Corbin structure chemistry. Carbyne is a new form of carbon, superior in strength to graphene and carbon nanotubes

24.09.2019

Properties

Carbyne is a fine-crystalline black powder (density 1.9 ÷ 2 g / cm³), has semiconducting properties. Made in artificial conditions from long chains of carbon atoms arranged parallel to each other. Carbyne is a linear polymer of carbon. In a carbyne molecule, carbon atoms are connected in chains alternately either by triple and single bonds (polyyne structure), or permanently by double bonds (polycumulene structure). This substance was first obtained by Soviet chemists V.V. Korshak, A.M. Sladkov, V.I. Kasatochkin, and Yu. P. Kudryavtsev in the early 1960s. at the USSR Academy of Sciences (INEOS). Carbyne has semiconducting properties, and under the influence of light, its conductivity is greatly increased. The first practical application is based on this property - in photocells.

Prehistory of the discovery

The question of the possibility of the existence of forms of carbon with sp-hybridization of atoms has been repeatedly considered theoretically. Back in 1885, German chemist Adolf Bayer tried to synthesize chain carbon from acetylene derivatives using a stepwise method. However, Bayer's attempt to obtain polyyne(a compound containing at least three isolated or conjugated C≡C bonds in a molecule) turned out to be unsuccessful, he obtained a hydrocarbon consisting of four acetylene molecules connected in a chain, which turned out to be extremely unstable. The instability of lower polyyns served as the basis for Bayer to create a theory of stress, in which he postulated the impossibility of obtaining chained carbon. The authority of the scientist cooled the interest of researchers in the synthesis of polyyns, and work in this direction stopped for a long time.

The one-dimensional (linear) form of carbon has long remained the missing link in the allotropy of carbon. An important stimulus for the resumption of work in this area was the discovery in the 1930s of representatives of the polyacetylene series in nature. In some plants and lower fungi, polyyne compounds containing up to five conjugated acetylene groups were found. Vasily Vladimirovich Korshak and Aleksey Mikhailovich Sladkov, head of the laboratory of macromolecular compounds of INEOS, were among the first who decided to challenge the authority of their predecessors. Their work led to the discovery of a new linear allotropic form of carbon.

In 1959-1960, in the laboratory of high-molecular compounds INEOS, headed by Academician Korshak, systematic studies of the reaction of oxidative combination of diacetylene compounds were carried out. It was found that in the presence of divalent copper salts, this reaction can be carried out with any diacetylene compounds with the formation of polymers, the elementary unit of which retains the carbon skeleton of the starting diacetylene. In this case, polymeric polyacetylenides Cu (I) are first formed. This variant of the oxidative coupling reaction was named oxidative dehydro-polycondensation. Scientists have suggested that acetylene can be taken as a monomer for such polycondensation. Indeed, when acetylene was passed into an aqueous ammonia solution of the Cu (II) salt, a black precipitate quickly formed. It was this path that led A.M. Sladkov, V.V. Korshak, V.I. Kasatochkin and Yu.P. Kudryavtsev to the discovery of a linear form of carbon, which, at the suggestion of Sladkov, they called “ carbyne».

According to the discoverers of Carbyne, the most difficult thing for them was to determine by what bonds the carbon atoms are connected in a chain. These could be alternating single and triple bonds (–C≡C – C≡C–), only double bonds (= C = C = C = C =), or both at the same time. Only a few years later it was possible to prove that there are no double bonds in the resulting carbyne. The polyyne structure of the chains was confirmed by the formation of oxalic acid during ozonation of carbyne.

However, the theory admitted the existence of a linear carbon polymer only with double bonds, which was obtained in 1968 by V.P. Nepochatykh, a graduate student of Sladkov: counter synthesis (reduction of polymer glycol) led to the formation of a linear carbon polymer with cumulene bonds, which was called polycumulene. The proof of the presence of double bonds in the resulting substance was the fact that when polycumulene is ozonized, only carbon dioxide is obtained.

So, two forms of linear carbon were obtained: polyyne (–C≡C–) n, or α-carbyne, and polycumulene (= C = C =) n, or β-carbyne. The authors of the discovery carried out a detailed study of the structure of carbyne by various methods, studied its thermodynamic and electrophysical properties.

