Engineering Two-Dimensional Multilevel Supramolecular Assemblies from a Bifunctional Ligand on Au(111)

Area of Science:

• Surface chemistry and materials science
• Supramolecular chemistry
• Nanotechnology

Background:

• Engineering complex two-dimensional (2D) nanostructures is crucial for advanced materials.
• Controlling self-assembly at the nanoscale requires precise molecular design and understanding of bonding interactions.

Purpose of the Study:

• To demonstrate the formation of multilevel nanostructures using a bifunctional ligand on a gold (Au(111)) surface.
• To investigate the role of multiple bonding motifs in directing the self-assembly process.
• To provide a protocol for deliberate control over surface-confined (metal-)organic nanostructures.

Main Methods:

• Utilizing a bifunctional ligand with bromine atoms and a carboxylic terminal for varied bonding.
• Employing scanning tunneling microscopy (STM) to visualize nanostructure formation.
• Performing density functional theory (DFT) calculations to understand bonding interactions and configurations.

Main Results:

• The bifunctional ligand self-selectively formed subunits based on multiple bonding motifs (hydrogen, halogen, alkali-carboxylate).
• STM and DFT revealed distinct bonding configurations and energies dictating assembly levels.
• A multilevel assembly protocol was established, enabling controlled fabrication of nanostructures.

Conclusions:

• The study successfully demonstrated a method for engineering 2D (metal-)organic multilevel nanostructures.
• Judicious choice of bonding motifs allows for precise control over nanostructure architecture.
• This approach offers new possibilities for fabricating complex nanomaterials with diverse applications.