Intermolecular On-Surface σ-Bond Metathesis.

Area of Science:

• Surface Chemistry
• Organic Chemistry
• Materials Science

Background:

• Silylation and desilylation are crucial for protecting functional groups in solution-phase organic chemistry.
• On-surface chemistry offers unique pathways for molecular assembly and synthesis.
• Certain molecules are too unstable for traditional solution or solid-state manipulation.

Purpose of the Study:

• To explore the σ-bond metathesis of silylated alkynes with aromatic carboxylic acids on metal surfaces.
• To demonstrate a new protecting group strategy for on-surface synthesis.
• To fabricate self-assembled structures and covalent polymers from unstable precursors.

Main Methods:

• σ-bond metathesis reactions on Ag(111) and Au(111) surfaces.
• Density Functional Theory (DFT) calculations for mechanistic insights.
• X-ray Photoelectron Spectroscopy (XPS) for surface analysis.
• On-surface synthesis techniques.

Main Results:

• First examples of surface-mediated σ-bond metathesis between silylated alkynes and carboxylic acids.
• Formation of terminal alkynes and silyl esters on Ag(111) and Au(111).
• Successful self-assembly of hexaethynylbenzene on Ag(111).
• Cascade process combining σ-bond metathesis and Glaser coupling on Au(111) to form covalent polymers.

Conclusions:

• Surface-mediated silylation/desilylation provides a robust strategy for on-surface synthesis.
• This approach allows the construction of complex architectures from unstable molecules.
• The combined reaction pathway on Au(111) opens new avenues for covalent polymer fabrication.