) is a spherical fullerene
molecule with the formula C60
. It has a cage-like fused-ring structure (truncated icosahedron
) which resembles asoccer ball
, made of twenty hexagons
and twelve pentagons
, with a carbon atom at each vertex of each polygon and a bond along each polygon edge.
Buckminsterfullerene is one of the largest objects to have been shown to exhibit wave–particle duality
; as stated in the theory every object exhibits this behavior.
Its discovery led to the exploration of a new field of chemistry, involving the study of fullerenes
derives from the name of the noted futurist and inventor Buckminster Fuller
. One of his designs of a geodesic dome
structure bears great resemblance to C60
; as a result, the discoverers of the allotrope named the newfound molecule after him. The general public, however, sometimes refers to buckminsterfullerene, and even Mr. Fuller’s dome structure, as buckyballs.
The structure associated with fullerenes was described by Leonardo da Vinci. Albrecht Dürer
also reproduced a similar icosahedron containing 12 pentagonal and 20 hexagonal faces but there are no clear documentations of this.
Theoretical predictions of buckyball molecules appeared in the late 1960s – early 1970s,
but they went largely unnoticed. In the early 1970s, the chemistry of unsaturated carbon configurations was studied by a group at the University of Sussex
, led by Harry Kroto and David Walton. In the 1980s a technique was developed by Richard Smalley and Bob Curl at Rice University
, Texas to isolate these substances. They used laser vaporization
of a suitable target to produce clusters of atoms. Kroto realized that by using a graphite
any carbon chains formed could be studied. Another interesting fact is that, at the same time, astrophysicists were working along with spectroscopists to study infrared emissions from giant red carbon stars.
Smalley and team were able to use a laser vaporization technique to create carbon clusters which could potentially emit infrared at the same wavelength as had been emitted by the red carbon star.
Hence, the inspiration came to Smalley and team to use the laser technique on graphite to create the first fullerene molecule.
was discovered in 1985 by Robert Curl, Harold Kroto and Richard Smalley. Using laser evaporation
they found Cn
clusters (where n>20 and even) of which the most common were C60
. A solid rotating graphite disk was used as the surface from which carbon was vaporized using a laser beam creating hot plasma that was then passed through a stream of high-density helium gas.
The carbon species were subsequently cooled and ionized resulting in the formation of clusters. Clusters ranged in molecular masses but Kroto and Smalley found predominance in a C60
cluster that could be enhanced further by letting the plasma react longer.[3, 6] They also discovered that the C60
molecule formed a cage-like structure, a regular truncated icosahedron.
The experimental evidence, a strong peak at 720 atomic mass units, indicated that a carbon molecule with 60 carbon atoms was forming, but provided no structural information. The research group concluded after reactivity experiments, that the most likely structure was a spheroidal molecule. The idea was quickly rationalized as the basis of an icosahedral symmetry
closed cage structure. Kroto mentioned geodesic dome structures of the noted futurist and inventor Buckminster Fuller
as influences in the naming of this particular substance as buckminsterfullerene.
The versatility of fullerene molecules has led to a large amount of research exploring their properties. One interesting property is fullerene’s large-capacity internal spaces. Atoms of different elements may be placed inside the molecular cage formed by the carbon atoms, producing a shrink-wrapped version of these elements.
Beam-experiments conducted between 1985 and 1990 provided more evidence for the stability of C60
while supporting the closed-cage structural theory and predicting some of the bulk properties such a molecule would have. Around this time, intense theoretical group theory activity also predicted that C60
should have only four IR-active vibrational
bands, on account of its icosahedral symmetry.
In 1989 physicists Wolfgang Krätschmer and Donald R. Huffman observed unusual optical absorptions in thin carbon films produced by arc-processed graphite rods. Among other features, the IR spectra showed four discrete bands in close agreement to those proposed for C60
. A paper published by the group in 1990 followed on from their thin film experiments, and detailed the extraction of a benzene
soluble material from the arc-processed graphite. This extract had crystal and X-ray
analysis consistent with arrays of spherical C60
molecules, approximately 0.7 nm in diameter.
