- 3064 Shelby Hall
BA in Chemistry, 1997, Cornell University
MS, MPhil, 2002, Columbia University
PhD, 2002, Columbia University
We are inspired by the use of hydrogen bonds and proton transfer events to control catalysis. This inspiration comes from both natural and man-made catalysts. The types of reactions we catalyze are those that are relevant to energy sources and energy storage; those that impact the environment; and those that are relevant to human health. Furthermore, catalysts that resemble natural catalysts (enzymes) are called enzyme mimics, and these mimics frequently teach us lessons about enzyme structure and function. These projects include those that closely resemble enzymes (bioinorganic projects) and those that are bio-inspired but utilize non-biologic metals (organometallic projects) are described further below:
- Organometallic project 1 – hydrogenation chemistry. Hydrogenation of organic substrates can be achieved via the transfer of H+ and H- (a.k.a. ionic hydrogenation). We have an interest in using ligands that can transfer H+ to improve hydrogenation. Furthermore, some of these ligands impart water solubility to the complexes, and have led to greener chemical reactions. See Nieto et al. Organometallics, 2011 and DePasquale et al. Organometallics, 2013 and other papers here. Hydrogenation reactions can be also used to store hydrogen; this hydrogen storage amounts to an energy storage solution.
- Organometallic project 2 – water oxidation chemistry. Water oxidation is one of the most promising means of storing the sun’s energy. The products of water oxidation are O2, electrons and protons (H+), and ideally the electrons and protons can be combined to give H2 to store as a fuel. The Papish group has pioneered the use of dihydroxybipyridine ligands for water oxidation. Changing the pH of water can activate these homogeneous water oxidation catalysts by ligand deprotonation. Dianionic ligands are known to enhance water oxidation by facilitating catalyst oxidation, but the use of ligands that change from neutral to dianionic in situ is novel and leads to switchable catalyst properties. For more details see DePasquale et al. Inorganic Chemistry 2013.
- Anticancer Project – Ruthenium dihydroxybipyridine complexes. For a general introduction to this project, please see our video. We aim to develop a new class of pH-Activated Metallo Prodrugs (pHAMPs) that are primed for cytotoxicity by light and pH triggered ligand dissociation. We take advantage of a key characteristic of cancer cells (acidity) that can be exploited to lessen the side effects of chemotherapy. The long-term goal of this work is to design highly cytotoxic and selective prodrugs that transform into an active drug in acidic cancerous tissue and yet are inactive in normal tissue. The central hypothesis of this work is that through synthesis the pH range for prodrug activation can be adjusted to better differentiate between normal and cancerous tissue. This work also aims to increase conjugation of the ligands and increase geometric distortion at the metal center to increase the wavelength of light required for photodissociation. The rationale for this approach includes the use of proven methods to make ruthenium produgs that photodissociate in red light. Red light penetrates tissue more deeply than blue light and is therefore more useful for medicinal applications. Our group has made new ruthenium complexes that are light and pH activated, as described in our initial paper and patent application on this topic.
- Bioinorganic Projects – We are working on a number of projects wherein hydrogen bonding ligands are used to model enzyme active sites. These ligands provide hydrogen bonds near the metal center and in some cases alter the electronic properties as a function of pH. This is similar to how enzymes work. In this way, we can design smart catalysts that have their function changed with pH.
- New Projects – Design of new ligands with hydrogen bonds on novel scaffolds – talk to Dr. Papish about this in person, as this work is in progress. We are always coming up with new ideas and new uses for our ligands and complexes. If you are a student interested in our group, stop by and ask what new projects we have recently started.
- For more information on the above projects see our research page.
