Dynamically stable and amplified circularly polarized excimer emission regulated by solvation of chiral co-assembly...

Chiral supramolecular assembly has been assigned to be one of the most favorable strategies for the development of excellent circularly polarized luminescent (CPL)-active materials. Herein, we report our study of an achiral boron-containing pyrene (Py)-based chromophore (PyBO) as a circularly polarized excimer emission (CPEE) dye induced by chiral co-assemblies containing chiral binaphthyl-based enantiomers (R/S-M). Chiral co-assembly R/S-M-(PyBO)₄ fresh film spin-coated from toluene solution can exhibit orderly nanofibers and strong green CPEE (λ_em = 512 nm, g_em = ±0.45, Φ_FL = 51.2 %) resulting from an achiral PyBO excimer. In contrast, only a very weak blue CPL was observed (λ_em = 461 nm, g_em = ±  0.0125, Φ_FL = 19.0 %) after 187 h due to PyBO monomer emission as spherulite growth. Interestingly, this kind of chiral co-assembly R-M-(PyBO)₄-T film from tetrahydrofuran (THF) solution retains uniform morphology and affords the most stable and strongest CPEE performance (λ_em = 512 nm, g_em = + 0.62, Φ_FL = 53.3 %) after 10 days.