Multiple molecular interactions between alkyl groups and dissociated bromine atoms on Ag(111)

Area of Science:

• Surface Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• On-surface molecular assembly offers precise control over material structures.
• Intermolecular interactions are key to designing molecular networks.

Purpose of the Study:

• To investigate the formation of molecular networks using functionalized anthraquinone derivatives on Ag(111).
• To understand the role of alkyl chain length and bromine atom diffusion in self-assembly.

Main Methods:

• High-resolution scanning tunneling microscopy (STM) at low temperatures.
• Deposition of 11,11,12,12-tetrabromo-1,4,5,8-tetraaza-9,10-anthraquinodimethane derivatives with C4 and C8 alkyl chains on Ag(111).
• High-temperature annealing to induce C-Br bond cleavage and bromine diffusion.

Main Results:

• Two distinct molecular networks were formed based on alkyl chain length.
• Bromine atoms diffused upon annealing and mediated self-assembly through C-H⋯Br hydrogen bonding.
• Variations in van der Waals interactions between alkyl groups led to different network structures.

Conclusions:

• Alkyl chain length significantly impacts the self-assembly of these anthraquinone derivatives.
• Bromine atom diffusion and interactions with alkyl groups are crucial for Br-mediated self-assembly.
• The interplay between van der Waals forces and hydrogen bonding dictates the final molecular network structures.