Franklin A. Schultz
Distinguished Teacher of the Year, 1980, and C.G. Saltarelli
Sigma Xi Research Award, 1986, Florida Atlantic University; Treasurer,
Society for Electroanalytical Chemistry, 1988-94; Chairman, Division
of Organic and Biological Electrochemistry, The Electrochemical
Society, 1997-99; Purdue School of Science Research Award, IUPUI,
1998.
Research
The principal objective of our research is to understand
relationships between molecular structure and electron transfer
reactivity of transition metal compounds. The work has two directions.
The first seeks to obtain a detailed understanding of the molecular
features which control the rates and spontaneities of electron transfer
reactions. To achieve this goal, we measure rates and activation
parameters using electrochemical techniques and correlate findings
with structural data and the results of chemical calculations. A
significant conclusion is that, because electronic and nuclear motions
are highly correlated, displacements of atomic nuclei constitute
the largest barrier to electron transfer. This imparts important
consequences to the coupling of electron transfer and structural
change. Currently, we are investigating compounds characterized
by large amounts of electron transfer-initiated structural reorganization
and the manner in which the charge transfer event is correlated
with changes in vibrational frequencies, solvent organization, ionic
association, and metal atom spin state. Structural control of electron
transfer is important in the function of biological redox systems
and in the construction of molecular devices.
A second line of research involves electrochemical investigation
of compounds that model the active sites of molybdenum-containing
enzymes. There are two families of such enzymes. One contains high-valent,
mononuclear oxo molybdenum centers that metabolize toxins in mammalian
systems. A second contains a polynuclear Fe, Mo and S cluster that
catalyzes the reduction of dinitrogen (N2) to ammonia,
a process known as nitrogen fixation. A common feature of both enzyme
classes is their ability to transfer more than one electron at a
time. We have pursued understanding of this behavior through investigations
of model systems and have identified examples in which processes
such as protonation or changes in metal coordination promote multielectron
transfer. A more subtle explanation may be operative in nitrogen
fixation. Currently, we are conducting studies of binuclear, ligand-bridged
complexes that model this important biological reaction. The compounds
undergo two-electron transfer in a single step that is accompanied
by reversible cleavage of a metal-metal bond. We seek to understand
the molecular features that produce this behavior and to understand
the energetics of multielectron transfer through a series of synthetic
and electrochemical studies.
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Recent Publications
F. Hossain, M. A. Rigsby, C. T. Duncan, P. L. Milligan, Jr., R. L. Lord, M.-H. Baik and
F. A. Schultz "Synthesis, structure, and properties of low-spin
manganese(III)-poly(pyrazolyl)borate complexes" Inorg. Chem. 2007, 46, in press.
F. A. Schultz, C. T. Duncan and M. A. Risgby "Electrochemistry of the group 7 elements:
manganese, technetium, and rhenium" in: The Encyclopedia of Electrochemistry, Volume 7b,
Inorganic Electrochemistry; A. J. Bard, M Stratman, F. Scholz and C. J. Pickett, Eds.:
Wiley-VCH, Weinheim, 2006, pp 399-460.
J. R. Sheets and F. A. Schultz "Coupled electron-transfer and spin- exchange reactions of
metal-bis[(tris)pyrazolyl)methane complexes" Polyhedron 2004, 23, 1037-1043.
D. Uhrhammer and F. A. Schultz "Modulation of molybdenum-centered redox potentials and
electron transfer rates by sulfur versus oxygen ligation" Inorg. Chem. 2004, 43,
7389-7395.
D. C. L. De Alwis and F. A. Schultz "Metal-bis[poly(pyrazolyl)borate] complexes.
electrochemical, magnetic, and spectroscopic properties and coupled electron-transfer
and spin exchange reactions" Inorg. Chem. 2003, 42, 3616-3622.
A.-K. Duhme-Klair, D. C. L. De Alwis and F. A. Schultz "Electrochemistry of
molybdenum(VI)-catecholamide siderophore complexes in aqueous solution" Inorg. Chim.
Acta 2003, 351, 150-158.
D. Uhrhammer and F. A. Schultz “Energetics of concerted two-electron transfer and
metal-metal bond cleavage in phosphido-bridged molybdenum and tungsten carbonyl
complexes” J. Phys. Chem. A 2002, 106, 11630-11636.
J. W. Turner and F. A. Schultz “Electrochemical activation parameters of coupled
electron-transfer and spin-exchange reactions. Experimental studies of [M(Tacn)2]3+/2+
and [Fe(Pzb)2]+/0 redox systems” J. Phys. Chem. B, 2002, 106, 2009-2017.
J. W. Turner and F. A. Schultz “Coupled electron-transfer and spin- exchange reactions”
Coord. Chem. Rev. 2001, 219-221, 81-97.
J. W. Turner and F. A. Schultz “Solution characterization of the iron (II)
bis(1,4,7-triazacyclononane) spin-equilibrium reaction” Inorg. Chem. 2001, 40, 5296-5298.
J. U. Mondal, J. G. Zamora, M. D. Kinon and F. A. Schultz “Six- coordinate monooxo
molybdenum(VI) complexes with catecholate and salicylaldelyde thiosemicarbazone ligands"
Inorg. Chim. Acta 2000, 309, 147-150.
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