Electron Transport and a Rectifying Effect of Oligourea Foldamer Films Entrapped within Nanoscale Junctions

alpha-Helicomimetic oligoureas are a class of compounds with a broad spectrum of applications, yet their use in materials science remains still unexplored. In this work, we have synthesized three oligomers composed of 8-12 residues and studied their electron transport characteristic. We have found that the conductance of oligoureas depends on the length of the molecule. The distance dependence yields a low value of the decay constant, which indicates that the dominant mechanism is hopping. Moreover, we describe here an entirely new property of oligoureas, that is, directional dependence of electron transport. The latter is manifested on current-voltage characteristic as current rectification. The highest rectification ratio observed was approximate to 12, which is around 3 times greater than that observed for helical peptides of similar length. This effect demonstrates that carefully designed oligomers with a well-defined secondary structure (e.g., oligourea foldamers) may be considered as potential candidates for use in nanoelectronics.