Boosting the Luminescence of a Europium(III)-β-Diketonate Complex-Nanoclay Aqueous Solution by Acetylcholine.

It is a challenging task to prepare lanthanide complex-based luminescent materials with high quantum efficiency in aqueous solution, since the excited state of Ln 3+ can be significantly quenched by water through the excitation of the O-H vibrations. Herein, we present a simple and environmentally friendly strategy to prepare strongly red-light-emitting lanthanide complex-based luminescent materials by loading 2-thenoyltrifluoroacetate (TTA) on the Eu 3+ -exchanged nanoclay (Eu 3+ (TTA n )-NC, NC = nanoclay) and coadsorption of choline chloride (ChCl) or acetylcholine chloride (AChCl) in water. The coadsorbed molecules remarkably boosted the luminescence of Eu 3+ (TTA n )-NC, which is tentatively ascribed to the removal of waters coordinated in the Eu 3+ coordination sphere via the complete coordination of TTA mediated by ChCl or AChCl. Highly luminescent films were facilely prepared by mixing a Eu 3+ (TTA n )-NC aqueous solution with PVA-ChCl (PVA-AChCl) deep eutectic solvents. This work provides a simple and environmentally friendly way for preparing highly luminescent emitting luminescent materials in aqueous solution.