Supramolecular Corrals on Surfaces Resulting from Aromatic Interactions of Nonplanar Triazoles.

Interaction forces between aromatic moieties, often referred to as π-π interactions, are an important element in stabilizing complex supramolecular structures. For supramolecular self-assembly occurring on surfaces, where aromatic moieties are typically forced to adsorb coplanar with the surface, the possible role of intermolecular aromatic interactions is much less explored. Here, we report on unusual, ring-shaped supramolecular corral surface structures resulting from adsorption of a molecule with nonplanar structure, allowing for intermolecular aromatic interactions. The discrete corral structures are observed using high-resolution scanning tunneling microscopy, and the energetic driving forces for their formation are elucidated using density functional theory calculations and Monte Carlo simulations. The individual corrals involve between 11 and 18 molecules bound through triazole moieties to a ring-shaped ensemble of bridge site positions on (111) surfaces of copper, silver, or gold. The curvature required to form the corrals is identified to result from the angle dependence of aromatic interactions between molecular phenanthrene moieties. The study provides detailed quantitative insights into triazole-surface and aromatic interactions and illustrates how they may be used to drive surface supramolecular self-assembly.

Revealing the structural detail of individual polymers using a combination of electrospray deposition and UHV-STM.

A phenylene vinylene polymer derivative is deposited onto a Au(111) surface under Ultra-High Vacuum (UHV) conditions using electrospray ionisation deposition and characterised using Scanning Tunnelling Microscopy (STM). High resolution STM images reveal the polymer structure on the monomeric scale, allowing the identification of regioisomerism, the intricate isomerisations of the polymer side-chains, as well as the larger-scale topologies of the polymer strands.

Adsorption of a dihydro-TTF derivative on Au(111) via a thiolate complex bonding to gold adatoms.

A dihydro-TTF derivative with four acetyl-protected thiol ligands was synthesised and adsorbed on Au(111) under UHV conditions. Scanning Tunnelling Microscopy (STM) and Infrared (IR) spectroscopy show that self-organised structures are formed following annealing to 333 K, with each pair of bidentate thiolate ligands bonding to a single gold adatom in a S-Auad-S complex. Due to the lack of a direct orbital overlap between the dihydro-TTF moieties and the surface, relatively little charge transfer between TAT-TTF and the gold surface occurs.