Associate Professor
    Ph.D., Colorado State Univ.
    Physical Inorganic Chemistry
    curriculum vitae
Light driven reactions employ photonic energy to break and make bonds within complexes and compounds. As such, these reactions are of fundamental and applied importance in the fields of chemistry, biology and materials science. Photochromic compounds (those that change color when exposed to light) are unusually efficient in this regard and specifically and selectively break and make bonds within the excited state lifetime of a chromophore. Accordingly, study of these compounds reveals much regarding how these compounds utilize light energy to prepare an excited state, how these compounds transduce photonic energy to potential energy and how these compounds break and make bonds on a femtosecond, picosecond or nanosecond timescale. In the Rack research group, our interests are in the preparation of these complexes, in the ultrafast spectroscopy of these complexes, and in the design of new materials based on these complexes.

The last of these objectives have led to us to identify a rare photomechanical effect with polymers comprising photochromic ruthenium sulfoxide monomers. Indeed, there are few materials that exhibit such features. The most well known compound of this type is azobenzene. Photomechanical effects are of fundamental importance in biomaterials: the eye lens changes shape with different wavelengths of light to focus light onto the retina; also, the protein rhodopsin undergoes a shape change following opsin isomerization that prompts proton pumping across the membrane, a fundamental step in vision. We are working to elucidate and elaborate this effect in the development of new photoactive materials that feature photomechanical properties.

Shown here on our website are examples of these studies as well as pictures of the people and instruments that make things happen. Please be sure to send us an e-mail if you have any comments, questions or suggestions!