Two‐Dimensional Supramolecular Chemistry

Abstract

Two‐dimensional assembly of molecular assemblies on surfaces represents a significant challenge to chemists, materials scientists, and physicists. Supramolecular chemistry offers many advantageous strategies for the development of such arrays through the use of intermolecular interactions to control the process of molecular organization and self‐assembly. This article reveals how hydrogen bonds, dipole–dipole, van der Waals interactions, and metal–ligand coordination can be used to assemble two‐dimensional arrays on surfaces. Such supramolecular assemblies can be used to trap guest species mimicking host–guest chemistry in the solution phase. By the use of the molecular resolution of scanning‐probe microscopies, particularly scanning tunneling microscopy, the precise arrangement of the supramolecular assemblies can be probed and evaluated including the relative orientation with respect to the surface. The influence of the surface on the self‐assembly process is discussed and it is shown that far from playing a passive role in the self‐assembly process the substrate can strongly influence the supramolecular chemistry observed. Such images provide great insight into the advantages and restrictions of working in two dimensions in comparison to the solution phase or the solid state.

Molecular Epitaxy on Two-Dimensional Materials: The Interplay between Interactions

“…The concepts of interactions in the process of molecular epitaxy on 2D materials interfaces, can be learned from the field of epitaxy and self-assembly on bulk interfaces. ,,, A molecule in the bulk form and on a densely covered surface feels the interactions from the other epitaxial molecules, known as the intermolecular interactions. On the other hand, a molecule undergoes various processes on a 2D surface, including adsorption, diffusion, rotation, and vibration, which is governed by the molecule–2D material interactions.…”

“…In addition to the epitaxial behavior induced by the specific adsorption site on 2D materials, a rich set of sub-2D assembled structures can be obtained by tailoring the intermolecular and molecule–substrate interactions. The concept of 2D supramolecular self-assembly , which was previously extensively studied on bulk surfaces, such as metal and highly oriented pyrolytic graphite (HOPG), has been shown to be also extendable under the scope of 2D materials, yielding a broad possibility for fabricating hybrid function 2D heterostructures. Intermolecular hydrogen bonding is widely used to guide the orientation of surface-assisted self-assemblies, due to its relatively high strength.…”