Introduction to Fullerenes

Introduction to Fullerenes

• Fullerenes belong to the carbon family, the third allotrope of carbon.
• They are hollow cages, with carbon atoms interconnected in pentagonal and hexagonal rings.
• A fullerene is a pure carbon molecule, C₆₀ being the smallest.
• The most famous fullerene is C₆₀, also known as a buckyball.
• Fullerenes are extensively used in biomedical applications including MRI contrast agents, X-ray imaging contrast agents, photodynamic therapy, and drug/gene delivery.

Brief History of Fullerenes

• In 1985, Sir Harold Kroto, Richard Smalley, and Robert Curl discovered fullerenes.
• They vaporized graphite rods in a helium gas atmosphere using a pulsed laser.
• The structure of fullerenes was theorized to be like a soccer ball.
• C₆₀ was named "buckminsterfullerene," in honor of Buckminster Fuller, and the shortened name "fullerene" refers to all fullerenes
• In 1996, Curl, Kroto, and Smalley received the Nobel Prize in Chemistry for their discovery.

Importance of Geodesic Domes

• Geodesic domes are a strong and durable architectural form, able to withstand extreme weather conditions.
• Versatile, with applications in diverse areas like residential, commercial, industrial buildings, also greenhouses and temporary shelters.
• Energy efficient, needing less heating and cooling compared to traditional buildings.

Synthesis of Fullerenes

• Kratschmer-Huffman Method: Graphite electrodes are vaporized using restrictive heating in a helium atmosphere. The resulting soot can be extracted with benzene. Modified by Smalley using an electric arc.
• Combustion Process: Fullerenes are produced in sooting flames through a premixed benzene-oxygen-argon mix under low pressure.

Types of Fullerenes

• Buckyball clusters
• Nanotubes
• Megatubes
• Polymers
• Nano"onions".
• Linked "ball-and-chain" dimers
• Fullerene Rings

Properties of Fullerenes: Chemical Reactivity

• Aromatic, but C₆₀ is non-aromatic.
• Insoluble in polar solvents, soluble in aromatic solvents and carbon disulfide.
• High electron affinity and chemically reactive, especially with free radicals
• Rapid decomposition in presence of trace amounts of ozone.
• In pure oxygen, C₆₀ sublimes at 350°C and ignites at 365°C, rapidly oxidizing to CO and CO₂.
• Catalyzes the oxidation of H₂S to sulfur.

Physical Properties of Fullerenes

• Insoluble in water
• Cannot conduct electricity
• Soft and slippery
• Brittle
• Low melting point

Applications of Fullerenes: Medicinal

• Antioxidant
• Antimicrobial agents
• Drug delivery
• Photosensitizers in photodynamic therapy

Other Applications of Fullerenes

• Personal care products
• Dry lubricants
• Solar cells
• Hydrogen gas storage
• Strengthening/hardening metals
• Sensors
• Molecular wires
• Organic photovoltaics (OPV)
• Catalysts
• Water purification/biohazard protection
• Bulletproof vents

Conclusion

• This study provides a basis for understanding fullerene structure, properties, and applications in science and technology.
• Due to useful properties, fullerenes are key in nanotechnology and industrial research.
• Fullerenes are widely used in drug and cosmetics industry, mainly as antioxidants.