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

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 (lambda(em) = 512 nm, g(em) = +/- 0.45, phi(FL) = 51.2 %) resulting from an achiral PyBO excimer. In contrast, only a very weak blue CPL was observed (lambda(em) = 461 nm, g(em) = +/- 0.0125, phi(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 (lambda(em) = 512 nm, g(em) = + 0.62, phi(FL) = 53.3 %) after 10 days. Chiral supramolecular assembly is an important strategy for the development of excellent circularly polarized luminescent (CPL)-active materials, but often they suffer from low quantum yield and luminescence dissymmetry factor. Herein, the authors we report a chiral coassembly process of achiral pyrene-based dyes leading to chiral excimers emitting with a high dissymmetry factor.