Faculty

Stephen A. KochStephen A. Koch, Professor

B. S. Fordham University, 1970
Ph.D. Massachusetts Institute of Technology, 1975
Postdoctoral Research Associate, Texas A & M University, 1975-77
Postdoctoral Research Associate, Cornell University, 1978

679 Chemistry
Phone: (631) 632-7944
Email:

Inorganic Chemistry

Our research efforts are centered on the synthesis and characterization of new types of transition metal compounds that exhibit interesting structural, spectroscopic, and reactivity properties. In the area of bioinorganic chemistry, we are elucidating the structure and function of metal ions in biological systems through an inorganic approach. Our most recent work involves the interaction of diatomic molecules, such as N2, CO, H2, CN1- and NO with Fe-sulfur centers in enzymes including nitrogenase, hydrogenase, and carbon monoxide dehydrogenase. A prime goal is to develop iron based nitrogen fixation chemistry. We also have an established program involving the study of active site analogs for zinc-, cadmium-, and mercury-containing proteins. The "zinc finger" proteins that regulate gene transcription by binding to DNA and RNA are of fundamental interest.

In collaboration with the Welch group at Washington University Medical School, we have developed a new class of gallium and indium radiopharmaceuticals. The ability of the 68Ga complex to cross the intact blood brain barrier is a major discovery.

Solid-state metal sulfides and oxides have scientifically interesting and technologically significant electronic, electrochemical, and catalytic properties. We are exploring the analogies between these solid- state materials and homogeneous molecular compounds. In particular, we are attempting to model with homogeneous compounds, the chemistry of heterogeneous metal-sulfide catalysts that are used in the hydroprocessing of crude petroleum. The synthesis and electronic and electrochemical properties of hybrid solid-state/molecular materials is another area under investigation.

Publications

Refinement of the nickel site structure in Desulfovibrio gigas hydrogenase using range-extended EXAFS spectroscop.y Weiwei Gu , L. Jacquamet , D.S. Patil , H-X. Wang , D.J. Evans , M.C. Smith , M. Millar , S. Koch , D.M. Eichhorn , M. Latimer , S.P. Cramer J. Inorg. Biochem., 93, 41–51(2003)

Two Dimensional Materials based on trans-[FeII(CN)4(CO)2]2- Building Blocks; First Structural Evidence for a Hydrated Metal Carbonyl Ligation. Jianfeng Jiang and Stephen A. Koch Chem. Commun.,1724–1725 (2002).

fac-[FeII(CN)3(CO)3]1- and cis-[FeII(CN)4(CO)2]2- New members of the Class of [FeII(CN)x(CO)y] Compounds Jianfeng Jiang and Stephen A. Koch Inorg. Chem. 4, 158-160, (2002)

Chemistry of [Fe(CN)5(CO)]3- New Observations for a 19th century Compound. Jianfeng Jiang, Andrew Acunzo, Stephen A. Koch, J. Am. Chem. Soc.123, 12109 (2001)

trans [Fe(CN)4(CO)2]2-, a 21st Century [Fe(CO)(CN)] compound. JianFeng Jiang and Stephen A. Koch Angew. Chem., Int. Ed. 40(14), 2629-2631 (2001)

The unprecedented [Fe(CN)2(CO)] and [Fe(CN)(CO)] centers in hydrogenase enzymes? Why did nature choose such combinations of vile ligands? Stephen A. Koch, HuaFen Hsu, Sechin Chang, Andy Ancunzo, and JianFeng Jiang. J. Inorg. Biochem. 74, 34 (1999)

Evaluation of Gallium-68 Tris(2-Mercaptobenyzyl)Amine: A complex with Brain and Myocardial Uptake. Cathy S. Cutler, M. Cecillia Geron, David. E. Reichert, Abraham Z. Synder, Pilar Herrero, Carolyn J. Anderson, Duncan A. Quarless, Stephen A. Koch and Michael J. Welsh Nuclear Medicine & Biology, 26, 305-316 (1999)

The Gallium(III) and Indium(III) Complexes of Tris(2-mercaptobenzyl)amine and Tris(2-hydroxybenzyl)amine, R. J. Motekaitis, A. E. Martell, S. A. Koch, J.-W. Hwang, D. A. Quarless, Jr., M. J. Welch Inorg. Chem. 37, 5902-5911 (1998)

The Coordination Chemistry of Amine Triphenolate Tripod Ligands with Iron(III). Old Organic Compounds but New Tripod Ligands. J.W. Hwang, K. Govindaswamy, S. A. Koch, J. Chem. Soc. Chem. Comm. 1667-1668 (1998).

