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Research Interests:
Organometallic, Polymer and Materials Chemistry; Catalysis -- Synthetic, structural, and reactivity studies on transition metal compounds are pursued in the search for new chemical transformations, polymers with novel properties, catalysts, and advanced solid state materials.
The research projects in Professor Tilley's group involve exploratory synthetic, structural, and reactivity studies on novel inorganic systems. Reactivity studies focus on new compounds that exhibit unusual electronic and/or coordination environments for the metal center. Mechanistic investigations are often undertaken to define reactivity patterns for these new species. Metal-mediated routes to new polymers are being explored, and molecular, chemical approaches to the designed construction of advanced solid state materials and heterogeneous catalysts are being developed.
Research in organometallic chemistry involves the synthesis of transition metal complexes that exhibit new chemical properties, often via the design and introduction of new ancillary ligands. For example, chelating, nitrogen-based ligands are being explored in attempts to obtain early transition metal complexes that efficiently activate the bonds of substrate molecules (via "sigma-bond metathesis"). Along these lines, mechanistic studies are helping to shed light on possible pathways to facile reactions of various bonds (e.g., C-H, Si-H, C-Si, P-H, B-H, etc.). A second interest concerns the activation of bonds via 1,2-migrations between a metal and a donor atom. This reaction type has been developed, for example, to activate both Si-H bonds of secondary silanes to produce silylene dihydride complexes of Pt, Ir, Os, and W. Efforts are underway to incorporate the new reactivity patterns that have been discovered into catalytic cycles.
The program in polymer synthesis involves use of coordination polymerizations with transition-metal complexes to develop new methods for polymerizations involving alkene, alkyne, silane, and/or stannane monomers. A particular emphasis is placed on development of electron-delocalized polymers, which show great promise as advanced materials that function as conductors, semiconductors, photoconductors, nonlinear optical materials, photochromic materials, and light-emitting materials. Metal-catalyzed dehydropolymerizations have been used to obtain the first high molecular weight polystannanes. These low band-gap polymers are semiconducting when doped, and display interesting temperature-dependent optical properties. An approach to new pi-conjugated structures is based on zirconocene-coupling of diynes to polymers with metallacycle units in the main chain. The zirconacyclopentadiene residues provide versatile chemical pathways for placement of a variety of conjugated groups (dienes, aromatic heterocycles) into a delocalized chain. A related topic is based on the discovery that zirconocene-coupling methods are extremely useful in high-yield syntheses of macrocycles from readily-available diynes. This method is being used to produce macrocycles of various sizes, shapes, and functionalities. Applications in host-guest chemistry, catalysis, anion-binding, and supramolecular chemistry are being developed.
A project on the molecular design and synthesis of solid-state materials targets the development of chemical routes to complex, 3-dimensional networks via molecular-level control. Primary targets are oxide-based materials, which are fabricated from tailored, oxygen-rich precursor molecules. Such compounds undergo mild elimination reactions (of alkenes and water) to give homogeneous, mixed-element oxides. This method has recently been modified to produce multi-component, mesoporous solids. A strong emphasis is on use of this approach to provide new generations of catalysts for important reactions such as selective hydrocarbon oxidations (for example, the oxidative dehydrogenation of alkanes). A second molecular chemical approach makes use of dendrimeric building blocks to generate hybrid organic-inorganic materials with tailored porosities and functionalities. In general, the goal of the research in this area is to provide designed materials possessing new and specific structural, electronic, optical, and/or catalytic properties.
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Biography:
Born 1954; B.S. University of Texas (1977); Ph.D. University of California, Berkeley (1982); NSF Exchange Postdoctoral Associate, California Institute of Technology and ETH, Zürich, Switzerland (1981-1983); Faculty of Chemistry, University of California, San Diego (1983-1994); Professor, University of California, Berkeley, and Faculty Senior Scientist, Chemical Sciences Division, Lawrence Berkeley National Laboratory (1994-present); Alfred P. Sloan Fellow (1988-90); Union Carbide Innovation Recognition Awards (1991, 1992); Japan Society for the Promotion of Science Fellow (1993); Visiting Professor, ETH, Zürich, Switzerland (1998); Alexander von Humboldt Senior Scientist (1998); Fellow of the American Association for the Advancement of Science (1998); Visiting Professor, University of Montpellier, Montpellier, France (1999-2000); ACS Award in Organometallic Chemistry (2002); Chair of the ACS Division of Inorganic Chemistry (2003); Wacker Silicon Award (2003); Miller Research Professor (2004-05); Centenary Lectureship and Medal, Royal Society of Chemistry (2007); ACS Frederic Stanley Kipping Award in Silicon Chemistry, 2008.
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