D‐π‐A Type [7]Helicene‐like Imide Derivatives with Tunable Photophysical Properties and Circularly Polarized Luminescence

Helicenes and their derivatives show great application prospects as circularly polarized luminescence (CPL) materials, but their fluorescence quantum yields (Φ_FLs) need a breakthrough urgently. Herein, we reported a series of D-π-A type helical luminescent emitters by combining the [7]helicene-like imide acceptor with five different donors. The obtained five emitters display blue-to-orange luminescence and markedly enhanced Φ_FL. Notably, TPA-NiBTI exhibits the maximum Φ_FL in solution, while TPE-NiBTI achieves a maximum Φ_FL in the solid state. Their two pairs of enantiomers, (P/M)-TPA-NiBTI and (P/M)-TPE-NiBTI, exhibit remarkable CPL activities, and their doped PS film both displayed doubled Φ_FLs. Among them, [(P/M)-TPE-NiBTI]-doped PS film exhibits the maximum luminescence dissymmetry factor (|g_lum|) value of 9.0×10^-4 and the maximum Φ_FL of 22 %. This molecular design strategy presents a promising approach to improving the Φ_FL of helicene derivatives, thereby facilitating their potential application into chiral optoelectronic devices.