Chiral Nanographene Propeller Embedding Six Enantiomerically Stable [5]Helicene Units

Abstract

A one-step synthesis of a nanographene propeller with a D₃-symmetry was obtained starting from 7,8-dibromo[5]helicene by Yamamoto nickel(0) couplings. It afforded a chiral polyaromatic hydrocarbon (PAH) embedding six enantiomerically stable [5]helicene units. This dense accumulation of helical strain resulted in a distorted geometry, but stable stereochemistry. The conformational, structural, chiroptical, and photophysical properties of the molecule are reported.