Molecular Diffusion in a Flexible Mesoporous Metal–Organic Framework over the Course of Structural Contraction,The Journal of Physical Chemistry Letters

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Molecular Diffusion in a Flexible Mesoporous Metal–Organic Framework over the Course of Structural Contraction
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-11-02 , DOI: 10.1021/acs.jpclett.0c02745
Francesco Walenszus ₁ , Volodymyr Bon ₁ , Jack D Evans ₁ , Stefan Kaskel ₁ , Muslim Dvoyashkin ₂

Affiliation

In situ ¹H pulsed field gradient (PFG) NMR was used to investigate the molecular diffusion of n-butane in the pores of the flexible metal–organic framework DUT-49(Cu) at 298 K at different pore loadings, including pressure ranges below and above the negative gas adsorption (NGA) transition caused by structural contraction of the material. Supported by molecular dynamics simulations, the investigation provided crucial insight into confined diffusion within a highly flexible pore environment. The self-diffusion coefficients were derived from the experiment and compared with simulations, capturing the diffusion during n-butane adsorption and desorption. This complementary approach has yielded experimental characterization of molecular diffusion mechanisms during the unique process of NGA. This includes the observation of a 4-fold decrease of diffusivity within a less than 2 kPa gas pressure variation, corresponding to the NGA transition point.

中文翻译：

结构收缩过程中柔性介孔金属有机框架中的分子扩散

原位¹ H 脉冲场梯度 (PFG) NMR 用于研究298 K 下不同孔隙负荷（包括以下压力范围）下正丁烷在柔性金属有机骨架 DUT-49(Cu) 孔隙中的分子扩散以及由材料结构收缩引起的负气体吸附（NGA）转变。在分子动力学模拟的支持下，这项研究为高度灵活的孔隙环境中的有限扩散提供了重要的见解。自扩散系数由实验得出，并与模拟进行比较，捕捉正丁烷吸附和解吸过程中的扩散。这种互补的方法已经在 NGA 的独特过程中产生了分子扩散机制的实验表征。这包括在小于 2 kPa 的气压变化内观察到扩散率下降 4 倍，对应于 NGA 转变点。

更新日期：2020-11-19

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