| Abstract: | A theoretical analysis based upon large-scale self-consistent Hartree-Fock calculations at a semiempirical quantum theory level (CNDO/S) is performed to investigate long-range electron transfer in a donor-DNA-acceptor molecule, where the donor and acceptor moieties are tethered to the DNA. The π-stacked base pairs are found to dominate the long-range electronic coupling. Despite the π-electron mediated coupling, the exponential distance decay constant of the electron transfer rate is ∼ 1.2–1.6 Å−1, values typical of electron transfer proteins. The calculated long-range electron transfer rate of the order of 106 s−1 for a metal-to-metal distance of 21 Å is found to be in agreement with kinetic measurements by Meade and Kayyem. Based on the current analysis, the π-electrons dominate the long-range electronic coupling interactions in DNA, but they do not lead to one-dimensional molecular wire-like properties. © 1996 John Wiley & Sons, Inc. |
