Transforming Hydroxides in Metal-Organic Framework Nodes for Catalytic Applications

MOFs have provided a highly tunable platform to access site-isolated catalysts that do not undergo multimetallic decomposition. Such site-isolation effect has allowed the design and synthesis of a large variety of novel catalysts that do not have homogeneous or heterogeneous analogues. My research was focused on the hydroxide groups on the MOF nodes, which offer powerful means for introducing catalytic functionalities. Chapter 1 of this thesis discusses general design strategies for MOFs, with specific focus on Zr-based MOFs. This class of MOFs offer an ideal platform to create novel and stable catalysts on the inorganic nodes through different post-synthetic modifications. Chapter 2 through Chapter 6 of this thesis explore the use of inorganic MOF nodes with bridging hydroxides as binding sites for generating various single-site solid catalysts. For example, the Zr3-OH functionality in Zr6TPDC was metalated with MgMe2 or CoCl2 to afford highly active catalysts for carbonyl hydroboration or C-H bond borylation reactions. To increase the electron-donating ability and open space around the Zr3-OH group, three MOFs including Zr8MTBC, Zr12TPDC and Ti8BDC with new inorganic nodes were synthesized. These inorganic nodes were shown to provide superior supports for cobalt catalysts. Chapter 7 through Chapter 10 of this thesis examine the transformation of inorganic nodes with terminal hydroxides into competent catalysts for a variety of transformations. For example, Ce6-BTC has six terminal hydroxides per Ce6 node which can be activated by pinacol borane to afford terminal hydrides that are active for pyridine hydroboration, alkene hydroboration and alkene hydrophosphination. Other MOFs with terminal hydroxides were similarly activated to generate highly effective catalysts for olefin polymerization and pyridine hydroboration and hydrosilylation reactions.