A Self-Assembled Cage Binds Xenon via Xe-F Dispersion Interactions

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Chemical Physics

Background:

• Tetrahedral imine cages are versatile supramolecular structures.
• Fluorine incorporation can tune cage properties.
• Xenon (Xe) binding in solution is challenging but important for sensing applications.

Purpose of the Study:

• To synthesize and evaluate fluorinated imine cages for xenon binding.
• To understand the role of fluorine position and number in xenon recognition.
• To elucidate the key interactions governing xenon-cage affinity in solution.

Main Methods:

• Synthesis of structurally analogous tetrahedral imine cages with varying fluorine content and orientation.
• Xenon binding affinity measurements in solution (chloroform and tetrachloroethane).
• Cavity volume analysis and theoretical calculations (e.g., DFT).

Main Results:

• A specific cage (F2) with 12 inwardly directed fluorine atoms demonstrated significant xenon affinity.
• Cages lacking fluorine (F0), with outward-facing fluorine (F3), or rotatable fluorine groups (F1) showed negligible binding.
• Xe-F London dispersion forces and cavity size complementarity were identified as critical factors for xenon recognition.

Conclusions:

• Inwardly directed fluorine atoms are crucial for effective xenon binding in these imine cages.
• The spatial arrangement and electronic nature of fluorine substituents significantly impact guest recognition.
• This study provides insights into designing selective host molecules for noble gas capture and sensing.