The development of methods for the bottom-up fabrication of hierarchical assemblies that incorporate nanostructured carbon is integral to the rational design of electronic materials that implement their useful properties. We report studies that probe the application of patterned monolayers of five-coordinate gallium porphyrins as templates that direct the organization of fullerenes on highly oriented pyrolytic graphite (HOPG) under ambient conditions. Gallium octaethylporphyrins of the type Ga(OEP)(C≡CR) (R = Ph, 3-thiophene, 1-pyrene, 2-pyrene, 9-triptycene, 9-anthracene) self-assemble into ordered monolayers on HOPG upon deposition from solution, as determined by STM imaging. The monolayers present a pseudo-hexagonal lattice in which the C≡CR ligands are perpendicular to the surface, forming corrals with dimensions that are appropriate for accommodating C60. Addition of solutions of C60 and its derivatives to Ga(OEP)(C≡CR) monolayers results, for specific R groups, in the formation of bilayer structures comprised of the original porphyrin monolayer and an adlayer of fullerene. The R groups were chosen to allow systematic investigation of the effects of their C60 binding constant, contact point, and orientation upon the extent of fullerene incorporation. For example, Ga(OEP)(C≡CPh) monolayers are not observed to coordinate C60, consistent with the low solution affinity of its R group. Monolayers of the higher-affinity R = pyrene derivatives exhibit inclusion of fullerenes across a range of concentrations, and the thiophene derivative produces a unique multilayer structure. The factors that control the formation and structures of these assemblies will be discussed.

Templated 2D supramolecular assembly of fullerenes on graphite by five-coordinate gallium–porphyrin monolayers

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.