Inorganic, Organic, and Bioinorganic Chemistries; Material Science
NIH Postdoctoral Fellow, University of Minnesota
University of California-Berkeley
Assistant Professor, Ithaca College, Kansas State University, University of Kansas
Associate Professor, University of Kansas
Professor, University of Kansas
My group is developing synthetic systems containing structural motifs and functional properties found in the active sites of metalloproteins. Protein active sites have unique architectural features that control the immediate environment surrounding metal ions (microenvironment). These features, in turn, are instrumental in controlling protein activity, much of which has not yet been achieved in synthetic systems. Non-covalent interactions, particularly hydrogen bonds (H-bonds) have been implicated as key regulators of microenvironmental properties. However, little is known about how H-bonds are able to influence metal-mediated processes. We are working to understand these important effects through basic studies in which the effects of single components can be analyzed individually. We design and prepare synthetic systems whereby control of the molecular components that define the structure around the metal ion is obtained, permitting formation of systems whose activity is tailored to a particular function. Ultimately, this research will provide insights into the properties of biological catalysts and lead to new classes of synthetic catalysts that incorporate the exquisite control of reactivity characteristic of metalloproteins.
Our approach combines organic and inorganic chemistry, and protein science to create new metal-containing species. These new systems are characterized with a variety of spectroscopic and analytical tools, such as electron paramagnetic resonance spectroscopy, X-ray diffraction, and cryogenic optical spectroscopy. The objectives of our research are both fundamental and applied and include: 1) examining metal-mediated binding and activation of dioxygen; 2) developing new synthetic heterogeneous catalysts having selectivity and rate-enhancement approaching that found in metalloproteins but functioning under conditions in which most biomolecules are inactive; and 3) fabricating materials and nanoparticles for the storage/release and sensing of biologically important compounds.
Research in the group is currently divided into two general areas. One involves designing new organic compounds that create rigid organic frameworks when bonded to metal ions. These frameworks position H-bond donors proximal to metal ion(s) to form specific chemical microenvironments. For instance, iron(II) and manganese(II) complexes with intramolecular H-bonds activate O2, yielding M(III) or M(IV) (M = Fe and Mn) complexes with terminal oxo ligands—these complexes are effective O-atom transfer agents (with the oxygen atom derived directly from O2). A second area involves the design and fabrication of inorganic/organic hybrid materials and nanoparticles. The materials are made from monomeric precursors and are composed of metal complexes immobilized in porous polymers. The nanoparticles are prepared with molecular species using compressed supercritical CO2. These systems are being used to deliver nitric oxide, a medicinally important compound.
Preparation and Properties of a Monomeric High-Spin MnV–Oxo Complex. Taguchi, T.; Gupta, R.; Lassalle-Kaiser, B.; Boyce, D. W.; Yachandra, V. K.; Tolman, W. B.; Yano, J.; Hendrich, M. P.; Borovik, A. S. J. Am. Chem. Soc. 2012, 134, 1996-1999.
Stabilization of Bimetallic Terminal Bis(hydroxo) Complexes with Intramolecular Hydrogen Bonds. Ng, G. K.-Y.; Ziller, J. W.; Borovik, A. S. Chem. Commun. 2012, 48, 2546-2548.
Effects of Non-Redox Active Metal Ions on the Activation of Dioxygen: Isolation and Characterization of a Heterobimetallic Complex Containing a MnIII–(µ-OH)–CaII Core. Park, Y. J.; Ziller, J. W.; Borovik, A. S. J. Am. Chem. Soc. 2011, 133, 9258-9261.
Catalytic Reduction of Dioxygen to Water with a Monomeric Manganese Complex at Room Temperature. Shook, R. L.; Peterson, S. J.; Moore, C.; Rheingold, A. L.; Borovik, A. S. J. Am. Chem. Soc. 2011, 133, 5810-5817.
Formation, Structure, and EPR Detection of a High Spin FeIV–Oxo Species Derived from Either an FeIII–Oxo or FeIII–OH Complex. Lacy, D. C.; Gupta, R.; Stone, K. L.; Greaves, J.; Ziller, J. W.; Hendrich, M. P.; Borovik, A. S. J. Am. Chem. Soc. 2010, 132, 12188-12190.
The Role of the Secondary Coordination Sphere in Metal-Mediated Dioxygen Activation. Shook, R. L.; Borovik, A. S. Inorg. Chem. 2010, 49, 3646-3660.
Lessons from Nature: Untangling the Effects of Hydrogen Bonds on Iron-Mediated Dioxygen Activation. Stone, K. L.; Borovik, A. S. Curr. Opin. Chem. Bio. 2009, 13, 114-118.
C—H Bond Cleavage with Reductants: Re-Investigating the Reactivity of Monomeric MnIII/IV—Oxo Complexes and the Role of Oxo Ligand Basicity. Parsell, T. H.; Yang, M.-Y.; Borovik, A. S. J. Am. Chem. Soc. 2009, 131, 2762–2763