Synthesis of Ar@C₆₀ using molecular surgery

Area of Science:

• Fullerene chemistry
• Noble gas encapsulation
• Supramolecular chemistry

Background:

• Endohedral fullerenes, where atoms or molecules are encapsulated within fullerene cages, are of significant interest.
• Previous methods for encapsulating noble gases like argon within fullerenes have faced challenges in efficiency and yield.
• Characterization of such endohedral complexes is crucial for understanding their properties and potential applications.

Purpose of the Study:

• To develop an efficient synthesis route for argon-filled fullerenes (Ar@C60).
• To achieve high encapsulation yields of argon within the C60 cage.
• To enable detailed structural characterization of the synthesized Ar@C60 complex.

Main Methods:

• High-pressure argon gas filling of an open fullerene precursor.
• Photochemical desulfinylation reaction to close the fullerene cage.
• Recycling High-Performance Liquid Chromatography (HPLC) for purification and enrichment.
• Solution 13C Nuclear Magnetic Resonance (NMR) spectroscopy for characterization.

Main Results:

• Achieved >95% encapsulation of argon within the C60 cage in the initial synthesis step.
• Quantitative incorporation of argon into the endohedral fullerene product through recycling HPLC.
• Obtained a mass recovery of tens of milligrams of Ar@C60.
• Provided the first detailed characterization of the fine structure in the solution 13C NMR spectrum of Ar@C60.

Conclusions:

• The described method provides an efficient and scalable route for synthesizing Ar@C60.
• High encapsulation yields and product purity are achievable.
• The detailed NMR characterization confirms the successful synthesis and provides insights into the electronic environment of the encapsulated argon.