Contributed by Harry B. Gray, January 17, 2021 (sent for review December 28, 2020; reviewed by David N. Beratan and David I. Schuster)Long-range electron transfer pervades biology, chemistry, and engineering, as it is critical for life-sustaining processes, chemical transformations, energy conversion, as well as electronic and photonic technologies. Elucidating the factors that control the rates of long-range electron transfer remains an outstanding challenge, owing in part to the complexity of proteins and other macromolecular structures that mediate such processes. We have found that...…Contributed by Harry B. Gray, January 17, 2021 (sent for review December 28, 2020; reviewed by David N. Beratan and David I. Schuster)Long-range electron transfer pervades biology, chemistry, and engineering, as it is critical for life-sustaining processes, chemical transformations, energy conversion, as well as electronic and photonic technologies. Elucidating the factors that control the rates of long-range electron transfer remains an outstanding challenge, owing in part to the complexity of proteins and other macromolecular structures that mediate such processes. We have found that...WW…