Effects of Distance, Energy and Molecular Structure on Electron Transfer Rates

Abstract

Electron transfer reactions are known to occur at long distances in a number of proteins. Among these are the photosynthetic reaction centers which have recently been crystallized to yield an exciting picture of an arrangement of chromophores designed to facilitate charge separation in photosynthesis. We do not yet know in detail how this structure carries out its function. We know a few of the basic principles, but some of the others still need to be learned. At Argonne National Laboratory, our research has focused on the question, “How do long distance electron transfer processes occur; at what distances can they occur; and how are they controlled by energy, distance and molecular structure?” Here, in this extended abstract, I present in a brief summary form some of our findings. I will also review some of what is known about how charged molecules interact with their surrounding medium and the way in which the dynamics of the medium can control the rates of electron transfer processes. It is plausible that similar effects occur to couple the protein dynamics to electron transfer processes occurring within proteins.

Work performed under the auspices of Work performed under the auspices of Division of Chemical Science US-DOE contract number W-31-109-ENG-38.