Helicene-derived aggregation-induced emission conjugates with highly tunable circularly polarized luminescence

Abstract : Chiral organic molecules play an important role in generating circularly polarized luminescence (CPL) with high quantum yield and tunable colours. However, their CPL performance is virtually limited by the small dissymmetric factor vertical bar g(lum)vertical bar value and the aggregation-caused quenching issue in the solid state. Here, we report a series of luminescent molecules with tailored marriage of helicenes and aggregation-induced emission (AIE) luminophores. The resulting adducts are highly fluorescent in the aggregated state with colour varying from blue to green and quantum yield up to 37.0%, depending on the linkage position, conjugation and length. The efficient association of the helical conjugated skeleton of helicene and the AIE moiety also enables a relatively high vertical bar g(lum)vertical bar value ranging from 0.001 to 0.011. Notably the vertical bar g(lum)vertical bar value could be further enhanced to ca. 0.015 by the substitution of two AIE luminophores onto a single helicene. This work provides a practical synthetic strategy for advanced molecular CPL materials, and would also favour the fabrication of high-performance circularly polarized organic light-emitting devices.