Supramolecular assemblies of a nitrogen-embedded buckybowl dimer with C₆₀

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Azabuckybowls are nitrogen-containing fullerene derivatives with potential for complexation.
• Fullerenes (C60) are important carbon allotropes with unique electronic properties.

Purpose of the Study:

• To synthesize a directly connected azabuckybowl dimer.
• To investigate the complexation behavior of the azabuckybowl dimer with C60.
• To characterize the resulting supramolecular assemblies.

Main Methods:

• Palladium-catalyzed C-H/C-Br coupling for dimer synthesis.
• Solution-phase complexation studies.
• Crystallization and precipitation experiments.
• Scanning electron microscopy (SEM) for morphology analysis.
• Variable-temperature 1H NMR spectroscopy for structural elucidation.

Main Results:

• A directly connected azabuckybowl dimer was successfully synthesized.
• The dimer demonstrated strong complexation with C60 due to electron-donating pyrrolic nitrogen atoms.
• Crystalline complexes with a 1:2 dimer:C60 stoichiometry were formed.
• In dilute solutions, 1:1 complexes were predominant, leading to precipitation upon C60 addition.
• SEM revealed fiber-like aggregates, indicating 1D supramolecular chain formation.
• NMR confirmed a 1:1 dimer:C60 ratio in the precipitated assemblies.

Conclusions:

• The azabuckybowl dimer acts as an effective host for C60.
• Stoichiometry dictates the formation of crystalline or 1D supramolecular structures.
• This work highlights the potential of azabuckybowl derivatives in designing ordered fullerene-based materials.