Carbine structure

According to some researchers, unambiguous and rigorous evidence of the individuality of carbyne and its structure has not yet been obtained, while other authors, on the contrary, believe that such evidence is available. The discussion about the existence of carbyne is largely due to the fact that its diagnostics has a number of technical difficulties, since when using high-energy methods, the transition of carbyne to other forms of carbon is possible. In addition, the concept of the structure of carbyne was imperfect for a long time. The authors of the discovery of carbyne proposed a model of its crystal structure in the form of a set of cumulene or polyyne-type chains packed into crystals due to van der Waals forces. The chains were assumed to be straight, since each carbon atom is in the sp-hybridization state.

Indeed, to date, it has been established that the structure of carbyne is formed by carbon atoms collected in chains by double bonds (β-carbyne) or alternating single and triple bonds (α-carbyne). Polymer chains have chemically active ends (i.e., carry a localized negative charge) and bends with chain vacancies, in the places of which the chains are interconnected due to the overlapping of the π-orbitals of carbon atoms. The presence of such metal impurities as iron and potassium is important for the formation of crosslinks. Convincing evidence of the presence of zigzags in a linear carbon chain was obtained in the theoretical work of Korshak: the results of his calculations are in good agreement with the IR spectrum of carbyne.

Based on the results of further studies of the structure of crystalline carbyne, a model of its unit cell was proposed. According to this model, the unit cell of carbyne is composed of parallel chains of carbon with zigzags, due to which the cell turns out to be two-layer. The thickness of one layer is a chain of six carbon atoms. In the lower layer, the chains are closely packed and located in the center and at the corners of the hexagon, while in the upper layer there is no central chain, and impurity atoms can be located in the formed vacancy. It is possible that they are catalysts for the crystallization of carbyne. This model provides a clue to the disclosure of the phenomenon of carbyne and explains in what configuration a generally unstable set of linear carbon chains can be stabilized.

Notes (edit)

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Synonyms:

Carbin

Carbyne will take away the title of the most durable material from graphene, if and as soon as they learn to produce it in significant quantities. This is stated in an article by theoretical physicist Boris Yakobson and his colleagues, published this week.

Not so long ago, graphene made it into all the news, becoming the most durable material. For experiments with graphene in 2010, the Nobel Prize was awarded. But scientists may have synthesized a new, strongest material known as carbyne.

The properties of carbyne became known back in the summer. This material is a chain of carbon atoms connected either in series with double bonds or by alternating triple and single bonds. This, in some way, makes carbyne a one-dimensional material - as opposed to two-dimensional graphene or three-dimensional hollow carbon nanotubes.

A new article says that if produced in sufficient quantities, a number of the unique properties of carbyne can be exploited. In particular, calculations have shown that the ultimate strength of the new material can be twice as high as that for graphene. In addition, it is twice as hard as graphene and three times as hard as diamond. In addition, carbyne has pronounced semiconducting properties and can act as a material for energy storage devices.

But few people already remember that Karbin is also called CARBON ALEXEY SLADKOV.

In 1960, carbyne was synthesized by the Soviet chemist A.M. Sladkov 1922-1982 within the walls of the Institute of Organoelement Compounds in Moscow and named by him carbyne... He was not aware that, possessing unique properties, this artificially created substance interested the whole world and began its practical use in various areas of human life, for example, in medicine and electronics. In 1968, American scientists A. El Goresi and G. Donnay, examining samples of a meteorite crater (Germany, Bavaria), demineralized them by treating them with various acids. In the insoluble concentrate, it was graphite. Scientists have found in it inclusions of an unknown substance of a silvery-white color - carbon. The optical properties of the substance were absolutely not similar to the properties of natural diamond or its artificially obtained crystalline modification - lonsdaleite. The discovered substance turned out to be a new allotropic form of carbon ("white carbon"), which was confirmed by studying it using X-ray diffraction. Scientists concluded that this form of eel was formed from graphite as a result of a meteorite falling under the influence of high temperature and pressure.