Single-Crystal, Solid-State, and Solution 113Cd and 77Se NMR and X-ray Single-Crystal Study of a [Cd(SeR)2(N-donor)2] Complex R. Subramanian, N. Govindaswamy, R. A. Santos, S. A. Koch, G. S. Harbison, Inorg. Chem. 37, 4929-4933 (1998).

The Limitation of X-ray Absorption Spectroscopy for Determining the Structure of Zinc Sites in Proteins. When is a Tetrathiolate not a Tetrathiolate? K. Clark-Baldwin, D. L. Terney, N. Govindaswamy, E. S. Gruff, C. Kim, J. Berg, S. A. Koch, J. E. Penner-Hahn, J. Am. Chem. Soc. 120, 8401-8409 (1998).

Factors influencing the in vivo of Behavior of In(III)S3N and Ga(III)S3N C. S. Cutler D. E. Reichert, C. J. Anderson, M. C. Giron, R. J. Motekaitis, D. A. Quarless, L. A. Jones, J. S. Lewis, S. A. Koch, A. E. Martell, M. J. Welch. J. Labeled Compounds and Radiopharmaceuticals, 40, 504-50 (1997).

Development of a new Gallium-68 Imaging Agent that Crosses the Intact Blood Brain Barrier, C. S. Cutler, M. C. Giron, D. E. Reicher, C. J. Anderson, S. A. Koch, M. J. Welch, J. Nucl. Med. 38, 466(1997)

A Neutral Spirocyclic Hexacoordinated Germanium(IV) Complex: Hypervalent Germanium Compounds with Sulfur-Containing Eight-Membered Rings, S. D. Pastor, V. Huang, D. NabiRahni, S. A. Koch, H-F. Hsu, Inorg. Chem. 36, 5966 (1997)

Chemistry of Iron Thiolate Complexes with CN- and CO. Models for the [Fe(CO)(CN)2]Structural Unit in Ni-Fe Hydrogenase Enzymes, H-F. Hsu, S. A. Koch and C. V. Popescu, E. Münck, , J. Am. Chem. Soc. 119, 8371(1997).

Nickel(II) Thiolate Complex with Carbon Monoxide and its Fe(II) Analog: Synthetic Models for CO Adducts of Nickel-Iron-Containing Enzymes, D. H. Nguyen, H-F. Hsu, M. Millar, S. A. Koch, C. Achim, E. L. Bominaar, E. Münck, J. Am. Chem. Soc. 118, 8963 (1996).

Synthetic Models for the Iron-Sulfur Protein Rubredoxin: The Use of Sterically Hindered Thiolate Ligands To Stabilize [Fe(SR)4]1- Complexes; Some Considerations of the Structure of the [Fe(S-Cys)4] Center in Oxidized Rubredoxin, M. Millar, J. F. Lee, T. O'Sullivan, S. A. Koch, R. Fikar, Inorg. Chim. Acta 243, 333-343 (1996).

A One-dimensional Germanium Sulfide Polymer Akin to the Ionosilicates: Synthesis and Structural Characterization of DPA-GS-8, Ge4S9(C3H7)2NH2(CH3H7)NH2(C2H5). D. M. Nellis, Y. Kee, K. Tan, S. Koch, J. B. Parise J. Chem. Soc., Chem. Commun. 541 (1995)

Structural Evolution from Tin Sulfide (Selenide) Layered Structures to Novel 3- and 4-Connected Tin Oxy-sulfides. J. B. Parise, Y. Ko, K. Tan, D. M. Nellis, S. Koch J. Solid State Chem. 117, 219 (1995)

A New Aminetrithiolate Tripod Ligand and its Fe(II) and Fe(III) Complexes
N. Govindaswamy, D. A. Quarless, Jr., and S. A. Koch, J. Am. Chem. Soc. 117, 8468 (1995).

