Circularly polarized luminescence from a common alkoxy pillar[5]arene and its co-aggregates withπ-conjugated rods

Cylinder-shaped macrocycles composed ofπ-panels have attracted special attention as one of the best platforms for the development of organic molecule-based chi-roptical materials.Pillar[n]arenes are a class of macrocycles with the advantage of easy preparation but have not been extensively investigated from the perspective of luminescent molecules.However,common alkoxy pillar[n]arenes arefluorescent in non-haloalkane solvents,showing potential to be used for molecule-based chi-roptical materials.In this work,circularly polarized luminescence(CPL)spectra are reported for a pillar[5]arene with stable planar chirality using tetrahydrofu-ran(THF)and cyclohexane as solvents,which has been missing for many years.The pillar[5]arene also forms co-aggregates with 1,4-bis(phenylethynyl)benzene and 1,4-bis[(pentafluorophenyl)ethynyl]benzene in THF/H2O mixtures,owing to a hydrophobic effect.The co-aggregates with thefluorinatedπ-rod display a new low-energy absorption peak and broad emission band as well as intense circular dichroism and CPL signals.Chiral information from the enantiopure pillar[5]arene core is efficiently transmitted to the co-aggregates with theπ-conjugated rod,lead-ing to the highest dissymmetry factor for CPL(2.9×10-2 at 472 nm)among pillar[n]arene-based CPL materials.