> | > Fullerene

Fullerene

Posted on Tuesday, February 10, 2015 | Comments Off

Buckminsterfullerene C60 (left) and carbon nanotubes (right) are two examples of structures in the fullerene family.
Part of a series of articles on
Nanomaterials
Fullerenes
Nanoparticles
A fullerene is a molecule of carbon in the form of a hollow sphere, ellipsoid, tube, and many other shapes. Spherical fullerenes are also called buckyballs, and they resemble the balls used in football (soccer). Cylindrical ones are called carbon nanotubes or buckytubes. Fullerenes are similar in structure to graphite, which is composed of stackedgraphene sheets of linked hexagonal rings; but they may also contain pentagonal (or sometimes heptagonal) rings.[1]
The first fullerene molecule to be discovered, and the family's namesake,buckminsterfullerene (C60), was prepared in 1985 by Richard Smalley, Robert Curl,James Heath, Sean O'Brien, and Harold Kroto at Rice University. The name was a homage to Buckminster Fuller, whose geodesic domes it resembles. The structure was also identified some five years earlier by Sumio Iijima, from an electron microscope image, where it formed the core of a "bucky onion."[2] Fullerenes have since been found to occur in nature.[3] More recently, fullerenes have been detected in outer space.[4] According to astronomer Letizia Stanghellini, "It’s possible that buckyballs from outer space provided seeds for life on Earth."[5]
The discovery of fullerenes greatly expanded the number of known carbon allotropes, which until recently were limited to graphite, diamond, and amorphous carbon such as soot and charcoal. Buckyballs and buckytubes have been the subject of intense research, both for their unique chemistry and for their technological applications, especially in materials science, electronics, and nanotechnology.

History[edit]

The icosahedral fullerene C540, another member of the family of fullerenes.
The icosahedral C60H60 cage was mentioned in 1965 as a possible topological structure.[6] Eiji Osawa of Toyohashi University of Technology predicted the existence of C60 in 1970.[7][8] He noticed that the structure of a corannulenemolecule was a subset of a Association football shape, and he hypothesised that a full ball shape could also exist. Japanese scientific journals reported his idea, but it did not reach Europe or the Americas.
Also in 1970, R. W. Henson (then of the Atomic Energy Research Establishment) proposed the structure and made a model of C60. Unfortunately, the evidence for this new form of carbon was very weak and was not accepted, even by his colleagues. The results were never published but were acknowledged in Carbon in 1999.[9][10]
Independently from Henson, in 1973 a group of scientists from the USSR, directed by Prof. Bochvar, made a quantum-chemical analysis of the stability of C60 and calculated its electronic structure. As in the previous cases, the scientific community did not accept the theoretical prediction. The paper was published in 1973 in Proceedings of the USSR Academy of Sciences (in Russian).[11]
In mass spectrometry, discrete peaks appeared corresponding to molecules with the exact mass of sixty or seventy or more carbon atoms. In 1985, Harold Kroto (then of the University of Sussex), James R. Heath, Sean O'Brien, Robert Curl and Richard Smalley, from Rice University, discovered C60, and shortly thereafter came to discover the fullerenes.[12] Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry [13] for their roles in the discovery of this class of molecules. C60 and other fullerenes were later noticed occurring outside the laboratory (for example, in normal candle-soot). By 1991, it was relatively easy to produce gram-sized samples of fullerene powder using the techniques of Donald Huffman, Wolfgang Krätschmer and Konstantinos Fostiropoulos. Fullerene purification remains a challenge to chemists and to a large extent determines fullerene prices. So-called endohedral fullerenes have ions or small molecules incorporated inside the cage atoms. Fullerene is an unusual reactant in many organic reactions such as the Bingel reaction discovered in 1993. Carbon nanotubes were recognized in 1991.[14]
Minute quantities of the fullerenes, in the form of C60, C70, C76, C82 and C84 molecules, are produced in nature, hidden in soot and formed by lightning discharges in the atmosphere.[15] In 1992, fullerenes were found in a family of minerals known as Shungites in Karelia, Russia.[3]
In 2010, fullerenes (C60) have been discovered in a cloud of cosmic dust surrounding a distant star 6500 light years away. Using NASA's Spitzer infrared telescope the scientists spotted the molecules' unmistakable infrared signature. Sir Harry Kroto, who shared the 1996 Nobel Prize in Chemistry for the discovery of buckyballs commented: "This most exciting breakthrough provides convincing evidence that the buckyball has, as I long suspected, existed since time immemorial in the dark recesses of our galaxy."[16]

Naming[edit]

Buckminsterfullerene (C60) was named after Richard Buckminster Fuller, a noted architectural modeler who popularized the geodesic dome. Since buckminsterfullerenes have a shape similar to that sort of dome, the name was thought appropriate.[17] As the discovery of the fullerene family came afterbuckminsterfullerene, the shortened name 'fullerene' is used to refer to the family of fullerenes. The suffix "-ene" indicates that each C atom is covalently bonded to three others (instead of the maximum of four), a situation that classically would correspond to the existence of bonds involving two pairs of electrons ("double bonds").

Types of fullerene[edit]

Since the discovery of fullerenes in 1985, structural variations on fullerenes have evolved well beyond the individual clusters themselves. Examples include:[18]
  • Buckyball clusters: smallest member is C
    20     (unsaturated version of dodecahedrane) and the most common is C
    60    ;
  • Nanotubes: hollow tubes of very small dimensions, having single or multiple walls; potential applications in electronics industry;
  • Megatubes: larger in diameter than nanotubes and prepared with walls of different thickness; potentially used for the transport of a variety of molecules of different sizes;[19]
  • polymers: chain, two-dimensional and three-dimensional polymers are formed under high-pressure high-temperature conditions; single-strand polymers are formed using the Atom Transfer Radical Addition Polymerization (ATRAP) route;[20]
  • nano"onions": spherical particles based on multiple carbon layers surrounding a buckyball core;[21] proposed for lubricants;[22]
  • linked "ball-and-chain" dimers: two buckyballs linked by a carbon chain;[23]
  • fullerene rings.[24]

Buckyballs[edit]

C60 with isosurface of ground state electron density as calculated withDFT

Buckminsterfullerene[edit]

Main article: Buckminsterfullerene (See Below)
Buckminsterfullerene is the smallest fullerene molecule containing pentagonal and hexagonal rings in which no two pentagons share an edge (which can be destabilizing, as in pentalene). It is also the most common in terms of natural occurrence, as it can often be found in soot.
The structure of C60 is a truncated icosahedron, which resembles an association football ball of the type made of twenty hexagons and twelve pentagons, with a carbon atom at the vertices of each polygon and a bond along each polygon edge.
The van der Waals diameter of a C60 molecule is about 1.1 nanometers (nm).[25] The nucleus to nucleus diameter of a C60molecule is about 0.71 nm.
The C60 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 1.4 angstroms.
Silicon buckyballs have been created around metal ions.

