A Fused [5]Helicene Dimer with a Figure-Eight Topology: Synthesis, Chiral Resolution, and Electronic Properties

Qifeng Zhou; Xudong Hou; Jinyi Wang; Yong Ni; Wei Fan; Zhengtao Li; Xiao Wei; Ke Li; Wei Yuan; Zhuofan Xu; Manzhou Zhu; Yanli Zhao; Zhe Sun; Jishan Wu

doi:10.1002/anie.202302266

A Fused [5]Helicene Dimer with a Figure-Eight Topology: Synthesis, Chiral Resolution, and Electronic Properties

Angew Chem Int Ed Engl. 2023 Jun 5;62(23):e202302266. doi: 10.1002/anie.202302266. Epub 2023 Apr 28.

Authors

Qifeng Zhou^{1

2}, Xudong Hou², Jinyi Wang², Yong Ni², Wei Fan², Zhengtao Li², Xiao Wei³, Ke Li⁴, Wei Yuan⁵, Zhuofan Xu⁴, Manzhou Zhu³, Yanli Zhao⁵, Zhe Sun⁴, Jishan Wu^{1

2}

Affiliations

¹ Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University Binhai New City, Fuzhou, 350507, China.
² Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
³ Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information, Technology and Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei, Anhui, 230601, China.
⁴ Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin University, Tianjin, 300072, China.
⁵ School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore, 637371, Singapore.

PMID: 37009840
DOI: 10.1002/anie.202302266

Abstract

Chiral shape-persistent molecular nanocarbons are promising chiroptical materials; their synthesis, however, remains a big challenge. Herein, we report the facile synthesis and chiral resolution of a double-stranded figure-eight carbon nanobelt 1 in which two [5]helicene units are fused together. Two synthetic routes were developed, and, in particular, a strategy involving Suzuki coupling-mediated macrocyclization followed by Bi(OTf)₃ -catalyzed cyclization of vinyl ether turned out to be the most efficient. The structure of 1 was confirmed by X-ray crystallographic analysis. The isolated (P,P)- and (M,M)- enantiomers show persistent chiroptical properties with relatively large dissymmetric factors (|g_abs |=5.4×10^-3 and |g_lum |=1.0×10^-2 ), which can be explained by the effective electron delocalization along the fully conjugated belt and the unique D₂ symmetry. 1 exhibits local aromatic character with a dominant structure containing eight Clar's aromatic sextet rings.

Keywords: Carbon Nanobelt; Chirality; Circular Dichroism; Circularly Polarized Luminescence; Figure-Eight.

Abstract

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