When things are not as they seem: quantum interference turns molecular electron transfer "rules" upside down.

We present an interesting consequence of the differences between cross-conjugated and linearly conjugated molecules: the breakdown of conventional understanding of trends in molecular electron transfer. Interference effects are dominant in cross-conjugated molecules with unusual results: long molecules may have faster rates of electron transfer than short molecules, saturated molecules may have faster rates of electron transfer than conjugated molecules of the same length, and the rate of electron transfer cannot be correlated with energy gaps between the donor and acceptor states and the energy levels of the bridging molecule.