Buckminsterfullerene(C₆₀)

What is Buckminsterfullerene?

The 1996 Nobel Prize in Chemistry was awarded to Richard Smalley, Robert Curl, and Harold Kroto for their discovery of a new allotrope of carbon, C₆₀ called buckminsterfullerene.

Buckminsterfullerene (C₆₀) is a spherical carbon allotrope where 60 atoms are assembled in pentagons and hexagons, in a geometry similar to a soccer ball. All the carbon atoms are connected by single and double bonds, these are often called BuckyBalls. Their cage structure and poly aromaticity cause the formation of a displaced electron cloud that allows these molecules to act as charge-transfer complexes.

Table of Contents

• Structure of Buckminsterfullerene
• Chemical data on Buckminsterfullerene
• Preparations of Buckminsterfullerene
• Physical Properties of Buckminsterfullerene
• Chemical Properties of Buckminsterfullerene
• Application of Buckminsterfullerene
• Health risks of Buckminsterfullerene
• Frequently Asked Questions

Structure of Buckminsterfullerene

The fullerene, C₆₀, consists of fused five and six-membered carbon rings. Each six membered rings is surrounded, alternately, by hexagons and pentagons of carbons; each pentagon is fused to five hexagons. The consequence of this structural motif is that each hexagon is like the base of a bowl; the three pentagons fused to this ring, linked by hexagons, force the structure to curve resulting in a dome-like structure that eventually curves around itself to give a structure resembling a sphere. The shape of fullerene,C₆₀ resembles a soccer ball. All the 60 carbon atoms are equivalent and give rise to a single 13C NMR resonance.

Chemical data on Buckminsterfullerene

Preparations of Buckminsterfullerene

When an electric spark is struck between graphite electrodes, soot is produced. This soot is mainly carbon black but contains a significant amount of C₆₀ carbon cluster compound, in this process smaller amounts of other fullerenes C₃₂, C₅₀, C₇₀, C₇₆ and C₈₄ may also be produced.

The following are easily extracted from the soot by dissolving them in benzene or hydrocarbon solvents, giving a red solution and finally mustard colour crystals. The different compounds are separated by chromatographically

Physical Properties of Buckminsterfullerene

• Buckminsterfullerene is stable at high temperatures and high pressures.
• Fullerenes are covalent; hence they are soluble in organic solvents but insoluble in water.
• Solutions of pure C₆₀ have a deep purple color which leaves a brown residue on evaporation.
• In solid state buckminsterfullerene C₆₀ molecules adopt the fcc arrangement.
• Buckminsterfullerene(C₆₀) is used as a superconductor below 18K, which means that it carries an electric current with zero resistance.
• crystallization of C₆₀ in benzene solution yields triclinic crystals with the formula C₆₀·4C₆H₆.

Chemical Properties of Buckminsterfullerene

• Buckminsterfullerene can easily be reduced electrochemically to form fulleride ion, It reacts with group-1 metals forming solid K₃C₆₀ , which acts as a superconductor below 18K. 
• Hydrogenation: C₆₀  addition with hydrogen to give polyhydrofullerenes.  Buckminsterfullerene exhibits a small degree of aromatic character so it also undergoes Birch reduction.   
• Halogenation:  Halogens undergo addition reaction with C₆₀ produces the following compounds such as C₆₀Br₈ and C₆₀Br₂₄.
• Addition of oxygen: Ozonation of C₆₀ in 1,2-xylene at 257K gives an intermediate ozonide C₆₀O₃, which can be decomposed to form epoxide C₆₀O.
• Formation of metal complexes:  Fullerenes act as ligands in transition metal complexes due to the immense π system. Osmium tetroxide, a powerful oxidizing agent. When OsO₄ is reacted with C₆₀ and 4-tert-butylpyridine, it produceing C₆₀(OsO₄)(4-t-butylpyridine)₂. 
• Compounds containing encapsulated metals. These may contain one, two, or three metals inside the fullerene sphere. Examples: UC₆₀.

Application of Buckminsterfullerene

• Fullerene in its pure state acts as insulators but can be converted to semiconductors and superconductors under suitable conditions.
• Buckminsterfullerene’s ability to trap different atoms or molecules makes them useful in the medical field. For example, radioactive C₆₀O can be used in cancer as well as AIDS therapy.
• Fullerenes help in improving antiwear and anti-friction properties of lubricating oils.
• It can catalyse photochemical refining in industry.
• It has a high electron affinity, hence it is used as common electron acceptor in donor/acceptor based solar cells.
• Buckminsterfullerene may be used to store hydrogen, possibly as a fuel tank for fuel cell powered cars.

Health risks of Buckminsterfullerene

• C₆₀ is sensitive to light, so leaving C₆₀ under light exposure causes it to degrade, becoming dangerous.
• The ingestion of C₆₀ solutions that have been exposed to light could lead to developing cancer.