Molecular Wires: An Overview of the Building Blocks of Molecular Electronics

Molecular wires are the archetypal components in molecular electronics, performing the simple electronic function of conducting charge from one side of a circuit to the other. At the most basic level, a molecular wire is composed of a backbone through which the transmission of charge can take place, either via a coherent superexchange (tunneling) or incoherent charge-hopping mechanism and binding or anchoring groups to physically attach and electronically couple the wire to the rest of the circuit (typically metal electrodes). However, despite the simplicity of concept, the design of an efficient molecular wire, i. e., one able to conduct charge close to the ideal quantum of conductance G(0) and with extremely low attenuation with distance, in a uniform and reproducible fashion remains a topic of debate and intense investigation. In this chapter an empirical overview of the chemistry of molecular wires is presented, with emphasis on the chemical structures and influence on the electrical properties of the molecular junctions formed from them.