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 sp2 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.
Two molecular nanocarbons result from merging a negatively curved nanographene and a carbon nanoring in two constitutional isomers of D 2 and C 2v symmetry, respectively. They were synthesized by attachment o f C -s h a p e d p a r a p h e n y l e n e p r e c u r s o r s t o 2 , 1 1 , 1 8 , 2 7tetrabromooctabenzo[8]circulene and the subsequent intramolecular Yamamoto coupling and reductive aromatization reactions. The flexible nature of octabenzo[8]circulene enabled two different ways of connection in the Yamamoto coupling reactions, leading to the two constitutional isomers. The D 2 isomer is shaped like a figure eight, as revealed by X-ray crystallography, and is resolved into two enantiomers by chiral HPLC. The synthesis of the C 2v isomer is regarded as a further step toward precision synthesis of carbon schwarzites through a bottom-up approach.
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 sp2 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.
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