Ph.D.: Brown University, 1971
Awards:International Center for Advanced Studies Fellowship (Russia), 1997STINT Visiting Scientist/Scholar Fellowship (Sweden) 1997TMU Fellowship (Japan) 1996Swedish Natural Science Research Council Fellowship, 1994National Academy of Sciences Fellowship, 1990
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.
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).
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, 2008, 361, 2941-2949.
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. 2009, 103, 87-93.
A. M. Morris, C. G. Pierpont, R. G. Finke, “Synthesis and Characterization of VV(3,6-DBSQ)(3,6-DBCat)2, a d0 Metal Complex with Catalytic Dioxygenase Activity”, Inorg. Chem. 2009, 48, 3496-3498.
A. M. Morris, C. G. Pierpont, R. G. Finke, “Dioxygenase Catalysis by d0 Metal-Catecholate Complexes Containing Vanadium and Molybdenum for H2(3,5-DTBC) and H2(3,6-DTBC) Substrates”, J. Mol. Catal. A, Chemical 2009, 309, 137-145.
J. Christ, C. Epps, V. Pritchard, D. Schmeh, C. G. Pierpont, E. Nordlander, “Synthesis and Reactivity of Catechol Complexes Containing Quadruply Bonded Metal Ions“ Inorg. Chem. 2010, 49, 2029-2031.
J. Porter, S. Arreguin, C. G. Pierpont, “Ferric Iron Complexes of Dopamine and 5,6-Dihydroxyindole with NTA, EDDA, and EDTA as Ancillary Ligands” Inorg. Chim. Acta, (Special Issue Honoring Prof. Anamesh Chakravorty), 2010, 363, 2800-2803.