Key Laboratory of Biomedical Polymers-Ministry of Education, College of Chemistry and Molecular Sciences , Wuhan University , Luojiashan, Wuhan 430072 , China.
UC Berkeley-Wuhan University Joint Innovative Center, The Institute for Advanced Studies , Wuhan University , Luojiashan, Wuhan 430072 , China.
J Am Chem Soc. 2019 Jan 9;141(1):488-496. doi: 10.1021/jacs.8b11230. Epub 2018 Dec 4.
We report the design and synthesis of two metal-organic frameworks (MOFs) with permanent porosity, MOF-818 and MOF-919, using a small ditopic organic linker, 1H-pyrazole-4-carboxylic acid (HPyC), 0.4 nm in length. Three mesoporous cages of unprecedented polyhedra are identified in these MOFs, a wuh cage in MOF-818 and yys and liu cages in MOF-919, with diameters of 3.8, 4.9, and 6.0 nm, respectively. The ditopic HPyC linker functions as the edge in the structure, while two types of metal-containing second building units (SBUs) function as the vertices. 28 vertices are present in the wuh cage; 50 in the yys cage; and 70 in the liu cage. Systematic analysis of these cages along with other mesoporous cages in supramolecules and MOFs constructed by ditopic linkers reveals that the extension of cage size is dictated by both the number and connectivity of the vertices. The increase in cage size is proportional to the number of vertices, while the growth rate is determined by their connectivity. The reduction in connectivity is found to be an effective way to create large cages. All three cages in this report are constructed by three-connecting (3-c) vertices and two-connecting (2-c) vertices. This [2-c, 3-c] connectivity represents the least connectivity required for the construction of cages and the most effective one for cage size expansion. The largest cage, liu, exhibits a cage size to linker size ratio of 15, outstanding in supramolecules and MOFs. MOF-818 is stable in water with a wide pH range (pH = 2-12), and the wuh cage is big enough for the inclusion of biomolecules such as vitamin B and insulin.
我们报告了两种具有永久孔隙率的金属有机骨架（MOF）的设计和合成，使用了一种小的双齿有机配体 1H-吡唑-4-羧酸（HPyC），长度为 0.4nm。在这些 MOF 中，鉴定出了三个前所未有的多面体介孔笼，分别为 MOF-818 中的 wuh 笼和 MOF-919 中的 yys 和 liu 笼，直径分别为 3.8nm、4.9nm 和 6.0nm。双齿 HPyC 配体作为结构中的边缘，而两种类型的含金属的第二建筑单元（SBU）作为顶点。wuh 笼中有 28 个顶点；yys 笼中有 50 个顶点；liu 笼中有 70 个顶点。沿着双齿配体构建的超分子和 MOF 中的这些笼以及其他介孔笼进行系统分析表明，笼尺寸的扩展由顶点的数量和连接性决定。笼尺寸的增加与顶点的数量成正比，而增长率由它们的连接性决定。降低连接性被发现是一种创建大笼的有效方法。本报告中的所有三个笼都是由三连接（3-c）顶点和两连接（2-c）顶点构建的。这种[2-c，3-c]连接性代表了构建笼所需的最小连接性，也是扩展笼尺寸最有效的连接性。最大的笼 liu 表现出笼尺寸与配体尺寸比为 15，在超分子和 MOF 中表现出色。MOF-818 在宽 pH 范围（pH=2-12）的水中稳定，wuh 笼足够大，可以容纳生物分子，如维生素 B 和胰岛素。