In 2012 a toxicity study by Tarek Baati and Fathi Moussa from the University of Paris, showed that C60 dissolved in Olive Oil and provided to rodents was not toxic.
In a video interview with Professor Fathi Moussa regarding the study, further information was provided regarding the toxicity study, and the method of action that could have caused the rodents intake of C60 Olive Oil providing an increase of lifespan by 90% over controls. 
In 1990, W. Krätschmer and D. R. Huffman developed a simple and efficient method of producing fullerenes in gram and even kilogram amounts, which has boosted the fullerene research. In this technique, carbon soot is produced from two high-purity graphite electrodes by igniting an arc discharge between them in an inert atmosphere (helium gas). Alternatively, soot is produced by laser ablation of graphite or pyrolysis
of aromatic hydrocarbons
. Fullerenes are extracted from the soot using a multistep procedure. First, the soot is dissolved in appropriate organic solvents. This step yields a solution containing up to 75% of C60
, as well as other fullerenes. These fractions are separated using chromatography
Generally, the fullerenes are dissolved in hydrocarbon or halogenated hydrocarbon and separated using alumina columns.
The structure of a buckminsterfullerene is a truncated icosahedron
with 60 vertices
and 32 faces (20 hexagons and 12 pentagons where no pentagons share a vertex) with a carbon atom at the vertices of each polygon and a bond along each polygon edge. The van der Waals diameter
of a C
molecule is about 1.01 nanometers
(nm). The nucleus to nucleus diameter of a C
molecule is about 0.71 nm. The C
molecule has two bond lengths. The 6:6 ring bonds (between two hexagons) can be considered “double bonds
” and are shorter than the 6:5 bonds (between a hexagon and a pentagon). Its average bond length is 0.14 nm. Each carbon atom in the structure is bonded covalently with 3 others.
molecule is extremely stable,
withstanding high temperatures and high pressures. The exposed surface of the structure can selectively react with other species while maintaining the spherical geometry.
Atoms and small molecules can be trapped within the molecule without reacting.
undergoes six reversible, one-electron reductions to C6−
, but oxidation
is irreversible. The first reduction needs ~1.0 V
), showing that C60
is a moderately effective electron acceptor. C
tends to avoid having double bonds in the pentagonal rings, which makes electron delocalization
poor, and results in C
not being not “superaromatic”. C60
behaves very much like an electron deficientalkene
and readily reacts with electron rich species.
A carbon atom in the C
molecule can be substituted by a nitrogen or boron atom yielding a C
Fullerenes are sparingly soluble in aromatic solvents
such as toluene
and carbon disulfide
, but insoluble in water. Solutions of pure C60
have a deep purple color which leaves a brown residue upon evaporation. The reason for this color change is the relatively narrow energy width of the band of molecular levels responsible for green light absorption by individual C60
molecules. Thus individual molecules transmit some blue and red light resulting in a purple color. Upon drying, intermolecular interaction results in the overlap and broadening of the energy bands, thereby eliminating the blue light transmittance and causing the purple to brown color change.
crystallises with some solvents in the lattice (“solvates”). For example, crystallization of C60
solution yields triclinic crystals with the formula C60
. Like other solvates, this one readily releases benzene to give the usual fcc C60
. Millimeter-sized crystals of C60
can be grown from solution both for solvates and for pure fullerenes.
In solid buckminsterfullerene, the molecules C60
stick together via the van der Waals forces
in the fcc motif. At low temperatures the individual molecules are locked against rotation. Upon heating, they start rotating at about −20 °C. This results in a first-order phase transition to a face-centered cubic (fcc) structure and a small, yet abrupt increase in the lattice constant from 1.411 to 1.4154 nm.
solid is as soft as graphite, but when compressed to less than 70% of its volume it transforms into a superhard
form of diamond
(see aggregated diamond nanorod
films and solution have strong non-linear optical properties; in particular, their optical absorption increases with light intensity (saturable absorption).
forms a brownish solid with an optical absorption threshold at ~1.6 eV.
