Polycyclic aromatic chains on metals and insulating layers by repetitive [3+2] cycloadditions.

Area of Science:

• Materials Science
• Organic Chemistry
• Surface Science

Background:

• Organic materials offer significant potential for electronic, optoelectronic, and spintronic devices.
• Fabricating π-conjugated systems with specific functions directly on insulating interfaces is challenging.
• High-yield and selective on-surface synthesis on non-metal surfaces is yet to be achieved.

Purpose of the Study:

• To present a novel method for the on-surface synthesis of polyaromatic chains.
• To demonstrate the fabrication of these materials on metallic substrates, insulating layers, and in the solid state.
• To explore the potential of intermolecular cycloaddition reactions for creating regioregular polyaromatic polymers.

Main Methods:

• Synthesis of CN-substituted polycyclic aromatic azomethine ylide (PAMY) intermediates.
• On-surface reactions on Au(111), Ag(111), and h-BN/Cu(111) substrates.
• Characterization using Scanning Probe Microscopy (SPM) and Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry.

Main Results:

• Formation of azaullazine repeating units via intermolecular homo-coupling and dehydrogenation of PAMY intermediates.
• Successful synthesis on metallic substrates and insulating layers (h-BN/Cu(111)).
• Demonstration of the reaction occurring in the solid state without a catalyst, confirmed by MALDI.

Conclusions:

• Intermolecular cycloaddition reactions provide a promising route for direct synthesis of regioregular polyaromatic polymers.
• This method offers a pathway for fabricating functional organic materials on arbitrary insulating surfaces.
• The findings advance the development of organic electronics and related fields.