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

Novel soft materials, Eu(III)-containing complex dissolved in [C 8mim][X] (X=Cl −, PF 6 − and Tf 2N −) ionic liquids, were synthesized. FT-IR and elementary analysis of complex proved that the molecular formula is [C 8mim][Eu(TTA) 4]. The complex and ionic liquids had high thermal stability according to TGA. The photoluminescence spectra showed that the [C 8mim][Eu(TTA) 4] exhibited typical red emission deriving from 5D 0– 7F 2 transition. After dissolving the complex in [C 8mim][X] (X=Cl −, PF 6 − and Tf 2N −) ionic liquids, the luminescence intensity decreased in the following order: [C 8mim][Tf 2N]≈[C 8mim][PF 6]>[C 8mim][Cl]. This was because Tf 2N − and PF 6 − anions had larger molecular volume and weaker coordination ability than Cl −.