Programming Hierarchical Supramolecular Nanostructures at Surfaces
Yeliang WANG ( )
Max-Planck-Institute for Solid State Research, Heisenbergstr 1, 70569 Stuttgart ,Germany.
Tel: +49 711 689 1596 Fax: +49 711 689 1662
E-mail: y.wang@fkf.mpg.de
Hierarchical self-assembly is an extremely efficient way of constructing complex functional architectures that has been developed by nature through billions of years of evolution. A major advantage of this approach is that the formation of ordered superstructures at higher levels of organization does not dismantle but builds upon the lower-lying levels. Using a hierarchical stepwise process for the molecular assembly allows a much higher control and predictability of the final supramolecular arrangements. Elementary molecular building blocks can in fact be chemically designed so as to develop identical binding motifs at the first level of organization but different ones at the higher-lying levels. The hierarchy of interactions warrants that the first-level organization units are always formed but their assembly at the higher complexity level can be arbitrarily tuned.
Here the hierarchical organometallic nanostructures, from 1D chains to 2D sheets, are built on Cu surfaces by molecular design. Three different molecules are used that are able to self assembly into 1D metal-organic polymeric chains with the same [-metal-molecule-metal-]n basic unit. These chains are used as elementary units for the secondary organization level where the inter-chain interaction is rationally tuned in order to obtain the desired dimensionality of the final arrangements. Each supramolecular arrangement corresponds in a predictable fashion to the details of the geometry of the selected molecules.
