NMR and luminescence experiments reveal the structure and symmetry adaptation of a europium ionic liquid to solvent polarity.

By combining NMR data (nuclear Overhauser effect and pseudocontact shifts) with luminescence measurements, we uncover how the structure of an anionic europium complex adapts to different solvent polarities as a result of the different relative proximities of the ion pairs. In nonpolar solvents, the detected contact ion pairs, CIPs, indicate that the ions remain in proximity, with the molecular cation, and then perturbing and distorting the coordination polyhedron of the anion complex to a low symmetry configuration, which promotes luminescence. Differently, solvent separated ion pairs occur in polar solvents, indicating that the molecular ions have been disconnected.

Substantial Intensification of the Quantum Yield of Samarium(III) Complexes by Mixing Ligands: Microwave-Assisted Synthesis and Luminescence Properties.

A luminescence quantum yield of 7.8% was obtained for a quaternary mixed-ligand samarium complex; this value is higher than those previously reported in the literature for such complexes in solution. The complex was prepared by microwave-assisted synthesis in 15 min with a yield of 69%; that is, ∼400 times faster than the usual synthesis that required 4 days and led to a yield of only 30%.