The research in my laboratory is concerned with experimental studies of molecular dynamics in the solid state. This area is now recognized to have substantial importance in a variety of areas ranging from the structure and activity of proteins to electron exchange and even the basic properties of ice. As such, our experimental efforts, supported by the biophysics division of the National Science Foundation, find us delving into such diverse endeavors as the preparation of crystalline proteins and transition metal clusters. The primary experimental tool for us is solid state nuclear magnetic resonance spectroscopy and all of these studies are performed on an instrument constructed here in the chemistry department.
The feature of this spectroscopic method which renders it useful for studying molecular dynamics is that atomic motions result in an understandable modification or averaging of anisotropic nuclear spin interactions readily measured in the solid state. Often times the theory for interpreting the results lags behind the richness of our experimental observations. Thus, in addition to a wide variety of chemical problems, we also find ourselves building electronic devices as well as doing a bit of theory and computer programming.
Recent published results from the group have established the connection between solvate dynamics and rapid intramolecular electron exchange in trinuclear iron acetate clusters, that water molecules in ice move at a rate of about 105 rotations per second and that the water of hydration in a crystalline protein is not rigidly fixed in space but rather rotationally disordered much like liquid water. Furthermore, the protein's water of hydration does not freeze until cooled to about -100oC; the temperature at which enzymatic activity is often lost. Other results have demonstrated that ferrocene molecules in a high temperature cubic lattice rapidly reorient their molecular axes along any of the cubic lattice directions. In short, one's traditional view that molecules in solids are stationary has many exceptions. Our job is to understand the chemical and biophysical consequences of this situation.