Designer Ligands and Organometallic Complexes for New Reaction Chemistry, Materials and Catalysis

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My research program merges chemical synthesis, catalysis and polymerization so as to tackle meaningful questions, both fundamental and applied, which are relevant to chemistry and society at large. More specifically, the primary goal of my research is the preparation of new and unusual metal containing molecules that catalyze the synthesis of materials, value-added chemicals, pharmaceuticals and key chemical intermediates. Over the next 5 years, my group will develop controlled methodologies for preparing new materials that are not derived from fossil fuels. One such material, polylactide, can be sourced from inexpensive, renewable resources and has found utility in various niche applications, such as absorbable sutures, bone screws and slow release pharmaceuticals. Although much effort has focused on tunable catalyst systems that can be rationally altered to vary key polymer properties (e.g. molecular weight and relative monomer orientation/order of insertion (stereochemistry)), many challenges, including a deep understanding of structure-activity relationships and the synthesis of highly active, moisture tolerant systems, remain. This information will be used to create new generations of improved catalysts (neutral and positively charged (cationic)) based on inexpensive main group (e.g. zinc, magnesium, indium) and reactive rare earth metals (e.g. scandium, yttrium, lutetium). Long term goals include the development of new catalytic systems for the synthesis of green materials, as well as contributing to the fundamental knowledge of reactions that occur at both main group and rare earth metals. We will also synthesize low-coordinate late transition metal complexes for application in various bond-forming catalytic processes, such as hydrogenation, hydrosilation, and particularly, the challenging goal of copolymerizing polar monomers and nonpolar olefins. Polymers that incorporate polar functional groups generally exhibit enhanced surface properties, such as better adhesion, dyability, and printability; however, commercial production of such materials is limited to processes that provide limited control over polymer structure, and hence, the desirable features of the polymers. There is also a need for catalysts that can polymerize a wider range of polar monomers, and more environmentally friendly catalysts that can operate under lower concentration of the polar monomer. As such, my team will make a series of neutral and cationic late transition metal (palladium, nickel and iron) complexes supported by custom-designed organic frameworks (pincer ligands) previously developed in my laboratory. As these species are realized, their efficacy as catalysts for the copolymerization of polar monomers with nonpolar olefins will be examined, with an eye to ultimately creating commercially relevant catalysts for the synthesis of new functional materials.