On-Surface Synthesis and Characterization of [7]Triangulene Quantum Ring

Area of Science:

• Materials Science
• Nanotechnology
• Quantum Physics

Background:

• Triangulene quantum rings (TQRs) offer tunable high-spin ground states essential for molecular spintronics.
• Engineering geometrically defined antidots in triangulene structures is key to TQR development.

Purpose of the Study:

• To report the synthesis of an open-shell [7]triangulene quantum ring ([7]TQR) molecule.
• To investigate its electronic properties and ground state spin on a Au(111) surface.

Main Methods:

• Surface-assisted cyclodehydrogenation of a kekulene derivative.
• Bond-resolved scanning tunneling microscopy (BR-STM) for molecular imaging.
• Scanning tunneling spectroscopy (STS) and spin-polarized density functional theory (sp-DFT) calculations.

Main Results:

• Successfully synthesized a [7]TQR molecule with a triangular zigzag edge topology on Au(111).
• BR-STM confirmed the molecular structure, resembling [7]triangulene with a central coronene-like antidot.
• dI/dV mapping showed edge-localized and spin-polarized electronic states from both inner and outer zigzag edges.
• Experimental and computational results confirmed the open-shell septuple ground state (S = 3) for [7]TQR on Au(111).

Conclusions:

• Demonstrated a new synthetic route for high-spin graphene quantum rings.
• The synthesized [7]TQR is a promising candidate for next-generation molecular spintronic devices.
• Confirms the viability of creating tunable high-spin states in graphene nanostructures.