Fullerenes, also known as buckyballs or buckytubes, represent a fascinating class of carbon molecules with unique structural and electronic properties. Fullerenes were discovered in 1985 by scientists Robert F. Curl Jr., Sir Harold W. Kroto, and Richard E. Smalley.

Fullerenes were named after the renowned architect and inventor Buckminster Fuller, whose geodesic domes inspired their nomenclature. In this article, we will discuss the concept of fullerene in detail including its structure as well as various types.

What is Fullerene?

Fullerenes are special carbon molecules made only of carbon atoms. They come in different shapes like a ball, egg, or tube. Think of them as a unique type of carbon, like how diamonds and graphite are different forms of carbon.

The most famous fullerene is C60. It’s made of 60 carbon atoms arranged in a ball shape, kind of like a soccer ball. Each carbon atom is connected to three nearby carbon atoms, forming patterns of hexagons and pentagons, just like the shapes on a soccer ball.

Discovery of Fullerene

In 1985, three scientists named Robert F. Curl Jr., Sir Harold W. Kroto, and Richard E. Smalley found something super cool called fullerenes. They got a Nobel Prize in Chemistry in 1996 for this. They were doing experiments with lasers and graphite, which is a form of carbon like in pencils. While zapping graphite with lasers, they discovered fullerenes.

Structure of Fullerene

Fullerenes have a special structure that’s like a cage made entirely of carbon atoms. This cage can be shaped like a ball, an egg, or even a bunch of connected shapes. Some of the key features of the structure of fullerenes are:

• Hollow Cage: Fullerenes are hollow inside, like a tiny ball or container. This hollow part is made of carbon atoms.

• Carbon Atoms: Inside the cage, there are lots of carbon atoms. They’re all connected together in a pattern of hexagons (with six sides) and pentagons (with five sides). Each carbon atom is connected to three others.

• Hexagonal and Pentagonal Rings: The carbon atoms form rings inside the cage. Most fullerenes, like the famous C60, have a mix of 20 hexagonal rings and 12 pentagonal rings. This mix of shapes gives fullerenes their unique look and structure.

• Sp2 Hybridization: The carbon atoms in fullerenes typically undergo sp2 hybridization to form the double bonds in the hexagonal rings, which contributes to the stability of the structure.

• High Symmetry: Fullerenes exhibit high symmetry, which contributes to their stability. The most well-known fullerene, C60, has icosahedral symmetry.

Types of Fullerenes

Some types of fullerenes which all hav ball like structure are:

• Buckminster Fullerene: C60
• C70
• C84
• Higher Fullerenes

Some other types of fullerenes include:

• Nanotubes
• Endohedral Fullerene
• Exohedral and Endohedral Metallofullerenes
• Substituted Fullerene

Let’s dicuss about these types in detail as follows:

Buckminster Fullerene: C60

This is the most famous and widely studied fullerene. It consists of 60 carbon atoms arranged in a spherical shape with hexagonal and pentagonal rings. C60 resembles a soccer ball and is known for its unique properties and potential applications.

C70

With 70 carbon atoms, C70 is larger than C60 and has a slightly elongated shape. Researchers investigate its properties for applications in organic solar cells, nanotechnology, and drug delivery systems.

C84

C84 fullerene contains 84 carbon atoms and has a more elongated shape compared to C60. It can be synthesized in various isomeric forms and has been explored for its potential in materials science and nanotechnology.

Higher Fullerenes

Fullerenes with more than 60 carbon atoms, such as C120, C180, and C240, offer exciting possibilities for research due to their complex structures. However, they are generally less stable than smaller fullerenes.

Endohedral Fullerene

These fullerenes encapsulate atoms or molecules inside their cage-like structures. The enclosed species can alter the properties of the fullerene, making them useful in fields like medicine, catalysis, and energy storage.

Exohedral and Endohedral Metallofullerenes

Metallofullerenes contain metal atoms either inside or attached to the outer surface of the carbon cage. They exhibit unique electronic and magnetic properties, making them valuable for applications in areas such as electronics, catalysis, and medical imaging.

Substituted Fullerene

Functionalized fullerenes have specific atoms or groups replacing carbon atoms in their structure. These substitutions can tailor the properties of fullerenes for applications like drug delivery, sensors, and lubricants, expanding their versatility in various industries.

Properties of Fullerene

Fullerenes exhibit a diverse array of properties, making them a subject of significant scientific interest and practical application. There are various properties of fullerenes, encompassing both their physical and chemical characteristics. Lets discuss these properties in detail.

Physical Properties of Fullerene

Some common physical properties of fullerene are:

• Molecular Structure: Fullerenes have a unique and symmetrical molecular structure. C60, for example, resembles a soccer ball with 12 pentagonal and 20 hexagonal faces, forming a hollow sphere.

• Low Density: Despite their size and carbon atom content, fullerenes have relatively low densities. For example, the density of C60 is around 1.65 g/cm³.

• High Melting and Boiling Point: Fullerenes showcase high melting and boiling points which makes them more stable.

• High Stability: Fullerenes are stable molecules, and C60, in particular, is known for its exceptional stability. This stability is due to the strong covalent bonds between carbon atoms in the cage-like structure.

• Insolubility: Fullerenes are typically insoluble in water but can be dissolved in certain organic solvents, such as toluene or benzene.

