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

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 subs...

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Bibliographic Details
Published in:European journal of inorganic chemistry 2020-01, Vol.2020 (2), p.191-199
Main Authors: Ansari, Seraj A., Mohapatra, Prasanta K., Verma, Parveen K., Leoncini, Andrea, Yadav, Ashok K., Jha, Shambhu N., Bhattacharyya, Dibyendu, Huskens, Jurriaan, Verboom, Willem
Format: Article
Language:English
Subjects:
Actinides
Cation exchanging
Complexation
Coordination compounds
Dodecane
Europium
Inorganic chemistry
Ionic liquids
Ions
Lanthanides
Ligands
Luminescence
Room temperature
Separation
Solvation
Stability constants
Water chemistry
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Summary: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. Complexation of several N‐pivot tripodal DGA ligands with trivalent f‐cations was investigated by extraction, luminescence and UV/Vis spectrophotometry. The complexation constants are reported in ionic liquid medium for the first time and display interesting trends
ISSN:1434-1948
1099-0682
DOI:10.1002/ejic.201900956