This research of Professors Harry B. Gray and Jay R. Winkler of the California Institute of Technology is funded by the Inorganic, Bioinorganic and Organometallic Chemistry Program. The research is aimed at probing the role of electron tunneling (super exchange) in long range electron transfer through materials such as proteins. Electron transfer of this type is extremely sensitive to the difference in energy between the bridge and those of the donor and acceptor. Biphenylene bridges will be used to link two metal ions and the effects of tunneling energy through a common set of bridging ligands will be determined by varying both the electron donor and acceptor metal ions. Electron-transfer reactions are the simplest of chemical transformations in that no bonds are formed or broken as the electron migrates from the donor to the acceptor. When the redox partners are separated by long distances, the rate of electron transfer is mediated by the intervening medium. This research will study the effects of energy differences between electronic states in the bridge and those of the donor and acceptor metal ions.
