Helium entry and escape through a chemically opened window in a fullerene

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nuclear Magnetic Resonance Spectroscopy

Background:

• Fullerenes are carbon-based molecules with unique cage-like structures.
• Open-cage fullerenes offer potential for encapsulating atoms and molecules.
• Understanding guest molecule dynamics within fullerene cages is crucial for applications.

Purpose of the Study:

• To encapsulate helium-3 (³He) into an open-cage fullerene derivative.
• To determine the activation barrier for ³He escape from the fullerene cage.
• To compare the orifice size of the open-cage fullerene with other derivatives.

Main Methods:

• Encapsulation of ³He into an open-cage fullerene derivative near room temperature.
• Monitoring ³He escape rates using ³He Nuclear Magnetic Resonance (NMR) spectroscopy.
• Measurement of the equilibrium constant for ³He encapsulation.

Main Results:

• Achieved an incorporation fraction of 0.1% for ³He within the fullerene derivative.
• Quantified the activation barrier for ³He escape.
• Provided data for comparing the orifice size of this open-cage fullerene.

Conclusions:

• Demonstrated successful ³He encapsulation in an open-cage fullerene derivative.
• The study provides valuable data on the dynamics and confinement properties of ³He within fullerene cages.
• The methodology allows for characterization of fullerene cage orifices and guest molecule interactions.