Gong Wei, Geng Yuan, Gao Pengfu, Zhang Jingjing, Zhou Kaiyuan, Dong Jinqiao, Farha Omar K, Cui Yong
School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.
Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, Evanston, Illinois 60208, United States.
J Am Chem Soc. 2024 Aug 7;146(31):21806-21814. doi: 10.1021/jacs.4c06046. Epub 2024 Jul 26.
Water adsorption/desorption cyclability of porous materials is a prerequisite for diverse applications, including atmospheric water harvesting (AWH), humidity autocontrol (HAC), heat pumps and chillers, and hydrolytic catalysis. However, unambiguous molecular insights into the correlation between underlying building blocks and the cyclability are still highly elusive. In this work, by taking advantage of the well-established isoreticular synthetic principle in Zr(IV) metal-organic frameworks (Zr-MOFs), we show that the inherent density of hydrogen atoms in the organic skeleton can play a key role in regulating the water sorption cyclability of MOFs. The ease of isoreticular practice of Zr-MOFs enables the successful syntheses of two pairs of isostructural Zr-MOFs (NU-901 and NU-903, NU-950 and SJTU-9) from pyrene- or benzene-cored carboxylate linkers, which feature and topological nets, respectively. NU-901 and NU-950 comprised of pyrene skeletons carrying more hydrogen-bonding anchoring sites show distinctly inferior cyclability as compared with NU-903 and SJTU-9 built of benzene units. Single-crystal X-ray crystallography analysis of the hydrated structure clearly unveils the water molecule-involved interactions with the hydrogen-bonding donors of benzene moieties. Remarkably, NU-903 and SJTU-9 isomers exhibit outstanding water vapor sorption capacities as well as working capacities at the desired humidity range with potential implementations covering indoor humidity control and water harvesting. Our findings uncover the importance of hydrogen-bonding anchoring site engineering of organic scaffold in manipulating the framework durability toward water sorption cycle and will also likely facilitate the rational design and development of highly robust porous materials.
多孔材料的水吸附/解吸循环性是包括大气水收集（AWH）、湿度自动控制（HAC）、热泵和冷水机以及水解催化在内的各种应用的前提条件。然而，对于潜在结构单元与循环性之间的相关性，仍缺乏明确的分子层面认识。在这项工作中，我们利用锆（IV）金属有机框架（Zr-MOFs）中成熟的同构合成原理，表明有机骨架中氢原子的固有密度在调节MOFs的水吸附循环性方面可发挥关键作用。Zr-MOFs易于进行同构合成，这使得我们能够成功地从芘或苯核羧酸连接体合成两对同构的Zr-MOFs（NU-901和NU-903、NU-950和SJTU-9），它们分别具有 和 拓扑网络。与由苯单元构建的NU-903和SJTU-9相比，由带有更多氢键锚定位点的芘骨架组成的NU-901和NU-950的循环性明显较差。对水合结构的单晶X射线晶体学分析清楚地揭示了水分子与苯部分的氢键供体之间的相互作用。值得注意的是，NU-903和SJTU-9异构体在所需湿度范围内表现出出色的水蒸气吸附容量和工作容量，其潜在应用涵盖室内湿度控制和水收集。我们的研究结果揭示了有机支架的氢键锚定位点工程在控制框架对水吸附循环的耐久性方面的重要性，也可能有助于合理设计和开发高度稳健的多孔材料。
