Supramolecular Assemblies on Surfaces: Nanopatterning, Functionality, and Reactivity

Abstract

Understanding how molecules interact to form large-scale hierarchical structures on surfaces holds promise for building designer nanoscale constructs with defined chemical and physical properties. Here, we describe early advances in this field and highlight upcoming opportunities and challenges. Both direct intermolecular interactions and those that are mediated by coordinated metal centers or substrates are discussed. These interactions can be additive, but they can also interfere with each other, leading to new assemblies in which electrical potentials vary at distances much larger than those of typical chemical interactions. Earlier spectroscopic and surface measurements have provided partial information on such interfacial effects. In the interim, scanning probe microscopies have assumed defining roles in the field of molecular organization on surfaces, delivering deeper understanding of interactions, structures, and local potentials. Self-assembly is a key strategy to form extended structures on surfaces, advancing nanolithography into the chemical dimension and providing simultaneous control at multiple scales. In parallel, the emergence of graphene and the resulting impetus to explore 2D materials have broadened the field, as surface-confined reactions of molecular building blocks provide access to such materials as 2D polymers and graphene nanoribbons. In this Review, we describe recent advances and point out promising directions that will lead to even greater and more robust capabilities to exploit designer surfaces.

Halogen Bonding in Two‐Dimensional Crystal Engineering

“…On the other hand, solution phase STM offers a real‐life scenario, where dynamic self‐assembly processes can also be studied, albeit on relatively slow time scales. STM data provides a direct visual cue to the self‐assembled system and thus has the added advantage of immediate aesthetic appeal where one can directly ‘see’ the structure of the self‐assembled system …”

“…STM data provides a direct visual cue to the self-assembled system and thus has the added advantage of immediate aesthetic appeal where one can directly 'see' the structure of the self-assembled system. [6] In a typical STM experiment, molecules are deposited onto a solid surface either via sublimation, typically for experiments carried out under UHV conditions or from the solution phase, when the STM imaging is carried out under ambient conditions at the air/solid or liquid/solid interface. A combination of intermolecular and interfacial interactions leads to (often) spontaneous self-assembly of the building blocks on the solid surface.…”

Chemical modification of 2D materials using molecules and assemblies of molecules

“…Self-assembly of organic molecules on highly oriented pyrolytic graphite (HOPG) into self-assembled molecular networks (SAMNs) [31], which can be considered as a model system for molecular assembly on graphene, has been thoroughly studied experimentally and theoretically, resulting in a good understanding of molecular self-assembly on planar surfaces. Similarly, functionalization by SAMNs is being considered a promising approach for other 2D materials.…”

Bioelectronics and Interfaces Using Monolayer Graphene

“…As an example, the control of the adsorption and subsequent electrochemical reduction of the aryl diazonium salt with a long aliphatic chain 4‐docosyloxy‐benzenediazonium tetra fluoroborate (DBT) was proposed as a strategy for molecular orientation on graphene . The other important aspect of covalent coupling of molecules on to graphene concerns the possibility to control the local deposition at the basal plane or at the edge of the electrodes for future molecular electronics . Atomically resolved imaging techniques using Scanning Tunneling Microscopy (STM) has showed to be a powerful tool for acquiring such precious information about structural changes of graphene, such as by investigation of attachment of organic molecules.…”