A Near-Infrared Absorbing and Emissive Quadruple Helicene Enabled by the Scholl Reaction of Perylene

Authors：Pun, Sai Ho; Cheung, Ka Man; Yang, Daiyue; Chen, Han; Wang, Yujing; Kershaw, Stephen, V; Miao, Qian^*

Source：Angewandte Chemie - International Edition, 2022, 61(8): e202113203.

DOI：10.1002/anie.202113203

• Chiroptical Properties
• Helicenes
• Near Infrared
• Polycyclic Aromatics
• Scholl Reactions

Herein, we report the synthesis, structural analysis, optical and chiroptical properties of a novel quadruple helicene, which has two [6] and two [7]helicene moieties fused in a contorted framework of 92 sp(2) carbon atoms. It was synthesized by the Scholl reaction of a perylene-containing substrate with the formation of eight carbon-carbon bonds on the perylene unit in a single synthetic operation. Chemical oxidation of the quadruple helicene with tris(4-bromophenyl)ammoniumyl hexachloroantimonate resulted in an air-stable dication, which exhibits the same helicity in its four helicene moieties as unambiguously identified by single-crystal X-ray crystallography. The quadruple helicene exhibits unusual near-infrared absorption and emission with absorption and emission maxima at 848 nm and 977 nm, respectively, and its isolated enantiomers exhibit electronic circular dichroism in the near-infrared and visible-light regions.

• Institution
  中国科学院