Dimerization of tri(4-bromophenyl)benzene by aryl-aryl coupling from solution on a gold surface

Area of Science:

• Surface science
• Organic chemistry
• Nanotechnology

Background:

• Studying molecular self-assembly on surfaces is crucial for developing advanced materials.
• Controlled synthesis of larger molecules from smaller precursors is a key challenge in nanotechnology.

Purpose of the Study:

• To investigate the surface-induced coupling of 1,3,5-tri(4-bromophenyl)benzene (TBPB) on a gold surface.
• To explore the formation of dimerized products and nanostructures via aryl-aryl coupling reactions.
• To demonstrate a solution-phase method for creating complex molecular architectures.

Main Methods:

• Ambient scanning tunneling microscopy (STM) for imaging molecular monolayers.
• Time-of-flight secondary ion mass spectrometry (ToF-SIMS) for chemical analysis.
• Controlled deposition of TBPB solutions on gold substrates at varying temperatures.

Main Results:

• Ordered arrays of monomer TBPB were observed at room temperature in three distinct packing arrangements.
• Heating the substrate induced surface-mediated aryl-aryl coupling, forming the dimerized product 3,3",5,5"-tetra(4-bromophenyl)quaterphenyl (TBPQ).
• ToF-SIMS confirmed the conversion of TBPB to TBPQ, with coexisting regions of disordered multiply linked molecules.

Conclusions:

• A solution-phase approach enables surface-induced coupling reactions for synthesizing larger molecules.
• This method offers an alternative route to forming nanostructures with potential applications in materials science.
• Controlled surface chemistry can be leveraged to create complex molecular assemblies from simple precursors.