A Carbazole-Centered Expanded Helicene Stabilized with Hexabenzocoronene (HBC) Units

Abstract

The synthesis and stabilization of heteroatom-doped nanocarbon molecules, such as carbazole-containing (super)helicenes, present significant challenges due to the complexities involved in maintaining structural integrity and electronic functionality. In this study, we successfully synthesized a carbazole-centered expanded tris-hexabenzo[7]helicene (1) via a facile FeCl₃-mediated Scholl coupling reaction. 1 exhibits both chemical and chiral stability and demonstrates fluorescence at 628 nm with a quantum yield of 0.40. Additionally, the enantiomers of 1 display pronounced chiroptical properties, including a distinct circular dichroism (CD) signal spanning from 300 to 600 nm. The absorption dissymmetry factor (|g_abs|) is determined to be 2.98×10⁻³, while the circularly polarized luminescence brightness (B_CPL) is measured as 32.50 M⁻¹ cm⁻¹.