Amphidynamic character of crystalline MOF-5: Rotational dynamics of terephthalate phenylenes in a free-volume, sterically unhindered environment
Amphidynamic character of crystalline MOF-5: Rotational dynamics of terephthalate phenylenes in a free-volume, sterically unhindered environment
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DOI：
10.1021/ja077122c
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发表时间：
2008-03-19
影响因子：
15
通讯作者：
Garcia-Garibay, Miguel A.
中科院分区：
文献类型：
--
作者：
Gould, Stephanie L.;Tranchemontagne, David;Garcia-Garibay, Miguel A.
金属有机框架（mof）在储氢和其他材料应用中一直是人们关注的焦点。mof是一种由能够进行内部旋转的轴向取代有机间隔剂连接的静态金属团簇，是研究和利用结晶固体动力学的最有前途的两动力材料之一。在这篇通讯中，我们报告了MOF-5的1,4-苯乙烯二羧酸桥的旋转动力学的实验研究，它没有可能有助于旋转势垒的空间接触。从高压（约3 mTorr）下密封的高质量样品中获得了高重复性的H-1 T，松弛，高分辨率C-13 CPMAS和变温度四极回波H-2 NMR数据，H-2 NMR线形状模拟显示，旋转的激活势垒为11.3 +/- 2.0 kcal/mol，低于截断模型理论研究中报道的14-16 kcal/mol值。虽然我们的研究结果表明MOF-5所用的模型不足以解释扩展晶格的性质，但它们也表明具有静态和动态成分的非动力材料可能达到气体动力学的无摩擦旋转运动特性。
Metal-organic frameworks (MOFs) have been the focus of much interest within the context of hydrogen storage and other materials applications. With static metal clusters linked by axially substituted organic spacers capable of experiencing internal rotations, MOFs are one of the most promising amphidynamic materials to investigate and exploit the dynamics of crystalline solids. In this communication we report an experimental study of the rotational dynamics of the 1,4-phenylenedicarboxylate bridge of MOF-5, which has no steric contacts that might contribute to the rotational barrier. Highly reproducible H-1 T, relaxation, high-resolution C-13 CPMAS, and variable temperature quadrupolar echo H-2 NMR data were obtained from high quality samples that were sealed at reduced pressure (ca. 3 mTorr), H-2 NMR line shape simulation revealed an activation barrier for rotation of 11.3 +/- 2.0 kcal/mol, which is lower than the 14-16 kcal/mol values reported in theoretical studies of truncated models. While our results suggest that the models used for MOF-5 are insufficient to account for the properties of the extended crystal lattice, they also suggest that the amphidynamic materials with static and dynamic components may reach the friction-free rotational motion characteristic of gas dynamics.