Chiral Heptagon‐Embedded Double [6]Helicenes via Scholl Reaction

A series of heptagon-embedded multiple helicenes was synthesized in which the heptagon subunit was fused to the π-framework through Knoevenagel condensation reactions. By controlling the conditions of the cyclodehydrogenation (Scholl) reactions, different fused chiral and twisted PAHs were accessible. The optical and electronic properties of all products were investigated by UV-vis, fluorescence spectroscopy, and cyclic voltammetry. One member of the series displays an unusual anti-Kasha-like fluorescence emission. In addition, all the enantiopure [6]helicenes were separated by chiral HPLC and characterized by circular dichroism spectroscopy.