Self-Assembly of Linear Three-Ring Aromatic Thiols on Au(111)

Area of Science:

• Surface Science
• Materials Chemistry
• Nanotechnology

Background:

• Self-assembled monolayers (SAMs) are crucial for tailoring surface properties.
• Aromatic thiols offer versatile building blocks for ordered molecular structures.
• Understanding molecular packing is key to controlling SAM functionality.

Purpose of the Study:

• To investigate the self-assembly of linear three-ring aromatic thiols on Au(111)/mica.
• To analyze the structural impact of different terminal groups on terphenylthiol (TPT) derivatives.
• To elucidate the molecular arrangements and packing densities of the resulting SAMs.

Main Methods:

• Utilized X-ray photoelectron spectroscopy (XPS) for chemical analysis.
• Employed low-energy electron diffraction (LEED) for structural characterization.
• Applied scanning tunneling microscopy (STM) for high-resolution imaging of molecular arrangements.

Main Results:

• Terphenylthiol (TPT), fluorinated TPT (FTPT), trifluoromethyl TPT (CF3TPT), and pyridinebiphenyl (PyBPT) formed densely packed SAMs with hexagonal unit cells (21.55 Ų/molecule).
• Nitro-substituted TPT (NTPT) exhibited two coexisting structures: a hexagonal (21.55 Ų/molecule) and a squared arrangement (42.25 Ų/molecule).

Conclusions:

• Terminal groups significantly influence the self-assembly behavior and structural ordering of aromatic thiols.
• The NTPT molecule demonstrates unique adaptability in forming multiple distinct SAM structures.
• These findings provide insights into designing functional surfaces using tailored molecular building blocks.