Tom Guarr

Long distance electron transfer in polymers and proteins

Abstract Initial work in our labs and many others has shown that some aspects of long distance electron transfer is simple glasses are reasonably described by current theories.2–4,12–14 For example, electron transfer rates do decrease exponentially with increasing donor acceptor separation. Also, when diffusion is precluded, the full dependence of rate on exothermicity emerges, which is otherwise obscured. Some aspects of theory based on nuclear tunneling may require serious reexamination: for example, it appears that the dependence of long distance rate on electron (hole) binding energy is weaker than suggested by many popular theories. Work with proteins shows that while nature is a subtle designer, the general reactivity trends observed in proteins are quite similar to those found in polar glasses. Such studies of protein electron transfer have provided some surprises and challenges for experimentalists and theorists alike. As a clearer understanding of the governing principles of long distance biological electron transfer emerge, we hope it will become easier to design meaningful “biomimetic” strategies for solar energy conversion.