Molecular self-assembly of the gold(I) cyclic trinuclear complexes (CTCs) on the 1-phenyloctane/highly ordered pyrolytic graphite (HOPG) (0001) solution-solid interface is studied with scanning tunneling microscopy (STM). The gold(I) cyclotrimers form epitaxial nanostructures on the HOPG surface. At a concentration of ~1×10-4 M, Au(I) carbeniate (Au3Cb3) complexes exhibit a polymorphology. Two polymorphs, one non-porous and the other porous, are observed at 22.0 ±2.0 °C. A non-porous, low-surface-density (0.82 molecules/nm2) Au3Cb3 nanostructure forms first then transforms into a high-density (1.43 molecules/nm2) porous nanostructure. This is the first time any porous surface nanostructure is reported for an organometallic system. The porous structure is thought to be stabilized by a combination of hydrogen bonding and monolayer-substrate interactions. These pores are utilized to incorporate pyrene into the film, rendering this the first organometallic host-guest system imaged at the solid-solution interface. Molecular and periodic density functional theory (DFT) calculations shed light on the two-dimensional topography and polymorphic self-assembly revealed by STM; these calculations suggest significant electronic hybridization of the Au3 trimer orbitals and HOPG. The multiple-technique approach used herein provides insights concerning molecule-substrate and molecule-molecule interactions which can be used toward rational functionalization of graphene based electronic devices.

Epitaxial self-assembly of polymorphic, porous, and host-guest nanostructures on surfaces using monolayer-substrate interactions

251st National Meeting (2016)

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