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Title
Japanese: 
English:sln-Topological Covalent Organic Frameworks with Shape Dimorphism and Dipolar Rotorse 
Author
Japanese: Wang Xiaohan, Syunto Goto, 小川 竹次郎, 宮崎 拓也, Kouki Kawamura, 小阪 敦子, Hiroaki Suzuki, Wang Zhang, Koji Yazawa, Yutaro Ogaeri, Takayuki Kamihara, Kiyohiro Adachi, Daisuke Hashizume, Yukihito Kondo, Takumi Sannomiya, Hidehiro Uekusa, Masaki Kawano, 竹原 陵介, 庄子 良晃, 福島 孝典, Yoichi Murakami.  
English: Xiaohan Wang, Syunto Goto, Takejiro Ogawa, Takuya Miyazaki, Kouki Kawamura, Atsuko Kosaka, Hiroaki Suzuki, Wang Zhang, Koji Yazawa, Yutaro Ogaeri, Takayuki Kamihara, Kiyohiro Adachi, Daisuke Hashizume, Yukihito Kondo, Takumi Sannomiya, Hidehiro Uekusa, Masaki Kawano, Ryosuke Takehara, Yoshiaki Shoji, Takanori Fukushima, Yoichi Murakami.  
Language English 
Journal/Book name
Japanese: 
English:Journal of the American Chemical Society 
Volume, Number, Page Vol. 147    Issue 34    Page 31204–31211
Published date Aug. 14, 2025 
Publisher
Japanese: 
English: 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
English: 
Official URL https://pubs.acs.org/doi/10.1021/jacs.5c10010
 
DOI https://doi.org/10.1021/jacs.5c10010
Abstract We report herein the first (i) covalent organic frameworks (COFs) with sln topology, (ii) drastic control of the shape of COF crystals with the same topology and chemical composition, (iii) insight that these different shapes are accompanied by conformational isomerism, and (iv) installation of dipolar rotors into three-dimensional (3D) COFs. We used a new building block, hexaarylbenzene with three dipolar 1,2-difluorophenyls. Depending on the solution composition, we generated two types of COF crystals with different shapes: hexagonal prism (TK-COF-P) and membrane (TK-COF-M). Although they exhibit distinctly different powder X-ray diffraction patterns, they are chemically identical. The structural determinations revealed that they have a low-symmetric, low-density sln topology that is yet to be reported for COFs. The two distinct shapes─shape dimorphism─is found to accompany conformational isomerism. Temperature-dependent dielectric and 19F NMR relaxation-time measurements reveal that the rotor motion is suppressed at room temperature, but the rotors respond to an external electric field at elevated temperatures owing to the high activation energy for rotation (∼20 kcal mol–1), which is desired for room-temperature applications including molecular memories. These outcomes have not only expanded the diversity of COFs but have also provided a foundation for installing external-field-responsive functions into COFs that have high thermal stability, which is expected to invoke broad applications.

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