Solvent-switchable continuous-breathing behaviour in a diamondoid metal-organic framework and its influence on CO2 versus CH4 selectivity
Solvent-switchable continuous-breathing behaviour in a diamondoid metal-organic framework and its influence on CO2 versus CH4 selectivity
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DOI：
10.1038/nchem.2747
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发表时间：
2017-09-01
期刊：
影响因子：
21.8
通讯作者：
Brammer, Lee
中科院分区：
文献类型：
--
作者：
Carrington, Elliot J.;McAnally, Craig A.;Brammer, Lee
了解柔性金属有机框架（MOF）的行为——多孔晶体材料在受到外部刺激时会发生结构变化——支持它们作为特定应用的响应材料的设计，例如气体分离、分子传感、催化和药物输送。 MOF 在开孔和闭孔形式之间的可逆转变（一种称为“呼吸”的行为）通常通过明确的晶体转变发生。相比之下，连续呼吸很少见，详细的表征仍然非常有限。在这里，我们报告了一种连续呼吸机制，该机制通过单晶衍射在具有类金刚石网络的 MOF 中研究，(Me2NH2)[In(ABDC)(2)]（ABDC，2-氨基苯-1,4-二羧酸酯）。 MOF 在两种不同溶剂中的去溶剂化导致两种多晶型活化形式，它们具有非常不同的孔开口、明显不同的气体吸附能力以及不同的 CO2 与 CH4 选择性。部分去溶剂化引入了与二氧化碳吸附相关的门控压力，这表明该框架还可以经历逐步呼吸和连续呼吸的组合。
Understanding the behaviour of flexible metal-organic frameworks (MOFs)-porous crystalline materials that undergo a structural change upon exposure to an external stimulus-underpins their design as responsive materials for specific applications, such as gas separation, molecular sensing, catalysis and drug delivery. Reversible transformations of a MOF between open-and closed-pore forms-a behaviour known as 'breathing'-typically occur through well-defined crystallographic transitions. By contrast, continuous breathing is rare, and detailed characterization has remained very limited. Here we report a continuous-breathing mechanism that was studied by single-crystal diffraction in a MOF with a diamondoid network, (Me2NH2)[In(ABDC)(2)] (ABDC, 2-aminobenzene-1,4-dicarboxylate). Desolvation of the MOF in two different solvents leads to two polymorphic activated forms with very different pore openings, markedly different gas-adsorption capacities and different CO2 versus CH4 selectivities. Partial desolvation introduces a gating pressure associated with CO2 adsorption, which shows that the framework can also undergo a combination of stepped and continuous breathing.