Superior Circularly\nPolarized Luminescence Brightness\nAchieved with Chiral Heteroleptic Nine-Coordinate Coumarin-Based Tb<sup>3+</sup> Complexes

In\norder to facilitate the practical application of circularly\npolarized luminescence (CPL) active molecules, the CPL brightness\n(<i>B</i><sub>CPL</sub>) must be optimized. We have applied\na binary modular strategy to synthesize two chiral organo-Tb<sup>3+</sup> complexes, [Tb(Coum)<sub>3</sub>(1<i>R</i>,2<i>R</i>-Ph-PyBox)] (<b>2</b>) and [Tb(Coum)<sub>3</sub>(1<i>S</i>,2<i>S</i>-Ph-PyBox)] (<b>5</b>), combining 3-acetyl-4-hydroxy-coumarin\n(<b>Coum</b>) and enantiopure 2,6-bis(4-phenyl-2-oxazolin-2-yl)\npyridine (<b>1</b><i><b>R</b></i>,<b>2</b><i><b>R</b></i>/<b>1</b><i><b>S</b></i>,<b>2</b><i><b>S</b></i><b>-Ph-PyBox</b>). The photophysical properties of these novel complexes have been\nfully characterized. The combined point-chiral induction capability\nof chiral bis(oxazoline) derivatives and the outstanding photophysical\nproperties of the coumarin-derived ligand have resulted in an intense\nexcited-state chiroptical activity (|<i>g</i><sub>lum</sub>| = 0.097–0.103) for both Tb<sup>3+</sup> enantiomers, with\na bright Tb<sup>3+</sup>-centered high-purity green emission (<i>Φ</i><sub>PL</sub> = 74%) and enhanced antenna-centered\nabsorption behavior (<i>ε</i><sub>320 nm</sub> = 47820–47940 M<sup>–1</sup> cm<sup>–1</sup>). A superior <i>B</i><sub>CPL</sub> (1132.7–1205.8\nM<sup>–1</sup> cm<sup>–1</sup> at <sup>5</sup>D<sub>4</sub> → <sup>7</sup>F<sub>5</sub>) has been established\nfor complexes <b>2</b> and <b>5</b>. The strategy adopted\nin this work provides a new route to chiroptical organo-Tb<sup>3+</sup> luminophores with outstanding comprehensive performance.