Structural properties of azobenzene self-assembled monolayers by atomistic simulations

Area of Science:

• Nanotechnology
• Materials Science
• Computational Chemistry

Background:

• Azobenzene self-assembled monolayers (SAMs) are optomechanical nanostructures.
• They generate mechanical work via azobenzene photoisomerization.
• Existing experimental studies lack atomistic descriptions of SAMs in cis and trans states.

Purpose of the Study:

• To computationally investigate the atomistic structures of azobenzene SAMs.
• To develop validated atomistic models for both cis and trans isomers.
• To bridge the gap between experimental data and theoretical understanding of SAMs.

Main Methods:

• Classical molecular dynamics simulations with a dedicated force field.
• Development of SAM models with varying molecular densities based on experimental unit cell data.
• Validation of models using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) data.
• Comparison of simulated and experimental scanning tunneling microscopy (STM) images.

Main Results:

• Atomistic models for azobenzene SAMs in both cis and trans configurations were successfully generated.
• Optimal SAM structures were identified by matching computational models with experimental spectroscopic data.
• The developed models were validated against experimental STM images, confirming their accuracy.

Conclusions:

• This work provides the first atomistic description of azobenzene SAMs in both photoisomeric states.
• The validated computational models can serve as a basis for further research in optomechanical nanostructures.
• The findings enhance the understanding of structure-property relationships in azobenzene-based materials.