Negative Linear Compressibility in Organic Mineral Ammonium Oxalate Monohydrate with Hydrogen Bonding Wine-Rack Motifs

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• 作者：Yuancun Qiao ; Kai Wang ; Hongsheng Yuan ; Ke Yang ; Bo Zou
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：July 16, 2015
• 年：2015
• 卷：6
• 期：14
• 页码：2755-2760
• 全文大小：342K
• ISSN：1948-7185

文摘

Negative linear compressibility (NLC) is a relatively uncommon phenomenon and rarely studied in organic systems. Here we provide the direct evidence of the persistent NLC in organic mineral ammonium oxalate monohydrate under high pressure using synchrotron X-ray powder diffraction, Raman spectroscopy and density functional theory (DFT) calculation. Synchrotron X-ray powder diffraction measurement reveals that ammonium oxalate monohydrate shows both positive and negative linear compressibility along b-axis before 11.5 GPa. The red shift of the external Raman modes and abnormal changes of several selected internal modes in high-pressure Raman spectra further confirmed the NLC. DFT calculations demonstrate that the N鈥擧路路路O hydrogen bonding 鈥渨ine-rack鈥?motifs result in the NLC along b-axis in ammonium oxalate monohydrate. We anticipate the high-pressure study of ammonium oxalate monohydrate may represent a promising strategy for accelerating the pace of exploitation and improvement of NLC materials especially in organic systems.