Mobility of Aromatic Guests and Isobutane in ZIF-8 Metal–Organic Framework Studied by 2H Solid State NMR Spectroscopy
Mobility of Aromatic Guests and Isobutane in ZIF-8 Metal–Organic Framework Studied by 2H Solid State NMR Spectroscopy
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DOI：
10.1021/acs.jpcc.9b03081
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
A. E. Khudozhitkov;S. Arzumanov;D. Kolokolov;A. Stepanov
中科院分区：
文献类型：
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作者：
A. E. Khudozhitkov;S. Arzumanov;D. Kolokolov;A. Stepanov
金属有机骨架ZIF-8因其骨架柔性影响其吸附和分离性能而闻名。尽管人们在理解这种门打开的分子机制（动态和静态）方面付出了很多努力，但大客体本身的流动性仍然不清楚。在这项工作中，我们提出了一个详细的2 H固态NMR调查的大客人（二甲苯异构体，苯，甲苯和异丁烷）内的ZIF-8。根据扩散客体分子存在三种不同的运动状态解释了线型和T1、T2弛豫时间随温度的演化：（i）高移动的客体分子位于笼的中心部分，（ii）客体分子的束缚态位于笼壁或窗口附近，（iii）客体分子的束缚态位于笼的中心部分，（iv）客体分子的束缚态位于笼的中心部分。以及（iii）客人通过窗口挤压，随后释放到下一个笼子。我们报告详细的定量分析的分子动力学在每个国家和动力学之间的交换约束…
Metal–organic framework ZIF-8 is renowned for its adsorption and separation properties influenced by the framework flexibility. Although much effort was put into understanding the molecular mechanism of such gate-opening (dynamical and static), the mobility of large guest themselves remained unclear. In this work, we present a detailed 2H solid-state NMR investigation of large guests (xylene isomers, benzene, toluene, and isobutane) confined inside the ZIF-8. Evolution of line shape and T1, T2 relaxation times with temperature were interpreted in terms of existence of three different motional states for diffusing guest molecules: (i) the highly mobile guest molecules located in the central part of the cage; (ii) the bound state for a guest located on the cage wall or near the window; and (iii) the guest squeezing through the window with a subsequent release to the next cage. We report detailed quantitative analysis of molecular dynamics in each of the states and the kinetics of exchange between the bound ...