9 ms·

Chemists make first-ever ring of pure carbon

157 points by headalgorithm 7y ago

dlivingston 7y ago
> Elusive 18-atom ‘cyclocarbon’ could be a step towards molecule-scale transistors. Can someone 'in the know' on semiconductor device fabrication expand on this more?
- mjevans 7y ago
  NDAs being what they are, someone in the industry might be able to point us to public sources that hint in the correct direction... it seems risky otherwise.
- Veedrac 7y ago
  This just seems like pondering, not anything concrete. I doubt there's much to expand on.
- analog31 7y ago
  The press release always mentions the cool new technology du jour as a possible spinoff of the discovery. Today, it's transistors. When the Superconducting Super Collider was proposed, the newspapers said that research done at the SSC would lead to breakthroughs in computer graphics and flat panel displays.
- im3w1l 7y ago
  I'm not in the know at all. But maybe they base it on this > Initial studies of the properties of the molecule, called a cyclocarbon, suggest that it acts as a semiconductor.
apo 7y ago
> Gawel and his collaborators have now created and imaged the long-sought ring molecule carbon-18. Using standard ‘wet’ chemistry, his collaborator Lorel Scriven, an Oxford chemist, first synthesized molecules that included four-carbon squares coming off the ring with oxygen atoms attached to squares. The team then sent their samples to IBM laboratories in Zurich, Switzerland, where collaborators put the oxygen–carbon molecules on a layer of sodium chloride, inside a high-vacuum chamber. They manipulated the rings one at a time with electric currents (using an atomic-force microscope that can also act as a scanning-transmission microscope), to remove the extraneous, oxygen-containing parts. After much trial-and-error, micrograph scans revealed the 18-carbon structure. “I never thought I would see this,” says Scriven. The molecule (an all-carbon cycle of 18 atoms) was prepared in a very unusual way - by directly manipulating the atoms using an atomic force microscope. In other words, each molecule is made individually. This is not the way that chemists typically work, and will not result in quantities of material that can be seen. The abstract says nothing about chemical stability, but I suspect C-18 quite unstable and may never be prepared in gram quantities. Higher cycles containing more carbons may be more stable, but this is likely to remain a curiosity for some time. Still, this is a new kind of "allotrope" of carbon. The cyclic, relatively rigid nature of the structure and the potential for electrons to circulate under applied fields could lead to some unusual applications.
- mjevans 7y ago
  It's still a good first step towards that future being possible. Now "we" know that it's actually maybe possible as well as properties of the material which might lead to better techniques for producing it or similar things using less exotic processes.
- staticautomatic 7y ago
  Could you explain why you think it's probably unstable? Is it just that the pi bonds don't like those angles?
  - Knufen 7y ago
    The orbitals of the pi bonds are probably in awkward angles resulting in ring strain, and thus instability. It can be explained by the antibonding orbital overlap of the pi bonds. Edit: Expanded a bit
  - gus_massa 7y ago
    In the ideal configuration, when you have single-triple-single bond, they "want" to be in the same line. A molecule where they are bles have more energy. (Imagine that it's like a spring, but don't take the analogies to literally.) The molecules where the bonds have wrong angles usually have more energy and they end to decompose in other molecules where the bonds have the correct angles or they have other bonds. [Oversimplifying warning, Chemistry is more complicated.] Some nice graphics: https://www.sciencedirect.com/topics/chemistry/triple-bond https://www.sciencedirect.com/topics/chemistry/triple-bond Perhaps the text is too technical, but the graphics are nice.
    - jeffwass 7y ago
      In this case, since all atoms form a ring, everything is symmetric within the plane so forces cancel out. So maybe it’s more stable than one would think, similar to cubane. But upon further consideration , the potential energy surface may be more like a saddle point, with each atom having a stable local minimum in-plane but unstable local maxima perpendicular to the plane. (I’m not a chemist).
loa_in_ 7y ago
A short, straight to the point read. Fascinatingly the scan image appears to have 9 vertices. Nit: Article confusingly uses name carbon-18 to denote a molecule with 18 atoms of carbon. Carbon-18 suggests otherwise an isotope of carbon.
- sp332 7y ago
  The notation is confusing, but I don't think it's that uncommon. For example a buckyball is denoted Carbon-60.
  - thaumasiotes 7y ago
    Geez, I wonder how radioactive carbon with 54 neutrons would be.
- kccqzy 7y ago
  No one would really be confused by this. Most carbon isotopes are carbon-12, with some carbon-13. Something as large as carbon-18 would immediately suggest that something fishy is going on.
  - Someone 7y ago
    https://en.wikipedia.org/wiki/Isotopes_of_carbon https://en.wikipedia.org/wiki/Isotopes_of_carbon: ”Carbon (6C) has 15 known isotopes, from ⁸C to ²²C, of which ¹²C and ¹³C are stable” ⇒ ¹⁸C exists (albeit with a half-life of about 92ms)
- zazagura 7y ago
  There is probably another atom in the middle of each edge.
- caf 7y ago
  The triple bonds have a shorter bond length than the single bonds, so presumably each vertex is a C≡C pair.
- henryaj 7y ago
Endy 7y ago
Can we draw carbon out of the atmosphere to make this?
- fian 7y ago
  I don't know the details of the "wet" chemistry step described, but I imagine it would be possible to extract CO2 from the atmosphere and transform it over many step to eventually get to the required precursors. The practical reality is that each transformation step has imperfect yeilds and I would guess that the equipment required to do the molecule by molecule transformation in the last step would require significant energy to run. So to attempt to this today, you would end up producing more CO2 into the atmosphere than you removed.
