Hexabenzoperylene-Cored Double Thiahelicenes with Strong Luminescence

Abstract

Thiahelicenes, an important subclass of helicenes, are renowned for their pronounced chiroptical properties, particularly circular dichroism. However, the exploration of their circularly polarized luminescence (CPL) has been hindered due to their inherently weak fluorescence, leaving a critical gap in the development of thiahelicenes as efficient CPL emitters. To address this limitation, a novel strategy for enhancing the luminescence of thiahelicenes by integrating thiophene-containing units with a highly emissive hexabenzoperylene (HBP) core is presented. Two isomeric HBP-cored double thiahelicenes are synthesized, which serve as proof of concept. These molecules exhibit exceptionally high fluorescence quantum yields (Φ_F = 83% and 91%), surpassing all previously reported thiahelicenes. Furthermore, their luminescence dissymmetry factors show a four-fold enhancement compared to the parent HBP, resulting in a remarkable CPL brightness of up to 84.9 M⁻¹ cm⁻¹. These findings not only address the fluorescence limitation of thiahelicenes but also establish a new pathway for developing high-performance CPL materials.