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Updated: Jun 12, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Rational Design of Crystalline and Enantiomerically Pure Helicenes with Open-Shell Singlet Ground States
Tao Wang1, Shuxuan Tang2, Xue Dong1
1State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Abstract:
Helicene diradical derivatives have attracted widespread attentions because of their unique magnetic and chiroptoelectronic properties, however, crystalline and enantiomerically pure forms of helicene diradicals are extremely rare. Herein, we describe the rational design and synthesis of o-quinone functionalized helicene diradicals with crystalline enantiomerical purity. Diradical dianion salt Rac-3K and its enantiomers P/M-3K were obtained by reduction of corresponding precursors Rac-3 and P/M-3 with two equivalent potassium graphite in THF in the presence of (di)benzo-18-crown-6. Neutral dioxoborocyclic helicene diradicals (Rac-3B and P/M-3B) were produced by reactions of Rac-3 or P/M-3 with chlorobis(perfluorophenyl)borane (B(C6F5)2Cl. Crystal structures of compounds Rac-3K, Rac-3B and P/M-3K were obtained by single crystal X-ray diffraction. Their open-shell singlet state ground states were confirmed by electron paramagnetic resonance (EPR) spectroscopy, superconducting quantum interference device (SQUID) measurements and theoretical calculations. Their chiroptical properties were investigated by the electronic circular dichroism (ECD) spectroscopy. This work provides the first examples of enantiopure helicene diradical dianions and boron-containing helicene diradicals.
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