Ionic liquids as novel spectroscopic solvents for Eu(III)-containing complex

Novel soft materials, Eu(III)-containing complex dissolved in [C8mim][X] (X=Cl−, PF6− and Tf2N−) ionic liquids, were synthesized. FT-IR and elementary analysis of complex proved that the molecular formula is [C8mim][Eu(TTA)4]. The complex and ionic liquids had high thermal stability according to TGA. The photoluminescence spectra showed that the [C8mim][Eu(TTA)4] exhibited typical red emission deriving from 5D0–7F2 transition. After dissolving the complex in [C8mim][X] (X=Cl−, PF6− and Tf2N−) ionic liquids, the luminescence intensity decreased in the following order: [C8mim][Tf2N]≈[C8mim][PF6]>[C8mim][Cl]. This was because Tf2N− and PF6− anions had larger molecular volume and weaker coordination ability than Cl−.