The future use of single molecules or specific assemblies of few molecules for electronic and optoelectronic devices will require strategies for controlling the self-assembly of molecular species on surfaces. For self-assembly in solution a high degree of control can be achieved by tailoring the mutual molecule-molecule interactions, mostly by non-covalent interactions e.g. hydrogen-bonds. The validity of this approach to achieve specific molecular assemblies also on surfaces has recently been proven by different groups. In addition to intermolecular interactions, the molecule-substrate interaction can be exploited to control the self-assembly at surfaces. The length scale at which the surface structure modulates the molecular adsorption potential should, however, be larger than 1 nm.
Here, I will report on recent advances towards efficient strategies for parallel, two-dimensional molecular self-assembly on surfaces, with a particular focus on the use of nanostructured template surfaces. Scanning tunneling microscopy (STM) and X-ray photoelectron diffraction investigations of site-specific adsorption and (supra-)molecular self-assembly on a naturally structured gold template surface will be presented. The vicinal Au(11,12,12) surface, exhibiting a rectangular superlattice of steps and discommensuration lines, not only serves as an excellent template for the self-assembly of a two-dimensional long-range ordered superlattice of C60 nanochains [1], but also induces unachieved internal order and regularity in a system of surface-supported binary molecular wires and ribbons [2].
[1] W. Xiao, P. Ruffieux, K. Aït-Mansour, O. Gröning, K. Palotas, W. A. Hofer, P. Gröning, and R. Fasel, Formation of a regular fullerene nanochain lattice, J. Phys. Chem. B 110 (43), 21394 (2006).
[2] M. Cañas-Ventura, W. Xiao, D. Wasserfallen, K. Müllen, H. Brune, J.V. Barth, and R. Fasel, Self-assembly of periodic bicomponent wires and ribbons, Angew. Chem. Int. Ed. 46, 1814 (2007). |