Molecules as wires: molecule-assisted movement of charge and energy.

In this chapter, we explore experimental and theoretical aspects of molecular wire-like charge transport from the mechanistic point of view. We discuss competition between coherent superexchange and sequential mechanisms of transport through donor-bridge-acceptor systems, where the donor and acceptor are either molecules or metal/semiconductor contacts. The focus is on the two major determinants of mechanism: electronic coupling and energy level matching. Some methods of calculating conductance are outlined, and the relationship between conductance in a metal/molecule/metal junction and electron transfer, where donor and acceptor have relatively discrete electronic energy levels is explored. Finally, we give several examples of chemical systems that have displayed wire-like behavior and discuss their characterization.