(430a) Supramolecular Templating of Nanoporous Catalysts

Nanostructured materials are of interest for a variety of applications. This talk describes the synthesis of novel nanoporous materials with tailored oxidation states, coordination chemistry and electronic structure. We have found that sol-gel processing can be combined with supramolecular templating agents in deriving well-defined porous structures of a variety of metal oxides. Through ligand interaction between metal alkoxide precursors and surfactant head groups, we have successfully derived a family of stable mesoporous and microporous transition metal oxide molecular sieves (termed TMS) with hexagonally-packed cylindrical pore structures. The compositional flexibility and pore size tailoring of the TMS system open new possibilities for catalytic applications beyond the silicate-based zeolitic materials or mesoporous MCM-41 structures. Besides surfactant templates, we have also utilized triblock copolymers for the synthesis of mesoporous tungstated metal oxides with nanocrystalline colloidal building blocks for solid acid catalysis. Lastly, the combination of triblock copolymer and oil has been introduced to derive siliceous mesocellular foams with open, ultralarge mesopores. These unique materials have been used to immobilize various organometallic, organic and enzyme catalysts for a broad range of reactions. These heterogenized catalysts provide for excellent activity, enantioselectivity and recyclability.