Brown's Chemistry Revision Notes
NANOCHEMISTRY - Nanoscience - Nanotechnology - Nanostructures
Part 4. From fullerenes & bucky balls to carbon nanotubes
Alphabetical keyword index for
the nanoscience pages : Index of nanoscience pages
: boron nitride *
Buckminsterfullerenes-bucky balls *
carbon nanotubes * fat nanoparticles
* fluorographene *
graphene * health and
* liposomes *
nanoscale * nanoscience *
* nanotechnology *
problems in nanomaterial use *
silver nanoparticles *
safety issues * sunscreens-sunblockers *
and carbon nanotubes
are fullerenes? What is the formula and structure of
Buckminsterfullerene? What are fullerenes used for? What is a 'bucky
ball'? What is a nanotube?
- Apart from the
carbon allotropes of diamond and graphite, a 3rd form of carbon exists as
fullerenes or 'bucky balls'.
- They consist of hexagonal rings like
graphite and alternating pentagonal carbon rings to allow curvature of the
surface (see diagram further down). They are a sort of a hollow
'cage' shaped pure carbon molecule.
- Fullerenes are NOT nanoparticles BUT
they are smaller molecular versions equating to sections of the tiny
molecular carbon tubes called carbon nanotubes, AND they are very
interesting molecules in themselves and provide a way into studying
carbon nanotubes in terms of their molecular structure and
applications in nanotechnology.
- The carbon-carbon bonds in Buckminster Fullerene C60
(shown on right) form a pattern like a soccer ball and is a
brownish-reddish-magenta colour in organic solvents. It is a black? solid insoluble in
- The name Buckminsterfullerene
(fullerene-60), is derived from the American architect R.
Buckminster Fuller who invented the geodesic dome design in building
- Other typical fullerenes have
formulae such as ...
- C28, C32,
C70 (red in solution, rugby ball shape - US American
- In these fullerenes the carbon atoms
lie at vertices of a polyhedron with 12 pentagonal faces with a
minimum of two hexagonal faces.
- They are
considered giant covalent
structures and are classed as simple relatively small molecules,
even those above Cn!
- They do dissolve in
organic solvents giving coloured solutions.
- The colour depends on the solvent
ranging from red to deep purple and violet.
- They are the only soluble allotrope
- Although solid, their melting points are not that
- Uses of fullerenes
- They have many chemical synthetic and pharmaceutical
- Chemical derivatives of fullerenes have
fascinating electrical and magnetic behaviour including
superconductivity and ferromagnetism
(nano nature?, beyond the scope of this page?)
- C60 is an optical
limiter. When light is shone on it, a solution of fullerene-60 turns
darker instantly and the more intense the light, the darker it gets,
so the intensity of transmitted light is limited to a maximum value.
This limiting light transmittance property can be used in the design of
safety goggles in intense light situations e.g. people working with
- Fullerenes are mentioned here to
illustrate the different forms of carbon AND they can be
formed into continuous tubes to give very strong fibres of 'pipe like'
molecules called 'nanotubes'. These nanotube molecules-particles behave differently
compared to bulk carbon materials like
graphite and the much smaller fullerene molecules.
- What are Nanotubes? -
What is the molecular structure of carbon nanotubes? (sometimes
called 'buckytubes') and of what use are they in carbon
Carbon nanotubes are one of the
most intensively studied and characterised used nanomaterials, consisting of
tiny cylinders of carbon, no wider than a strand of DNA with a wide range of properties
of great use to materials scientists.
In other words, lots of varieties of
differing in size and atomic arrangement can have very different properties.
- You can also fabricate multiple layered
carbon nanotubes like an elongated 'Russian doll'!
- These presumably would make
a stronger material?
Uses of Carbon nanotubes
Some nanotubes are excellent
insulators, semiconductors or conduct electricity as well as
- They can be used as semiconductors or
'miniature wires' in electrical circuits and of great use in miniature electronic circuitry
in computers and other electronic devices.
- They act as a component
of industrial catalysts for certain reactions whose economic
efficiency is of great importance (time = money in business!).
