title: Orientation-controlled single-molecule junctions.
abstract: The conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM-BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat-oriented mesitylene molecules on Au(111) to enable direct tip/π contacts, a result that is not possible by conventional methods. The measured conductance of Au/π/Au junction is about 0.1 G(o) , two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long-range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation-controlled molecular junctions.
authors.affiliation: Department of Chemistry, Temple University, Philadelphia, PA 19122 (USA) http://www.temple.edu/borguet/
authors.forename: Sepideh
authors.initials: S
authors.lastname: Afsari
authors.forename: Zhihai
authors.initials: Z
authors.lastname: Li
authors.forename: Eric
authors.initials: E
authors.lastname: Borguet
keywords: benzene derivatives; mesitylene; molecular electronics; self-assembly; single-molecule conductivity