Superior Circularly Polarized Luminescence Brightness Achieved with Chiral Heteroleptic Nine-Coordinate Coumarin-Based Tb 3+ Complexes.

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