Boron buckyball[edit]

A type of buckyball which uses boron atoms, instead of the usual carbon, was predicted and described in 2007. The B80 structure, with each atom forming 5 or 6 bonds, is predicted to be more stable than the C60 buckyball.[26] One reason for this given by the researchers is that the B-80 is actually more like the original geodesic dome structure popularized by Buckminster Fuller, which uses triangles rather than hexagons. However, this work has been subject to much criticism by quantum chemists[27][28] as it was concluded that the predicted Ih symmetric structure was vibrationally unstable and the resulting cage undergoes a spontaneous symmetry break, yielding a puckered cage with rare Th symmetry (symmetry of a volleyball).[27] The number of six-member rings in this molecule is 20 and number of five-member rings is 12. There is an additional atom in the center of each six-member ring, bonded to each atom surrounding it. By employing a systematic global search algorithm, later it was found that the previously proposed B80 fullerene is not global minimum for 80 atom boron clusters and hence can not be found in nature.[29] In the same paper by Sandip De et al., it was concluded that born energy land scape is significantly different from other fullerenes already found in nature hence pure boron fullerenes are unlikely to exist in nature.

Other buckyballs[edit]

Another fairly common fullerene is C70,[30] but fullerenes with 72, 76, 84 and even up to 100 carbon atoms are commonly obtained.
In mathematical terms, the structure of a fullerene is a trivalent convex polyhedron with pentagonal and hexagonal faces. In graph theory, the term fullerenerefers to any 3-regular, planar graph with all faces of size 5 or 6 (including the external face). It follows from Euler's polyhedron formula, V − E + F = 2 (where V,E, F are the numbers of vertices, edges, and faces), that there are exactly 12 pentagons in a fullerene and V/2 − 10 hexagons.
Graph of 20-fullerene w-nodes.svgGraph of 26-fullerene 5-base w-nodes.svgGraph of 60-fullerene w-nodes.svgGraph of 70-fullerene w-nodes.svg
20-fullerene
(dodecahedral graph)		26-fullerene graph60-fullerene
(truncated icosahedral graph)		70-fullerene graph
The smallest fullerene is the dodecahedral C20. There are no fullerenes with 22 vertices.[31] The number of fullerenes C2n grows with increasingn = 12, 13, 14, ..., roughly in proportion to n9 (sequence A007894 in OEIS). For instance, there are 1812 non-isomorphic fullerenes C60. Note that only one form of C60, the buckminsterfullerene alias truncated icosahedron, has no pair of adjacent pentagons (the smallest such fullerene). To further illustrate the growth, there are 214,127,713 non-isomorphic fullerenes C200, 15,655,672 of which have no adjacent pentagons. Optimized structures of many fullerene isomers are published and listed on the web.[32]
Trimetasphere carbon nanomaterials were discovered by researchers at Virginia Tech and licensed exclusively to Luna Innovations. This class of novel molecules comprises 80 carbon atoms (C
80) forming a sphere which encloses a complex of three metal atoms and one nitrogen atom. These fullerenes encapsulate metals which puts them in the subset referred to as metallofullerenes. Trimetaspheres have the potential for use in diagnostics (as safe imaging agents), therapeutics[33] and in organic solar cells.[34]

Carbon nanotubes[edit]

This rotating model of a carbon nanotubeshows its 3D structure.
Main article: Carbon nanotube
Nanotubes are cylindrical fullerenes. These tubes of carbon are usually only a few nanometres wide, but they can range from less than a micrometer to several millimeters in length. They often have closed ends, but can be open-ended as well. There are also cases in which the tube reduces in diameter before closing off. Their unique molecular structure results in extraordinary macroscopic properties, including high tensile strength, high electrical conductivity, high ductility, high heat conductivity, and relative chemical inactivity (as it is cylindrical and "planar" — that is, it has no "exposed" atoms that can be easily displaced). One proposed use of carbon nanotubes is in paper batteries, developed in 2007 by researchers at Rensselaer Polytechnic Institute.[35] Another highly speculative proposed use in the field of space technologies is to produce high-tensile carbon cables required by a space elevator.

Carbon nanobuds[edit]

Main article: Carbon nanobud
Nanobuds have been obtained by adding buckminsterfullerenes to carbon nanotubes.

Fullerite[edit]

The C60 fullerene in crystalline form
Fullerites are the solid-state manifestation of fullerenes and related compounds and materials.
"Ultrahard fullerite" is a coined term frequently used to describe material produced by high-pressure high-temperature (HPHT) processing of fullerite. Such treatment converts fullerite into a nanocrystalline form of diamondwhich has been reported to exhibit remarkable mechanical properties.[36]
Fullerite (scanning electron microscope image)

Inorganic fullerenes[edit]

Materials with fullerene-like molecular structures but lacking carbon includeMoS2, WS2, TiS2 and NbS2. Prof. J. M. Martin from Ecole Central de Lyon in France tested the new material under isostatic pressure and found it to be stable up to at least 350 tons/cm2.[37]
See also: Inorganic nanotube

Properties[edit]

For the past decade, the chemical and physical properties of fullerenes have been a hot topic in the field of research and development[according to whom?], and are likely to continue to be for a long time. Popular Science has discussed possible uses of fullerenes (graphene) in armor.[38] In April 2003, fullerenes were under study for potential medicinal use: binding specific antibiotics to the structure to target resistant bacteria and even target certain cancer cells such as melanoma. The October 2005 issue of Chemistry & Biology contains an article describing the use of fullerenes as light-activated antimicrobial agents.[39]
In the field of nanotechnology, heat resistance and superconductivity are some of the more heavily studied properties.
A common method used to produce fullerenes is to send a large current between two nearby graphite electrodes in an inert atmosphere. The resulting carbonplasma arc between the electrodes cools into sooty residue from which many fullerenes can be isolated.
There are many calculations that have been done using ab-initio quantum methods applied to fullerenes. By DFT and TD-DFT methods one can obtain IR,Raman and UV spectra. Results of such calculations can be compared with experimental results.

Aromaticity[edit]

Researchers have been able to increase the reactivity of fullerenes by attaching active groups to their surfaces. Buckminsterfullerene does not exhibit "superaromaticity": that is, the electrons in the hexagonal rings do not delocalize over the whole molecule.
A spherical fullerene of n carbon atoms has n pi-bonding electrons, free to delocalize. These should try to delocalize over the whole molecule. The quantum mechanics of such an arrangement should be like one shell only of the well-known quantum mechanical structure of a single atom, with a stable filled shell for n= 2, 8, 18, 32, 50, 72, 98, 128, etc.; i.e. twice a perfect square number; but this series does not include 60. This 2(N + 1)2 rule (with N integer) for spherical aromaticity is the three-dimensional analogue of Hückel's rule. The 10+ cation would satisfy this rule, and should be aromatic. This has been shown to be the case using quantum chemical modelling, which showed the existence of strong diamagnetic sphere currents in the cation.[40]
As a result, C60 in water tends to pick up two more electrons and become an anion. The nC60 described below may be the result of C60 trying to form a loosemetallic bond.

