Balls from Fury: Buckminsterfullerene (C60)

  There’s a molecule out there that can hit a stainless steel plate at 15,000 mph and just bounce back. It’s the state molecule of Texas, if that says anything. And you probably already know what it looks like. If you said the molecule is a buckyball, you’re correct. Buckyballs, specifically C60, look almost exactly like a regulation soccer ball, in order to produce extremely stable sp2 bonds throughout all 60 of the

carbons. Buckminsterfullerene, the more technical name for buckyball, was based on the domes of world famous architect Buckminster Fuller. The purported structure of C60 upon its discovery looked remarkably like many of his domes (well, more like B80but that’s another story).

Buckminsterfullerene has a density of 1.65 g/cm3. In its solid form it takes on the appearance of rather dark, needle-shaped crystals. It won’t stay that way for long, for it sublimes at around 800 K. Being that it’s made up of all carbons, it’s a nonpolar substance; it won’t dissolve in water, and it’ll barely dissolve in other nonpolar substances like benzene. When stimulated with life, it prefers to act as an electron acceptor, in the same manner as an electron-deprived alkene. Unless it’s in solution, it doesn’t prefer to be reduced, with each individual reduction from C60 to C606- being negative and approaching the penultimate -2.549 V at the final reduction at 213 K. It does prefer being oxidized, however, at very low temperatures, though past C60+ the products tend to be rather unstable. And here’s a kicker–buckyballs are the largest known molecule to exhibit wave-particle duality (at least in a diffraction grating). It’s a wonder we’ve even discovered a molecule with these properties; in fact, mostly everything about this molecule is still a wonder.

 One of the Best Accidents?

 C60 became nothing short of a chemist’s dream come true upon its discovery in 1985. Yet, it was discovered purely by accident by H.W. Kroto, J. R. Heath, S. C. O’Brien, R. F. Curl & R. E. Smalley at RICE University in Houston, Texas. The understanding of how long chains of carbon were formed in interstellar space was sought. Lasers shot at a rotating disk of graphite in concentrated helium, and… well, the researchers ended up being inevitably shocked. Sure, they found molecules containing 40 or more carbons, but most prominent was the presence of 60 carbons (followed by 70). Conventional structures did not seem to work in having a molecule of 60 carbons be stable, so they sought alternatives. One structure they noted is as follows: “the C60 molecule which results when a carbon atom is placed at each vertex of this structure has all valences satisfied by two single bonds and one double bond, has many resonance structures, and appears to be aromatic.” Even by this alone was the structure hinted at. They hypothesized that “fragments are torn from the surface as pieces of the planar graphite fused six-membered ring structure. … When these hot ring clusters are left in contact with high-density helium, the clusters equilibrate by two- and three-body collisions towards the most stable species, which appears to be a unique cluster containing 60 atoms.” They even specified the diameter of the molecule, 7 angstroms, which was enough to stick an atom inside. The rest of the chemistry world found this discovery to be nothing short of awesome, and Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for this.

The only issue in the discovery was that the initial method of production failed to produce substantial quantities of buckyballs. 5 years later, a technique using the evaporation of graphite electrodes in a light atmosphere of helium emerged, allowing for the mass production of buckyballs. Or, as discovered later on, one could just sublime the buckyballs out of graphite.

Possibly the Only Ball Safe for Human Consumption

    In these previous 29 years of existence buckyballs have found potential uses in this world. For instance, doping a buckyball with potassium results in a superconductor that is functional at temperatures of 18 K, which a high temperature for a superconductor. Moreover, there’s evidence to show that buckyballs can bind to the insides of the protein HIV protease, effectively inhibiting their function and not allowing the HIV virus to replicate. And they may be even useful antioxidants. Buckyballs have a tendency to act as an electron reservoir; they can give free radicals (molecules specifically desiring an electron to become stable) the extra needed electron in order to stop them from taking electrons from other molecules inside the body. Plus, C60 is known to not be toxic to human cells, and it has the ability to go inside of cells rather easily. In fact, there’s olive oil with buckyballs dissolved in it at a concentration of 45 mg/50 mL on the market.

You Might Want to Duck

 

Even when leaving the confines of Earth, buckyballs were from its discovery speculated to exist in interstellar space, specifically because it has the ability to form in some of the mostadverse conditions known to exist. One theory about its formation is that UV irradiation takes PAHs (polycyclic aromatic hydrocarbons) and converts them to graphene and then into buckyballs. This is seemingly more efficient than an alternate explanation, one in which carbon atoms clump together in the hot, dense center region of stars.

The first place that buckyballs were found in (along with hydrogen) were planetary nebulae. Three nebulae with dying stars like ours contained these buckyballs; what makes this remarkable is that these stars were in our own galaxy. (Even more so, there was a nearby star containing buckyballs in a mass of nearly 15 times larger than that of our own moon). Nebulae are emitted by dying stars; in the middle of all the layers of gas being shed there is a white dwarf holding it all together. There is a stage where the white dwarf spits out a lot of carbon. Even more astounding was the hydrogen it was found with: researchers had previously assumed that the presence of hydrogen would cause it to form the chains and rings originally sought after. And that was just in the gaseous form: in 2012 it was found in solid form. What that means is not yet clear, but it can imply that it might have been a building block of life.

You’re probably sitting there shaking your head. So what if a molecule’s been found in space? It probably isn’t of much importance, is it? All these claims are surely false. Wrong. Buckyballs have been found in meteorites. Meteors, being the huge hunks of rock they are, have the ability to house materials not seen and never before seen on a planet. When they become meteorites and slam into Earth, not only does the resulting collision cause adverse climate changes (which no organism really likes, as evidenced by mass extinctions usually brought along with them) but it can also spread those materials all over Earth.

As stated at the beginning, a buckyball can hit a stainless steel plate at 15,000 mph and just bounce back, and it can also house atoms or even molecules inside. For instance, there was anasteroid impact marking the end of the Permian period, which took out nearly all life on Earth. The meteorite has been found to contain buckyballs housing helium-3 and helium-4, with helium-3 now being present in the atmosphere.

“Buckyballs are carbon molecules in the shape of a cage and they are very tough and hard to destroy,” said Kris Sellgren, a professor of astronomy at The Ohio State University in Columbus, OH.  She noted that although life forms, let alone a single molecule of DNA, absolutely dwarf a buckyball, “single atoms or small molecules can become trapped and can survive inside the cage while the buckyball safely travels through the harsh conditions of space.”

“Buckyballs with extraterrestrial gases trapped inside them, for example, have previously been found in meteorites that have slammed into Earth. Spotting buckyballs in interstellar space also reveals that relatively big molecules can persist and maybe even form in the diffuse, unforgiving voids between the stars.” These are something your regular soccer balls can’t handle.