Fullerenes.pptx

INTRODUCTION

 Fullerenes are closed hollow cages consisting of

carbon atoms interconnected in pentagonal and hexagonal rings. Each carbon atom on the cage surface is bonded to three carbon neighbors

therefore is sp2 hybridized.

 C

60 is most studied fullerene due to its

availability, high symmetry and low price.

 Functionalizing the fullerene C

60 molecule

What are fullerenes? (continued…)

C₆₀

How are fullerenes made?

Fullerenes can be made by vaporizing carbon within a gas medium (they could form spontaneously in a

condensing carbon vapor)

Arc discharge method

• _{High voltage between two graphite electrodes develops an arc}

(distance between electrodes is important)

• _{Plasma generation results high temperature and evaporation of}

graphite

• _{Deposition on the reactor walls}

• UV emission by arc plasma will excite C₆₀ and react with other clusters (Cn) to form Cx and reduces the yield

• _{C60 (S0 ) + h} → C60 ( T₁ )

⎯⎯⎯

• _{Larger the electrodes lower the yield of carbon because of larger}

plasma zone and higher emission of UV radiation

• _{Fullerenes yield depends on the quality of carbon used.}

Derivatizations of C

Hetero

Endohedral Exohedral

Open

Supramolecular, crystallization

Properties of fullerenes

_{No other element has such wonderful properties as}

carbon.

Buckyballs are relatively cheap; carbon is

everywhere!

Even though each carbon atom is only bonded with

three other carbons (they are most comfortable with four bonds) in a fullerene molecule, dangling a single

carbon atom next to the structure is not strong enough

Properties of fullerenes (continued…)

_{In fullerenes, 12 pentagonal rings are necessary and}

sufficient to effect the cage closure.

Fullerenes contain carbon atoms arranged as a combination

of 12 pentagonal rings and n hexagonal rings. The chemical

formula is C20+2n.

_{Fullerene cages are about 7-15 Å in diameter, and are one}

Properties of fullerenes (continued…)

Quite stable from chemical and physical points of view

(breaking the balls requires temperatures of about 1000 °C).

Highest tensile strength of any known 2D structure or

element.

Highest packing density of all known structures.

_{Impenetrable to all elements under normal circumstances,}

Applications of fullerenes

Researchers have found that water-soluble derivates of

fullerenes inhibit the HIV-1 protease (enzyme responsible for the development of the virus) and are therefore useful in fighting the HIV virus that leads to AIDS.

HIV Protease Inhibition by C

 Derivatives of C60 are

currently being investigated as potential inhibitors of the protease enzyme, which is specific to the HIV (virus) generation.

 Active site of the enzyme

roughly described as an open-ended cylinder structure, which is with large hydrophobic amino acids.

 The C60 has the same radius

as cylinder & C60 and derivatives are primarily hydrophobiccan able to block the active side

reduce the HIV (virus)

generation Cartoon for the C60 HIV protease

inhibition.

Hydrophobic sites

C₆₀ (as inhibitor)

Applications of fullerene C₆₀

A. Super conductivity in

A₃C₆₀ A = Alkali metal)

Resistance of a substance tends to “zero” at a transition temperature (T_c)

Eg.: K₃C₆₀

C₆₀ - Non conducting K₃C₆₀ - Conducting at RT K₃C₆₀ - Super conducting at T_c ~18 K

 _K

3C60 Partial filling of Conduction

band

 _{It retains the basic FCC structure of}

C₆₀ and lattice constants to

accommodate the alkali ions

 Holczer et al. demonstrated that

potassium-doped C₆₀ has only a

single stable superconducting

phase, K₃C60, with a transition temperature of 19.3 K.

 _Rb

2CsC60 has maximum Tc of 31K

R e si st an ce

Superconductivity of Doped C

3C60 is cooled, its resistivity begins to drop sharply at about 18°K,

indicating the onset of superconductivity (Hebard, 1991).

 As larger alkali-metal cations are incorporated into the lattice and the fcc lattice

parameter (a) increases, the superconducting transition temperature, T, also increases (see Figure ).

 The T for Rb

3 C60 rises to 28°K. This rise in T may be related to an increase in



The few of the applications of fullerenes

are-A.

Artificial photosynthesis

B.

In cosmetics.

C.

In surface coatings

FULLERENE IN PERSONAL CARE PRODUCTS

 It is a powerful antioxidant, reacting readily and

at a high rate with free radicals, which are often the cause of cell damage or death.

 It behaves like a "radical sponge," as it can

sponge-up and neutralize 20 or more free radicals per fullerene molecule.

 It possess a novel ability of selectively entering

• _{It enhances skin}

absorbtion and helps fight the appearance of fine lines, wrinkles sagging skin and dark spots caused by the oxidation of cells.

UV Whitening Cream contains Fullerene RS™, a patented Nobel Prize technology, which is a superior radical scavenger with unparallel anti-oxidation effect that eliminates free radicals and inhibits UVA-Induced melanin formation. 

•

_It

_enhances

_skin

absorption and help

fight the appearance of

fine

lines,

wrinkles,

 Fullerenes hold great promise also in

Biological applications of

fullerene

.

Factors That need to be kept in mind !



Compatibility



Degree of its Usage in the body



Target Area

•

_Drug



Fullerenes form an interesting system for

Drug Delivery.



They are Strong Drug Adsorbents.



Water soluble Fullerene Derivatives

which were localized closely to

Mitochondria gave a new perspective on

the use of Fullerenes in drug delivery

Buckminsterfullerenes act as

dry lubricants in coating

Fullerenes offer lubricant coatings

 Composite coatings based on inorganic

fullerene-like material (IFLM) Nanosphere

powders are being developed to reduce friction and improve wear resistance in parts where

there are rolling and sliding contacts, such as:

 Ball bearings  Chains

 Gears  Pumps  Screws

 Fullerenes act as ‘radical sponges’

scavenging around 20 free radicals per molecule of fullerene.

 This action is due to the electron

deficient alkene nature of fullerenes which take up the electrons and

scavenge the radicals.

 The efficiency of these entities goes up

to around 100 times the leading antioxidants.

 Oxidation causes cell death & damage

and also deterioration of plastics, food spoilage and metal corrosion and so the application of fullerene based on this