Part 4. From fullerenes - bucky balls to carbon nanotubes
- structure, properties and uses
Brown's Chemistry Revision Notes
NANOCHEMISTRY Nanoscience Nanotechnology Nanostructures
GCSE Chemistry Revision
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Buckminsterfullerenes-bucky balls *
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chemistry revision notes science GCSE chemistry, IGCSE chemistry, O level
& ~US grades 8, 9 and 10 school science courses or equivalent for ~14-16 year old
science students for national examinations in chemistry for topics including
nanoparticles nanoscience nanochemistry uses of nanomaterials
and carbon nanotubes
Many of the basic ideas
described here are ok for GCSE level chemistry, but, beware GCSE students,
there are some quite advanced details on the uses and properties of
fullerenes and nanotubes described as well.
are fullerenes? What is the formula and structure of
Buckminsterfullerene? What are fullerenes used for? What is a 'bucky
ball'? What is a nanotube?
- Fullerenes and nanotubes are another
allotrope of carbon.
are different atomic/molecular forms of the same element in the
same physical state - in this case three solid allotropes of the
- Apart from the
carbon allotropes of diamond and graphite, a 3rd form of carbon exists as
fullerenes or 'bucky balls'. [see table of
- They consist of hexagonal rings of
carbon atoms (like
in graphite or graphene) and alternating pentagonal or heptagonal carbon rings to allow curvature of the
surface (see diagram further down) producing molecules that have a
complete hollow shape.
- They are a sort of a hollow
'cage' or 'ball' or 'closed tube' shaped molecules of pure carbon
atoms. [see table of diagrams]
- The carbon atoms still form three bonds
per carbon atom, and most of their carbon atom rings are
hexagonal, but some are five and seven membered rings.
- Fullerenes can be classed as nanoparticles BUT
they are smaller molecular versions equating to sections of the tiny
molecular carbon tubes called
which are nanoparticles.
- 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.
- These fullerenes (and carbon
nanotubes) are quite different from other forms of carbon e.g. in
the form of soot, graphite or diamond.
The carbon-carbon bonds in Buckminster Fullerene C60
(shown on right) form a pattern like a soccer ball and this
fullerene is a
brownish-reddish-magenta colour when dissolved in organic solvents. It is a black? solid insoluble in
- The first fullerene to be discovered (C60)
was named 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 which is 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. [see table of
- They are
considered giant covalent
structures and are classed as relatively small simple molecules,
even though fullerenes have the general formula
- 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
- These small molecules of nanoparticle size
have very different properties compared to 'lumps' of graphite and
What are the uses of fullerenes?
- Fullerene molecules can be used for drug
delivery into the body, as lubricants, as catalysts and in the form
of carbon nanotubes can be used for reinforcing composite materials,
eg sports equipment like tennis rackets (see further down the
- They have many chemical synthetic and pharmaceutical
- Chemical derivatives of fullerenes have
fascinating complex electrical and magnetic behaviour including
superconductivity and ferromagnetism.
(nano nature?, beyond the scope of this page?)
C60 is an optical
- 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 may used in certain
medical applications - an example of nanomedicine
- The idea is to use the very small
fullerene molecules to easily deliver drugs directly into cells in a
highly controlled manner.
- This is possible because the
extremely small diameter of the nanoparticle fullerenes (which act
like a cage to hold the drug molecules) allows them to readily pass through
cell membranes and readily absorbed into the body.
- Fullerene molecules have very a high surface
area / volume ratio and may be used in the development of new types
of catalysts in the chemical industry, perhaps catalyst
molecules can be attached to fullerene structure.
- Fullerenes are being developed that
have excellent lubricating properties (maybe superior to
lubrication oils) and these lubricants significantly reduce friction
in moving metal parts of machines from cog wheels to ball bearings
and maybe artificial joints after orthopaedic operations on hips and
- Perhaps the nanoparticles behave like tiny ball
- 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
and their properties and uses? -
- What is the molecular structure of carbon nanotubes? (sometimes
called 'buckytubes') and of what use are they in carbon
Carbon nanotubes are essentially long
Carbon nanotubes are one of the
most intensively studied and characterised used nanomaterials, consisting of
tiny cylinders of made carbon atoms, no wider than a strand of DNA with a wide range of properties
of great use to materials scientists.
You can think of them as
stretched out fullerenes, but using many more carbon atoms. [see
table of diagrams]
Despite being composed of so
many carbon atoms, they are still considered nanomaterials because their
diameter is of nanoscale proportions.
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 fabricated material.
Uses of carbon nanotubes -
long fullerene molecules, one
basis of the relatively new nanotechnology
- Carbon nanotubes have a very high tensile strength,
very good electrical conductivity and a relatively high thermal conductivity
- good conductors of electricity and heat.
- They are used as a component in strong composite
- This is partly due to carbon nanotubes have a
high length to diameter ratio and they don't easily break when
Some carbon nanotubes are excellent
insulators, semiconductors or conduct electricity as well as
- Nanotubes can conduct electricity and will find
technological applications tiny electrical circuits in
computer chips and electronic instruments (see last section on type A and B carbon
- 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.
- Carbon nanotube fibres are very
strong and so they are used in 'composite materials' e.g.
reinforcing graphite and plastics with very fine carbon fibres in
sports equipment like tennis rackets and golf clubs.
Carbon nanotubes could be used to make tiny mechanical
devices, molecular computers as well as extremely strong materials.
- Carbon nanotubes are an
important additive in other oil based lubricants to enhance their
- Additives are added to lubricating oils to improve
their effectiveness in reducing friction and as a chemical stabiliser eg to inhibit thermal degradation
of the oil in high temperature situation, but I'm not sure what the function
of carbon nanotubes is in this case? I suspect the reasons involve some complex physics
of viscosity well beyond the
scope of these notes!
- The structure and properties of carbon nanotubes
[see table of diagrams]
- 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 carbon 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 carbon nanotubes 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 carbon nanotube, so some forms are excellent conductors and others
- 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
shown for comparison, one isolated layer is the same as graphene)
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 bond order is 1.5 in
benzene, the average of a carbon-carbon single bond (bond order 1) and
carbon=carbon double bond (bond order 2), but there is a C-H bond too.
The orbitals of three of carbon's
electrons will overlap with each other to form three discrete sigma bonds in
a trigonal planar arrangement, but the fourth electron from each carbon
contributes to a pi bonding orbital that extends throughout the layer, above
and below it, just like in benzene!
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. This intermolecular bonding
distance is a much greater distance than covalent, metallic or ionic
To understand this point, you must be
clear in you mind about the difference in nature between a weak
intermolecular bond force and the strong bonding between atoms in covalent,
ionic and metallic structures.
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.
The two diagrams below
illustrate a short section of long carbon nanotubes displaying the two
principal symmetries of hexagonal carbon ring orientation with respect to
the central axis of a carbon nanotube.
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.
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NANOSCIENCE - NANOCHEMISTRY INDEX
Introduction to nanoscience,
nanoparticles, commonly used terms explained
Part 2. Nanochemistry - introduction,
uses & potential
Uses of Nanoparticles of titanium(IV) oxide (e.g. sun
cream), fat (e.g. cosmetics), silver (e.g. medical applications)
From fullerenes & bucky balls to carbon nanotubes -
structure, properties, uses
graphene oxide and
fluorographene - structure, properties, uses
Cubic and hexagonal boron nitride BN
Problems, issues and
implications associated with
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