction of Am3+ or Eu3+ with all the ligands followed a cation-exchange extraction mechanism, which is in sharp contrast to the results obtained in a molecular solvent (n-dodecane), where a solvation extraction mechanism prevalied. Luminescence studies on the Eu3+ extract in RTIL confimed the absence of water molecules in the inner coordination sphere of the complex. EXAFS studies indicated that all three DGA arms were binding to the Eu3+ cation.

Original languageEnglish
Pages (from-to)191-199
Number of pages9
JournalEuropean journal of inorganic chemistry
Volume2020
Issue number2
DOIs
Publication statusPublished - 16 Jan 2020

Keywords

  • UT-Hybrid-D
  • Complexation
  • Luminescence
  • Separation
  • Stability constants
  • Actinides

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