A Double Helicene with Quadruple Indole‐Fused Skeleton and Double NBN‐Type Cove‐Edged Structure†

Abstract

Comprehensive SummaryConstruction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties. We report a facile synthesis of a multiple helicene based on four indoles with two electron‐rich NBN‐coved edges. The structure of the NBN‐coved multiple helicene was confirmed by single‐crystal X‐ray diffraction analysis, revealing a twisted double [5]helicene motif with a saddle‐shaped skeleton. This NBN‐coved helicene showed strong green fluorescence with good photoluminescence quantum yield. Both theoretical calculations and experimental investigation have been exploited to probe the impact of electron‐rich NBN units on aromaticity and photophysical properties of the helicene.