Hierarchical structuring of metal–organic framework thin-films on quartz crystal microbalance (QCM) substrates for selective adsorption applications
Hierarchical structuring of metal–organic framework thin-films on quartz crystal microbalance (QCM) substrates for selective adsorption applications
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DOI：
10.1039/c5ta05620a
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发表时间：
2015-11
影响因子：
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通讯作者：
S. Wannapaiboon;M. Tu;K. Sumida;Kira Khaletskaya;S. Furukawa;S. Kitagawa;R. Fischer
中科院分区：
文献类型：
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作者：
S. Wannapaiboon;M. Tu;K. Sumida;Kira Khaletskaya;S. Furukawa;S. Kitagawa;R. Fischer
连续分步液相外延（LPE）生长是将金属有机框架（MOFs）结构化为二维超结构（如薄膜）的最有效方法之一。在各个LPE生长循环之间交替结构单元前体（即从一个连接体到另一个连接体）允许在精确控制生长顺序的情况下合成由具有不同结构或化学性质的两种不同M0 F组成的异质结构M0 F膜。在这里，我们采用LPE生长策略制备高功能的，分层结构的核-壳架构组成的[Zn 4 O（3，5-dialkylcarboxypyrazolate）3] n-为基础的框架。具体地，小孔[Zn 4 O（3-甲基-5-异丙基-4-羧基吡唑酸酯）3]n（Zn-MI）和[Zn 4 O（3，5-二乙基-4-羧基吡唑酸酯）3]n（Zn-DE）骨架分别作为尺寸选择性层沉积在较大孔[Zn 4 O（3，5-二甲基-4-羧基吡唑酸酯）3]n（Zn-DM）和[Zn 4 O（3-甲基-5-乙基-4-羧基吡唑酸酯）3]n（Zn-ME）层上。在石英晶体微天平（QCM）传感器的Au表面上直接生长的MOF层允许实时探测异质结构的吸附性质。在环境控制的QCM装置中的多组分吸附实验揭示了相对于醇类的吸附的尺寸选择性，以及甲醇在水中的分子识别。这些性质源于小孔Zn-MI（或Zn-DE）层在较大孔Zn-DM（或Zn-ME）层上的定位，促进了吸附选择性的有吸引力的协同性质，并为基于MOF的传感应用的进一步发展提供了可能性。
Continuous stepwise liquid-phase epitaxial (LPE) growth is one of the most effective procedures for structuring metal–organic frameworks (MOFs) as two-dimensional superstructures, such as thin-films. Alternation of the building block precursors between the individual LPE growth cycles (i.e. from one linker to the other) allows heterostructured MOF films consisting of two different MOFs with different structural or chemical properties to be synthesized with a precise control of the growth sequence. Here, we employ the LPE growth strategy for the preparation of highly functional, hierarchically structured core–shell architectures consisting of [Zn4O(3,5-dialkylcarboxypyrazolate)3]n-based frameworks. Specifically, the small-pore [Zn4O(3-methyl-5-isopropyl-4-carboxypyrazolate)3]n (Zn-MI) and [Zn4O(3,5-diethyl-4-carboxypyrazolate)3]n (Zn-DE) frameworks are respectively deposited as a size selective layer upon larger-pore [Zn4O(3,5-dimethyl-4-carboxypyrazolate)3]n (Zn-DM) and [Zn4O(3-methyl-5-ethyl-4-carboxypyrazolate)3]n (Zn-ME) layers. Direct growth of the MOF layers on the Au surfaces of quartz crystal microbalance (QCM) sensors allowed the adsorption properties of the heterostructures to be probed in real-time. Multiple-component adsorption experiments in an environment-controlled QCM apparatus revealed size selectivity with respect to the adsorption of alcohols, as well as the molecular recognition of methanol over water. These properties stem from the positioning of the small-pore Zn-MI (or Zn-DE) layer on the larger-pore Zn-DM (or Zn-ME) layer, facilitating attractive synergistic properties for adsorptive selectivity and providing a possibility for further development in MOF-based sensing applications.