Stress-Based Model for the Breathing of Metal-Organic Frameworks
Stress-Based Model for the Breathing of Metal-Organic Frameworks
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DOI：
10.1021/jz9003087
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发表时间：
2010-01-01
影响因子：
5.7
通讯作者：
Fuchs, Alain H.
中科院分区：
文献类型：
--
作者：
Neimark, Alexander V.;Coudert, Francois-Xavier;Fuchs, Alain H.
柔性金属有机框架（MOF）的孔中的气体吸附引起与材料的逐步膨胀和收缩相关的弹性变形和结构转变，称为大孔（lp）和窄孔（np）相之间的呼吸转变。我们在这里提出了一个简单而有指导意义的模型，考虑到吸附引起的应力施加在材料上的刺激，触发呼吸过渡的物理机制，这个神秘的现象。所提出的模型意味着当应力达到一定的临界阈值时，MOFs中的结构转变发生。我们展示了这个模型的例子，在MIL-53（铝）在220 K，表现出两个连续的滞后呼吸LP和NP阶段之间的过渡吸收。我们还提出了一个解释的实验，观察到的MIL-53材料中的NP和LP相共存。
Gas adsorption in pores of flexible metal organic frameworks (MOF) induces elastic deformation and structural transitions associated with stepwise expansion and contraction of the material, known as breathing transitions between large pore (lp) and narrow pore (np) phases. We present here a simple yet instructive model for the physical mechanism of this enigmatic phenomenon considering the adsorption-induced stress exerted on the material as a stimulus that triggers breathing transitions. The proposed model implies that the structural transitions in MOFs occur when the stress reaches a certain critical threshold. We showcase this model by drawing on the example of Xe adsorption in MIL-53 (Al) at 220 K, which exhibits two consecutive hysteretic breathing transitions between lp and np phases. We also propose an explanation for the experimentally, observed coexistence of np and lp phases in MIL-53 materials.