Structure and applications of Graphite and Fullerenes
Graphite is soft and slippery because there are only weak intermolecular forces between its layers. Graphite is a good conductor of heat and electricity.
This is because, like metals, graphite contains delocalised electrons.
Fullerenes
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 Buckminster fullerenes and they resemble the balls used in football.
Carbon exists as graphite and diamond, but it can also form fullerenes.
These are cages and tubes with different number of carbon atoms. Buckminsterfullerene is one type of fullerene.
Its molecules are spherical and contain 60 carbon atoms.
Fullerenes may be used for drug delivery systems in the body, in lubricants and as catalysts.
Types of fullerene
Since the discovery of fullerenes in 1985, structural variations on fullerenes have evolved well beyond the individual clusters themselves.
Buckyball clusters:
Smallest member is C20 and the most common is C60.
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;
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;
Nano"onions":
Spherical particles based on multiple carbon layers surrounding a buckyball core; proposed for lubricants;
Linked "ball-and-chain" dimers:
Two buckyballs linked by a carbon chain.
Properties of Fullerene
For the last decade, the characteristics of fullerenes both chemical and physical have been the subject in the field of research. Some restricted properties are still in use in the field of medical sciences for diagnosing cancer and bacteria in the living body.
Physical properties of C60(fullerene)
| Density | 1.65 g cm-3 |
| Standard heat of formation | 9.08 k cal mol -1 |
| Boiling point | Sublimes at 800K |
| Resistivity | 1014 ohms m-1 |
| Index of refraction | 2.2 (600nm) |
| Vapour density | N/A |
| Crystal form Hexagonal cubic | |
| Vapour pressure | 5 x 10-6 torr at room temperature |
| 8 x 10 -4 torr at 800K |
Organoleptic properties :
Appearance| Bucky ball soot | Very finely divided black powder |
| Fullerite | Brown/black powder |
| C60 | Black solid |
| Odour | Odourless |
Applications of Fullerenes
1. Antioxidants and Biopharmaceuticals
Fullerenes are very powerful antioxidants, reacting readily and at a high rate with free radicals, which are often the cause of cell damage or death.
The fullerenes hold great promise in health and personal care applications.
also useful in non-physiological applications where oxidation and radical processes are destructive like food spoilage, plastics deterioration and metal corrosion.
2. PCBM (Phenyl Cn Butyric Acid Methyl Ester)
The commercialization of the PCBM range of derivatives began in 1994.
The PCBM has become today’s market standard in polymer electronics and photovoltaics as a result of its flexibility and historic research
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