Thermally Induced Intra-Carboxyl Proton Shuttle in a Molecular Rack-and-Pinion Cascade Achieving Macroscopic Crystal Deformation

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• 作者：Dr. You-Gui Huang ; Yoshihito Shiota ; Sheng-Qun Su ; Shu-Qi Wu ; Zi-Shuo Yao ; Guo-Ling Li ; Shinji Kanegawa ; Soonchul Kang ; Takashi Kamachi ; Kazunari Yoshizawa ; Prof. Katsuhiko Ariga and Prof. Osamu Sato
• 刊名：Angewandte Chemie
• 出版年：2016
• 出版时间：November 14, 2016
• 年：2016
• 卷：128
• 期：47
• 页码：14848-14852
• 全文大小：1664K
• ISSN：1521-3757

文摘

Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra-carboxyl proton shuttle can be generated in a molecular assembly akin to a rack-and-pinion cascade via a thermally induced single-crystal-to-single-crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4′-azopyridine (azpy) molecule connects to two biphenyl-3,3′,5,5′-tetracarboxylic acid (H₄BPTC) molecules to form a functional molecular system with switchable mechanical properties. A temperature change reversibly triggers a molecular movement akin to a rack-and-pinion cascade, which mainly involves 1) an intra-carboxyl proton shuttle coupled with tilting of the azo molecules and azo pedal motion and 2) H₄BPTC translation. Moreover, both the molecular motions are collective, and being propagated across the entire framework, leading to a macroscopic crystal expansion and contraction.