Designing 2D stripe winding network through crown-ether intermediate Ullmann coupling on Cu(111) surface.

Area of Science:

• Surface Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Chemical synthesis typically favors ordered structures.
• On-surface synthesis usually produces linear, ordered 2D networks.
• Generating 2D random networks via on-surface synthesis has been a challenge.

Purpose of the Study:

• To demonstrate the fabrication of a 2D random network using on-surface synthesis.
• To explore the controlled formation of convoluted 1D stripes into a 2D network.
• To investigate the potential of this method for creating advanced supramolecular hosts.

Main Methods:

• On-surface synthesis on a Cu(111) surface.
• Utilizing 4,4',5,5'-tetrabromodibenzo[18]crown-6 ether (BrCR) precursors.
• Employing Ullmann reaction conditions with controlled intermediate states.
• Characterization via ultrahigh vacuum low-temperature scanning tunneling microscopy and spectroscopy (UHV-LT-STM/STS).
• Theoretical analysis using density functional theory (DFT) calculations.

Main Results:

• Successful synthesis of a 2D random network of convoluted stripes from BrCR precursors.
• Demonstration that adjusting intermediate state quantities controls network topology.
• Observation of stripe formation facilitated by the crown ether precursor's structure and Ullmann coupling.
• Detailed understanding of growth mechanisms and electronic properties through STM/STS and DFT.

Conclusions:

• On-surface synthesis can be leveraged to create 2D random networks, not just ordered structures.
• The method allows for the construction of complex, winding 2D networks by controlling precursor bonding.
• This provides a new pathway for designing advanced ring host supramolecules with enhanced guest capture capabilities.