An S-Shaped Double Helicene Showing both Multi-Resonance Thermally Activated Delayed Fluorescence and Circularly Polarized Luminescence

We present the first example of a multi-resonant thermally activated delayed fluorescent (MR-TADF) helicene, Hel-DiDiKTa. This S-shaped double helicene exhibits sky-blue emission, a singlet-triplet energy gap, EST, of 0.15 eV and narrow emission at a peak maximum of 473 nm with a full-width at half-maximum of 44 nm in toluene. The MR-TADF character is confirmed by the small degree of positive solvatochromism and temperature-dependent increase in intensity of the delayed emission. The chiroptical properties of the separated enantiomers are similar to other large helicenes with comparable dissymmetry values, but with the added benefit of MR-TADF. Thus, this study further strengthens the burgeoning area of chiral TADF emitters for use in cutting-edge optoelectronic and photocatalytic molecules and materials.