In the Lab with William Tolman

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inorganicWhen William Tolman, Editor-in-Chief of Inorganic Chemistry, isn’t in the lab, he’s taking long weekend rides around Minneapolis and St. Paul, Minnesota. An avid cyclist, Tolman rides his bike to and from his lab at the University of Minnesota’s Kolthoff Hall almost every day. That’s quite a feat, considering temperatures in the Twin Cities are below freezing more than 76 days a year, on average.Kolthoff Hall sits next to the bridge that connects the Minneapolis campus’ east and west banks. Similarly, Tolman’s lab works at the nexus between bioinorganic chemistry and polymerization catalysis.

“These are two areas that are not commonly combined in a single research group. I think the synergy between these areas provides a novel learning environment for the students and postdoctoral associates,” the Distinguished McKnight University Professor and Chair of the Department of Chemistry says.

The lab’s bioinorganic focus is to study the fundamental structure, physical properties, and mechanisms of how proteins and metal ions in metalloprotein complexes interact to yield novel reactivity patterns. Metalloproteins are proteins that form composites with metal ion cofactors to carry out biological functions. Chemists can better understand this process by studying model complexes designed to replicate key aspects of the metalloenzyme active sites. Tolman’s group is looking specifically at oxygen activation—the detailed process by which the O-O bond is broken—and oxidation catalysis—how C-H bonds on organic substrates are attacked—by copper complexes.

Tolman and his colleagues have made headway in these studies recently using a copper (III)-hydroxo complex model of active oxidants in catalytic oxidation reactions (1–3). “Through detailed thermodynamic and kinetic studies, we are beginning to figure out what underlies the high rates of hydrogen atom abstraction from carbon-hydrogen bonds by these complexes,” Tolman says.

The lab’s polymerization focus involves developing new ways to prepare raw materials from biological sources and build plastics from renewable resources. The lab collaborates with the Center for Sustainable Polymers, an NSF Center for Chemical Innovation. Their goal is to make polymers that are safe for the environment and human health and also have commercial viability.

They have developed new understanding of how cyclic esters are converted into polymers using aluminum-alkoxide complexes as catalysts (6). This work involved synergistic experimental and theoretical research with fellow University of Minnesota chemistry professors Christopher J. Cramer and Marc A. Hillmyer. Tolman and Hillmyer’s groups also have developed biologically derived, renewable materials that have the properties of thermoplastic elastomers—versatile plastics with viscosity and pliability—and pressure-sensitive adhesives (5). They have also discovered new ways of producing useful olefins from biologically derived carboxylic acids (4).

Tolman has been Editor-in-Chief of Inorganic Chemistry since 2012. This role is yet another way he bridges gaps in his field.

5 Recent Articles by the Research Group of William Tolman

  1. Perturbing the Copper(III)–Hydroxide Unit through Ligand Structural Variation
    J. Am. Chem. Soc., 2016, 138 (1), pp 356–368
    DOI: 10.1021/jacs.5b10985
  2. Hydrogen Atom Abstraction from Hydrocarbons by a Copper(III)-Hydroxide Complex
    J. Am. Chem. Soc., 2015, 137 (3), pp 1322–1329
    DOI: 10.1021/ja512014z
  3. [CuO]+ and [CuOH]2+ Complexes: Intermediates in Oxidation Catalysis?
    Acc. Chem. Res., 2015, 48 (7), pp 2126–2131
    DOI: 10.1021/acs.accounts.5b00169
  4. Aliphatic Polyester Block Polymers: Renewable, Degradable, and Sustainable
    Acc. Chem. Res., 2014, 47 (8), pp 2390–2396
    DOI: 10.1021/ar500121d
  5. Mechanistic Studies of ε-Caprolactone Polymerization by (salen)AlOR Complexes and a Predictive Model for Cyclic Ester Polymerizations
    ACS Catal., 2016, 6 (2), pp 1215–1224
    DOI: 10.1021/acscatal.5b02607