Department of Chemical Engineering , University of California , Davis , California 95616 , United States.
Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455 , United States.
J Am Chem Soc. 2018 Mar 14;140(10):3751-3759. doi: 10.1021/jacs.7b13330. Epub 2018 Mar 2.
Some metal-organic frameworks (MOFs) incorporate nodes that are metal oxide clusters such as ZrO. Vacancies on the node surfaces, accidental or by design, act as catalytic sites. Here, we report elucidation of the chemistry of ZrO nodes in the MOFs UiO-66 and UiO-67 having used infrared and nuclear magnetic resonance spectroscopies to determine the ligands on the node surfaces originating from the solvents and modifiers used in the syntheses and having elucidated the catalytic properties of the nodes for ethanol dehydration, which takes place selectively to make diethyl ether but not ethylene at 473-523 K. Density functional theory calculations show that the key to the selective catalysis is the breaking of node-linker bonds (or the accidental adjacency of open/defect sites) that allows catalytically fruitful bonding of the reactant ethanol to neighboring sites on the nodes, facilitating the bimolecular ether formation through an S2 mechanism.
一些金属-有机骨架（MOFs）包含金属氧化物簇作为节点，例如 ZrO。节点表面的空位，无论是偶然的还是有意设计的，都充当催化位点。在这里，我们通过使用红外和核磁共振光谱法来确定源自合成中使用的溶剂和修饰剂的节点表面上的配体，从而阐明了具有 MOF UiO-66 和 UiO-67 的 ZrO 节点的化学性质，并阐明了节点对乙醇脱水的催化性质，该反应在 473-523 K 下选择性地进行以生成二乙醚而不是乙烯。密度泛函理论计算表明，选择性催化的关键是打破节点-连接体键（或开放/缺陷位点的偶然相邻），这允许反应物乙醇与节点上相邻位点进行催化上有利的键合，通过 S2 机制促进双分子醚的形成。
