Aromatic Azide Transformation on the Ag(111) Surface Studied by Scanning Probe Microscopy

Area of Science:

• Surface Chemistry
• Organic Chemistry
• Materials Science

Background:

• Understanding chemical reactions at the single-molecule level on surfaces is crucial for developing new materials and catalysts.
• Aryl azides are versatile precursors for generating reactive intermediates like nitrenes, but their surface chemistry is not fully understood.
• The Ag(111) surface provides a well-defined platform for studying fundamental surface reactions.

Purpose of the Study:

• To investigate the chemical transformation of 9-azidophenanthrene on the Ag(111) surface.
• To elucidate the reaction pathways and identify the intermediate species involved.
• To demonstrate the formation of covalent bonds between transformation products at the single-molecule level.

Main Methods:

• Non-contact Atomic Force Microscopy (nc-AFM) under Ultra-High Vacuum (UHV) conditions for high-resolution imaging.
• First-principle calculations to support the structural determination of reaction products and intermediates.
• Analysis of reaction products to identify key transformation channels.

Main Results:

• Identified a common and elusive 9-phenanthryl nitrenoid intermediate chemisorbed on the Ag(111) surface.
• Revealed main reaction channels including formal nitrene insertion into C-H bonds, dimerization, and hydrogenation.
• Determined the structure of final products originating from the nitrenoid intermediate.

Conclusions:

• Demonstrated the formation of covalent sigma (σ) and pi (π) bonds between transformation products of aryl azides on a solid surface at the single-molecule level.
• Highlighted the significance of the nitrenoid intermediate in directing the surface chemical transformations.
• Provided fundamental insights into the surface chemistry of aryl azides with potential applications in molecular assembly and surface functionalization.