One of the earliest ideas for the use of π-conjugated molecules in molecular computation was proposed by Ari Aviram from IBM in 1988. The motivation for this work was to develop theoretical models for mixed-valence type-σ-π-σ-bonded molecules and explore their stereochemical properties for potential applications in molecular devices. The system comprised two π-conjugated systems, 1 and 2, made of oligothiophenes joined by a spiro linkage, and connected to gold electrodes by thiol linkers. π-system 1 is non-conducting in its neutral state, whereas system 2 is electrically conducting in its radical cation form. The twisted structure of the system courtesy of the spiro linkage provides hindrance to the transport of electrons between the two π-systems. However, through electrodes directed toward the linkage, a strong electric field could facilitate electron transfer from system 1 to system 2, with the radical cation going the opposite way.
