State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
J Phys Chem B. 2012 Mar 15;116(10):3092-8. doi: 10.1021/jp212349h. Epub 2012 Mar 5.
We report the high-pressure response of guanidinium methanesulfonate (C(NH(2))(3)(+)·CH(3)SO(3)(-), GMS) using in situ Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques up to the pressures of ~11 GPa. GMS exhibits the representative supramolecular structure of two-dimensional (2D) hydrogen-bonded bilayered motifs under ambient conditions. On the basis of the experimental results, two phase transitions were identified at 0.6 and 1.5 GPa, respectively. The first phase transition, which shows the reconstructive feature, is ascribed to the rearrangements of hydrogen-bonded networks, resulting in the symmetry transformation from C2/m to Pnma. The second one proves to be associated with local distortions of methyl groups, accompanied by the symmetry transformation from Pnma to Pna2(1). The cooperativity of hydrogen bonding, electrostatic, and van der Waals interactions, as well as mechanisms for the phase transitions is discussed by means of the local nature of the structure.
我们使用原位拉曼光谱和同步辐射 X 射线衍射（XRD）技术研究了胍甲烷磺酸盐（C(NH(2))(3)(+)·CH(3)SO(3)(-), GMS）在高达约 11 GPa 的压力下的高压响应。GMS 在环境条件下表现出二维（2D）氢键双层图案的代表性超分子结构。根据实验结果，在 0.6 和 1.5 GPa 处分别确定了两个相转变。第一个相转变表现出重构特征，归因于氢键网络的重新排列，导致对称从 C2/m 转变为 Pnma。第二个转变与甲基局部变形有关，同时对称从 Pnma 转变为 Pna2(1)。通过结构的局部性质讨论了氢键、静电和范德华相互作用的协同作用以及相转变的机制。
