Research Interests

Physical Inorganic & Bioinorganic Chemistry

Programs investigate transition-metal catalysis of biologically and industrially relevant reactions; main group oxidants; 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 and main group 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.

Since 1998 we have been exploring solution-phase oxidation chemistry relevant to a variety of reactions of synthetic, industrial, biological and military interest. In particular, we have been focused on the main-group peroxides of carbonates (peroxycarbonates), catalysis of dioxygen oxidations of hydrocarbons by iron-pyridyl complexes, and the portable production of chlorine dioxide.

Prior to our work beginning in 1998, surprisingly little was known about the thermodynamics and reactivity of the peroxides of carbon dioxide. Much of our support has come from the U.S. Army, which is developing new chemical decontamination solutions for military applications. We have considered several approaches that could increase the usefulness of hydrogen peroxide in formulating a universal chemical/biological warfare agent (CWA/BWA) decontamination system. Bicarbonate-activated peroxide (BAP) has many potential advantages for such applications. Bicarbonate also enhances the microbicidal properties of hydrogen peroxide. Investigations of the peroxycarbonate oxidation of biomolecules such as peptides, proteins, unsaturated fatty acids, and nucleic acids have also been done to investigate possible roles of this oxidant ion biochemistry. This work has potential far-reaching implications in aging and disease linked to oxidative stress.

In recent work on production of chlorine dioxide for chemical and biological decontamination, we have developed a safe and highly efficient method for generation of this unstable but effective decontaminant using a binary device. The method is being developed commercially as the Reliox process.