Transition-metal catalysis of biologically and industrially relevant reactions; applications of Fourier transform mass spectrometry to inorganic reaction kinetics and thermochemistry; metal ions in biology and metalloprotein model compounds.

Our research program focuses on the study of reactivity in transition metal chemistry, particularly in catalytic reactions of biochemical or industrial interest. We seek to identify the mechanistic principles that lead to efficient and selective catalysts for a variety of biochemical and industrial processes.

Physical inorganic research in our group has often focused on the study the reactivity and thermodynamic properties of gas-phase metal complexes that have direct solution analogues. Thus, the gas-phase species we have investigated are usually coordinatively saturated or near-saturated complexes that also exist as stable molecules or ions in the condensed phase. The opportunity then arises to address fundamental questions regarding the intrinsic chemistry of such systems and to gain insight into the effect of solvation on reactivity and thermochemistry. In addition, we have explored synthesis of novel condensed-phase molecules, such as polymerization catalysts, suggested by our improved understanding of the intrinsic reactivity of metal compounds.

The principal instrumental technique used in the gas-phase research is Fourier transform mass spectrometry. New mass spectral methods, particularly electrospray ionization, have allowed us to study a wide array of molecules normally found only in solution, such as multi-charged complexes, metal clusters, and metalloproteins. Recent publications have explored the thermodynamics of electron attachment to gas-phase metal organometallics and coordination compounds to provide previously unavailable information on metal-ligand bond energies and solvation energies. Recent work explores the photochemical and spectroscopic properties of complex ions in the gas phase to provide a deeper understanding of the role of solvation in reactivity and excited state properties.

Our bioinorganic research uses the tools and techniques of modern inorganic chemistry to answer fundamental questions concerning the chemistry of metals in biological systems. Most of our efforts focus on the development of models for biological transition metal catalysts. For example, we are interested in understanding the nature of hydrolysis and oxidation reactions catalyzed by metals in biology. Kinetic methods are used to probe the mechanisms of catalytic and stoichiometric reactions involving synthetic models for metal centers in biological systems.

In recent years our interests have turned to the potential for combining molecular recognition and catalytic metal complexes to provide models for the reactivity of certain metalloenzymes. Much of the effort in this area is directed toward the use of antibodies and other proteins as the molecular recognition elements. The goal of this interdisciplinary research is to prepare proteins that incorporate both metal-binding and substrate-binding sites. Since the structures of complex model systems are not easily determined, we use computer modeling extensively to assess the conformations and structures of the new systems.