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 (Φs) 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. Notably, TPA-NiBTI exhibits the maximum Φ in solution, while TPE-NiBTI achieves a maximum Φ 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 Φs. Among them, [(P/M)-TPE-NiBTI]-doped PS film exhibits the maximum luminescence dissymmetry factor (|g|) value of 9.0×10 and the maximum Φ of 22 %. This molecular design strategy presents a promising approach to improving the Φ of helicene derivatives, thereby facilitating their potential application into chiral optoelectronic devices.