Chemistry[edit]

Main article: Fullerene chemistry
Fullerenes are stable, but not totally unreactive. The sp2-hybridized carbon atoms, which are at their energy minimum in planar graphite, must be bent to form the closed sphere or tube, which produces angle strain. The characteristic reaction of fullerenes is electrophilic addition at 6,6-double bonds, which reduces angle strain by changing sp2-hybridized carbons into sp3-hybridized ones. The change in hybridized orbitals causes the bond angles to decrease from about 120° in the sp2 orbitals to about 109.5° in the sp3 orbitals. This decrease in bond angles allows for the bonds to bend less when closing the sphere or tube, and thus, the molecule becomes more stable.
Other atoms can be trapped inside fullerenes to form inclusion compounds known as endohedral fullerenes. An unusual example is the egg shaped fullerene Tb3N@C84, which violates the isolated pentagon rule.[41] Recent evidence for a meteor impact at the end of the Permian period was found by analyzing noble gases so preserved.[42] Metallofullerene-based inoculates using the rhonditic steel process are beginning production as one of the first commercially-viable uses of buckyballs.

Solubility[edit]

C60 in solution
C60 in extra virgin olive oil showing the characteristic purple color of pristine C60 solutions.
Fullerenes are sparingly soluble in many solvents. Common solvents for the fullerenes include aromatics, such astoluene, and others like carbon disulfide. Solutions of pure buckminsterfullerene have a deep purple color. Solutions of C70 are a reddish brown. The higher fullerenes C76 to C84 have a variety of colors. C76 has two optical forms, while other higher fullerenes have several structural isomers. Fullerenes are the only known allotrope of carbon that can be dissolved in common solvents at room temperature.
SolventC60C70
1-chloronaphthalene51 mg/mL*
1-methylnaphthalene33 mg/mL*
1,2-dichlorobenzene24 mg/mL36.2 mg/mL
1,2,4-trimethylbenzene18 mg/mL*
tetrahydronaphthalene16 mg/mL*
carbon disulfide8 mg/mL9.875 mg/mL
1,2,3-tribromopropane8 mg/mL*
chlorobenzene7 mg/mL*
xylene5 mg/mL3.985 mg/mL(p-xylene)
bromoform5 mg/mL*
cumene4 mg/mL*
toluene3 mg/mL1.406 mg/mL
benzene1.5 mg/mL1.3 mg/mL
carbon tetrachloride0.447 mg/mL0.121 mg/mL
chloroform0.25 mg/mL*
n-hexane0.046 mg/mL0.013 mg/mL
cyclohexane0.035 mg/mL0.08 mg/mL
tetrahydrofuran0.006 mg/mL*
acetonitrile0.004 mg/mL*
methanol0.000 04 mg/mL*
water1.3×10−11 mg/mL*
pentane0.004 mg/mL0.002 mg/mL
heptane*0.047 mg/mL
octane0.025 mg/mL0.042 mg/mL
isooctane0.026 mg/mL*
decane0.070 mg/mL0.053 mg/mL
dodecane0.091 mg/mL0.098 mg/mL
tetradecane0.126 mg/mL*
acetone*0.0019 mg/mL
isopropanol*0.0021 mg/mL
dioxane0.0041 mg/mL*
mesitylene0.997 mg/mL1.472 mg/mL
dichloromethane0.254 mg/mL0.080 mg/mL
* : Solubility not measured
Some fullerene structures are not soluble because they have a small band gap between the ground and excited states. These include the small fullerenes C28,[43] C36 and C50. The C72 structure is also in this class, but the endohedral version with a trapped lanthanide-group atom is soluble due to the interaction of the metal atom and the electronic states of the fullerene. Researchers had originally been puzzled by C72 being absent in fullerene plasma-generated soot extract, but found in endohedral samples. Small band gap fullerenes are highly reactive and bind to other fullerenes or to soot particles.
Solvents that are able to dissolve buckminsterfullerene (C60 and C70) are listed at left in order from highest solubility. The solubility value given is the approximate saturated concentration.[44] [45][46][47][48]
Solubility of C60 in some solvents shows unusual behaviour due to existence of solvate phases (analogues of crystallohydrates). For example, solubility of C60 in benzene solution shows maximum at about 313 K. Crystallization from benzene solution at temperatures below maximum results in formation of triclinic solid solvate with four benzene molecules C60·4C6H6 which is rather unstable in air. Out of solution, this structure decomposes into usual face-centered cubic (fcc) C60 in few minutes' time. At temperatures above solubility maximum the solvate is not stable even when immersed in saturated solution and melts with formation of fcc C60. Crystallization at temperatures above the solubility maximum results in formation of pure fcc C60. Millimeter-sized crystals of C60 and C70 can be grown from solution both for solvates and for pure fullerenes.[49][50]

Quantum mechanics[edit]

In 1999, researchers from the University of Vienna demonstrated that wave-particle duality applied to molecules such as fullerene.[51] One of the co-authors of this research, Julian Voss-Andreae, has since created several sculptures symbolizing wave-particle duality in fullerenes (see Fullerenes in popular culture for more detail).

Superconductivity[edit]

Main article: Buckminsterfullerene

Chirality[edit]

Some fullerenes (e.g. C76, C78, C80, and C84) are inherently chiral because they are D2-symmetric, and have been successfully resolved. Research efforts are ongoing to develop specific sensors for their enantiomers.

Construction[edit]

Two theories have been proposed to describe the molecular mechanisms that make fullerenes. The older, “bottom-up” theory proposes that they are built atom-by-atom. The alternative “top-down” approach claims that fullerenes form when much larger structures break into constituent parts.[52]
In 2013 researchers discovered that asymmetrical fullerenes formed from larger structures settle into stable fullerenes. The synthesized substance was a particular metallofullereneconsisting of 84 carbon atoms with two additional carbon atoms and two yttrium atoms inside the cage. The process produced approximately 100 micrograms.[52]
However, they found that the asymmetrical molecule could theoretically collapse to form nearly every known fullerene and metallofullerene. Minor perturbations involving the breaking of a few molecular bonds cause the cage to become highly symmetrical and stable. This insight supports the theory that fullerenes can be formed from graphene when the appropriate molecular bonds are severed.[52][53]

Production technology[edit]

Fullerene production processes comprise the following five subprocesses: (i) synthesis of fullerenes or fullerene-containing soot; (ii) extraction; (iii) separation (purification) for each fullerene molecule, yielding pure fullerenes such as C60; (iv) synthesis of derivatives (mostly using the techniques of organic synthesis); (c) other post-processing such as dispersion into a matrix. The two synthesis methods used in practice are the arc method, and the combustion method. The latter, discovered at the Massachusetts Institute of Technology, is preferred for large scale industrial production.[54][55]

Applications[edit]

Fullerenes have been extensively used for several biomedical applications including the design of high-performance MRI contrast agents, X-Ray imaging contrast agents, photodynamic therapy and drug and gene delivery, summarized in several comprehensive reviews.[56]

Tumor research[edit]

