Shape-selective transport through rectangle-based molecular materials: thin-film scanning electrochemical microscopy...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Microporous thin films are crucial for separation and transport applications.
• Molecular rectangles offer unique structural motifs for designing porous materials.
• Understanding transport mechanisms in these materials is key to optimizing their performance.

Purpose of the Study:

• To prepare and characterize microporous thin films from discrete, cavity-containing molecular rectangles.
• To investigate the shape-selective transport properties of these novel films.
• To compare transport rates with related molecular square-based materials.

Main Methods:

• Preparation of microporous thin films (50-400 nm) using molecular rectangles.
• Electrochemical measurements utilizing redox-active probe molecules to determine transport rates.
• Scanning electrochemical microscopy (SECM) for spatially resolved transport analysis.

Main Results:

• The films exhibited shape-selective transport, allowing small or dimensionally restricted molecules.
• Transport selectivity was attributed to intramolecular cavities within the molecular rectangles.
• Transport rates were found to be approximately two orders of magnitude slower than in molecular square films.

Conclusions:

• Molecular rectangle films demonstrate tunable shape selectivity based on intramolecular cavities.
• The lack of aligned cavities in rectangle films hinders efficient transport compared to square films.
• These findings provide insights into designing porous materials for specific molecular transport applications.