Multilevel supramolecular architectures self-assembled on metal surfaces.

We report the controllability of the complexity of surface-supported supramolecular assembly on metal surfaces. By introducing mismatch between the molecular packing and the surface atomic periodicity in the systems with comparable strength of intermolecular and molecule-substrate interactions, a homomolecular assembly exhibiting two-dimensional multilevel structures up to quaternary level was observed. In such a multiperiodicity modulated system, neither the intermolecular nor molecule-substrate interactions solely dominate the assembly, resulting in complicated multilevel structures. We further demonstrated that the multilevel assemblies can serve as templates for site-selective adsorption of guest molecules.