Effects of Distance, Energy and Molecular Structure on Long-Distance Electron-Transfer Between Molecules

Abstract

The centerpiece of this meeting is the exciting measurements of the structure of the photosynthetic reaction center of R. viridis by MICHEL, DEISENHOFER and co-workers [1–3]. To understand the marriage of structure to function in this beautiful machine, we need to understand the basic principles of several processes, one of which is electron transfer (ET) between molecules. Things we must know are how electron transfer rates depend on distance, energy, spatial orientation, polarity of the medium and molecular structure of all the material involved. Our work is aimed at learning these basic principles through experimental measurements of electron transfer between molecules. The molecules we use are not components of photosynthesis, but are usually aromatic molecules. To learn how ET rates depend on distance, it has been necessary to hold electron donors and acceptors at fixed distances. It turns out that fixed distances are very helpful, perhaps even necessary, to answer the other questions as well.

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