- Filligree 7y ago
  We can draw carbon from the atmosphere, sure. It's an inefficient process costing a lot of energy, but given they're making the final rings molecule by molecule, it isn't as if we'd need a lot. ...for the purposes of scrubbing CO2 from the air? There's absolutely no reason we'd use this as the final product. Graphite or diamond would do the trick just as well, and either is cheap to make.
Lerc 7y ago
The question that springs to my mind from this is 'could rings be interlinked?' I'm not very familiar with chemistry. Are there other instances where other molecules can interlink in a way that, while not having bonds between them cannot be separated without breaking the bonds of one or the other? At the very least it's fun to imagine a form of ringmail made of these.
- Filligree 7y ago
  It's fun to imagine. I'll admit I did as well, but you wouldn't want to wear it. Broken rings no doubt turn into nanotubes, and free carbon nanotubes have roughly the same properties as asbestos.
  - skykooler 7y ago
    In this case, they wouldn't turn into nanotubes but rather nanowires. I have no idea what the properties of carbon nanowires are though.
    - logfromblammo 7y ago
      Depends on the bond pattern. Alternating single and triple bonds (polycarbyne or polyyne) would be arrow-straight, rigid, semiconducting, untwisting, and explosive in bulk. Triple C-C bonds are an open invitation for cross-linking. In order to be stable, they have to be capped with a less-reactive group than hydrogen. If you break a ring, and get a C18 with naked electrons instead of protons on the ends, that's going to react with something, quickly and probably energetically. That bond-bending energy has to go somewhere, too. If you break the ring, you're probably going to break the molecule near the antipode, too, giving you two highly reactive C9s, or a C10 and a C8. Like if you cut a bowstring at full draw, you're probably going to break one of the limbs of the bow.
- theideaofcoffee 7y ago
  Very much so. There are different synthetic methods that could be used to create these so called “catenanes”, from a slapdash wait-and-see process where the starting material is thrown together and by hope and statistics a product comes out of the reaction with two interlocked rings. Otherwise one could build up a reaction with a starting material in a shape that’s conducive to a ring structure then attempt complexation/liganding etc etc finish and close the rings so they interlock. For some interesting reading in self-assembling structures see: Hao Li et al. Quantitative self-assembly of a purely organic three-dimensional catenane in water, Nature Chemistry (2015). DOI: 10.1038/nchem.2392
jldugger 7y ago
so basically benzene without the hydrogen?
- mirimir 7y ago
  Sort of, but three times as long. Maybe 18 carbons is the minimum (C≡C-C)ₙ, because smaller rings would be too strained. But larger rings would probably be more stable.
- logfromblammo 7y ago
  No. Benzene is an aromatic ring. It has C-C=C sequences that easily flip to C=C-C, making electrons in the ring highly mobile. A C≡C-C sequence does not easily flip to C=C=C, or vice versa. Those electrons are a lot less mobile. Also, alternating single and double bonds leave a bonding site on each carbon for a functional group. Alternating single and triple bonds use up all four (easy) carbon bonds, and you can't cram another bond in there without an insanely powerful acid.
ChuckMcM 7y ago
This is really cool. Both the action of assembling it and how they imaged it. One of the amazing things about carbon is that it can lots of interesting things (conductor, insulator, semi-conductor, Etc) with no added elements, just different bonding and structures. Further, it is an excellent thermal conductor. As a result it has the potential to be the material that replaces silicon in computer chips on a very large scale.
tempguy9999 7y ago
IANAChemist but > ...showed that the 18-carbon rings had alternating triple and single bonds. Stable alternating single/triple bonds? As in the bonds don't flicker around? How is that even possible? 1. Surely the bonds can't stay in the same place 2. Surely they would 'nebulise'/spread out/whatever the right term is, over the ring 3. if 2. doesn't apply, why on earth is it more energetically favourable to have a very high energy (ok, my assumption) triple bond next to a much lower energy (ditto) single bond, and for it not to immediately snap into a pair of double bonds? Given my n00b level of teh chemistry, what is going on here?
- kortex 7y ago
  These alkyne (C≡C) bonds are indeed strained and unstable, but there is an energy barrier to jumping to alkane (C-C) or alkene (C=C). Otherwise, polyynes like Ichthyothereol [1] would not be stable. Resonance is not possible with this configuration because the orbitals are not symmetric. Benzene is often drawn with alternating alkane and -ene bonds, ⌬. It's not obvious, but benzene is radially symmetric in its electronic configuration. Each carbon has p-orbitals pointing vertically from the disc, forming a cloud, rather than discrete pi bonds between neighbors, and the electrons can "skate around the ring". The first bond between carbons is always sigma. In alkenes, there is one sigma bond, in -ynes, there are two pi's at 90 degrees to each other. I'm a bit fuzzy on my o-chem, but iirc there is an energy gap between this configuration and cumulene C=C=C, which makes spontaneous transition unlikely. In this c18 cycloalkyne, the p-orbitals are further strained into a bent cross shape if looking toroidally. This makes for an even bigger difference in energy levels, which means it can't flip to alkene or even swap positions. https://en.m.wikipedia.org/wiki/Ichthyothereol https://en.m.wikipedia.org/wiki/Ichthyothereol
  - tempguy9999 7y ago
    OMG which part of "I Is A N00b" did I not make clear? :-) The role of spdf and sigma/pi electrons, I'm aware of these things but don't have a mental model for them. And "p-orbitals pointing vertically from the disc"??. That was brutal but you've given me a lot to aim for so I'll get to reading this afternoon - thanks!
logfromblammo 7y ago
Should've called it a cyclyne.

