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Blobrana


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Fullerene Toxicity
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The Spitzer Space Telescope has located some elusive carbon molecules floating in space. Called "Buckyballs," due to their resemblance to architect Buckminster Fuller's geodesic domes, these three-dimensional, spherical structures are now the largest molecules known to exist in space, and until now, have escaped detection. Buckyballs hold unique properties in the physical and chemical processes of space .



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Blobrana


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Buckminsterfullerene
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NASA Telescope Finds Elusive Buckyballs In Space For First Time

Astronomers using NASA's Spitzer Space Telescope have discovered carbon molecules, known as "buckyballs," in space for the first time. Buckyballs are soccer-ball-shaped molecules that were first observed in a laboratory 25 years ago.
They are named for their resemblance to architect Buckminster Fuller's geodesic domes, which have interlocking circles on the surface of a partial sphere. Buckyballs were thought to float around in space, but had escaped detection until now.
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Blobrana


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Scientists have detected the largest molecules ever seen in space, in a cloud of cosmic dust surrounding a distant star.
The football-shaped carbon molecules are known as buckyballs, and were only discovered on Earth 25 years ago when they were made in a laboratory.
These molecules are the "third type of carbon" - with the first two types being graphite and diamond.
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Blobrana


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The birth secret of buckyballs -- hollow spheres of carbon no wider than a strand of DNA -- has been caught on tape by researchers at Sandia National Laboratory and Rice University. An electron microscope video and computer simulations show that "shrink-wrapping" is the key; buckyballs start life as distorted, unstable sheets of graphite, shedding loosely connected threads and chains until only the perfectly spherical buckyballs remain.
The research is available online and slated to appear in an upcoming issue of Physical Review Letters (PRL). It is among a small number of PRL papers chosen as an "Editors' Suggestion." Buckyballs were discovered at Rice in 1985, but understanding the intimate details their formation has vexed scientists. Buckyballs form at high temperatures, and one long-standing theory of their genesis is the "hot giant" hypothesis, which suggests that the carbon atoms first assemble by the thousands in flat graphite sheets. Heat distorts the sheets, "shrink wrapping" them into ever-smaller shapes, and buckyballs survive thanks to their perfect symmetry.


Shrink wrap buckyball


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Blobrana


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Buckminster Fullerene
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Title: Electron affinities and C60 anion clusters of certain bowl-shaped polycyclic aromatic hydrocarbons
Authors: Guodong Chen, Shuguang Ma, R. Graham Cooks, Hindy E. Bronstein, Michael D. Best, Lawrence T. Scott

The kinetic method is applied to the determination of the electron affinities (EAs) of the bowl-shaped polycyclic aromatic hydrocarbons (PAHs) dibenzo[a,g]corannulene (C28H14) 1 and diindenochrysene (C26H12) 2 using electron attachment desorption chemical ionisation mass spectrometry (DCI-MS) and triple-quadrupole tandem mass spectrometry. The estimated EAs of 1 and 2 are 1.00±0.20 and 1.16±0.20 eV respectively. In an analogous experiment, loosely bound dimeric radical anions comprising C60 with 1 and C60 with 2 were generated in the gas phase by electron attachment desorption chemical ionisation. The collision-induced dissociation of each of these cluster ions yields both the monomeric radical anions as products and yields calculated electron affinities of C60 of 1.20±0.20 eV (C60/1 dimer) and 1.24±0.20 eV (C60/2 dimer). These values are significantly different from the known electron affinity of C60 (2.65 eV) and support previous studies on electron-bound dimers comprising C6O and coronene [G. Chen, R. G. Cooks, E. Corpuz and L. T. Scott, J. Am. Soc. Mass Spectrom. 7, 619 (1996)] in showing that the dissociation of electron-bound dimers comprising C60 and reference PAHs is controlled by the electron affinity of a portion of the C60 surface, i.e. that a local electron affinity of C60 is measured. The local electron affinity value corresponds approximately to the electron affinity of the reference PAHs, C60 exhibiting an affinity for the extra electron in the cluster which approximately matches that of its PAH partner.

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Fullerene Toxicity
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In 2004 to 2005, a series of articles was published by different authors about fullerene toxicity, the series being initiated with reports by E. Obersdorster from Dallas University (USA) and V. Colvin from Rice University. It was noted in particular that the fish swimming in the water with the fullerene solution added into it experiences changes in the brain structure, and human skin cells die upon contact with the fullerene solution. These data allowed the authors of the articles to draw attention to environmental consequences of applying nanotechnologies, where fullerenes are of great importance. Apparently, once these technologies are eventually applied in industry, waste products will appear that contain such nanoparticles. The question arises as to how strict the requirements to such wastes should be?

The Kharkov researchers guided by G.V. Andrievsky, Ph. D. (Chemistry), called in question validity of fullerene apprehension.

We have been dealing with the fullerene aqueous solutions for more than ten years, and so far noticed no irritant impact on the skin. Moreover, aqueous solutions of pure fullerenes (i.e., no functional groups are attached to their surface) have positive biological effect and act as antioxidants. Modified fullerenes can certainly be toxic, but this is the way functional groups characteristics become apparent, but not the properties of the fullerene per se - G.V. Andrievsky at the 8th International Conference Fullerenes and Atomic Clusters that took place in St. Petersburg early in July 2007.

Besides, several articles were published within 2006, including the ones by E. Obersdorster, to describe recurrent experiments where toxicity effect had not been recorded.

Where can a mistake be? The point is in the method for the fullerene aqueous solutions preparation. To prepare the solution, fullerenes are first dissolved in the polar solvent, which itself well dissolves in water. For example, the American researchers used tetrahydrofurane. It is impossible to refine the fullerene aqueous solution obtained in such a way from an organic solvent. It was the organic solvent that caused fish poisoning.

It is very strange that there occur negative changes in the fish brain, as no such changes are observed either in the liver or gills. Furthermore, lipid peroxygenation in these organs turned out to be slowed, that is fullerenes demonstrated their antioxidant properties. Selective brain lesions can be caused by substances like inhalation narcotics. One of them is the diethyl ether. Tetrahydrofurane possesses the effect similar to that of the ether, but it is much more poisonous. It is tetrahydrofurane but not fullerenes that caused fish brain lesion. This model describes well the data available on toxicity of the fullerene aqueous solutions. We believe that non-modified fullerenes pose no hazard to the environment and they can be dealt with in the same way as ordinary soot -  G.V. Andrievsky

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