Steric Bulk Controls Δ/Λ Handedness Enabling Stereodivergent Self-Assembly of Fe^II₂L₃ Cages

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Chiral metal-organic cages (MOCs) are important for various applications.
• Developing stereodivergent synthesis for chiral MOCs remains a significant challenge.

Purpose of the Study:

• To establish a stereodivergent strategy for constructing chiral MOCs.
• To investigate the influence of steric properties on stereoselectivity.
• To explore the functional properties of the synthesized chiral MOCs.

Main Methods:

• Subcomponent self-assembly using a chiral diamine, 3-substituted 2-formylpyridines, and iron(II) ions.
• Systematic variation of 2-formylpyridine substituents to modulate steric bulk.
• Gas sorption studies (N2 and CO2) to evaluate cage performance.

Main Results:

• Structurally well-defined chiral MOCs were successfully synthesized.
• Selective control over cage handedness was achieved by altering subcomponent steric properties.
• A linear correlation was found between substituent molecular volume and diastereomeric excess.
• The Δ-isomer demonstrated significantly enhanced CO2 selectivity.

Conclusions:

• A sterically governed strategy for stereodivergent synthesis of chiral MOCs was established.
• This approach allows for predictable control over both chirality and functional properties.
• The synthesized MOCs show potential for selective gas capture applications.