157 points by headalgorithm 7y ago

> Elusive 18-atom ‘cyclocarbon’ could be a step towards molecule-scale transistors. Can someone 'in the know' on semiconductor device fabrication expand on this more?

mjevans 7y ago
NDAs being what they are, someone in the industry might be able to point us to public sources that hint in the correct direction... it seems risky otherwise.
Veedrac 7y ago
This just seems like pondering, not anything concrete. I doubt there's much to expand on.
analog31 7y ago
The press release always mentions the cool new technology du jour as a possible spinoff of the discovery. Today, it's transistors. When the Superconducting Super Collider was proposed, the newspapers said that research done at the SSC would lead to breakthroughs in computer graphics and flat panel displays.
im3w1l 7y ago
I'm not in the know at all. But maybe they base it on this > Initial studies of the properties of the molecule, called a cyclocarbon, suggest that it acts as a semiconductor.

apo 7y ago

> Gawel and his collaborators have now created and imaged the long-sought ring molecule carbon-18. Using standard ‘wet’ chemistry, his collaborator Lorel Scriven, an Oxford chemist, first synthesized molecules that included four-carbon squares coming off the ring with oxygen atoms attached to squares. The team then sent their samples to IBM laboratories in Zurich, Switzerland, where collaborators put the oxygen–carbon molecules on a layer of sodium chloride, inside a high-vacuum chamber. They manipulated the rings one at a time with electric currents (using an atomic-force microscope that can also act as a scanning-transmission microscope), to remove the extraneous, oxygen-containing parts. After much trial-and-error, micrograph scans revealed the 18-carbon structure. “I never thought I would see this,” says Scriven. The molecule (an all-carbon cycle of 18 atoms) was prepared in a very unusual way - by directly manipulating the atoms using an atomic force microscope. In other words, each molecule is made individually. This is not the way that chemists typically work, and will not result in quantities of material that can be seen. The abstract says nothing about chemical stability, but I suspect C-18 quite unstable and may never be prepared in gram quantities. Higher cycles containing more carbons may be more stable, but this is likely to remain a curiosity for some time. Still, this is a new kind of "allotrope" of carbon. The cyclic, relatively rigid nature of the structure and the potential for electrons to circulate under applied fields could lead to some unusual applications.

