Chiral selection of Troger's base-based macrocycles with different ethylene glycol chains length in crystallization

In the present work,two Troger's base-based macrocycles(TBBMs)with different bridging ethylene glycol chains(T1,n=1;T3,n=3)were successfully synthesized and studied via the crystal analysis.These two TBBMs possess rare rectangular-like cavities and show chiral selection during the crystallization.T1with short glycol chain(n=1)crystallized as racemates,while T3 with long glycol chain(n=3)was found as meso isomer.In contrast to T1 and T3,for T2(n=2)both rac-T2 and meso isomer R2NS2N-T2has been observed in our previous report.Thus,the synthesis of new TBBMs T1 and T3 with different bridging ethylene glycol chains not only makes the study of TBBMs more systematically,but also helps to understand the relationship between the size of the rectangular cavity and the chiral selection of Troger's base-based macrocycles during their crystallization.

Efficient circularly polarized photoluminescence and electroluminescence of chiral spiro-skeleton-based thermally activated delayed fluorescence molecules

Chiral thermally activated delayed fluorescence(TADF) molecules showing circularly polarized luminescence(CPL) have great potential in 3D displays. However, the relationships among CPL property, device performance and molecule structure are still not clear. In this article, we develop a strategy to promote dissymmetry factors without sacrifice in device performance and study the impact of molecule structures towards CPL property. Three novel TADF enantiomers are synthesized and studied.(R/S)-SCN with diminutive cyano group as an acceptor shows dissymmetry factor |gPL| ≈ 1.4×10^(-3) and noticeable organic light-emitting diode(OLED) performances with a maximum external quantum efficiency(EQEmax) of 23.0%. For(R/S)-SPHCN, the prolonged electron withdrawing group benzonitrile enhances |gPL| up to 3.6×10^(-3) with decreased device EQEmaxof 15.4%. By further replacing benzonitrile with(trifluoromethyl)pyridine, the enantiomers of(R/S)-SCFPY show similar |gPL| factors of 3.5×10^(-3) and device EQE_(max)up to 23.3%, which represents the highest efficiency among sprio-type TADF materials based OLEDs. Furthermore, the OLEDs also show obvious circularly polarized electroluminescence with gELfactors of-1.4/1.8×10^(-3),-3.6/3.6×10^(-3) and-3.7/3.6×10^(-3), respectively. These results indecate by delicate functional group engineering, high g factor can be achieved while maintaining decent device performances. Besides,(R/S)-SCFPY represents an impressive TADF emitter, which shows promoted g factor and recorded high device EQE_(max)among similar molecules.