Design of Molecular-Imprinted Metal-Complex Catalysts at Surfaces for Shape-Selective and Asymmetric Catalysis

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In this study, we proposed a designs of catalytically active surfaces by metal-complex attaching and molecular imprinting and succeeded in the preparation of novel supported metal-complex catalysts on oxide surfaces. A ligand of an attached metal complex is used as a template molecule and a cavity with similar shape to the template ligand is created on the active metal center, which acts as shape-selective reaction space on the surface. We prepared Pd-monomer catalysts on silica, alumina, and titania surfaces for alkene hydroamination, a series of metal-containing ionic liquid supported on silica surfaces, molecular-imprinted Rh-complex catalysts on silica, and N-interstitial Re clusters located in H-ZSM-5. The catalytic performances of these supported metal-complex catalysts were investigated.The structures of the prepared metal-complex catalysts were characterized by means of FT-IR, NMR, UV/VIS, ESR XRD, XRF, BET, ICP, Raman, XPS, XAFS and DFT calculations. The structural kinetics of the active metal catalysts were investigated by time-resolved energy-dispersive XAFS(DXAFS) with ms time resolution, and their catalytic reaction mechanism on surfaces and the relationship between the structures of active metal centers and their catalysis were demonstrated.For asymmetric catalysis on heterogeneous surfaces, we found the novel chiral self-dimerization of vanadium Schiff-base monomers on a silica surface and surface functionalizaiton with achial silane-coupling reagents promoting enantioselectivity on supported Cu-BOX catalysts on a silica surface. The obtained heterogeneous catalysts of chiral V dimers exhibited catalytic activity, 100% selectivity and high enantioselectivity for the asymmetric oxidative coupling of 2-naphthol. The surface-functionalized Cu-BOX catalyst dramatically increased enantioselectivity for asymmetric Diels-Alder reaction. These techniques are promising ways to develop asymmetric heterogeneous catalysts on oxide surfaces.