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Cortlandt G. PIERPONT Office Phone: 303 492 8420
E-mail: Cortlandt.Pierpont@colorado.edu
FAX: 303 492 0951
Lab: Ekeley M394
Lab Phone: 303 492 8025
Group Website:
Ph.D.: Brown University, 1971
Physical and Chemical Properties of Transition Metal Complexes Containing Quinone Ligands
Professor Pierpont is studying the structural, electrochemical, magnetic, and photochemical properties of transition metal complexes that contain organic ligands bearing quinone functionalities. o-Benzoquinones have vacant electronic levels that are similar in energy to the valence d-orbitals of transition metal ions. Electron transfer reactions have been investigated, and the results of these studies have shown that the distribution of charge in a metal-quinone coordination complex is dependent upon parameters that influence the relative energies of metal-d and quinone p electronic levels. These include the bonding effects of coligands, the overall charge of the complex, quinone-ligand substituent effects, and periodic variations in metal d-orbital energy. In cases where metal and quinone electronic levels are particularly close in energy, metal-ligand electron transfer may be observed as an equilibrium between redox isomers in a process that we have referred to as Valence Tautomerism. Thermodynamic parameters associated with these equilibria include large changes in enthalpy and entropy that are of the same sign associated with a transition between tight (low T) and floppy (high T) structural forms for the redox isomers.
Current projects under investigation include the formation and reactivity of catecholate complexes containing strong multiple M-M bonds, studies on the coordination chemistry of dopamine and the potential involvement of iron-dopamine coordination complexes in Parkinson’s disease, and the development of a new iron electrocatalyst for water oxidation. More detailed descriptions of these projects are contained in the Research link on this web page.
Selected Publications
C. G. Pierpont, S. Kitagawa, “Valence Tautomerism of Metal Complexes”. In Inorganic Chromotropism: Basic Concepts and Applications of Colored Materials, Ed. Y. Fukuda; Elsevier, Tokyo, 2007, pp. 116 - 142.
D. N. Hendrickson, C. G. Pierpont, “Valence Tautomeric Transition Metal Complexes”. In Topics in Current Chemistry, Vol. 234, Eds. P. Gütlich, H. A. Goodwin; Springer-Verlag, Berlin, 2004, pp. 63-95.
C. G. Pierpont, “Bending Crystals. Solid State Photomechanical Properties of Transition Metal Complexes Containing Semiquinonate Ligands” Proc. Indian Acad. Sci (Chem. Sci.), 114, 247-254 (2002).
C. G. Pierpont, “Studies on Charge Distribution and Valence Tautomerism in Transition Metal Complexes of Catecholate and Semiquinonate Ligands”, Coord. Chem. Rev., 216-217, 99-125 (2001).
C. G. Pierpont, A. S. Attia, “Spin Coupling Interactions in Transition Metal Complexes Containing Radical o-Semiquinone Ligands. A Review”, Collect. Czech. Chem. Commun., 66, 33-51 (2001).
C. G. Pierpont, “Unique Properties of Transition Metal Quinone Complexes of the MQ3 Series”, Coord. Chem. Rev., 219-221, 415-433 (2001).
C. G. Pierpont, C. W. Lange "The Chemistry of Transition Metal Complexes Containing Catechol and Semiquinone Ligands" Prog. Inorg. Chem., 41, 381-492 (1994).
Recent Publications:
C.-M. Liu, P. Restorp, E. Nordlander, D. Schmeh, R. Shoemaker, C. G. Pierpont, “Coordination Complexes of Molybdenum with 3,6-Di-tert-butylcatechol. Characterization on the Chiral [MoVIO(3,6-DBCat)2]4 Square and on Addition Products of DMSO, Pyridine-N-oxide, and Triphenylarsine Oxide to the Putative MoVIO(3,6-DBCat)2 Monomer” Inorg. Chem., 43, 2114-2124 (2004).
M. Ruf, W. S. Durfee, C. G. Pierpont, “Synthesis of the Quinone-Functionalized Macrocyclic Ligand 1,4,14,17-Tetrahydroxyhemiporphyrazine (H2(hp(OH)4) and Intense Fluorescence of the Zinc Complex [Zn(hp(OH)4)(py)]” J. Chem. Soc., Chem. Comm. 2004, 1022-1023.
Y. Suenaga, C. G. Pierpont, “Binuclear Complexes of Co(III) Containing Extended Conjugated Bis(Catecholate) Ligands” Inorg. Chem., 44, 6183-6191 (2005).
E. A. Gutkina, V. M. Trukhan, C. G. Pierpont, S. Mkoyan, V. V. Strelets, E. Nordlander, A. A. Shteinman, “Tetranuclear Iron(III) Complexes of a New Octadentate Pyridine-Carboxylate Ligand and Their Catalytic Activity in Alkane Oxidation with Hydrogen Peroxide” J. Chem. Soc., Dalton Trans. 2006, 492-501.
Y. Suenaga, Y. Umehata, Y. Hirano, T. Minematsu, C. G. Pierpont, ”Effect of Nitrogen-Donor Ancillary Ligands on Oxidation Behavior of Co(III) Binuclear Complexes with Conjugated Bis(Catecholate) Ligands”, Inorg. Chim. Acta, 361, 2941-2949 (2008)..
S. Arreguin, P. Nelson, S. Padway, M. Shirazi, C. G. Pierpont, “Dopamine Complexes of Iron in the Etiology and Pathogenesis of Parkinson’s Disease” J. Inorg. Biochem. 2008, in press (December).
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