A π-extended molecular belt with selective binding capability for fullerene C₇₀.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Fullerenes, such as C60 and C70, are important carbon allotropes with unique electronic properties.
• Efficient separation of different fullerene species is crucial for their application in various fields.
• Existing separation methods often face challenges in selectivity and scalability.

Purpose of the Study:

• To engineer a molecular host with high selectivity for fullerene C70.
• To investigate the binding mechanism and structural basis of selective fullerene recognition.
• To demonstrate the potential of the designed host for fullerene separation.

Main Methods:

• Bottom-up synthesis of a naphthalene-based molecular belt with an ellipsoidal cavity.
• Binding studies using techniques to determine association constants (K).
• Single crystal X-ray diffraction to elucidate the complex structure.

Main Results:

• A precisely engineered molecular belt with pre-arranged geometry was synthesized.
• The molecular belt exhibited remarkable selective binding for C70 (K = 1.3 × 10^6 M^-1) over C60 (K = 176 M^-1).
• Single crystal structure confirmed excellent concave-convex shape complementarity in the 1:1 C70 complex.

Conclusions:

• The designed molecular belt demonstrates exceptional selectivity for C70 due to precise geometric complementarity.
• This supramolecular approach offers a promising strategy for the purification and separation of fullerenes.
• The study highlights the potential of tailored molecular hosts in addressing challenges in fullerene separation.