Ion-Mediated Electron Transfer in a Supramolecular Donor-Acceptor Ensemble

Abstract

Charging Back and Forth Ion binding by proteins can exert a major influence on electron transfer events in biological systems. Park et al. (p. 1324 ) discovered an analogous phenomenon in a simpler synthetic system. Specifically, a certain flexible molecule, known as a calix[4]pyrrole derivative, adopts a conical conformation upon binding anions, such as chloride or bromide, and this in turn leads to electron transfer to a guest acceptor that drifts into the cone. Addition of a cation that fitted more snugly into the conical cavity resulted in a reversal of the electron transfer reaction. The whole process was mapped out by spectroscopic and crystallographic characterization of the intermediates and products.