Pyrene-Fused Azahelicene Showing Circularly Polarized Luminescence

Abstract

The Scholl reaction of 3,6-bis{2-(pyren-2-yl)phenyl}carbazole produces bispyrene-fused azahelicene. The two pyrenes are arranged in a cross-stack manner with an interplanar distance of 3.34 Å, which induces bright circularly polarized luminescence (CPL) in the visible region. Furthermore, the NH moiety could respond to the fluoride anion and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), leading to the CPL in the red region. The binding constant (K_a) for F^- has been determined to be 3 × 10⁵ M^-1, indicating tight binding, despite a single interaction.