Carbine

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Carbin (English. Carbyne ) is a laboratory-scale synthesized allotrope of carbon that is made up of chains of carbon atoms linked by alternating triple and single bonds or continuous double bonds . It thus represents the one-dimensional chain form of carbon. According to calculations, these chains are stronger than any other material, in particular carbon nanotubes , graphene and diamond .

discovery

The possibility of the existence of an arbitrarily long chain of carbon atoms was already discussed by Adolf von Baeyer in 1885. He came to the conclusion that the chain would be unstable due to the reactivity of the carbon and therefore undetectable. There were already publications from the 1960s by Russian chemists around VI Kasatochkin and YP Kudryavtsev, but these were later questioned and the signals observed at the time were attributed to contamination with silicates. Nevertheless, it was possible to synthesize carbon chains of increasing length. In 2003 the record was around 100 (according to other information, the record before the publication of Shei, Pichler et al. 44). A prerequisite was the protection of the chain ends by large molecules. In 2016 a group led by Thomas Pichler (University of Vienna) and his doctoral student Lei Shi (first author of the joint work) finally succeeded in breaking through chains in the micrometer range after years of research. The key was the use of double-walled carbon nanotubes as a jacket and protective shell (and nanoreactor ), the length being essentially determined by the length of the nanotubes. This made it possible to create chains of 6,400 carbon atoms, more than a factor of 50 compared to the previous length record. A large number of optimization steps were necessary for the breakthrough, including the detection methods (Raman spectroscopy, X-ray diffraction, transmission electron microscope).

In 1980 it was assumed that carbine occurs in meteorites of the carbonic chondrite type as a binding partner for abnormal noble gases . This was later rejected because the carbon in these meteorites was poorly ordered graphite .

features

A hexagonal diffractogram is considered a characteristic for carbines . Since this has also been proven for other substances, the definition has been criticized several times. Research in 1982 showed that there are no carbines in nature. For all known samples, the results under the transmission electron microscope as well as those of X-ray diffraction could be explained by layered silicates , nontronites or quartz components. Confusion is possible because the diffraction patterns of very flat layers are very similar to those of a hexagonal structure.

With a modulus of elasticity of 32.7 TPa predicted from theoretical calculations , carbine exceeds that of diamond (or graphene) by more than 30 times. The tensile strength is probably the highest of any known carbon material. At the same time, carbine is said to be highly reactive when two chains are brought into contact, whereby the activation energy could help prevent spontaneous reactions.

The electronic properties of the carbine depend on the length of the chain, which suggests nanoelectronic applications for quantum spin transport and magnetic semiconductors.

Individual evidence

  1. ↑ Also Linear Acetylenic carbon (LAC) since Carbyne is in English, and for compounds containing a carbon with three unbound electrons, ie a triradical of carbon.
  2. ↑ Mingjie Liu, Vasilii I. Artyukhov, Hoonkyung Lee, Fangbo Xu, Boris I. Yakobson: Carbyne from first principles: Chain of C atoms, a nanorod or a nanorope? . In: ACS Nano . 7, No. 11, December 2, 2013, pp. 10075-10082. arxiv : 1308.2258 . doi : 10.1021 / nn404177r .
  3. ↑ Baeyer, Über Polyacetylenverbindungen, reports Deutsche Chem. Ges., Volume 18, 1885, pp. 2269-2281
  4. ^ A b P. PK Smith, Peter R. Buseck: Carbyne Forms of Carbon: Do They Exist? In Science Volume 216, Issue 4549 (May 28, 1982), pages 984-986, DOI: 10.1126 / science.216.4549.984
  5. ↑ Carbin: The truly one-dimensional form of carbon . Max Planck Institute for the Structure and Dynamics of Matter. April 4, 2016. Retrieved April 4, 2016. (Angel Rubio)
  6. ↑ Shi, Pichler et al. a., Nature Materials, Volume 16, 2016, p. 634. You cite as a reference: Chalifoux, Tykwinski, Synthesis of polyynes to model the sp-carbon allotrope carbyne, Nature Chem., Volume 2, 2010, p. 967– 971
  7. ↑ Lei Shi, Philip Rohringer, Kazu Suenaga, Yoshiko Niimi, Jani Kotakoski, Jannik C. Meyer, Herwig Peterlik, Marius Wanko, Seymur Cahangirov, Angel Rubio, Zachary J. Lapin, Lukas Novotny, Paola Ayala, Thomas Pichler: Confined linear carbon chains as a route to bulk carbyne, Nature Materials, Volume 15, 2016, pp. 634-639, abstract
  8. Jump up ↑ Mingjie Liu, Vasilii I. Artyukhov, Hoonkyung Lee, Fangbo Xu, Boris I. Yakobson: Carbyne From First Principles: Chain of C Atoms, a Nanorod or a Nanorope? , ACS Nano, Volume 7, 2013, No. 11, pp. 10075-10082. Arxiv
  9. ↑ Carbyne: Stronger than graphs and diamond . TR Online. September 16, 2013. Retrieved April 24, 2014.