Intramolecular Electron Transfer in Organic Molecules. Molecular Nanowires

Abstract

In the last few years, considerable interest is being devoted to the obtaining of molecular wires that exhibit intramolecular electron transfer phenomena [1–4]. The interest arises from the potential use of such systems on integrated molecular devices [5,6] and the technical advantages that can be derived from there. First, the ever-increasing miniaturization of the architectural components of microchips reverts in the reduction size of computational systems. Second, time for an electron to travel through the circuit can be minimized using molecular-scale electronic architectures, which operate at far greater speeds. The main drawbacks are the high conformational requirements that the molecule to be used must fulfill. For instance, an average interelectrode distance of 100 Å obtained using “engineering-down” techniques; i.e., litographic techniques, requires the synthesis of molecular systems that in addition to a p-conjugated pathway, have similar dimensions to the interelectrode distance and restricted conformational geometries. One of the few examples of such exigent conformational systems has been reported by Gourdon et al. [7]. Another approach, which overcomes such difficulties, is the use of self-assembling techniques. Indeed, using this technique Tour et al. [8] were able to study quantitatively the conductance of a single benzene-1,4-dithiol molecule located between two gold nanoelectrodes. These results aim us to expect practical applications for this kind of systems in the near future. However, if a truly molecular computational device is to be achieved, new systematic studies that allow us to obtain rules for the prediction and control of the electron propagation in molecular wires are highly required.