It is an n-type semiconductor
with a low activation energy of 0.1–0.3 eV; this conductivity is attributed to intrinsic or oxygen-related defects.
contains voids at its octahedral and tetrahedral sites which are sufficient large (0.6 and 0.2 nm respectively) to accommodate impurity atoms. When alkali metals are doped into these voids, C60
converts from a semiconductor into a conductor or even superconductor.
In 1991, Haddon et al.
found that intercalation of alkali-metal atoms in solid C60
leads to metallic behavior. In 1991, it was revealed that potassium-doped C60
at 18 K.
This was the highest transition temperature for a molecular superconductor. Since then, superconductivity has been reported in fullerene doped with various other alkali metals.
It has been shown that the superconducting transition temperature in alkaline-metal-doped fullerene increases with the unit-cell volume V.
forms the largest alkali ion, caesium-doped fullerene is an important material in this family. Recently, superconductivity at 38 K has been reported in bulk Cs3
but only under applied pressure. The highest superconducting transition temperature of 33 K at ambient pressure is reported for Cs2
The increase of transition temperature with the unit-cell volume had been believed to be evidence for the BCS mechanism
solid superconductivity, because inter C60
separation can be related to an increase in the density of states on the Fermi level, N(εF
). Therefore, there have been many efforts to increase the interfullerene separation, in particular, intercalating neutral molecules into the A3
lattice to increase the interfullerene spacing while the valence of C60
is kept unchanged. However, this ammoniation technique has revealed a new aspect of fullerene intercalation compounds: the Mott transition
and the correlation between the orientation/orbital order of C60
molecules and the magnetic structure.
molecules compose a solid of weakly bound molecules. The fullerites are therefore molecular solids, in which the molecular properties still survive. The discrete levels of a free C60
molecule are only weakly broadened in the solid, which leads to a set of essentially nonoverlapping bands with a narrow width of about 0.5 eV. For an undoped C60
solid, the 5-fold hu
band is the HOMO
level, and the 3-fold t1u
band is the empty LUMO
level, and this system is a band insulator. But when the C60
solid is doped with metal atoms, the metal atoms give electrons to the t1u
band or the upper 3-fold t1g
This partial electron occupation of the band may lead to metallic behavior. However, A4
is an insulator, although the t1u
band is only partially filled and it should be a metal according to band theory.
This unpredicted behavior may be explained by the Jahn-Teller effect
, where spontaneous deformations of high-symmetry molecules induce the splitting of degenerate levels to gain the electronic energy. The Jahn-Teller type electron-phonon interaction is strong enough in C60
solids to destroy the band picture for particular valence states.
A narrow band or strongly correlated electronic system and degenerated ground states are important points to understand in explaining superconductivity in fullerene solids. When the inter-electron repulsion U is greater than the bandwidth, an insulating localized electron ground state is produced in the simple Mott-Hubbard model. This explains the absence of superconductivity at ambient pressure in caesium-doped C60
Electron-correlation-driven localization of the t1u
electrons exceeds the critical value, leading to the Mott insulator. The application of high pressure decreases the interfullerene spacing, therefore caesium-doped C60
solids turn to metallic and superconducting.
A fully developed theory of C60
solids superconductivity is still lacking, but it has been widely accepted that strong electronic correlations and the Jahn-Teller electron-phonon coupling
produce local electron-pairings that show a high transition temperature close to the insulator-metal transition.
