Remarkable Pressure Responses of Metal鈥揙rganic Frameworks: Proton Transfer and Linker Coiling in Zinc Alkyl Gates

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• 作者：Aur茅lie U. Ortiz ; Anne Boutin ; Kevin J. Gagnon ; Abraham Clearfield ; Fran莽ois-Xavier Coudert
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 13, 2014
• 年：2014
• 卷：136
• 期：32
• 页码：11540-11545
• 全文大小：381K
• ISSN：1520-5126

文摘

Metal鈥搊rganic frameworks demonstrate a wide variety of behavior in their response to pressure, which can be classified in a rather limited list of categories, including anomalous elastic behavior (e.g., negative linear compressibility, NLC), transitions between crystalline phases, and amorphization. Very few of these mechanisms involve bond rearrangement. Here, we report two novel piezo-mechanical responses of metal鈥搊rganic frameworks, observed under moderate pressure in two materials of the zinc alkyl gate (ZAG) family. Both materials exhibit NLC at high pressure, due to a structural transition involving a reversible proton transfer between an included water molecule and the linker鈥檚 phosphonate group. In addition, the 6-carbon alkyl chain of ZAG-6 exhibits a coiling transition under pressure. These phenomena are revealed by combining high-pressure single-crystal X-ray crystallography and quantum mechanical calculations. They represent novel pressure responses for metal鈥搊rganic frameworks, and pressure-induced proton transfer is a very rare phenomenon in materials in general.