Supramolecular Nanostructuring of Silver Surfaces via Self‐Assembly of [60]Fullerene and Porphyrin Modules

Abstract

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.

Molecular Dynamics Simulations of the Self-Assembly of Tetraphenylporphyrin-Based Monolayers and Bilayers at a Silver Interface

“…Although the sampled time was not sufficient to characterize the numerous aspects of the aggregation mechanism of all the units inserted in the simulation box, the analysis of the data suggested that the formed islands increased their size through collection of the free molecules, which, due to the Brownian motion, slowly migrated toward the initial nucleation centers. These results, in line with experimental data, 10,105 suggest that stabilizing effects on the molecular matrices could be enhanced by a higher surface coverage. Indeed, as this study will indicate, a progressive increase in the surface coverage can lead to the formation of ordered molecular networks through the expansion of localized molecular patches.…”

Supramolecular Pattern of Fullerene on 2D Bimolecular “Chessboard” Consisting of Bottom-up Assembly of Porphyrin and Phthalocyanine Molecules

“…This result indicates that the bimolecular chessboard makes it possible to form the supramolecular assembly of C 60 , resulting in enhancement of subtle intermolecular interactions. As previously reported by Spillmann et al, the formation of the assembled C 60 molecules was found on the porous network consisting of the cyanophenyl-substituted zinc porphyrin derivative formed on Ag(111) in UHV . Each C 60 molecule was located precisely on top of a porous porphyrin network, revealing that the selective inclusion of fullerene occurs within the hosting cavities arranged in a nanopatterned array.…”

Surfaces: Two-Dimensional Templates

“…This surface can now be utilized for the template-controlled deposition of C 60 molecules, which will reside as guests in the pores of the templating layer [201]. Similar results have also been obtained on Ag(100) [202]. This again proves the feasibility of a hierarchical template-controlled assembly of molecules on solid surfaces.…”