Cation-induced kinetic trapping and enhanced hydrogen adsorption in a modulated anionic metal–organic framework
Cation-induced kinetic trapping and enhanced hydrogen adsorption in a modulated anionic metal–organic framework
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DOI：
10.1038/nchem.333
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发表时间：
2009-08
期刊：
影响因子：
21.8
通讯作者：
Sihai Yang;Xiang Lin;A. Blake;G. Walker;P. Hubberstey;N. Champness;M. Schröder
中科院分区：
文献类型：
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作者：
Sihai Yang;Xiang Lin;A. Blake;G. Walker;P. Hubberstey;N. Champness;M. Schröder
金属有机框架（MOFs）-通过用有机配体桥接金属中心而构建的微孔材料-显示出在储氢方面的应用前景，这是“氢经济”发展中的关键挑战。然而，它们的吸附能力仍然不足以用于实际应用，因此需要增强氢-MOF相互作用的策略。在这里，我们描述了一种阴离子型的MOF材料建立从在（iii）中心和四羧酸配体（H4 L），其中动力学捕获行为，其中氢被吸附在高压下，但不立即释放降低压力，是由客体阳离子调制。在其孔中具有哌嗪双阳离子的情况下，该框架表现出滞后的氢吸附。在这些dications与锂阳离子交换，没有看到滞后，而是有一个增强的吸附容量耦合到增加的吸附的电子等排热。这是合理的孔内的阳离子的不同位置，确定与X射线晶体学的精度。
Metal–organic frameworks (MOFs)—microporous materials constructed by bridging metal centres with organic ligands—show promise for applications in hydrogen storage, which is a key challenge in the development of the ‘hydrogen economy’. Their adsorption capacities, however, have remained insufficient for practical applications, and thus strategies to enhance hydrogen–MOF interactions are required. Here we describe an anionic MOF material built from In(iii) centres and tetracarboxylic acid ligands (H4L) in which kinetic trapping behaviour—where hydrogen is adsorbed at high pressures but not released immediately on lowering the pressure—is modulated by guest cations. With piperazinium dications in its pores, the framework exhibits hysteretic hydrogen adsorption. On exchange of these dications with lithium cations, no hysteresis is seen, but instead there is an enhanced adsorption capacity coupled to an increase in the isosteric heat of adsorption. This is rationalized by the different locations of the cations within the pores, determined with precision by X-ray crystallography.