Dearomative Ring-Fused Azafulleroids and Carbazole-Derived Metallofullerenes: Reactivity Dictated by Encapsulation in a Fullerene Cage |
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Authors: | Prof Tong-Xin Liu Xin Wang Shilu Xia Prof Muqing Chen Mingjie Li Panting Yang Prof Nana Ma Ziqi Hu Prof Shangfeng Yang Prof Guisheng Zhang Prof Guan-Wu Wang |
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Institution: | 1. Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007 P. R. China;2. School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, Guangdong Province, 523808 P. R. China;3. Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026 P. R. China;4. Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui, 230026 P. R. China |
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Abstract: | Herein, we report divergent additions of 2,2′-diazidobiphenyls to C60 and Sc3N@Ih-C80. In stark contrast to that of the previously reported bis-azide additions, the unexpected cascade reaction leads to the dearomative formation of azafulleroids 2 fused with a 7-6-5-membered ring system in the case of C60. In contrast, the corresponding reaction with Sc3N@Ih-C80 switches to the C−H insertion pathway, thereby resulting in multiple isomers, including a carbazole-derived 6,6]-azametallofulleroid 3 and a 5,6]-azametallofulleroid 4 and an unusual 1,2,3,6-tetrahydropyrrolo3,2-c]carbazole-derived metallofullerene 5 , whose molecular structures have been unambiguously determined by single-crystal X-ray diffraction analyses. Among them, the addition type of 5 is observed for the first time in all reported additions of azides to fullerenes. Furthermore, unexpected isomerizations from 3 to 5 and from 4 to 5 have been discovered, providing the first examples of the isomerization of an azafulleroid to a carbazole-derived fullerene rather than an aziridinofullerene. In particular, the isomerism of the 5,6]-isomer 4 to the 5,6]-isomer 5 is unprecedented in fullerene chemistry, contradicting the present understanding that isomerization generally occurs between 5,6]- and 6,6]-isomers. Control experiments have been carried out to rationalize the reaction mechanism. Furthermore, representative azafulleroids have been applied in organic solar cells, thereby resulting in improved power conversion efficiencies. |
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Keywords: | Azides Cycloaddition Endohedral Fullerenes Fullerenes Structure Elucidation |
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