Structure formation in bis(terpyridine) derivative adlayers: molecule-substrate versus molecule-molecule...

Area of Science:

• Surface Science
• Materials Chemistry
• Nanotechnology

Background:

• Self-assembly of organic molecules on surfaces is crucial for creating ordered nanostructures.
• Understanding the interplay between intermolecular forces and substrate interactions is vital for controlling self-assembled monolayer (SAM) formation.

Purpose of the Study:

• To investigate how substrate type and deposition method influence the self-assembly of bis(terpyridine) derivative (2,4 '-BTP) monolayers.
• To elucidate the role of intermolecular interactions versus substrate-adsorbate interactions in determining the final adlayer structure.

Main Methods:

• High-resolution scanning tunneling microscopy (STM) was employed to visualize the self-assembled structures.
• Model calculations were performed to determine intermolecular energies and substrate-adsorbate interaction corrugation.

Main Results:

• Quasi-quadratic network structures with consistent lattice constants were observed across different substrates (HOPG, Au(111), Ag(111)).
• The observed structures closely matched theoretical optimum configurations driven by C-H...N bridging bonds, highlighting the dominance of intermolecular forces.
• Substrate-adsorbate interactions led to slight distortions and preferential orientation of the adlayer on metal surfaces.

Conclusions:

• Intermolecular interactions are the primary drivers of adlayer order in 2,4 '-BTP SAMs.
• Substrate-adsorbate interactions fine-tune the adlayer structure, causing commensurate distortions and orientation.
• Solvent effects appear minimal, as similar structures formed in both solid|gas and solid|liquid interfaces.