mjevans 7y ago
It's still a good first step towards that future being possible. Now "we" know that it's actually maybe possible as well as properties of the material which might lead to better techniques for producing it or similar things using less exotic processes.
staticautomatic 7y ago
Could you explain why you think it's probably unstable? Is it just that the pi bonds don't like those angles?
- Knufen 7y ago
  The orbitals of the pi bonds are probably in awkward angles resulting in ring strain, and thus instability. It can be explained by the antibonding orbital overlap of the pi bonds. Edit: Expanded a bit
- gus_massa 7y ago
  In the ideal configuration, when you have single-triple-single bond, they "want" to be in the same line. A molecule where they are bles have more energy. (Imagine that it's like a spring, but don't take the analogies to literally.) The molecules where the bonds have wrong angles usually have more energy and they end to decompose in other molecules where the bonds have the correct angles or they have other bonds. [Oversimplifying warning, Chemistry is more complicated.] Some nice graphics: https://www.sciencedirect.com/topics/chemistry/triple-bond https://www.sciencedirect.com/topics/chemistry/triple-bond Perhaps the text is too technical, but the graphics are nice.
  - jeffwass 7y ago
    In this case, since all atoms form a ring, everything is symmetric within the plane so forces cancel out. So maybe it’s more stable than one would think, similar to cubane. But upon further consideration , the potential energy surface may be more like a saddle point, with each atom having a stable local minimum in-plane but unstable local maxima perpendicular to the plane. (I’m not a chemist).

loa_in_ 7y ago

A short, straight to the point read. Fascinatingly the scan image appears to have 9 vertices. Nit: Article confusingly uses name carbon-18 to denote a molecule with 18 atoms of carbon. Carbon-18 suggests otherwise an isotope of carbon.

sp332 7y ago
The notation is confusing, but I don't think it's that uncommon. For example a buckyball is denoted Carbon-60.
- thaumasiotes 7y ago
  Geez, I wonder how radioactive carbon with 54 neutrons would be.
kccqzy 7y ago
No one would really be confused by this. Most carbon isotopes are carbon-12, with some carbon-13. Something as large as carbon-18 would immediately suggest that something fishy is going on.
- Someone 7y ago
  https://en.wikipedia.org/wiki/Isotopes_of_carbon https://en.wikipedia.org/wiki/Isotopes_of_carbon: ”Carbon (6C) has 15 known isotopes, from ⁸C to ²²C, of which ¹²C and ¹³C are stable” ⇒ ¹⁸C exists (albeit with a half-life of about 92ms)
zazagura 7y ago
There is probably another atom in the middle of each edge.
caf 7y ago
The triple bonds have a shorter bond length than the single bonds, so presumably each vertex is a C≡C pair.
henryaj 7y ago

Endy 7y ago

Can we draw carbon out of the atmosphere to make this?

fian 7y ago
I don't know the details of the "wet" chemistry step described, but I imagine it would be possible to extract CO2 from the atmosphere and transform it over many step to eventually get to the required precursors. The practical reality is that each transformation step has imperfect yeilds and I would guess that the equipment required to do the molecule by molecule transformation in the last step would require significant energy to run. So to attempt to this today, you would end up producing more CO2 into the atmosphere than you removed.
Filligree 7y ago
We can draw carbon from the atmosphere, sure. It's an inefficient process costing a lot of energy, but given they're making the final rings molecule by molecule, it isn't as if we'd need a lot. ...for the purposes of scrubbing CO2 from the air? There's absolutely no reason we'd use this as the final product. Graphite or diamond would do the trick just as well, and either is cheap to make.

Lerc 7y ago

The question that springs to my mind from this is 'could rings be interlinked?' I'm not very familiar with chemistry. Are there other instances where other molecules can interlink in a way that, while not having bonds between them cannot be separated without breaking the bonds of one or the other? At the very least it's fun to imagine a form of ringmail made of these.

