A homomolecular porous network at a Cu(111) surface

Anthraquinone molecules self-assemble on a Cu(111) surface into a large two-dimensional honeycomb network (root 304 x root 304 p)R23 degrees with pore diameters of approximate to 50 angstrom. The spontaneous formation of a pattern containing pores roughly five times larger than the size of the constituent molecules is unprecedented. The network originates from a delicate balance between substrate-mediated repulsion and intermolecular attraction involving an unusual chemical motif: hydrogen bonding between a carbonyl oxygen and an aromatic hydrogen atom. Substrate-mediated long-range adsorbate-adsorbate repulsion has been observed on anisotropic surfaces and in the context of the absence of pattern formation. Its applicability for the design of tailored molecular films is explored here.