Reaction Selectivity in On-Surface Chemistry by Surface Coverage Control-Alkyne Dimerization versus Alkyne...

Area of Science:

• Surface chemistry
• Organic synthesis
• Materials science

Background:

• On-surface reactions are crucial for creating novel molecular structures.
• Controlling reaction pathways is key to designing functional materials.
• Molecular coverage is a critical parameter influencing surface reaction outcomes.

Purpose of the Study:

• To investigate the effect of molecular coverage on C-C bond formation reactions.
• To elucidate the competing reaction pathways of 6-ethynyl-2-naphthoic acid on a Ag(111) surface.
• To understand the mechanistic basis for coverage-dependent reactivity.

Main Methods:

• Utilizing 6-ethynyl-2-naphthoic acid (ENA) as the organic molecule.
• Employing a silver(111) (Ag(111)) surface as the substrate.
• Analyzing reaction products using surface science techniques and mechanistic studies.

Main Results:

• Dimerization (Glaser coupling/hydroalkynylation) of ENA is favored at high surface coverage.
• Cyclotrimerization of ENA to form a benzene core is the major pathway at low surface coverage.
• Surface coverage acts as a switch to control the predominant reaction outcome.

Conclusions:

• Molecular coverage is a powerful tool to direct C-C bond formation on surfaces.
• Understanding coverage-dependent reactivity enables precise synthesis of molecular architectures.
• This study provides fundamental insights into controlling surface-catalyzed organic reactions.