DNA-mediated electron transfer: Chemistry at a distance

The DNA double helix, containing a pi-stacked array of base pairs in its core, represents a unique and efficient medium for long-range charge transport. DNA assemblies have been constructed containing tethered metallointercalators, and these provide chemically well-defined systems through which to probe the DNA pi-stack. Using both spectroscopy and chemical assays of reactivity, we find electron transfer reactions mediated by the DNA base pairs to occur over long molecular distances. The structure of DNA facilitates chemistry at a distance. Importantly, these long-range reactions depend sensitively upon base pair stacking, and hence are modulated by and report on the characteristic stacking within the double helix.