people
|Faculty
|David Waldeck
 |
David Waldeck Department of Chemistry |
Professor Waldeck's research program uses methods of ultrafast spectroscopy, electrochemistry, and UHV based spectroscopies to investigate primary processes in the condensed phase, which includes liquids, solids and liquid/solid interfaces. The current theme of the work is the fundamental understanding of electron transfer reactions and electron transport in supramolecular structures.
Solution Studies. Our research program studies electron transfer processes experimentally in order to directly evaluate and improve theoretical models. Our studies focus on the influence of solvents on the reaction rate, via solvation, friction, and electronic coupling. Four items under investigation are
Molecular Solvation Models. Rigorous, experimental studies that evaluate models of free energies for electron transfer reactions and span the range from non-polar to highly polar environments are being performed.
Dependence of Electron Tunneling Probabilities on Electronic Character. The dependence of the electronic coupling between electron donor and acceptor moieties on the electronic structure of molecular units that lie in the space between them is being systematically explored.
Transition from Weak to Strong Coupling. By performing well-characterized and quantitative studies, the change in the electron transfer mechanism, from a regime in which it is controlled by the tunneling probability to a regime in which it is controlled by the solvent relaxation is being explored.
Influence of Nuclear Motion. For electron transfer reactions that involve tunneling through noncovalent contacts between molecules, the electron transfer can depend strongly on the geometry and molecular motion.
These issues are especially important for an accurate description of electron transfer reactions in chemical and biological systems. Our present efforts are focused on novel electron transfer systems, in collaboration with M. Zimmt (Brown University) and M. Paddon-Row (U. New South Wales).
Interfacial Charge Transfer. These studies probe the charge transfer between a redox species near an electrode surface and the electrode. We are studying the charge transfer through nanometer thick films on the surface (SAMS) to redox species in solution, to redox species that are covalently attached to the surface, and to redox species that are adsorbed to the surface.
Importance of the Film . We are investigating how SAM composition and structure effect electron transfer rates, of particular interest is the role of film chirality.
Transition from Weak to Strong Coupling. We are investigating the change in mechanism (adiabatic to nonadiabatic) for molecules at electrodes by systematically varying the SAM composition and structure.
Bioelectrochemistry. We are using SAM coated electrodes to investigate fundamental issues in electron transfer between electrodes and proteins, e.g. medium and conformational effects on electron transfer in proteins.
New projects in our group are the development of 1) novel fluorescence based sensors for biomolecules and 2) electron and molecule transport through and in lipid bilayers.
Awards
Fellow of the American Physical Society, 2004; Belkin Visiting Professor, Weizmann Institute 1998 - 1999; Chancellor's Distinguished Research Award, University of Pittsburgh, 1994
Selected Publications
"The Chiroptical Signature of Achiral Metal Clusters induced by Dissymmetric Adsorbates," M. R. Goldsmith, C. B. George, G. Zuber, R. Naaman, D. H. Waldeck, P. Wipf, D. N. Beratan, PCCP, 2006, 8, 63-67
"Molecular Chirality and Charge Transfer through Self-Assembled Scaffold Monolayers," J. J. Wei, C. Schafmeister, G. Bird, A. Paul, R. Naaman, D. H. Waldeck, J. Phys. Chem. B, 2006, 110, 1301-1308
"The Fluorescence Quenching Mechanism of a Polyphenylene Polyelectrolyte With Other Macromolecules: Cytochrome c and Dendrimers," M. Liu, P. Kaur, D. H. Waldeck, C. Xue, Haiying Liu, Langmuir, 2005, 21, 1687-1690
"Conjugated Thiol Linker for Enhanced Electrical Conduction of Gold-Molecule Contacts," A. V. Tivanski, Y. He, E. Borguet, H. Liu, G. C. Walker, D. H. Waldeck, J. Phys. Chem. B, 2005, 109, 5398-5402
"Solvent Friction Effect on Intramolecular Electron Transfer," M. Liu, N. Ito, M. Maroncelli, D. H. Waldeck, A. M. Oliver, M. N. Paddow-Row, J. Am. Chem. Soc., 2005, 127, 17867-17876
"Inelastic Electron Tunneling Erases Coupling-Pathway Interferences," S. S. Skourtis, D. H. Waldeck, D. N. Beratan, J. Phys. Chem. B, 2004, 108, 15511-15518
"Probing Electron Tunneling Pathways: Electrochemical Study of Rat Heart Cytochrome c and its Mutant on Pyridine-Terminated SAMs," J. J. Wei, H. Liu, K. Niki, E. Margoliash, D. H. Waldeck, J. Phys. Chem. B, 2004, 108, 16912-16917
"SERR and Electrochemical Study of Cytochrome c Bound on Electrodes through Coordination with Pyridinyl-terminated SAMs," D. H. Murgida, P. Hildebrandt, J. Wei, Y.-F. He, Haiying Liu, and D. H. Waldeck, J. Phys. Chem. B, 2004, 108, 2261-2269
"Positive Activation Volume for a Cytochrome C Electrode Process: Evidence for a "Protein Friction" Mechanism from High-Pressure Studies," T. D. Dolidze, D. E. Khoshtariya, D. H. Waldeck, J. Macyk, R. van Eldik, J. Phys. Chem. B, 2003, 107, 7172-7179
"Hole Transfer in a C-shaped Molecule: Conformational Freedom versus Solvent Mediated Coupling," J. M. Nadeau, M. Liu, D. H. Waldeck, M. B. Zimmt, J. Am. Chem. Soc., 2003, 125, 15964-15973