Chirality at two-dimensional surfaces: A perspective from small molecule alcohol assembly on Au(111)

Area of Science:

• Surface Science
• Supramolecular Chemistry
• Physical Chemistry

Background:

• Molecular and supramolecular aggregate stability relies on hydrogen bonding and van der Waals forces.
• Studying these interactions at the molecular level on surfaces is experimentally challenging.
• Small alcohols on metal surfaces serve as a model system for understanding molecule-surface and molecule-molecule interactions.

Purpose of the Study:

• To investigate the adsorption and self-assembly of small alcohols (methanol to butanol) on Au(111).
• To elucidate the interplay between molecular structure, intermolecular forces, and surface interactions.
• To establish a framework for understanding 2D chiral supramolecular assembly.

Main Methods:

• Scanning Tunneling Microscopy (STM) for high-resolution surface imaging.
• Density Functional Theory (DFT) for computational analysis of interactions.
• Comparative study of alcohols from methanol to butanol on Au(111).

Main Results:

• Longer-chain alcohols form zigzag chains via hydrogen-bonded networks with alternating adsorbed chirality.
• Alcohols binding datively to the surface induce chirality, influencing chain structure and unit cell size.
• Intrinsic molecular chirality (e.g., 2-butanol) leads to distinct square packing structures with chiral pockets, preventing heterochiral chains.

Conclusions:

• The study provides a general framework for alcohol adstructure formation on surfaces.
• Molecular chirality significantly dictates self-assembly behavior, leading to different packing motifs.
• Findings advance the rational design of 2D chiral supramolecular assemblies.