Rational design of two-dimensional nanoscale networks by electrostatic interactions at surfaces.

The self-assembly of aromatic carboxylic acids and cesium adatoms on a Cu(100) surface at room temperature has been investigated by scanning tunneling microscopy and X-ray photoelectron spectroscopy. The highly ordered molecular nanostructures are comprised of a central ionic coupling motif between the anionic carboxylate moieties and Cs cations that generate distinctive chiral arrangements of the network structures. The primary electrostatic interaction results in highly flexible bond lengths and geometries. The adsorbate-substrate coupling is found to be important for the determination of the structures. With the use of rod-like carboxylic linker molecules, the dimension of the porous networks can be tuned through the variation of the aromatic backbone length.