While past cancer research has involved radiation therapy, photodynamic therapy is important to study because breakthroughs in treatments for tumor cells will give more options to patients with different conditions. More recent experiments using HeLa cells in cancer research involves the development of newphotosensitizers with increased ability to be absorbed by cancer cells and still trigger cell death. It is also important that a new photosensitizer does not stay in the body for a long time to prevent unwanted cell damage.[57]
Fullerenes can be made to be absorbed by HeLa cells. The C60 derivatives can be delivered to the cells by using the functional groups L-phenylalanine, folic acid, and L-arginine among others.[58] The purpose for functionalizing the fullerenes is to increase the solubility of the molecule by the cancer cells. Cancer cells take up these molecules at an increased rate because of an upregulation of transporters in the cancer cell, in this case amino acid transporters will bring in the L-arginine and L-phenylalanine functional groups of the fullerenes.[59]
Once absorbed by the cells, the C60 derivatives would react to light radiation by turning molecular oxygen into reactive oxygen which triggers apoptosis in the HeLa cells and other cancer cells that can absorb the fullerene molecule. This research shows that a reactive substance can target cancer cells and then be triggered by light radiation, minimizing damage to surrounding tissues while undergoing treatment.[60]
When absorbed by cancer cells and exposed to light radiation, the reaction that creates reactive oxygen damages the DNA, proteins, and lipids that make up the cancer cell. This cellular damage forces the cancerous cell to go through apoptosis, which can lead to the reduction in size of a tumor. Once the light radiation treatment is finished the fullerene will reabsorb the free radicals to prevent damage of other tissues.[61] Since this treatment focuses on cancer cells it is a good option for patients whose cancer cells are within reach of light radiation. As this research continues into the future it will be able to penetrate deeper into the body and more effectively absorbed by cancer cells.[57]

Safety and toxicity[edit]

See also: Carbon nanotube § Toxicity
A comprehensive and recent review on fullerene toxicity is given by Lalwani et al.[56] These authors review the works on fullerene toxicity beginning in the early 1990s to present, and conclude that very little evidence gathered since the discovery of fullerenes indicate that C60 is toxic. The toxicity of these carbon nanoparticles is not only dose and time-dependent, but also depends on a number of other factors such as: type (e.g., C60, C70, M@C60, M@C82, functional groups used to water solubilize these nanoparticles (e.g., OH, COOH), and method of administration (e.g., intravenous, intraperitoneal). The authors therefore recommend that pharmacology of every new fullerene- or metallofullerene-based complex must be assessed individually as a different compound.
Moussa et al. (1996–7)[62][63] studied the in vivo toxicity of C60 after intra-peritoneal administration of large doses. No evidence of toxicity was found and the mice tolerated a dose of 5 g/kg of body weight. Mori et al. (2006)[64] could not find toxicity in rodents for C60 and C70 mixtures after oral administration of a dose of 2 g/kg body weight and did not observe evidence of genotoxic or mutagenic potential in vitro. Other studies could not establish the toxicity of fullerenes: on the contrary, the work of Gharbi et al. (2005)[65] suggested that aqueous C60 suspensions failing to produce acute or subacute toxicity in rodents could also protect their livers in a dose-dependent manner against free-radical damage. In a 2012 primary study of an olive oil / C60 suspension administered to rats by intra-peritoneal administration or oral gavage, a prolonged lifespan to almost double the normal lifespan of the rats was seen and significant toxicity was not observed.[66] An investigator for this study, Professor Moussa, generalized from its findings in a video interview and stated that pure C60 is not toxic.[67]
With reference to nanotubes, a 2008 study[68] on carbon nanotubes introduced into the abdominal cavity of mice led the authors to suggest comparisons to "asbestos-like pathogenicity". It should be noted that this was not an inhalation study, though there have been several performed in the past, therefore it is premature to conclude that nanotubes should be considered to have a toxicological profile similar to asbestos. Conversely, and perhaps illustrative of how the various classes of molecules which fall under the general term fullerene cover a wide range of properties, Sayes et al. found that in vivo inhalation of C60(OH)24and nano-C60 in rats gave no effect, whereas in comparison quartz particles produced an inflammatory response under the same conditions.[69] As stated above, nanotubes are quite different in chemical and physical properties to C60, i.e., molecular weight, shape, size, physical properties (such as solubility) all are very different, so from a toxicological standpoint, different results for C60 and nanotubes are not suggestive of any discrepancy in the findings.
When considering toxicological data, care must be taken to distinguish as necessary between what are normally referred to as fullerenes: (C60, C70, ...); fullerene derivatives: C60 or other fullerenes with covalently bonded chemical groups; fullerene complexes (e.g., water-solubilized with surfactants, such as C60-PVP; host-guest complexes, such as with cyclodextrin), where the fullerene is supermolecular bound to another molecule; C60 nanoparticles, which are extended solid-phase aggregates of C60 crystallites; and nanotubes, which are generally much larger (in terms of molecular weight and size) molecules, and are different in shape to the spheroidal fullerenes C60 and C70, as well as having different chemical and physical properties.
The above different molecules span the range from insoluble materials in either hydrophilic or lipophilic media, to hydrophilic, lipophilic, or even amphiphilic molecules, and with other varying physical and chemical properties. Therefore any broad generalization extrapolating for example results from C60 to nanotubes or vice versa is not possible, though technically all are fullerenes, as the term is defined as a close-caged all-carbon molecule. Any extrapolation of results from one molecule to other molecules must take into account considerations based on a quantitative structural analysis relationship study (QSARS), which mostly depends on how close the molecules under consideration are in physical and chemical properties.

Popular culture[edit]

Main article: Fullerenes in popular culture
Examples of fullerenes in popular culture are numerous. Fullerenes appeared in fiction well before scientists took serious interest in them. In a humorously speculative 1966 column for New Scientist, David Jones suggested that it may be possible to create giant hollow carbon molecules by distorting a plane hexagonal net by the addition of impurity atoms.[70]
On 4 September 2010, Google used an interactively rotatable fullerene [71] C60 as the second 'o' in their logo to celebrate the 25th anniversary of the discovery of the fullerenes.[72][73]
see buckyball (disambiguation).
Buckminsterfullerene
Buckminsterfullerene.svgBuckminsterfullerene-perspective-3D-balls.png
Other names
Identifiers
CAS number99685-96-8 Yes
PubChem123591
ChemSpider110185 Yes
ChEBICHEBI:33128 Yes
5901022
Jmol-3D imagesImage
Properties
C60
Molar mass720.64 g·mol−1
AppearanceDark needle-like crystals
Density1.65 g/cm3
Melting pointsublimates at ~ 600 °C (1,112 °F; 873 K)[1]
insoluble in water
Structure
Crystal structureFace-centered cubic,cF1924
Space groupFm3m, No. 225
Lattice constanta = 1.4154 nm
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 Yes verify (what is: Yes/?)
Infobox references
Part of a series of articles on
Nanomaterials
Fullerenes
Nanoparticles
Buckminsterfullerene (or bucky-ball) is a spherical fullerene molecule with the formula C60. It has a cage-like fused-ring structure (truncated icosahedron) which resembles a soccer ball, made of twenty hexagons and twelvepentagons, with a carbon atom at each vertex of each polygon and a bond along each polygon edge.
It was first generated in 1985 by Harold Kroto, James R. Heath, Sean O'Brien, Robert Curl, and Richard Smalley atRice University.[2] Kroto, Curl and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of buckminsterfullerene and the related class of molecules, the fullerenes. The name is a reference toBuckminster Fuller, as C60 resembles his trademark geodesic domes. Buckminsterfullerene is the most common naturally occurring fullerene molecule, as it can be found in small quantities in soot.[3][4] Solid and gaseous forms of the molecule have been detected in deep space.[5]
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.[6][7] Its discovery led to the exploration of a new field of chemistry, involving the study of fullerenes.

