A Series of Carboxylic‐Functionalized Ionic Liquids and their Solubility for Lanthanide Oxides

Abstract Herein we report the synthesis of propanoic acid functionalized ionic liquids (ILs) with various lengths of alkyl chain on the imidazole ring. The synthesized propanoic acid functionalized ILs were used to dissolve Eu 2 O 3 (or Tb 4 O 7 ) due to the formation of europium(III) (or terbium(III)) carboxylate, aimed to get soft luminescent materials combining the properties of ILs and attractive luminescent properties of lanthanide ions. The luminescent behavior of Eu 3+ and Tb 3+ in the ILs were investigated by luminescence spectroscopy. The affect of the alkyl chain on the luminescent behavior (the asymmetry parameter ( R ), the lifetime of 5 D 0 , and the 5 D 0 quantum efficiency) of Eu 3+ has been discussed.