title: Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr6Nodes of UiO-66 and NU-1000.
abstract: Some metal organic frameworks (MOFs) incorporate nodes that are nanoscale metal oxides, and the hydroxy-containing functional groups on them provide opportunities for introducing catalytic sites with precisely defined structures. Investigations have been done to understand the structures of these groups on nodes and node vacancies, because, in prospect, atomic-scale modulation of the composition, areal density, and/or siting of the groups would open up possibilities for exquisite tuning of the siting and performance of subsequently anchored catalytic units (e.g., single metal ions, pairs of metal ions, or well-defined metal-ion-containing clusters). We have combined infrared (IR) spectroscopy and density functional theory (DFT) to demonstrate tuning of these sites, namely, hydrogen-bonded OH/OH2groups on the Zr6nodes of the MOFs UiO-66 and NU-1000 via the intermediacy of node methoxy (or ethoxy) groups formed from methanol (or ethanol). Methoxy (or ethoxy) groups on node vacancy sites are converted to a structure incorporating one vacant Zr site and one terminal OH group per face by reaction with water. Our results highlight how the combination of DFT and IR spectroscopy facilitates the determination of the identity and chemistry of the functional groups on MOF node vacancies and defect sites.
authors: Department of Chemical Engineering, University of California , Davis, California 95616, United States.
authors: Dong
authors: D
authors: Yang
authors: Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors: Varinia
authors: V
authors: Bernales
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Timur
authors: T
authors: Islamoglu
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Department of Chemistry, Faculty of Science, King Abdul-Aziz University , Jeddah 22254, Saudi Arabia.
authors: Omar K
authors: OK
authors: Farha
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Joseph T
authors: JT
authors: Hupp
authors: Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors: Christopher J
authors: CJ
authors: Cramer
authors: Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors: Laura
authors: L
authors: Gagliardi
authors: Department of Chemical Engineering, University of California , Davis, California 95616, United States.
authors: Bruce C
authors: BC
authors: Gates