Etymology[edit]

Buckminsterfullerene 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.[8]

History[edit]

Main article: Fullerene
The structure associated with fullerenes was described by Leonardo da Vinci.[9] Albrecht Dürer also reproduced a similar icosahedron containing 12 pentagonal and 20 hexagonal faces but there are no clear documentations of this.[10][11]

Discovery[edit]

Harold Kroto
Richard Smalley
Many association footballs have the same shape as buckminsterfullerene, C60.
Theoretical predictions of buckyball molecules appeared in the late 1960s – early 1970s,[12][13] 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 laservaporization of a suitable target to produce clusters of atoms. Kroto realized that by using a graphite target,[14] 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.[11][15][16] 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.[11][17]Hence, the inspiration came to Smalley and team to use the laser technique on graphite to create the first fullerene molecule.
C60 was discovered in 1985 by Robert Curl, Harold Kroto and Richard Smalley. Using laser evaporation of graphite they found Cn clusters (where n>20 and even) of which the most common were C60 and C70. 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.[18] 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.[11][18]
For this discovery they were awarded the 1996 Nobel Prize in Chemistry. The discovery of buckyballs was surprising, as the scientists aimed the experiment at producing carbon plasmas to replicate and characterize unidentified interstellar matter. Mass spectrometry analysis of the product indicated the formation of spheroidal carbon molecules.[12]
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 inventorBuckminster Fuller as influences in the naming of this particular substance as buckminsterfullerene.[12]

Further developments[edit]

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.[19]
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.[20]
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.[20]

Synthesis[edit]

High-vacuum electrolysis of a C60-fullerene derivative. Slow diffusion into the anode (right side) yields the characteristic purple color of pure C60.
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 usingchromatography.[21] Generally, the fullerenes are dissolved in hydrocarbon or halogenated hydrocarbon and separated using alumina columns.[22]

Properties[edit]

Molecule[edit]

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
60 molecule is about 1.01nanometers (nm). The nucleus to nucleus diameter of a C
60 molecule is about 0.71 nm. The C
60 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.[23]
The C
60 molecule is extremely stable,[24] withstanding high temperatures and high pressures. The exposed surface of the structure can selectively react with other species while maintaining the spherical geometry.[25] Atoms and small molecules can be trapped within the molecule without reacting.
C
60 undergoes six reversible, one-electron reductions to C6−
60, but oxidation is irreversible. The first reduction needs ~1.0 V (Fc/Fc+), showing that C60 is a moderately effective electron acceptor. C
60 tends to avoid having double bonds in the pentagonal rings, which makes electron delocalization poor, and results inC
60 not being not "superaromatic". C60 behaves very much like an electron deficient alkene and readily reacts with electron rich species.[20]
A carbon atom in the C
60 molecule can be substituted by a nitrogen or boron atom yielding a C
59N or C59B respectively.[26]
Orthogonal projections
Centered byVertexEdge
5–6		Edge
6-6		Face
Hexagon		Face
Pentagon
ImageDodecahedron t12 v.pngDodecahedron t12 e56.pngDodecahedron t12 e66.pngIcosahedron t01 A2.pngIcosahedron t01 H3.png
Projective
symmetry		[2][2][2][6][10]

Solution[edit]

C60 solution
Solubility of C60[27][28][29]
SolventSolubility
(mg/mL)
1-chloronaphthalene51
1-methylnaphthalene33
1,2-dichlorobenzene24
1,2,4-trimethylbenzene18
tetrahydronaphthalene16
carbon disulfide8
1,2,3-tribromopropane8
xylene5
bromoform5
cumene4
toluene3
benzene1.5
carbon tetrachloride0.447
chloroform0.25
n-hexane0.046
cyclohexane0.035
tetrahydrofuran0.006
acetonitrile0.004
methanol0.00004
water1.3×10−11
pentane0.004
octane0.025
isooctane0.026
decane0.070
dodecane0.091
tetradecane0.126
dioxane0.0041
mesitylene0.997
dichloromethane0.254
Optical absorption spectrum of C
60solution, showing reduced absorption for the blue (~450 nm) and red (~700 nm) light that results in the purple color.
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.[30]
C
60 crystallises with some solvents in the lattice ("solvates"). For example, crystallization of C60 in benzene solution yields triclinic crystals with the formula C60·4C6H6. Like other solvates, this one readily releases benzene to give the usual fcc C60. Millimeter-sized crystals of C60 and C
70 can be grown from solution both for solvates and for pure fullerenes.[31][32]

Solid[edit]

C60 solid
C
60 crystal structure
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.[33]
C
60 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). C
60 films and solution have strong non-linear optical properties; in particular, their optical absorption increases with light intensity (saturable absorption).
C
60 forms a brownish solid with an optical absorption threshold at ~1.6 eV.[34] 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.[35] Fcc C60 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.[33][36]

Band structure and superconductivity[edit]

Cs3C60 crystal structure
In 1991, Haddon et al.[37] found that intercalation of alkali-metal atoms in solid C60leads to metallic behavior.[38] In 1991, it was revealed that potassium-doped C60becomes superconducting at 18 K.[39] This was the highest transition temperature for a molecular superconductor. Since then, superconductivity has been reported in fullerene doped with various other alkali metals.[40][41] It has been shown that the superconducting transition temperature in alkaline-metal-doped fullerene increases with the unit-cell volume V.[42][43] As caesium 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 Cs3C60,[44] but only under applied pressure. The highest superconducting transition temperature of 33 K at ambient pressure is reported for Cs2RbC60.[45]
The increase of transition temperature with the unit-cell volume had been believed to be evidence for the BCS mechanism of C60 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 A3C60 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.[46]
Electronic structure of C60 under "ideal" spherical (left) and "real" icosahedral symmetry (right).
The C60 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.[38] For an undoped C60solid, 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 band.[47] This partial electron occupation of the band may lead to metallic behavior. However, A4C60 is an insulator, although the t1u band is only partially filled and it should be a metal according to band theory.[48] 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.[46]
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 solids.[44] 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[49] produce local electron-pairings that show a high transition temperature close to the insulator-metal transition.[50]

Chemical reactions and properties[edit]

Hydrated fullerene (HyFn)[edit]

C60HyFn water solution with a C60concentration of 0.22 g/L.
Hydrated fullerene C60HyFn 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@(H2O)24. This hydrated shell is formed as a result of donor-acceptor interaction between lone-electron pairs 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 C60HyFn is 1.6–1.8 nm. The maximal concentration of С60 in the form of C60HyFn achieved by 2010 is 4 mg/mL.[51] [52][53][54]

Hydrogenation[edit]

C60 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 C60H18, C60H32, C60H36, with C60H32 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 again.
Selective hydrogenation method exists. Reaction of C60 with 9,9',10,10'-dihydroanthracene under the same conditions, depending on the time of reaction, gives C60H32 and C60H18 respectively and selectively.[55]
C60 can be hydrogenated,[56] 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 a transition metal (TM) to C60 or C48B12 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.

