Uranyl Complexes of Carboxyl-Functionalized Ionic Liquids

Abstract

Uranium(VI) oxide has been dissolved in three different ionic liquids functionalized with a carboxyl group: betainium bis[(trifluoromethyl)sulfonyl]imide, 1-(carboxymethyl)-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and N-(carboxymethyl)-N-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide. The dissolution process results in the formation of uranyl complexes with zwitterionic carboxylate ligands and bis[(trifluoromethyl)sulfonyl]imide (bistriflimide) counterions. An X-ray diffraction study on single crystals of the uranyl complexes revealed that the crystal structure strongly depends on the cationic core appended to the carboxylate groups. The betainium ionic liquid gives a dimeric uranyl complex, the imidazolium ionic liquid a monomeric complex, and the pyrrolidinium ionic liquid a one-dimensional polymeric uranyl complex. Extended X-ray absorption fine structure measurements have been performed on the betainium uranyl complex. The absorption and luminescence spectra of the uranyl betainium complex have been studied in the solid state and dissolved in water, in acetonitrile, and in the ionic liquid betainium bistriflimide. The carboxylate groups remain coordinated to uranyl in acetonitrile and in betainium bistriflimide but not in water.

Crystallization in Ionic Liquids: Synthesis, Properties, and Polymorphs of Uranyl Salts

“…12,33 Formation of uranyl speciations (coordinated anions) in such IL systems appeared to be controlled. The results from experiments 26,40,41 and calculations 42,43 (6), 3TT, and 3TG, as observed in interionic interactions, are discussed in relation to the different cations and temperatures. Additionally, novel transformations were observed with multiple characterizations of compounds 2, 3TT, 3TG, and 6.…”

Homogeneous liquid–liquid extraction of U(VI) from HNO3 aqueous solution to betainium bis(trifluoromethylsulfonyl)imide ionic liquid and recovery of extracted U(VI)

“…Recently, Binnemans and coworkers have reported that the betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf 2 N], [Hbet] + = (H 3 C) 3 N + CH 2 COOH, [Tf 2 N] À = (CF 3 SO 2 ) 2 N À , see Scheme 1) has a selective solubilizing ability for metal oxides such as Sc 2 O 3 , Y 2 O 3 , Ln 2 O 3 (Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu), UO 3 , ZnO, and its binary mixture with water forms a homogeneous phase at P 328 K, so-called an upper critical solution temperature (UCST) [21][22][23][24][25][26][27][28][29][30][31][32]. Thus, raising temperature above UCST does not only promote chemical reactions like complexation of M n+ with an extractant, but also give an additional benefit to homogenize the biphasic system.…”

Design and Synthesis of Piperazine-Based Task-Specific Ionic Liquids for Liquid–Liquid Extraction of CuII, NiII, and CoII from Water

“…Some recent reports have involved task-specific ionic liquid (TSILs) that have potential applications in metal extraction. [24][25][26][27][28][29][30][31][32][33][34][35] TSILs appended with some functional groups that could impart particular reactivity, thereby enhancing their capacity for interaction with metal ions are an interesting option. This approach that does not require the addition of extra extracting agent would effectively solve the problem of miscibility between the extracting agent and solvent.…”