Aggregation induced emission dynamic chiral europium(III) complexes with excellent circularly polarized luminescence...

The synthesis of dynamic chiral lanthanide complex emitters has always been difficult. Herein, we report three pairs of dynamic chiral Eu^III complex emitters (R/S-Eu-R-1, R = Et/Me; R/S-Eu-Et-2) with aggregation-induced emission. In the molecular state, these Eu^III complexes have almost no obvious emission, while in the aggregate state, they greatly enhance the Eu^III emission through restriction of intramolecular rotation and restriction of intramolecular vibration. The asymmetry factor and the circularly polarized luminescence brightness are as high as 0.64 (⁵D₀ → ⁷F₁) and 2429 M^-1cm^-1 of R-Eu-Et-1, achieving a rare double improvement. R-Eu-Et-1/2 exhibit excellent sensing properties for low concentrations of Cu^II ions, and their detection limits are as low as 2.55 and 4.44 nM, respectively. Dynamic Eu^III complexes are constructed by using chiral ligands with rotor structures or vibration units, an approach that opens a door for the construction of dynamic chiral luminescent materials.