Temperature-induced molecular reorganization on Au(111) driven by oligomeric defects

Area of Science:

• Surface Science
• Materials Chemistry
• Supramolecular Chemistry

Background:

• Ordered molecular structures on surfaces depend on molecule-molecule and molecule-substrate interactions.
• Understanding these interactions is key for predicting structural features and developing bottom-up fabrication.
• Theoretical models and experimental observations are crucial for explaining on-surface phase transitions.

Purpose of the Study:

• Investigate the self-assembly of tribromo-substituted heterotriangulene on Au(111).
• Determine the role of halogen bonding and dehalogenation in molecular organization.
• Explore the influence of defects on the stability of molecular structures.

Main Methods:

• Scanning tunneling microscopy (STM) for surface investigation.
• X-ray photoelectron spectroscopy (XPS) to analyze dehalogenation.
• Density functional theory (DFT) and Monte Carlo (MC) simulations for theoretical modeling.

Main Results:

• Tribromo-substituted heterotriangulene initially forms a close-packed structure stabilized by BrBr halogen bonds.
• Annealing induces partial dehalogenation, forming less stable BrO networks and oligomers.
• Dimer moieties act as defects, hindering stable configurations and driving reorganization into lower energy phases.

Conclusions:

• Combined DFT-MC approach is vital for understanding molecular system evolution on substrates.
• Defect formation significantly impacts molecular self-assembly and structural stability.
• Precise control over interactions is essential for designing ordered molecular architectures.