Hydrated fullerene C60
HyFn is a stable, highly hydrophilic, supra-molecular complex consisting of С60
fullerene molecule enclosed into the first hydrated shell that contains 24 water molecules: C60
. This hydrated shell is formed as a result of donor-acceptor interaction
of oxygen, water molecules and electron-acceptor centers on the fullerene surface. Meanwhile, the water molecules which are oriented close to the fullerene surface are interconnected by a three-dimensional network of hydrogen bonds. The size of C60
HyFn is 1.6–1.8 nm. The maximal concentration of С60
in the form of C60
HyFn achieved by 2010 is 4 mg/mL. 
exhibits a small degree of aromatic character, but it still reflects localized double and single C-C bond characters. Therefore C60
can undergo addition with hydrogen to give polyhydrofullerenes. C60
also undergoes Birch reduction
. For example, C60
reacts with lithium in liquid ammonia, followed by tert
-butanol to give a mixture of polyhydrofullerenes such as C60
, with C60
being the dominating product. This mixture of polyhydrofullerenes can be re-oxidized by 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
to give C60
Selective hydrogenation method exists. Reaction of C60
with 9,9′,10,10′-dihydroanthracene under the same conditions, depending on the time of reaction, gives C60
respectively and selectively.
can be hydrogenated,
suggesting that a modified buckminsterfullerene called organometallic buckyballs (OBBs) could become a vehicle for “high density, room temperature, ambient pressure storage of hydrogen
“. These OBBs are created by binding atoms of atransition metal
(TM) to C60
and then binding many hydrogen atoms to this TM atom, dispersing them evenly throughout the inside of the organometallic buckyball. The study found that the theoretical amount of H2
that can be retrieved from the OBB at ambient pressure
approaches 9 wt %
, a mass fraction that has been designated as optimal for hydrogen fuel by the U.S. Department of Energy
Fluorine atoms are small enough for a 1,2-addition, while Cl2
add to remote C atoms due to steric factors
. For example, in C60
, the Br atoms are in 1,3- or 1,4-positions with respect to each other.
Under various conditions a vast number of halogenated derivatives of C60 can be produced, some with extraordinary selectivity on one or two isomers over the other possible ones.
Addition of fluorine and chlorine usually results in a flattening of the C60
framework into a drum-shaped molecule.
Solutions of C60
can be oxygenated to the epoxide
O. Ozonation of C60
in 1,2-xylene at 257K gives an intermediate ozonide C60
, which can be decomposed into 2 forms of C60
O. Decomposition of C60
at 296K gives the epoxide, but photolysis gives a product in which the O atom bridges a 5,6-edige.
The Diels-Alder reaction
is commonly employed to functionalize C60
. Reaction of C60
with appropriate substituted diene gives the corresponding adduct.
The Diels-Alder reaction between C60 and 3,6-diaryl-1,2,4,5-tetrazines affords C62. The C62 has the structure in which a four-membered ring is surrounded by four six-membered rings.
molecules can also be coupled through a [2+2] cycloaddition
, giving the dumbbell-shaped compound C120
. The coupling is achieved by high-speed vibrating milling of C60
with a catalytic amount of KCN
. The reaction is reversible as C120
dissociates back to two C60
molecules when heated at 450 K (177 °C; 350 °F). Under high pressure and temperature, repeated [2+2] cycloaddtion between C60
results in a polymerized fullerene chains and networks. These polymers remain stable at ambient pressure and temperature once formed, and have remarkably interesting electronic and magnetic properties, such as being ferromagnetic
above room temperature.
Reactions of C60
with free radicals
readily occur. When C60
is mixed with a disulfide RSSR, the radical C60
SR• forms spontaneously upon irradiation of the mixture.
Stability of the radical species C60
Y• depends largely on steric factors
of Y. When tert
-butyl halide is photolyzed and allowed to react with C60
, a reversible inter-cage C-C bond is formed:
Cyclopropanation (Bingel reaction
) is another common method for functionalizing C60
. Cyclopropanation of C60
mostly occurs at the junction of 2 hexagons due to steric factors.
