State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou, Fujian 350002, China.
Department of Chemistry, Texas A&M University , College Station, Texas 77843-3255, United States.
J Am Chem Soc. 2017 Nov 22;139(46):16939-16945. doi: 10.1021/jacs.7b09973. Epub 2017 Nov 9.
Ligands with flexible conformations add to the structural diversity of metal-organic frameworks but, at the same time, pose a challenge to structural design and prediction. Representative examples include Zr-tetracarboxylate-based MOFs, which afford assorted structures for a wide range of applications, but also complicate the structural control. Herein, we systematically studied the formation mechanism of a series of (4,8)-connected Zr-tetracarboxylate-based MOFs by altering the substituents on different positions of the organic linkers. Different ligand rotamers give rise to three types of structures with flu, scu, and csq topologies. A combination of experiment and molecular simulation indicate that the steric hindrance of the substituents at different positions dictates the resulting MOF structures. Additionally, the controllable formation of different structures was successfully implemented by a combination of linkers with different steric effects at specific positions.
配体具有灵活的构象，增加了金属有机骨架的结构多样性，但同时也对结构设计和预测提出了挑战。代表性的例子包括基于 Zr-四羧酸的 MOFs，它们为广泛的应用提供了各种结构，但也使结构控制变得复杂。在此，我们通过改变有机配体不同位置的取代基，系统地研究了一系列（4,8）连接的 Zr-四羧酸基 MOFs 的形成机制。不同的配体旋转异构体导致具有 flu、scu 和 csq 拓扑结构的三种类型的结构。实验和分子模拟的结合表明，不同位置取代基的空间位阻决定了所得 MOF 结构。此外，通过在特定位置结合具有不同空间效应的配体，成功地实现了不同结构的可控形成。
