Circularly polarized luminescence from Tb(III) interacting with chiral polyether macrocycles

Superior Circularly Polarized Luminescence Brightness Achieved with Chiral Heteroleptic Nine-Coordinate Coumarin-Based Tb3+ Complexes

In order to facilitate the practical application of circularly polarized luminescence (CPL) active molecules, the CPL brightness (BCPL) must be optimized. We have applied a binary modular strategy to synthesize two chiral organo-Tb3+ complexes, [Tb(Coum)3(1R,2R-Ph-PyBox)] (2) and [Tb(Coum)3(1S,2S-Ph-PyBox)] (5), combining 3-acetyl-4-hydroxy-coumarin (Coum) and enantiopure 2,6-bis(4-phenyl-2-oxazolin-2-yl) pyridine (1R,2R/1S,2S-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 (|glum| = 0.097-0.103) for both Tb3+ enantiomers, with a bright Tb3+-centered high-purity green emission (ΦPL = 74%) and enhanced antenna-centered absorption behavior (ε320 nm = 47820-47940 M-1 cm-1). A superior BCPL (1132.7-1205.8 M-1 cm-1 at 5D4 → 7F5) has been established for complexes 2 and 5. The strategy adopted in this work provides a new route to chiroptical organo-Tb3+ luminophores with outstanding comprehensive performance.

Pfeiffer effect on configurationally labile dyes within ternary complexes with metal ions and enantiopure macrocycles

A configurationally-labile helical dye, 2,4,5,7-tetranitrofluorenone oximate, is used to probe complexes made of enantiopure macrocycles and mono/divalent metal ions. Induced electronic circular dichroism (ECD) and 1H NMR responses are amplified at room temperature only in the presence of K+ and Na+ ions despite larger binding efficiency with alkaline earth metal ions.

Advances in circularly polarized luminescence materials based on chiral macrocycles

Development of circularly polarized luminescence (CPL) materials utilizing supramolecular strategies has recently attracted increasing interest in supramolecular chemistry and materials science. Chiral macrocycles, especially chiral macrocyclic hosts, have stable structures, adjustable internal cavities to encapsulate different guests, and host-guest complexation to induce special photophysical properties. Consequently, various CPL materials based on chiral macrocycles have been developed during the last decade. To gain a better understanding of this rapidly developing research area, it is necessary and also important to summarize the advances in CPL materials based on chiral macrocycles. In this review, CPL materials from different chiral macrocycles, especially classical and newly reported chiral macrocyclic hosts and their derivatives, will be comprehensively summarized. It is believed that this review will be of guiding significance and also very helpful for the development of macrocyclic chemistry and CPL materials.