Probing the Dynamics of the Porous Zr Terephthalate UiO-66 Framework Using 2H NMR and Neutron Scattering
Probing the Dynamics of the Porous Zr Terephthalate UiO-66 Framework Using 2H NMR and Neutron Scattering
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DOI：
10.1021/jp3029193
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发表时间：
2012-06-07
影响因子：
3.7
通讯作者：
Jobic, H.
中科院分区：
文献类型：
--
作者：
Kolokolov, D. I.;Stepanov, A. G.;Jobic, H.
用H-2核磁共振和准弹性中子散射技术研究了多孔立方UIO-66(Zr)金属有机骨架(MOF)中1，4-苯二羧酸酯(BDC)键的转动动力学。BDC连接体中苯环的转动是中子技术检测的极限，但它完全符合H-2核磁共振时间尺度。与其他MOF相比，UIO-66骨架中的芳环表现出最低的转动势垒，其pi-Flips的激活能为30kJ·mol(-1)。然而，与MOF-5、MIL-47或MIL-53中那样定义明确的翻转速率不同，UIO-66(Zr)显示了翻转关联时间的分布，这可能是由于结构中的局部无序所致。由于苯环的旋转运动，UIO-66(Zr)中微孔窗口的有效尺寸似乎与温度有关。
H-2 NMR and quasi-elastic neutron scattering techniques have been used to study the rotational dynamics of the 1,4-benzene-dicarboxylate (BDC) linkers in the porous cubic UiO-66(Zr) metal-organic framework (MOF). The rotation of the benzene rings in the BDC linkers is at the limit of detection of the neutron technique, but it fits perfectly on the H-2 NMR time scale. The aromatic rings in the UiO-66 framework exhibit the lowest rotational barrier compared to other MOFs, the activation energy for pi-flips being 30 kJ mol(-1). However, instead of having well-defined flipping rates like in MOF-5, MIL-47, or MIL-53, UiO-66(Zr) shows a distribution of flipping correlation times, probably due to local disorder in the structure. Because of the rotational motion of the benzene rings, the effective size of the microporous windows in UiO-66(Zr) appears to be temperature dependent.