Selecting the Reaction Path in On-Surface Synthesis through the Electron Chemical Potential in Graphene

Area of Science:

• Organometallic Chemistry
• Materials Science
• Surface Science

Background:

• On-surface synthesis offers precise control over molecular assembly.
• Rare-earth elements (lanthanides) exhibit unique electronic properties relevant for catalysis and electronics.
• Graphene serves as a versatile 2D substrate for surface reactions.

Purpose of the Study:

• To investigate the organometallic on-surface synthesis of cyclooctatetraene (Cot) with ytterbium (Yb) and thulium (Tm) on graphene (Gr).
• To explore how substrate doping influences the reaction outcome and product structures.
• To understand the fundamental interactions governing the formation of YbCot and TmCot structures.

Main Methods:

• Organometallic on-surface synthesis on graphene.
• Characterization using scanning probe microscopy (implied).
• Density Functional Theory (DFT) calculations.

Main Results:

• Yb synthesis yields long sandwich-molecular YbCot wires bound by van der Waals forces.
• Tm synthesis initially forms TmCot dots chemisorbed to graphene.
• N-doping graphene enables the transformation of TmCot dots into TmCot sandwich-molecular wires.
• DFT confirms that n-doping weakens substrate binding and charge transfer, favoring wire formation.

Conclusions:

• The outcome of organometallic on-surface synthesis can be tuned by controlling the substrate's electronic properties.
• Graphene's electron chemical potential acts as a crucial parameter for directing reaction pathways.
• This work demonstrates a method to control the assembly of rare-earth metal-organic complexes on surfaces.