A chiral column core surrounded by peripheral emitting moieties: a novel strategy for constructing columnar liquid crystals with circularly polarized luminescence

Abstract

The chiral transfer from peripheral chiral groups to the fluorescence achiral core has been confirmed as an effective strategy for preparing CPL liquid crystalline materials. In this work, we introduced a novel strategy for constructing columnar liquid crystals with CPL emission based on a chiral column core with peripheral emitting moieties. Three (1R, 2R)-1,2-cyclohexanediamine-bridged bis-cyanostilbene derivatives with pentyl, octyl or dodecyl chains (CC-5, CC-8 and CC-12) were synthesized in high yields. They possessed excellent aggregation-induced emission in various aggregated states. They displayed good gel properties and CC-8 exhibited an orderly self-assembled fibrous structure due to the cooperation of hydrogen bonds, van der Waals forces and π–π interaction forces. They showed a hexagonal columnar mesophase with chiral units as the core of the column surrounded by the moieties of cyanostilbene with alkyl chains. The CD and CPL investigation suggested that they had good CD and CPL properties for achiral cyanostibene units, suggesting the effective chiral transfer from the chiral column core to the peripheral emitting moieties. The highest CD and CPL properties were observed for CC-8 with octyl chains in the mesophase. This kind of chiral transfer from the core to the periphery was reported for the first time and supplied a new strategy for preparing CPL materials based on achiral dyes.