Halogenation[edit]

Addition of fluorine, chlorine, and bromine occurs for C60.
Fluorine atoms are small enough for a 1,2-addition, while Cl2 and Br2 add to remote C atoms due to steric factors. For example, in C60Br8 and C60Br24, 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.[55]

Addition of oxygen atoms[edit]

Solutions of C60 can be oxygenated to the epoxide C60O. Ozonation of C60 in 1,2-xylene at 257K gives an intermediate ozonide C60O3, which can be decomposed into 2 forms of C60O. Decomposition of C60O3 at 296K gives the epoxide, but photolysis gives a product in which the O atom bridges a 5,6-edige.[55]
Addition of O atom into C60 Scheme.png

Cycloadditions[edit]

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.
A C62 derivative [C62(C6H4-4-Me)2] synthesized from C60 and 3,6-bis(4-methylphenyl)-3,6-dihydro-1,2,4,5-tetrazine
The C60 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.[55]

Free radical reactions[edit]

Reactions of C60 with free radicals readily occur. When C60 is mixed with a disulfide RSSR, the radical C60SR• forms spontaneously upon irradiation of the mixture.
Stability of the radical species C60Y• 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:[55]
Free radical reaction of fullerene with tert-butyl radical.png

Cyclopropanation (Bingel reaction)[edit]

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 withdiazomethanes. For example, diphenyldiazomethane reacts readily with C60 to give the compound C61Ph2.[55] Phenyl-C61-butyric acid methyl ester derivative prepared through cyclopropanation has been studied for use in organic solar cells.

Redox reactions – C60 anions and cations[edit]

The LUMO in C60 is triply degenerate, with the HOMO-LUMO separation relatively small. This small gap suggests that reduction of C60 should occur at mild potentials leading to fulleride anions, [C60]n- (n = 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
Half-reactionE° (V)
C60 + e− ⇌ C−
60		−0.169
C−
60 + e− ⇌ C2−
60		−0.599
C2−
60 + e− ⇌ C3−
60		−1.129
C3−
60 + e− ⇌ C4−
60		−1.579
C4−
60 + e− ⇌ C5−
60		−2.069
C5−
60 + e− ⇌ C6−
60		−2.479
C60 forms a variety of charge-transfer complexes, for example with tetrakis(dimethylamino)ethylene:
C60 + C2(NMe2)4 → [C2(NMe2)4]+[C60]-
This salt exhibits ferromagnetism at 16K.
The paramagnetic fulleride ion [C60]2− has been isolated as the [K(crypt-222)]+ salt. It is synthesized by treating C60 with metallic potassium in the presence of2.2.2-Cryptand. The most common fulleride ion, however, is [C60]3−. Alkali metal salts of this trianion are superconducting. In M3C60 (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 Cs3C60, the cages are arranged in a bcc lattice.
Critical temperatures (Tc) of the fulleride salts M3C60
SaltTc (K)
Na3C60(non-superconductive)
K3C6018
Rb3C6028
Cs3C6040
C60 oxidizes with difficulty. Three reversible oxidation processes have been observed by using cyclic voltammetry with ultra-dry methylene chloride and a supporting electrolyte with extremely high oxidation resistance and low nucleophilicity, such as [nBu4N] [AsF6].[55]
Reduction potentials of C60 oxidation at low temperatures
Half-reactionE◌ (V)
C60 ⇌ C+
60		+1.27
C+
60 ⇌ C2+
60		+1.71
C2+
60 ⇌ C3+
60		+2.14
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 reduction.
A reaction showing the reduction shift of the C60-based voltaic sensor reduction.png

Metal complexes[edit]

Main article: Fullerene ligand
C60 forms complexes akin to the more common alkenes. Complexes have been reported molybdenum, tungsten, platinum, palladium, iridium, and titanium. The pentacarbonyl species are produced by photochemical reactions.
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
Titanocene complexes have also been reported:
(η5-Cp)2Ti(η2-(CH3)3SiC≡CSi(CH3)3) + C60 → (η5-Cp)2Ti(η2-C60) + (CH3)3SiC≡CSi(CH3)3
Coordinatively unsaturated precursors, such as Vaska's complex, for adducts with C60:
trans-Ir(CO)Cl(PPh3)2 + C60 → Ir(CO)Cl(η2-C60)(PPh3)2
One such iridium complex, [Ir(η2-C60)(CO)Cl(Ph2CH2C6H4OCH2Ph)2] has been prepared where the metal center projects two electron-rich 'arms' that embrace the C60 guest.[57]

Endohedral fullerenes[edit]

Main articles: Endohedral fullerene and Endohedral hydrogen fullerene
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.[58]
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.[57]

Applications[edit]

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.[citation needed]
Water-soluble derivatives of C60 were discovered to exert an inhibition on the three isoforms of nitric oxide synthase, with slightly different potencies (Papoiu).[59]
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 [60] 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-polymer cells.[61]

See also[edit]

Portal iconNanotechnology portal

References[edit]

