On-Surface Synthesis of C144 Hexagonal Coronoid with Zigzag Edges

Area of Science:

• Organic Chemistry
• Materials Science
• Nanotechnology

Background:

• Coronoids, polycyclic aromatic macrocycles, are noted for unique molecular and electronic structures.
• Their electronic properties depend on cavity size and periphery topology, akin to nanoporous graphene molecules.
• Extended hexagonal coronoids with zigzag edges have remained synthetically challenging and unreported.

Purpose of the Study:

• To achieve the on-surface synthesis of a C144 hexagonal coronoid with outer zigzag edges.
• To characterize its molecular structure and electronic properties.
• To explore potential applications in advanced materials and future electronic devices.

Main Methods:

• On-surface synthesis on a designed precursor using Ullmann coupling and cyclodehydrogenation on Au(111).
• Bond-resolved noncontact atomic force microscopy (nc-AFM) for molecular structure determination.
• Scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations for electronic properties investigation.

Main Results:

• Successful on-surface synthesis of a C144 hexagonal coronoid with outer zigzag edges.
• Unambiguous structural characterization using high-resolution nc-AFM.
• Electronic properties investigated via STS and DFT, confirming aromaticity consistent with Clar's model.

Conclusions:

• Demonstrated a viable synthetic route for hexagonal coronoids with zigzag edges.
• Provided insights into the electronic structure and aromaticity of these novel molecules.
• Paved the way for future research into hexagonal zigzag coronoids with potential radical characters.