Synthesis and Characterization of a Non-Planar Cyclophenylene on Au(111)

Area of Science:

• Surface chemistry
• Organic synthesis
• Materials science

Background:

• Controlled synthesis of complex organic molecules on surfaces is crucial for advanced materials.
• Non-planar aromatic structures offer unique electronic and steric properties.
• Gold surfaces (Au(111)) are widely used platforms for surface-assisted synthesis.

Purpose of the Study:

• To report the surface-assisted synthesis of a non-planar cyclophenylene derivative.
• To characterize its chemical structure and electronic properties.
• To elucidate the synthesis mechanism involving Ullmann coupling and C-C bond cleavage.

Main Methods:

• Surface-assisted synthesis on Au(111) using hierarchical Ullmann coupling.
• Synthesis involved a 1,10-dibrominated angular [3] phenylene precursor.
• Characterization via Scanning Tunneling Microscopy and Spectroscopy (STM/STS).
• Theoretical support through Density Functional Theory (DFT) calculations.

Main Results:

• Successful synthesis of a non-planar cyclophenylene derivative with specific connectivity (four meta-, two para-).
• Demonstration of C-C bond cleavage in four-membered rings as part of the synthesis.
• Detailed structural and electronic properties obtained from STM/STS measurements.
• DFT calculations confirmed the proposed structure and reaction pathway.

Conclusions:

• The study demonstrates a viable route for synthesizing complex non-planar molecules on surfaces.
• Surface-assisted Ullmann coupling combined with ring-opening is an effective strategy.
• The synthesized molecule exhibits unique electronic properties influenced by its non-planar structure.