The helical elongation of π-extended diazahelicenes with amplified circularly polarized luminescence.

Helicenes are circularly polarized luminescence (CPL)-active but suffer from a fundamental tradeoff between fluorescence quantum yield (Φ) and luminescence dissymmetry factor (||). Herein, we present a strategy combining lateral π-extension and helical elongation in carbazole-embedded helicenes to address this challenge. Specifically, π-extended diaza[7]helicene () and diaza[9]helicene () were synthesized and characterized, revealing nearly a 2-fold increase in Φ and a 6-fold enhancement in || from to . This approach offers a new pathway for high-performance CPL emitters.