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What are fullerenes and why does this material cost up to 150 million euros per gram?

In 2015 a rather particular sale was made: the startup “Designer Carbon Materials” affiliated withUniversity of Oxford he sold 220 milligrams (less than half the weight of a human hair) of a special type of fullerene – i.e. a molecular nanostructure composed solely of carbon atoms with a shape similar to a hollow sphere – for approximately €33,000setting a record of well €150 million per gram. But what are fullerenes? And why is their cost so high?

What are fullerenes and what are they for?

Fullerenes are one of the forms allotrope in which carbon can occur, as can diamonds, graphite and graphene. Discovered in the 1980s by chemists Harold Kroto, Robert Curl And Richard Smalleyfullerenes have a very particular structure: a hollow sphere composed of carbon atoms arranged in hexagons and pentagons, similar to a soccer ball, where every 5 hexagons there is a pentagon to allow the sphere to close. This configuration gives them unique properties, such as the ability to resist strong pressures and of trap other molecules inside their “cage”.

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Even though the news dates back to 2015, in recent times there has been a return to talking about fullerenes, especially the so-called endofullerenes, in which a molecule or atom is trapped within the spherical structure of carbon. Specifically about sales, we are talking about nitrogen-based endofullereneswhich is where a nitrogen molecule is encapsulated within the cage of carbon atoms. This feature offers unique properties and makes them very interesting for advanced applications, such as quantum technology, sensors and atomic clocks.

Why fullerenes cost so much

The astronomical price of €150 million per gram for nitrogen-based endofullerenes it derives from the combination of several factors. Starting from the synthesis which requires complex chemical reactions at high temperatures, to the purification process of endofullerenes, to the low efficiency of the synthesis itself up to the time invested in research and development to obtain them.

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Nitrogen-based endofullerene synthesized from “Designed carbon materials”.

Despite their exorbitant cost, the endofullerenes (but in general fullerenes) have extremely interesting applications. In the medical field, they can be used for targeted transport of drugs inside the body, taking advantage of their ability to encapsulate molecules and release them only in a certain environment. In electronics, they are studying to create components for quantum computers because they are capable of maintaining their properties even in the presence of high magnetic fields. In the energy field, they could be used to improve the efficiency of solar panels and of batteries of new generation. But the most interesting application is in the manufacture of atomic clocks: Thanks to the development of these new materials, atomic clocks could be miniaturized and integrated into GPS devices (such as smartphones), improving their precision.