• Superconductivity: Under high pressure or in certain chemical environments, fullerenes can exhibit superconducting properties at low temperatures.

• Photoluminescence: Fullerenes can emit light when exposed to certain wavelengths of light, a phenomenon known as photoluminescence. This property has led to their use in various photonic and optoelectronic devices.

• High Electron Affinity: Fullerenes have a high electron affinity, which makes them suitable for electron acceptor materials in organic solar cells and other electronic devices.

Chemical Properties of Fullerene

Fullerenes are highly reactive chemicals that readily undergo various reactions, including addition reactions. They interact with acids, alkalis, and other reactive molecules, highlighting their versatile chemical properties.

• Oxidation: Fullerenes can react with oxygen, leading to the formation of derivatives like fullerene oxides. Understanding how they react with oxygen is crucial because it affects their stability and functional properties.

• Electrophilic Addition: Fullerenes easily undergo electrophilic addition reactions, reacting with halogens and other electrophiles. This property allows for the creation of diverse derivatives with distinct properties.

• High Electron Affinity: Fullerenes have a high electron affinity, which makes them suitable for electron acceptor materials in organic solar cells and other electronic devices.

• Photochemical Properties: Fullerenes have interesting photochemical properties, including the ability to absorb and emit light. This makes them valuable in applications such as photovoltaic cells and optoelectronic devices.

• Biological Interactions: Certain fullerenes, especially C60, have been extensively studied for their interactions with biological systems. They may have antioxidant properties and interact with biomolecules, making them important in biomedicine and related fields.

• Magnetic Properties: Some derivatives of fullerenes show magnetic properties, which could be useful in magnetic materials. This adds another level of versatility to the fullerene family.

• Conductivity: Certain fullerenes and their derivatives can conduct electricity. This property is important for applications in electronics and conductive materials, contributing to advancements in technology and materials science.

Synthesis of Fullerene

The synthesis of fullerenes involves various methods that produce different types and sizes of these carbon structures. Some of the common methods are:

• Arc Discharge Method: This method involves passing a high current (arc) between two graphite electrodes within an inert gas atmosphere. The intense heat and pressure vaporize carbon from the anode, forming fullerenes. It’s effective for producing larger fullerenes like C60 and C70.
• Laser Ablation Method: A laser vaporizes a carbon target within an inert gas atmosphere, and the vaporized carbon condenses to form fullerenes. This method is versatile, producing various fullerenes, including higher fullerenes and endohedral fullerenes.
• Chemical Vapor Deposition (CVD): CVD decomposes a carbon-containing precursor gas on a substrate, yielding fullerene structures. It’s suitable for producing fullerenes on specific substrates or as thin films.
• Plasma Synthesis: Plasma discharge generates carbon clusters that evolve into fullerenes within a high-energy plasma environment, producing diverse fullerenes.
• Solvent-Extraction Method: Carbon-rich material is dissolved in a solvent, and fullerenes are extracted through selective solvent washing based on their solubility. This method is versatile for isolating and purifying fullerenes.

Uses of Fullerene

Fullerenes and their derivatives offer a wide array of potential applications across different scientific and industrial fields due to their unique properties:

• Material Science: Fullerenes can enhance the mechanical, electrical, and thermal properties of materials. Carbon nanotubes, a type of fullerene, are particularly useful in reinforcing composite materials for aerospace and automotive applications.

• Electronics: Fullerenes and carbon nanotubes exhibit semiconductive properties, making them suitable for electronic devices such as transistors and sensors.

• Medical Applications: Fullerenes, especially C60, have antioxidant properties and are being explored for potential therapeutic applications. Functionalized fullerenes can be used in drug delivery systems to target specific cells or tissues.

• Photovoltaics: Fullerenes are utilized in organic and hybrid solar cells. Their ability to accept and transport electrons improves the efficiency of solar cells.

• Catalysis: Certain metallofullerenes can act as catalysts in chemical reactions and are investigated for applications in catalysis and as catalyst support materials.

• Magnetic Materials: Metallofullerenes with encapsulated magnetic elements possess magnetic properties and are explored for use in magnetic materials and data storage.

• Nanomedicine: Fullerenes are studied for drug delivery due to their cage-like structure, which can encapsulate drugs, improve solubility, stability, and enable target-specific drug delivery.

Read More,

• Carbon
• Allotropes of Carbon
• Some Important Compounds of Carbon and Silicon 

Frequently Asked Questions on Fullerenes

What was the First Fullerene to be Discovered?

The first fullerene found was Buckminsterfullerene (C60) in 1985 by Sir Harry Kroto, Richard Smalley, and Robert Curl. They got the Nobel Prize in Chemistry in 1996 for finding it.

Can Fullerenes Conduct Electricity?

Yes, some fullerenes like carbon nanotubes can conduct electricity. They are good for electronics and tiny technology.

Is Fullerenes Hard or Soft?

Fullerenes are generally soft, but it depends on the kind. Carbon nanotubes are strong and can be called “hard”. Buckminsterfullerene (C60) is soft and can change shape easily.

What is Hybridization of Carbon in C60?

In C60, which is a fullerene molecule also known as a buckyball, all the carbon atoms are sp2 hybridized.

What is Buckminster Fullerene?

A Buckminster Fullerene, often simply referred to as a fullerene or buckyball, is a molecule composed entirely of carbon atoms arranged in a spherical structure resembling a soccer ball.