Synthesis, Structure, and Properties of a Binuclear Iron-Thiolate Complex with a trans-Disulfur Bridge: A Structural Isomer of the [Fe2S2] Core of 2-Fe Ferredoxins J. D. Franolic, M. Millar, S. A. Koch Inorg. Chem. 34, 1981 (1995)

Novel Two-Dimensional Tin Sulfide Networks: Preparation and Structural Characterization of Sn4S9[(CH3H7)4N]2 and Sn4S9[(CH3H7)4N].[(CH3)3NH] Y. Ko, K. Tan, D. M. Nellis, S. Koch, J. B. Parise J. Solid State Chem. 114, 506 (1995)

Syntheses and Structure of Titanium Tetrathiolate and Tantalum Pentathiolate Complexes. Metal-Sulfur bonding in Early Transition Metal Compounds. D. T. Corwin, Jr., J. F. Corning, S. A. Koch, M. Millar Inorg. Chim. Acta 229, 335 (1995)

Novel Layered Sulfides of Tin: Synthesis, Stuctural Characterization and Ion Exchange Properies of TMA-SnS-1, Sn3S7. (NMe4)2.H2O. J. B. Parise, Y. Ko, J. Rijssenbeek, D. M. Nellis, K. Tam, S. Koch J. Chem. Soc., Chem. Commun. 527(1994)

Resonance Raman Spectroscopy of Iron(III)tetrathiolate Complexes: Implications for the Conformation and Force Field of Rubredoxin. R. S. Czernuszewicz, L. K. Kilpatrick, S. A. Koch and T. G. Spiro J. Am. Chem. Soc. 116, 7134 (1994). .

X-ray Crystal Structures of a Series of [MII(SR)4]2- Complexes (M= Mn, Fe, Co, Ni, Zn, Cd, and Hg) with S4 Crystallographic Symmetry, A. Silver, S. A. Koch, M. Millar Inorg. Chim. Acta 205, 9 (1993)

X-ray Crystal Structures of a Series of [MII(SR)4]2- Complexes (M= Mn, Fe, Co, Ni, Zn, Cd, and Hg) with S4 Crystallographic Symmetry, A. Silver, S. A. Koch, M. Millar Inorg. Chim. Acta 205, 9 (1993)

Nitrogen-14 Single Crystal Study of the Schiff Base, N-(9-anthrylidene)methylimine R. Subramanian, S. A. Koch, G. S. Harbison J. Phys. Chem. 97, 8625 (1993).

A General Synthesis of Iron(III)Tetrathiolate Complexes. Structural and Spectroscopic Models for the [Fe(S-Cys)4] Center in Oxidized Rubredoxin, L. E. Maelia, M. Millar, S. A. Koch, Inorg. Chem. 31, 4594 (1992).

A Distorted [Hg(SR)4]2- Complex with Alkyl Thiolate Ligands; the Fictile Coordination Sphere of Monomeric [Hg(SR)n] Complexes K. Govindaswamy, J. Moy, M. Millar, S. A. Koch Inorg. Chem. 31, 5343 (1992)

[M(SR)3L2] Complexes of Ruthenium(IV,III) and Osmium(IV); Structural Integrity of the Trigonal [M(SR)3]1+,0 Cores. S. P. Satsangee, J. H. Hain, Jr., P. T. Cooper, S. A. Koch Inorg. Chem. 31, 5160 (1992).

Solid-State 199Hg and 113Cd NMR Studies of Mercury and Cadmium Thiolate Complexes. Spectroscopic Models for [Hg(S-Cys)n] Centers in Bacterial Mercury Resistance Proteins. R. A. Santos, E. S. Gruff, S. A. Koch, G. S. Harbison, J. Am. Chem. Soc. 113, 469 (1991).

Single Crystal Spectroscopic Studies of [Fe(SR)4]2- (R = 2Ph-C6H4): Electronic Structure of the Ferrous Site in Rubredoxin. M. S. Gebhard, S. A. Koch, M. Millar, F. J. Devlin, P. S. Stephens, E. I Solomon, J. Am. Chem. Soc. 113, 1640 (1991).

Single Crystal Spectral Studies of [Fe(SR)4]1- (R = 2,3,5,6-Me4C6H): The Electronic Structure of the Ferric Tetrathiolate Active Site. M. S. Gebhard, J. C. Deaton, S. A. Koch, M. Millar, E. I. Solomon, J. Am. Chem. Soc. 112, 2217 (1990).

Single-Crystal, Solid-State and Solution 113Cd NMR Studies of [Cd(SR)2(N-donor)2] Complexes. Structural and Spectroscopic Analogs for Biologically Occurring [M(S-Cys)2(his)2] Centers. R. A. Santos, E. S. Gruff, S. A. Koch, G. S. Harbison, J. Am. Chem. Soc. 112, 9257 (1990).

Trigonal Planar [M(SR)3]1- complexes of Cadmium and Mercury; Structural Similarities Between Mercury- and Cadmium-Cysteine Coordination Centers. E. S. Gruff, S. A. Koch J. Am. Chem. Soc. 112, 1245 (1990).

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