Engineering Dislocation Networks for the Directed Assembly of Two-Dimensional Rotor Arrays

Two-dimensional arrays of molecular rotors may provide entirely new approaches to signal processing, sensing, the development of dielectrics, and energy modulation, all based on rotational motions in the molecular adlayers. To this end, we have engineered a bimetallic surface system with a regular array of dislocations and studied the adsorption of a molecular rotor, dibutyl sulfide. Because of a size difference between the atoms, a single layer of Ag deposited onto Cu{111} reconstructs the Cu surface into a regular hexagonal array of hexagonally close-packed domains with an average spacing of 2.6 +/- 0.1 nm surrounded by face-centered cubic close-packed areas. Our data demonstrates that the affinity of adsorbates for these different domains can be used to spatially control single molecule adsorption; individual dibutyl sulfide rotors have been arranged in a hexagonal pattern via their binding preference for hcp sites in a manner analogous to placing cogs on a pegboard.