Odd-even effect of ionic liquid anion perfluoroalkyl chain length on ionic liquid chelate extraction of trivalent lanthanoids

Eguchi, Ayano ; Okamura, Hiroyuki   ; Sugita, Tsuyoshi   ; Ueda, Yuki   ; Morita, Kotaro*; Shimojo, Kojiro   ; Naganawa, Hirochika  ; Hirayama, Naoki*

In this study, the effect of the perfluoroalkyl (Rf) chain length of the ionic liquid (IL) anion on the IL chelate extraction of trivalent lanthanoids using 2-thenoyltrifluoroacetone was investigated. Four 1-butyl-3-methylimidazolium bis(perfluoroalkanesulfonyl)imides with different Rf chain length (n = 1-4) were synthesized and used as extraction solvents. The extracted species differed depending on odd-even number of the Rf chain length n, and it was found that the Rf chain length of IL anion has the odd-even effect on the extracted species. The fluorescence lifetime of the extracted Eu(III) complex was measured and the number of coordinating water of Eu(III) was determined. As a result, the Eu(III) complex did not have coordinating water. It was suggested that the Rf chain length of the IL anion does not affect the number of coordinating water of the extracted complex.