The first cyclopropanation was carried out by treating the β-bromomalonate with C60
in the presence of a base. Cyclopropanation also occur readily with diazomethanes
. For example, diphenyldiazomethane reacts readily with C60
to give the compound C61
. Phenyl-C61-butyric acid methyl ester
derivative prepared through cyclopropanation has been studied for use in organic solar cells
is triply degenerate, with the HOMO
separation relatively small. This small gap suggests that reduction of C60
should occur at mild potentials leading to fulleride anions, [C60
= 1–6). The midpoint potentials of 1-electron reduction of buckminsterfullerene and its anions is given in the table below:
|Reduction potential of C60 at 213K
|C60 + e− ⇌ C−
60 + e− ⇌ C2−
60 + e− ⇌ C3−
60 + e− ⇌ C4−
60 + e− ⇌ C5−
60 + e− ⇌ C6−
- C60 + C2(NMe2)4 → [C2(NMe2)4]+[C60]−
fulleride ion [C60
has been isolated as the [K(crypt-222)]+
salt. It is synthesized by treating C60
in the presence of 2.2.2-Cryptand
. The most common fulleride ion, however, is [C60
. Alkali metal salts of this trianion aresuperconducting
. In M3
(M = Na, K, Rb), the M+
ions occupy the interstitial holes in a lattice composed of ccp
lattice composed of nearly spherical C60
anions. In Cs3
, the cages are arranged in a bcc
|Critical temperatures (Tc) of the fulleride salts M3C60
oxidizes with difficulty. Three reversible oxidation processes have been observed by using cyclic voltammetry
with ultra-drymethylene chloride
and a supporting electrolyte with extremely high oxidation resistance and low nucleophilicity, such as [n
|Reduction potentials of C60 oxidation at low temperatures
|C60 ⇌ C+
60 ⇌ C2+
60 ⇌ C3+
Which the [C60]2+ ion is very unstable, and the third process can be studied only at low temperatures.
The redox potentials of C60
can be modified supramolecularly. A dibenzo-18-crown-6
derivative of C60
has been made, featuring a voltage sensor device, with the reversible binding of K+
ion causing an anodic shift of 90mV of the first C60
- M(CO)6 + C60 → M(η2-C60)(CO)5 + CO (M = Mo, W)
In the case of platinum complex, the labile ethylene ligand is the leaving group in a thermal reaction:
- Pt(η2-C2H4)(PPh3)2 + C60 → Pt(η2-C60)(PPh3)2 + C2H4
- (η5–Cp)2Ti(η2-(CH3)3SiC≡CSi(CH3)3) + C60 → (η5-Cp)2Ti(η2-C60) + (CH3)3SiC≡CSi(CH3)3
- trans-Ir(CO)Cl(PPh3)2 + C60 → Ir(CO)Cl(η2-C60)(PPh3)2
One such iridium complex, [Ir(η2
] has been prepared where the metal center projects two electron-rich ‘arms’ that embrace the C60
Metal atoms or certain small molecules such as H2
and noble gas can be encapsulated inside the C60
cage. These endohedral fullerenes are usually synthesized by doping in the metal atoms in an arc reactor or by laser evaporation. These methods gives low yields of endohedral fullerenes, and a better method involves the opening of the cage, packing in the atoms or molecules, and closing the opening using certain organic reactions
. This method, however, is still immature and only a few species have been synthesized this way.
Endohedral fullerenes show distinct and intriguing chemical properties that can be completely different from the encapsulated atom or molecule, as well as the fullerene itself. The encapsulated atoms have been shown to perform circular motions inside the C60
cage, and its motion has been followed by using NMR spectroscopy
No application of C60
has been commercialized. In the medical field, elements such as helium
(that can be detected in minute quantities) can be used as chemical tracers in impregnated buckyballs. Buckminsterfullerene also inhibits the HIV
virus. In particular, C60
inhibits a key enzyme
in the human immunodeficiency virus known as HIV-1 protease
; this could inhibit reproduction of the HIV
virus in immune cells.
Water-soluble derivatives of C60
were discovered to exert an inhibition on the three isoforms of nitric oxide synthase
, with slightly different potencies.
The optical absorption properties of C60
match solar spectrum in a way that suggests that C60
-based films could be useful for photovoltaic applications. Because of its high electronic affinity 
it is one of the most common electron acceptor
used in donor/acceptor based solar cells. Conversion efficiencies up to 5.7% have been reported in C60