In view of application of Ionic Liquids (IL) for extraction purpose only a very limited number has been studied yet. The extraction mechanism using ILs is totally different from what occurs in usual organic phases but there is a necessary yet missing fundamental understanding of the solution chemistry. The objective of the presented work is to understand classical solution reactions in ILs compared to the aqueous case. TRLFS is used to clarify the influence of Cu(II) on the fluorescence emission of Eu(III) and Cm(III) comparatively in BumimTf₂N and in water.

Two species are found for each cation in BumimTf₂N. Lifetime measurements of the Eu(III) and Cm(III) fluorescence (Fig.1) indicate that the first species corresponds to the metal ion solvated in the IL with one H₂O molecule in the first coordination sphere while the second one is complexed by the IL alone.

Fig. 1 Fluorescence Emission Spectrum and Lifetimes of Eu(III) and Cm(III) in BumimTf₂N

While the fluorescence emission of Eu(III) in BumimTf₂N is quenched by Cu(II) this is not the case for Cm(III). Solvation chemistry of Eu(III) and Cm(III) is comparable but not solution chemistry. According to two different Eu(III) species in BumimTf₂N two quenching constants could be calculated for this system (k_SV1=2.7e⁶M^-1s^-1; k_SV2=1.54e⁶M^-1s^-1). Investigations of the same quenching reaction in water result in a value of k_SV=1.2e⁴M^-1s^-1. Comparison of the calculated constants show that the interaction of Eu(III) and Cu(II) is accelerated in BumimTf₂N even though this is the solvent with the higher viscosity. The accelerated quenching reaction in IL can be a result of the Eu(III) solvation by BumimTf₂N.

A value of 1.27e⁴M^-1s^-1 was determined for the interaction of Cm(III) and Cu(II) in water. The investigations show that solvation chemistry has a great influence on solution chemistry and finally reactivity of lanthanides and actinides in ILs.