Supramolecular nanostructuring of silver surfaces via self-assembly of [60]fullerene and porphyrin modules

Recent achievements in our laboratory toward the “bottom-up” fabrication of addressable multicomponent molecular entities obtained by self-assembly of C₆₀ and porphyrins on Ag(100) and Ag(111) surfaces are described. Scanning tunneling microscopy (STM) studies on ad-layers constituting monomeric and triply linked porphyrin modules showed that the molecules self-organize into ordered supramolecular assemblies, the ordering of which is controlled by the porphyrin chemical structure, the metal substrate, and the surface coverage. Specifically, the successful preparation of unprecedented two-dimensional porphyrin-based assemblies featuring regular pores on Ag(111) surfaces has been achieved. Subsequent co-deposition of C₆₀ molecules on top of the porphyrin monolayers results in selective self-organization into ordered molecular hybrid bilayers, the organization of which is driven by both fullerene coverage and porphyrin structure. In all-ordered fullerene–porphyrin assemblies, the C₆₀ guests organize, unusually, into long chains and/or two-dimensional arrays. Furthermore, sublimation of C₆₀ on top of the porous porphyrin network reveals the selective long-range inclusion of the fullerene guests within the hosting cavities. The observed mode of the C₆₀ self-assembly originates from a delicate equilibrium between substrate–molecule and molecule–molecule interactions involving charge-transfer processes and conformational reorganizations as a consequence of the structural adaptation of the fullerene–porphyrin bilayer.