  1. Jump up^ Fullerene, Encyclopædia Britannica on-line
  2. Jump up^ Iijima, S (1980). "Direct observation of the tetrahedral bonding in graphitized carbon black by high resolution electron microscopy". Journal of Crystal Growth50 (3): 675. Bibcode:1980JCrGr..50..675I. doi:10.1016/0022-0248(80)90013-5.
  3. ^ Jump up to:a b Buseck, P.R.; Tsipursky, S.J.; Hettich, R. (1992). "Fullerenes from the Geological Environment". Science 257 (5067): 215–7.Bibcode:1992Sci...257..215B. doi:10.1126/science.257.5067.215.PMID 17794751.
  4. Jump up^ Cami, J; Bernard-Salas, J.; Peeters, E.; Malek, S. E. (2010-09-02). "Detection of C60 and C70 in a Young Planetary Nebula". Science 329 (5996): 1180–2.Bibcode:2010Sci...329.1180C. doi:10.1126/science.1192035.PMID 20651118.
  5. Jump up^ Atkinson, Nancy (2010-10-27). "Buckyballs Could Be Plentiful in the Universe". Universe Today. Retrieved 2010-10-28.
  6. Jump up^ Schultz, H.P. (1965). "Topological Organic Chemistry. Polyhedranes and Prismanes". Journal of Organic Chemistry 30 (5): 1361.doi:10.1021/jo01016a005.
  7. Jump up^ Osawa, E. (1970). Kagaku 25: 854.
  8. Jump up^ Halford, B. (9 October 2006). "The World According to Rick". Chemical & Engineering News 84 (41): 13. doi:10.1021/cen-v084n041.p013.
  9. Jump up^ Thrower, P.A. (1999). "Editorial". Carbon 37 (11): 1677. doi:10.1016/S0008-6223(99)00191-8.
  10. Jump up^ Henson, R.W. "The History of Carbon 60 or Buckminsterfullerene". Retrieved2010-07-04.
  11. Jump up^ Bochvar, D.A.; Galpern, E.G. (1973). Dokl. Acad. Nauk SSSR 209: 610.
  12. Jump up^ Kroto, H.W.; et al. (1985). "C60: Buckminsterfullerene". Nature 318 (6042): 162–163. Bibcode:1985Natur.318..162K. doi:10.1038/318162a0.
  13. Jump up^ "The Nobel Prize in Chemistry 1996". Retrieved 7 February 2014.
  14. Jump up^ Mraz, S.J. (14 April 2005). "A new buckyball bounces into town". Machine Design.
  15. Jump up^ "The allotropes of carbon". Interactive Nano-Visualization in Science & Engineering Education. Retrieved 2010-08-29.
  16. Jump up^ Stars reveal carbon 'spaceballs', BBC, July 22, 2010.
  17. Jump up^ Buckminsterfullerene, C60. Sussex Fullerene Group. chm.bris.ac.uk
  18. Jump up^ Miessler, G.L.; Tarr, D.A. (2004). Inorganic Chemistry (3rd ed.). Pearson Education. ISBN 0-13-120198-0.
  19. Jump up^ Mitchel, D.R.; et al. (2001). "The Synthesis of Megatubes: New Dimensions in Carbon Materials". Inorganic Chemistry 40 (12): 2751–5.doi:10.1021/ic000551q. PMID 11375691.
  20. Jump up^ Hiorns, R.C.; et al. (2010). "Synthesis of Donor-Acceptor Multiblock Copolymers Incorporating Fullerene Backbone Repeat Units". Macromolecules. 14 43 (14): 6033–6044. Bibcode:2010MaMol..43.6033H. doi:10.1021/ma100694y.
  21. Jump up^ Ugarte, D. (1992). "Curling and closure of graphitic networks under electron-beam irradiation". Nature 359 (6397): 707–709. doi:10.1038/359707a0.
  22. Jump up^ Sano, N.; et al. (2001). "Synthesis of carbon 'onions' in water". Nature 414(6863): 506–7. Bibcode:2001Natur.414..506S. doi:10.1038/35107141.PMID 11734841.
  23. Jump up^ Shvartsburg, A.A.; et al. (1999). "Ball-and-Chain Dimers from a Hot Fullerene Plasma". Journal of Physical Chemistry A 103 (27): 5275.doi:10.1021/jp9906379.
  24. Jump up^ Li, Y.; et al. (2001). "Structures and stabilities of C60-rings". Chemical Physics Letters 335 (5–6): 524. Bibcode:2001CPL...335..524L. doi:10.1016/S0009-2614(01)00064-1.
  25. Jump up^ Qiao, Rui; Roberts, Aaron P.; Mount, Andrew S.; Klaine, Stephen J.; Ke, Pu Chun. "Translocation of C60 and Its Derivatives Across a Lipid Bilayer". Nano Letters. Retrieved 4 September 2010.
  26. Jump up^ Gonzalez Szwacki, N.; Sadrzadeh, A.; Yakobson, B. (2007). "B80 Fullerene: An Ab Initio Prediction of Geometry, Stability, and Electronic Structure". Physical Review Letters 98 (16): 166804. Bibcode:2007PhRvL..98p6804G.doi:10.1103/PhysRevLett.98.166804. PMID 17501448.
  27. ^ Jump up to:a b Gopakumar, G.; Nguyen, M.T.; Ceulemans, A. (2008). "The boron buckyball has an unexpected Th symmetry". Chemical Physics Letters 450 (4–6): 175.arXiv:0708.2331. Bibcode:2008CPL...450..175G.doi:10.1016/j.cplett.2007.11.030.
  28. Jump up^ Prasad, D.; Jemmis, E. (2008). "Stuffing Improves the Stability of Fullerenelike Boron Clusters". Physical Review Letters 100 (16): 165504.Bibcode:2008PhRvL.100p5504P. doi:10.1103/PhysRevLett.100.165504.PMID 18518216.
  29. Jump up^ http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.106.225502
  30. Jump up^ Locke, W. (13 October 1996). "Buckminsterfullerene: Molecule of the Month".Imperial College. Retrieved 2010-07-04.
  31. Jump up^ Meija, J. (2006). "Goldberg Variations Challenge". Analytical and Bioanalytical Chemistry 385: 6–7. doi:10.1007/s00216-006-0358-9.
  32. Jump up^ Fowler, P. W. and Manolopoulos, D. E. Cn Fullerenes. nanotube.msu.edu
  33. Jump up^ Charles Gause. "Fullerene Nanomedicines for Medical and Healthcare Applications".
  34. Jump up^ "Luna Inc. Organic Photovoltaic Technology". 2014.
  35. Jump up^ Pushparaj, V.L.; et al. (2007). "Flexible energy storage devices based on nanocomposite paper". Proceedings of the National Academy of Sciences 104(34): 13574–7. Bibcode:2007PNAS..10413574P.doi:10.1073/pnas.0706508104. PMC 1959422. PMID 17699622.
  36. Jump up^ Blank, V.; Popov, M.; Pivovarov, G.; Lvova, N.; Gogolinsky, K.; Reshetov, V. (1998). "Ultrahard and superhard phases of fullerite C60: Comparison with diamond on hardness and wear". Diamond and Related Materials 7 (2–5): 427.Bibcode:1998DRM.....7..427B. doi:10.1016/S0925-9635(97)00232-X.
  37. Jump up^ Iddo Genuth (Dec 10, 2005). "Nano-Armor: Protecting the Soldiers of Tomorrow". Phys.org.
  38. Jump up^ Erik Sofge (12 Feb 2014). "How Real Is 'RoboCop'?". Popular Science.
  39. Jump up^ Tegos, G.; et al. (2005). "Cationic Fullerenes Are Effective and Selective Antimicrobial Photosensitizers". Chemistry & Biology 12 (10): 1127–1135.doi:10.1016/j.chembiol.2005.08.014. PMC 3071678. PMID 16242655.
  40. Jump up^ Johansson, M.P.; Jusélius, J.; Sundholm, D. (2005). "Sphere Currents of Buckminsterfullerene". Angewandte Chemie International Edition 44 (12): 1843–6. doi:10.1002/anie.200462348. PMID 15706578.
  41. Jump up^ Beavers, C.M.; et al. (2006). "Tb3N@C84: An improbable, egg-shaped endohedral fullerene that violates the isolated pentagon rule". Journal of the American Chemical Society 128 (35): 11352–3. doi:10.1021/ja063636k.PMID 16939248.
