On-Surface Synthesis of Azapolyarenes and Their Bromine-Assisted Chiral Self-Assembly

Area of Science:

• Surface chemistry
• Organic synthesis
• Materials science

Background:

• Precise control over the synthesis of heteroatom-doped π-conjugated nanostructures is crucial for advanced materials.
• On-surface synthesis offers a powerful platform for constructing complex molecular architectures.

Purpose of the Study:

• To report the on-surface synthesis of multiple distinct azapolyaromatic compounds from a single precursor.
• To investigate the self-assembly behavior of these synthesized nanostructures.

Main Methods:

• Utilized a single brominated molecular precursor on a gold(111) surface.
• Employed thermal activation to trigger dehalogenation, C-C/C-N coupling, and cyclodehydrogenation reactions.
• Characterized products using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations.

Main Results:

• Successfully synthesized three different azapolyaromatic compounds: a helicene, a pyrazine, and a nanographene.
• Observed bromine-assisted self-assembly into phase-separated 2D domains based on molecular properties like chirality and planarity.
• Elucidated the structures of the synthesized compounds via STM and DFT.

Conclusions:

• Demonstrated the potential of programmed on-surface chemistry for generating diverse heteroatom-doped aromatic architectures from a single feedstock.
• Highlighted a versatile strategy for the atomically precise construction of functional nanographenes and chiral π-systems.