- The catalyst can be attached
to the nanotubes which have a huge surface are per mass of catalyst
- They large surface combined
with the catalyst ensure two rates of reaction factors work in
harmony to increase the speed of an industrial reaction so making
the process more efficient and more economic.
- Nanotube fibres are very
strong and so they are used in 'composite materials' e.g.
reinforcing graphite in carbon fibre tennis rackets.
- Note that pure graphite is a soft slippery
solid with low physical strength.
- Bundles of the nanotubes, processed into
fibres, have very high tensile strength
and can be much stronger than steel on a weight for weight basis.
- Nanotubes can 'cage'
other molecules and can be used as a means of delivering drugs
in controlled way to the body because the thin carbon nanotubes can
penetrate cell walls.
Carbon nanotubes could be used to make tiny mechanical
devices, molecular computers or extremely strong materials
- The structure and properties of carbon nanotubes
(see diagrams further down)
- The main cylinder or tube is made only from carbon hexagons
(essentially graphite layers curved into a 'molecular pipe').
- However pentagons are
needed to close the structure at the
ends or form spherical or rugby football shaped molecules.
- The nanotube molecule is held
together by strong covalent
carbon-carbon bonds which extends all along the nanotube or all
round the smaller 'bucky ball' molecules as they are sometimes
- Single or multiple-walled tubes, made from concentric nanotubes
(i.e. one tube inside a larger nanotube), can be
- Note that
graphite is soft and malleable.
- The behaviour of electrons depends on the
length of the tube, so some forms are excellent conductors and others
are semiconductors. This is a typical nanoscale (quantum) effect,
i.e. there are major
differences between the properties of the bulk material the size-dependent properties on the
nanoscale (silver is another good example).
- Diagrams of the molecular structure of
buckminster fullerenes ('fullerenes') and nanotubes (graphite
shown for comparison)
A section of multi-layered graphite
One of the simplest 'buckyballs' C60
A longer buckminsterfullerene which
is 'rugby ball' or 'sausage' shaped, C72 etc.
A section of a
carbon nanotube e.g.
6 x 100 nm, the ends would
be like those of the 'sausage' above right.
All images © doc brown
Some further discussion on
One possible skeletal formula
representation of a layer of graphite or a molecule of graphene (graphene described in next section)
is shown above in Kekule style as in aromatic
The C-C bond length in graphite
or graphene is 0.142 nm, midway between a single C-C carbon-carbon bond
length of 0.154 nm and a double C=C carbon-carbon bond of 0.134 nm.
The carbon-carbon bond order in
graphite/graphene is 1.33, which follows from 4 valency electrons
overlapping from each carbon atom BUT each carbon atom forms three C-C
The C-C-C bond angle is exactly
120o, what you would expect for the planar carbon hexagons.
In graphite the planar hexagonal ring
layers of carbon atoms are 0.335 nm apart.
you get the curvature in the molecular shape of fullerenes and the ends of
nanotubes. The C-C-C bond angles for a planar carbon pentagon will be ~108o
and for a planar carbon hexagon ~120o.
Note the analogous
structure of carbon nanotubes and graphite layers or the graphene molecule.
An example of the versatility of
carbon nanotubes based on two possible fabrications, giving subtle
differences in molecular structure and properties is described below.
In A the longest axis of
the carbon hexagons is aligned at 90o to the principal axis of
the carbon nanotube.
In B the longest axis of
the carbon hexagons is aligned in the same direction as the principal axis
of the carbon nanotube.
Covalent Bonding - macromolecules and giant covalent structures
including diamond & graphite
Part 1. General introduction to nanoscience
and commonly used terms explained
Part 2. NANOCHEMISTRY - an introduction and potential
Uses of Nanoparticles of titanium(IV) oxide, fat and silver
From fullerenes & bucky balls to carbon nanotubes
Cubic and hexagonal boron nitride BN
Problems, issues and
implications associated with
see also INDEX
SMART MATERIALS PAGES
Keywords: uses applications bucky
balls * carbon nanotubes * nanochemistry * nanomaterials * nanoparticles *
nanoscale * nanoscience * carbon nanotubes *
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