  42. Jump up^ Luann, B.; et al. (2007). "Impact Event at the Permian-Triassic Boundary: Evidence from Extraterrestrial Noble Gases in Fullerenes". Science 291 (5508): 1530–3. Bibcode:2001Sci...291.1530B. doi:10.1126/science.1057243.PMID 11222855.
  43. Jump up^ Guo, T.; Smalley, R.E.; Scuseria, G.E. (1993). "Ab initio theoretical predictions of C28, C28H4, C28F4, (Ti@C28)H4, and M@C28 (M = Mg, Al, Si, S, Ca, Sc, Ti, Ge, Zr, and Sn)". Journal of Chemical Physics 99 (1): 352.Bibcode:1993JChPh..99..352G. doi:10.1063/1.465758.
  44. Jump up^ Beck, Mihály T.; Mándi, Géza (1997). "Solubility of C60". Fullerenes, Nanotubes and Carbon Nanostructures 5 (2): 291.doi:10.1080/15363839708011993.
  45. Jump up^ Bezmel'nitsyn, V.N.; Eletskii, A.V.; Okun', M.V. (1998). "Fullerenes in solutions". Physics-Uspekhi 41 (11): 1091. Bibcode:1998PhyU...41.1091B.doi:10.1070/PU1998v041n11ABEH000502.
  46. Jump up^ Ruoff, R.S.; et al. (1993). "Solubility of fullerene (C60) in a variety of solvents".Journal of Physical Chemistry 97 (13): 3379. doi:10.1021/j100115a049.
  47. Jump up^ Sivaraman, N.; Dhamodaran, R.; Kaliappan, I.; Srinivasan, T. G.; Vasudeva Rao, P. R. P.; Mathews, C. K. C. (1994). "Solubility of C70 in Organic Solvents".Fullerene Science and Technology 2 (3): 233.doi:10.1080/15363839408009549. edit
  48. Jump up^ Semenov, K. N.; Charykov, N. A.; Keskinov, V. A.; Piartman, A. K.; Blokhin, A. A.; Kopyrin, A. A. (2010). "Solubility of Light Fullerenes in Organic Solvents".Journal of Chemical & Engineering Data 55: 13. doi:10.1021/je900296s. edit
  49. Jump up^ Talyzin, A.V. (1997). "Phase Transition C60−C60*4C6H6 in Liquid Benzene".Journal of Physical Chemistry B 101 (47): 9679. doi:10.1021/jp9720303.
  50. Jump up^ Talyzin, A.V.; Engström, I. (1998). "C70 in Benzene, Hexane, and Toluene Solutions". Journal of Physical Chemistry B 102 (34): 6477.doi:10.1021/jp9815255.
  51. Jump up^ Arndt, M.; et al. (1999). "Wave-particle duality of C60". Nature 401 (6754): 680–2. Bibcode:1999Natur.401..680A. doi:10.1038/44348.PMID 18494170.
  52. ^ Jump up to:a b c form
  53. Jump up^ Zhang, J.; Bowles, F. L.; Bearden, D. W.; Ray, W. K.; Fuhrer, T.; Ye, Y.; Dixon, C.; Harich, K.; Helm, R. F.; Olmstead, M. M.; Balch, A. L.; Dorn, H. C. (2013). "A missing link in the transformation from asymmetric to symmetric metallofullerene cages implies a top-down fullerene formation mechanism".Nature Chemistry 5 (10): 880–885. doi:10.1038/nchem.1748.PMID 24056346. edit
  54. Jump up^ Osawa, Eiji (2002). Perspectives of Fullerene Nanotechnology. Springer Science & Business Media. pp. 29–. ISBN 978-0-7923-7174-8.
  55. Jump up^ Arikawa, Mineyuki (2006). "Fullerenes—an attractive nano carbon material and its production technology.". Nanotechnology Perceptions 2 (3): 121–128.ISSN 1660-6795.
  56. ^ Jump up to:a b G. Lalwani and B. Sitharaman, Multifunctional fullerene and metallofullerene based nanobiomaterials, NanoLIFE 08/2013; 3:1342003. DOI: 10.1142/S1793984413420038 Full Text PDF
  57. ^ Jump up to:a b Brown, S.B.; Brown, E.A. and Walker, I. (2004). "The present and future role of photodynamic therapy in cancer treatment". Lancet Oncology 5 (8): 497–508. doi:10.1016/S1470-2045(04)01529-3. PMID 15288239.
  58. Jump up^ Mroz, Pawel et al.; Pawlak, Anna; Satti, Minahil; Lee, Haeryeon; Wharton, Tim; Gali, Hariprasad; Sarna, Tadeusz; Hamblin, Michael R. (2007). "Functionalized fullerenes mediate photodynamic killing of cancer cells: type I versus typee II photochemical mechanism". Free Radical Biology & Medicine 43 (43): 711–719.doi:10.1016/j.freeradbiomed.2007.05.005.
  59. Jump up^ Ganapathy, Vadivel; Thanaraju, Muthusamy and Prasad, Puttur D. (2009). "Nutrient transporters in cancer: Relevance to Warburg hypothesis and beyond".Pharmacology & Therapeutics 121 (1): 29–40.doi:10.1016/j.pharmthera.2008.09.005.
  60. Jump up^ Hu, Zhen et al.; Zhang, Chunhua; Huang, Yudong; Sun, Shaofan; Guan, Wenchao; Yao, Yuhuan (2012). "Photodynamic anticancer activities of water-soluble C60 derivatives and their biolgoical consequences in a HeLa cell line".Chemico-biological interactions 195 (1): 86–94. doi:10.1016/j.cbi.2011.11.003.PMID 22108244.
  61. Jump up^ Markovic, Zoran et al.; Trajkovic, Vladimir (2008). "Biomedical potential of the reactive oxygen species generation and quenching by fullerenes". Biomaterials 29(26): 3561–3573. doi:10.1016/j.biomaterials.2008.05.005. PMID 18534675.
  62. Jump up^ Moussa, F.; et al. (1996). "Early effects of C60 Administration in Swiss Mice: A Preliminary Account for In Vivo C60 Toxicity". Fullerene Science and Technology4: 21. doi:10.1080/10641229608001534.
  63. Jump up^ Moussa, F.; et al. (1997). Proceedings of the Electrochemical Society 5: 332.
  64. Jump up^ Mori, T.; et al. (2006). "Preclinical studies on safety of fullerene upon acute oral administration and evaluation for no mutagenesis". Toxicology 225 (1): 48–54. doi:10.1016/j.tox.2006.05.001. PMID 16782258.
  65. Jump up^ Gharbi, N.; et al. (2005). "[60]fullerene is a powerful antioxidant in vivo with no acute or subacute toxicity". Nano Letters 5 (12): 2578–85.Bibcode:2005NanoL...5.2578G. doi:10.1021/nl051866b. PMID 16351219.
  66. Jump up^ Baati, Tarek; Bourasset F; Gharbi N; Njim L; Abderrabba M; Kerkeni A; Szwarc H; Moussa F (June 2012). "The prolongation of the lifespan of rats by repeated oral administration of [60] fullerene". Biomaterials 33 (19): 4936–4946.doi:10.1016/j.biomaterials.2012.03.036. PMID 22498298.
  67. Jump up^ Moussa, Loera (Director) (2012-10-08). Full Interview With Professor Fathi Moussa (Television production). Paris: Loera, C60.NET.
  68. Jump up^ Poland, C.A.; et al. (2008). "Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study". Nature Nanotechnology 3 (7): 423–8. doi:10.1038/nnano.2008.111.PMID 18654567.
  69. Jump up^ Sayes, C.M.; et al. (2007). "Comparative Pulmonary Toxicity Assessments of C60 Water Suspensions in Rats: Few Differences in Fullerene Toxicity in Vivo in Contrast to in Vitro Profiles". Nano Letters 7 (8): 2399–406.Bibcode:2007NanoL...7.2399S. doi:10.1021/nl0710710. PMID 17630811.
  70. Jump up^ Jones, D. (1966). New Scientist 32: 245.
  71. Jump up^ Google archive of the Sep. 4 2010 logo.
  72. Jump up^ 25th anniversary of the Buckyball celebrated by interactive Google Doodle, Telegraph.co.uk 4 September 2010
  73. Jump up^ Google celebrates 25 years of the 'buckyball'. Guardian.co.uk, 4 September 2010.

External links[edit]

Wikimedia Commons has media related to Fullerene.

Powered by Blogger.