Atomically precise bottom-up synthesis of π-extended [5]triangulene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Chemistry

Background:

• Zigzag-edged triangular graphene molecules (ZTGMs) are predicted to have ferromagnetically coupled edge states with tunable spin, essential for molecular spintronics.
• Scalable synthesis and direct observation of ZTGMs' edge states are challenging due to their chemical instability.

Purpose of the Study:

• To achieve bottom-up synthesis of large, π-extended [5]triangulene with atomic precision.
• To directly observe the edge states and magnetic properties of synthesized ZTGMs.

Main Methods:

• Surface-assisted cyclodehydrogenation of a designed molecular precursor on metallic surfaces.
• Atomic force microscopy (AFM) for structural resolution.
• Scanning tunneling spectroscopy (STS) for electronic state analysis.
• Density functional theory (DFT) calculations for theoretical validation.

Main Results:

• Successful synthesis of π-extended [5]triangulene with a ZTGM-like skeleton (15 fused benzene rings) using atomic precision.
• AFM confirmed the molecular structure, and STS revealed edge-localized electronic states.
• DFT calculations and experimental results demonstrated the open-shell π-conjugated character and magnetic ground states of [5]triangulenes on Au(111).

Conclusions:

• The study presents a viable method for synthesizing large ZTGMs with atomic precision.
• The synthesized [5]triangulenes exhibit the predicted edge states and magnetic properties, confirming their potential for molecular spintronics applications.