Solid-State Emissive Triarylborane-Based [2.2]Paracyclophanes Displaying Circularly Polarized Luminescence and Thermally Activated Delayed Fluorescence

Abstract

New types of [2.2]paracyclophane derivatives, g-BNMe₂-Cp and m-BNMe₂-Cp, in which electron-donating NMe₂ and the electron-accepting BMes₂ are introduced at the pseudo -gem and pseudo -meta positions, were designed and synthesized. The efficient through-space charge transfer enables the intense fluorescence with thermally activated delayed fluorescence characteristics. The quantum yields are up to 0.72 and 0.39 in cyclohexane. In addition, no significant fluorescence quenching was observed in the solid state with fluorescence quantum yields of powder up to 0.53 and 0.33. Moreover, the enantiomerically pure forms of g-BNMe₂-Cp exhibit strong CPL signals with g_lum up to 4.24 × 10^-3.