Cook Lab
University of Oregon
Research
We are a group of chemists who study catalysis
We explore the reactivity of organic molecules with transition metal centers both in solution and on surfaces
We care about sustainability and green chemistry
We discover and improve reactions that are relevant to the chemical industry
We employ principles of physical organic and inorganic chemistry to understand reaction mechanisms
Overview
Catalysts are agents used to enhance the rate of reactions and control selectivity of reactions.
There are two main categories of catalysts: homogeneous and heterogeneous. Homogeneous catalysts are in the same phase as the reactants, and conversely, heterogeneous catalysts are in a different phase than the reactants.
Catalysts used in industry are primarily heterogeneous and in the solid state. This preference arises because of some intrinsic properties of heterogeneous reactions: they are easily separable from the liquid phase, easy to recycle, and stable to high temperatures and pressures.
However, heterogeneous catalysts can have some disadvantages. Namely, they are not typically synthesized with molecular control of the structure of the active site. This imprecision often results in many types of active sites within one catalytic material, which in turn leads to unselective reactions (multiple products forming) and limits our understanding of the relationship between structure and activity.
In the Cook lab, we strive to synthesize both homogeneous and heterogeneous catalysts with molecular control. We accomplish this by using the knowledge of inorganic, organometallic, and organic chemistry and applying it to molecular and surface chemistry. In doing so, we can make new catalysts for old and new transformations.
Because the catalysts we make are structurally well-characterized, we can probe the mechanism of the transformation. The tools of physical organic and inorganic chemistry are used to elucidate the catalytic cycle, develop structure-activity relationships, and make improvements in catalysis.
We control the activity and selectivity of homogeneous catalysts by tuning the electronic and steric parameters of ancillary ligands.
The structure of the active sites in heterogeneous catalysts can be controlled using an approach called Surface Organometallic Chemistry (SOMC). This strategy enables control of the density, oxidation state, and coordination site of the active site metal center.
Catalysts for alkenyl chain functionalization
A primary challenge in catalysis is the selective functionalization of inert alkyl chains. We propose to control site selectivity using catalysts for alkene migration, then using the alkenes as reactive handles for further functionalization. Using judicious choice of catalyst, the site of functionalization can be controlled.
New ways to support active sites
Heterogeneous catalysts are mainly composed of a support, like silica or alumina, and an active site, such as a transition metal. The active site is linked to the support typically through covalent or ionic bonding.
One aim of research in the Cook lab is to make new solid catalysts by rethinking how the active site (a transition metal, in our case) is bound to the support (metal oxides like silica and alumina, in our case). This will be particularly valuable for those transition metals that don’t have strong interactions with unmodified supports. Creating new linkages between the active site and the support will increase the durability of the solid catalysts and allow for otherwise unattainable active sites to be synthesized.
With these new materials, we can explore their use as catalysts for the transformation of organic molecules. We will target reactions of potential industrial utility, because of industry’s great interest in solid catalysts.