Filligree 7y ago
It's fun to imagine. I'll admit I did as well, but you wouldn't want to wear it. Broken rings no doubt turn into nanotubes, and free carbon nanotubes have roughly the same properties as asbestos.
- skykooler 7y ago
  In this case, they wouldn't turn into nanotubes but rather nanowires. I have no idea what the properties of carbon nanowires are though.
  - logfromblammo 7y ago
    Depends on the bond pattern. Alternating single and triple bonds (polycarbyne or polyyne) would be arrow-straight, rigid, semiconducting, untwisting, and explosive in bulk. Triple C-C bonds are an open invitation for cross-linking. In order to be stable, they have to be capped with a less-reactive group than hydrogen. If you break a ring, and get a C18 with naked electrons instead of protons on the ends, that's going to react with something, quickly and probably energetically. That bond-bending energy has to go somewhere, too. If you break the ring, you're probably going to break the molecule near the antipode, too, giving you two highly reactive C9s, or a C10 and a C8. Like if you cut a bowstring at full draw, you're probably going to break one of the limbs of the bow.
theideaofcoffee 7y ago
Very much so. There are different synthetic methods that could be used to create these so called “catenanes”, from a slapdash wait-and-see process where the starting material is thrown together and by hope and statistics a product comes out of the reaction with two interlocked rings. Otherwise one could build up a reaction with a starting material in a shape that’s conducive to a ring structure then attempt complexation/liganding etc etc finish and close the rings so they interlock. For some interesting reading in self-assembling structures see: Hao Li et al. Quantitative self-assembly of a purely organic three-dimensional catenane in water, Nature Chemistry (2015). DOI: 10.1038/nchem.2392

jldugger 7y ago

so basically benzene without the hydrogen?

mirimir 7y ago
Sort of, but three times as long. Maybe 18 carbons is the minimum (C≡C-C)ₙ, because smaller rings would be too strained. But larger rings would probably be more stable.
logfromblammo 7y ago
No. Benzene is an aromatic ring. It has C-C=C sequences that easily flip to C=C-C, making electrons in the ring highly mobile. A C≡C-C sequence does not easily flip to C=C=C, or vice versa. Those electrons are a lot less mobile. Also, alternating single and double bonds leave a bonding site on each carbon for a functional group. Alternating single and triple bonds use up all four (easy) carbon bonds, and you can't cram another bond in there without an insanely powerful acid.

ChuckMcM 7y ago

This is really cool. Both the action of assembling it and how they imaged it. One of the amazing things about carbon is that it can lots of interesting things (conductor, insulator, semi-conductor, Etc) with no added elements, just different bonding and structures. Further, it is an excellent thermal conductor. As a result it has the potential to be the material that replaces silicon in computer chips on a very large scale.

tempguy9999 7y ago

IANAChemist but > ...showed that the 18-carbon rings had alternating triple and single bonds. Stable alternating single/triple bonds? As in the bonds don't flicker around? How is that even possible? 1. Surely the bonds can't stay in the same place 2. Surely they would 'nebulise'/spread out/whatever the right term is, over the ring 3. if 2. doesn't apply, why on earth is it more energetically favourable to have a very high energy (ok, my assumption) triple bond next to a much lower energy (ditto) single bond, and for it not to immediately snap into a pair of double bonds? Given my n00b level of teh chemistry, what is going on here?

kortex 7y ago
These alkyne (C≡C) bonds are indeed strained and unstable, but there is an energy barrier to jumping to alkane (C-C) or alkene (C=C). Otherwise, polyynes like Ichthyothereol [1] would not be stable. Resonance is not possible with this configuration because the orbitals are not symmetric. Benzene is often drawn with alternating alkane and -ene bonds, ⌬. It's not obvious, but benzene is radially symmetric in its electronic configuration. Each carbon has p-orbitals pointing vertically from the disc, forming a cloud, rather than discrete pi bonds between neighbors, and the electrons can "skate around the ring". The first bond between carbons is always sigma. In alkenes, there is one sigma bond, in -ynes, there are two pi's at 90 degrees to each other. I'm a bit fuzzy on my o-chem, but iirc there is an energy gap between this configuration and cumulene C=C=C, which makes spontaneous transition unlikely. In this c18 cycloalkyne, the p-orbitals are further strained into a bent cross shape if looking toroidally. This makes for an even bigger difference in energy levels, which means it can't flip to alkene or even swap positions. https://en.m.wikipedia.org/wiki/Ichthyothereol https://en.m.wikipedia.org/wiki/Ichthyothereol
- tempguy9999 7y ago
  OMG which part of "I Is A N00b" did I not make clear? :-) The role of spdf and sigma/pi electrons, I'm aware of these things but don't have a mental model for them. And "p-orbitals pointing vertically from the disc"??. That was brutal but you've given me a lot to aim for so I'll get to reading this afternoon - thanks!

logfromblammo 7y ago

Should've called it a cyclyne.