People | Faculty | David Pratt
 |
David Pratt Department of Chemistry |
Structure dictates function. Nowhere is this more apparent than in biological systems. An enzyme functions in the way that it does because of the three-dimensional arrangement of atoms or groups of atoms in its vicinity. Much of our current understanding of the molecular basis of life is based in large part on recent determinations of the structures of proteins by X-ray crystallography and NMR techniques. Knowing how proteins are constructed has given us much insight into how they form, how they function, and how they evolve in time.
Our own goals are no less ambitious. We develop new high resolution spectroscopic techniques for the determination of the structures of molecules and their assemblies. A recent example is rotationally resolved electronic spectroscopy in molecular beams, in which the resolution approaches 1 part in 109. We use this technique to determine the moments of inertia of isolated molecules and complexes, from which we obtain information about their three-dimensional structures. We also use this technique to determine how the structures change when they absorb light, thereby modeling chemical reactions. We ask, and answer, questions such as: What kind of interactions exist between two or more species to promote their assembly? How do the electronic charge distributions of the species interact? How are the structures of the individual species modified when they interact? Do they react? Why? And how do the answers to these questions depend upon the relative orientations of the constituents?
In recent work, we have shown how the electronic distributions of two atoms change when they are brought together to form a diatomic molecule, how a solute molecule is distorted towards a zwitterionic form when a solvent molecule is attached, how the motion of a molecule in free space is affected when it is weakly bound to a surface, how the lone pairs of a Lewis base orient themselves towards an acid in a proton-transfer (neutralization) reaction, initiated by light, and how the vibrational motions of a molecule are affected by neighboring molecules, with which only weak, van der Waals forces exist.
Our future work will continue to focus on these questions. We plan to study the geometric constraints on intramolecular excimer formation, hydrogen atom transfer, and "water-assisted" tautomerization reactions. We are designing gas-phase mimics of function in several biological systems, such as the catalytic triad in chymotrypsin. And we are developing new techniques for the study of analogous processes in the condensed phase, including a near-field scanning optical microscope that will employ a new CW laser as the light source.
Awards
Pittsburgh Award of the American Chemical Society, 2005; Chancellor's Distinguished Research Award, 2001; Earle K. Plyler Award, 1999; Fellow of Exeter College, Oxford, 1996; Chancellor's Distinguished Teaching Award, 1994; AAAS Fellow, 1993; Fellow of the APS, 1990; JSPS Fellow, 1988; Guggenheim Fellow, 1985; Fulbright Fellow, 1979
Selected Publications
"Probing the Electronic Structure of Peptide Bonds Using Methyl Groups", David F. Plusquellic and David W. Pratt, J. Phys. Chem. A., 2007, 111, 7391.
"Rotationally Resolved Electronic Spectra of 9,10-dihydrophenanthrene. A "floppy" Molecule in the Gas Phase", Leonardo Alvarez-Valtierra and David W. Pratt, J. Chem. Phys., 2007, 126, 224308.
"Molecular Recognition in the Gas Phase. Dipole-bound Complexes of Benzonitrile with Water, Ammonia, Methanol, Acetonitrile, and Benzonitrile Itself", David R. Borst, Martin Schaefer, and David W. Pratt, Phys. Chem. Chem. Phys., 2007, 9, 4563.
"The Molecular Universe", Ilana Stol and David W. Pratt, The Spectrum, 2007, 20, 12.
"On the Role of Methyl Torsional Modes in the Intersystem Crossing Dynamics of Isolated Molecules", Leonardo Alvarez-Valtierra, Xue-Qing Tan, and David W. Pratt, J. Phys. Chem., 2007, 111A, 12802.
"High Resolution Electronic Spectroscopy of p-Vinylphenol in the Gas Phase", Philip J. Morgan, Diane M. Mitchell, and David W. Pratt, Chem. Phys. 2008, 347, 340.
“Push-Pull Molecules in the Gas Phase. Stark-Effect Measurements of the Permanent Dipole Moments of p-Aminobenzoic Acid in Its Ground and Electronically Excited States”, Diane M. Mitchell, Philip J. Morgan, and David W. Pratt, J. Phys. Chem. 2008, 112A, 12597.
“Lifetime Broadening in the Rotationally Resolved Electronic Spectra of Dibenzothiophene, 2,5-Diphenylfuran, and 2,5-Diphenyl-1,3,4-oxadiazole in the Gas Phase. Intersystem Crossing Dynamics in the Statistical Limit”, Leonardo Alvarez-Valtierra, John T. Yi, and David W. Pratt, J. Phys. Chem. 2009, 113A, 2261.
"Chemistry in the Natural Sciences", Peter F. M. Koehler and David W. Pratt, J. Chem. Ed., submitted.
"Next Generation Techniques in the High Resolution Spectroscopy of Biomolecules", Brooks H. Pate and David W. Pratt, feature article in preparation for Physical Chemistry Chemical Physics.