- Siek, S.; Dixon, N. A.; Kumar, M.; Kraus, J. S.;* Wells, K. R.;* Rowe, B. W.;* Kelley, S. P.; Zeller, M.; Yap, G. P. A.; Papish, E. T. “The Synthesis of Biomimetic Zinc Complexes for CO2 Activation and the Influence of Steric Changes in the Ttz Ligands (Ttz = Tris(triazolyl)borate)” Eur. J. Inorg. Chem, 2016, 2495-2507, in Scorpionates special issue. DOI: 10.1002/ejic.201500819
- Serpas, L.;* Baum, R. R.;* McGhee, A.;* Nieto, I.; Jernigan, K. L.;*Zeller, M.; Ferrence, G. M.; Tierney, D. L.; Papish, E. T. “‘‘Scorpionate-like” complexes that are held together by hydrogen bonds: Crystallographic and spectroscopic studies of (3-NH(t-butyl)-5-methylpyrazole)nMX2 (M = Zn, Ni, Co, Mn; n = 3, 4; X = Cl, Br)“ Polyhedron, 2016, 114, 62-71, in Undergraduate Research special issue. DOI: 10.1016/j.poly.2015.10.003
- Gerlach, D. L.; Bhagan, S.; Cruce, A. A.; Burks, D. B.; Nieto, I.; Truong, H. T.;* Kelley, S. P.; Herbst-Gervasoni, C. J.; Jernigan, K. L.;* Bowman, M. K.; Pan, S.; Zeller, M.; Papish, E. T. “Studies of the Pathways Open to Copper Water Oxidation Catalysts Containing Proximal Hydroxy Groups During Basic Electrocatalysis” Inorganic Chemistry, 2014, 53 (24), 12689–12698. DOI: 10.1021/ic501018a.
- Marelius, D. C.; Bhagan, S.; Charboneau, D. J.; Schroeder, K. M.; Kamdar, J. M.; McGettigan, A. R.; Freeman, B. J.; Moore, C. E.; Rheingold, A. L.; Cooksy, A. L.; Smith, D. K.; Paul, J. J.; Papish, E. T.; Grotjahn, D. B. “How Do Proximal Hydroxy or Methoxy Groups on the Bidentate Ligand Affect (terpy)Ru(N,N)X Water Oxidation Catalysts? Synthesis, Characterization, and Reactivity at Acidic and Near-neutral pH” European Journal of Inorganic Chemistry, 2014, 676-689. Invited for special issue on water oxidation catalysis. DOI: 10.1002/ejic.201300826.
- Hufziger,K. T.; Thowfeik, F. S.; Charboneau, D. J.; Nieto,I.; Dougherty,W. G.; Kassel, W.S; Dudley,T. J.; Merino,E. J.; Papish,E. T.; Paul, J. J. “Ruthenium Dihydroxybipyridine Complexes are Tumor Activated Prodrugs Due to Low pH and Blue Light Induced Ligand Release” Journal of Inorganic Biochemistry, 2014, 130, 103-111. DOI: 10.1016/j.jinorgbio.2013.10.008.
- Dixon, N. A.; McQuarters, A. B.; Kraus, J. S.;* Soffer, J.; Lehnert, N.; Schweitzer-Stenner, R.; Papish, E. T. “Dramatic Tuning of Ligand Donor Properties in (Ttz)CuCO through Remote Binding of H+ (Ttz = tris(triazolyl)borate” Chem. Commun., 2013, 49, 5571-5573. http://pubs.rsc.org/en/Content/ArticleLanding/2013/CC/c3cc00036b
- DePasquale, J; Nieto, I.; Reuther, L. E.;* Herbst-Gervasoni, C. J.; Paul, J. J.; Mochalin, V.; Zeller, M.; Thomas, C. M.; Addison, A. W.; Papish, E. T. “Iridium Dihydroxybiypyridine Complexes show that Ligand Deprotonation Dramatically Speeds Rates of Catalytic Water Oxidation” Inorg. Chem., 2013, 52 (16), 9175-9183, chosen for cover artwork, dx.doi.org/10.1021/ic302448d.
- DePasquale, J.; Kumar, M., Zeller, M.; Papish, E. T. “Variations on an NHC Theme: Which Features are Essential for Catalysis of Transfer Hydrogenation with Ruthenium Complexes?” Organometallics, 2013, 966-979. http://dx.doi.org/10.1021/om300547f.
- DePasquale, J.; White, N. J.; Ennis, E. J.; Zeller, M.; Foley, J. P.; Papish, E. T. “Synthesis of Chiral N-Heterocyclic Carbene (NHC) Ligand Precursors and Formation of Ruthenium(II) Complexes for Transfer Hydrogenation Catalysts” Polyhedron – Invited for Michelle Millar special memorial issue, 2013, 58, 162-170. DOI: http://dx.doi.org/10.1016/j.poly.2012.10.010.
- Nieto, I.; Livings, M. S.; Sacci, J. B. III; Reuther, L. E.;* Zeller, M.; Papish, E. T. “Transfer hydrogenation in Water via a Ruthenium Catalyst with OH Groups near the Metal Center on a Bipy Scaffold.” Organometallics2011, 30, 6339–6342. DOI: 10.1021/om200638p