The most paradoxical in this story is that the existence of a carbine, which in the laboratory of A.M. Sladkov could be seen, touched, experimented with, but was not officially recognized in nature until it was discovered. More precisely, they were careful with its recognition, thereby once again confirming how strong conservative manifestations are in science, how difficult it is to prove the fallacy of the statements of recognized authorities. One of the first to dare to challenge the authority of his predecessors was the talented Russian scientist Alexei Mikhailovich Sladkov. The work he carried out at the Institute of Organoelement Compounds, which, according to the employees of his laboratory I. Golding and N. Vasneva, “amazing subtlety and clarity of design,” - the oxidative polycondensation of acetylene - led to the discovery of a new linear allotropic form of carbon.

As the son of a famous Russian scientist-chemist who was repressed in the thirties, a professor at the Moscow Institute of Chemical Technology. DI. Mendeleev, scientific director of the largest Institute of Food Products and Dyes (NIOPIK), A.M. Sladkov did not find recognition at that time. He avoided public affairs in every possible way and was not in the ranks of the CPSU because of his repressed father.

The copyright certificate for the method of obtaining carbine by the Committee for Inventions and Discoveries under the Council of Ministers of the USSR was registered as a discovery with the priority of 1960 only on December 7, 1971. Those. eleven years after a series of successful experiments. It took eleven years of waiting to break the mistrust of the discovery, refuting world authorities. Having received carbyne, A.M. Sladkov came to the idea of a plurality of carbyne forms of carbon, the existence of a large number of basic carbon polymers. Subsequent research by scientists confirmed this guess. Often in the scientific literature there are publications claiming the synthesis of a new crystalline form or allotropic modification of carbon.

In confirmation of this, in 1985, for example, the discovery was made of a large family of spherical carbon molecules called fullerenes. This discovery gave a new impetus to research around the world in the field of carbon and its allotropic forms. The authors of the next discovery - a group of American scientists - won the Nobel Prize in 1996. Doesn't all this mean that, being the discoverer of these new forms of carbon molecules, the Russian scientist has every reason to claim, moreover, to receive the Nobel Prize for his outstanding discovery of CARBINE !?

At the moment, obtaining carbyne remains an extremely difficult task, so scientists are currently conducting experiments not with a real substance, but resorting to using quantum mechanical modeling on supercomputers. “In previous works ... attention was focused on some of its individual characteristics, but we set out to characterize it from all sides at once, that is, to create a complete mechanical model of the material,” says Artyukhov.

The results of this simulation showed that carbyne has a uniquely high rigidity - its specific strength per kilogram of mass is 1 million kilonewtons per meter. This is twice the strength of nanotubes and graphene (0.45 million kilonewtons) and almost three times stronger than diamond - 0.35 million kilonewtons). “We found several other interesting phenomena, for example, that in carbyne it is possible to“ turn on ”the torsional stiffness by attaching certain functional groups at the ends,” the source said.

In addition, Jacobson and his colleagues were able to prove that stretching a carbyne thread radically changes its electrical properties - it "transforms" from the form of cumulene (which is a conductor) into the form of a polyin (dielectric), that is, by pulling the thread of carbyne, you can turn off and include conductivity.

Not a space elevator, but electronics

So far, the technologies for producing carbyne are extremely complex. The longest filament of carbyne - 6 nanometers - was obtained in 2010 by scientists from Canada. Therefore, according to Artyukhov, carbyne can be used as a component of various complex nanosystems. “It could serve as a 'nanotrope' or 'nanorod' (depending on the length), as well as a conductive or semiconductor 'cable', says the scientist.

Despite its unique mechanical strength, carbine is unlikely to be used to create ultra-strong macroscopic cables, for example, for "space elevators".

“The fact is that the strength of a material is always determined not by the strongest, but, on the contrary, by the weakest“ link ”in it. In carbon fibers, these are the joints between graphite sheets, in composites with nanotubes, it is the contact between the nanotube and the matrix. And no matter how you improve the properties of the reinforcing elements in the system, its strength will remain constant if they are poorly connected to each other, ”says Artyukhov.

Scientific discoveries in the study of the properties of carbon.

Scientific discovery "A new crystalline form of carbon - carbyne".

Discovery formula:"The previously unknown phenomenon of the existence of a new crystalline form of carbon - carbyne, which, unlike diamond and graphite, is characterized by a chain (linear) structure of carbon macromolecules, has been experimentally established."
Authors: V. I. Kasatochkin, A. M. Sladkov, Yu. P. Kudryavtsev, V. V. Korshak.
Priority number and date: No. 107 dated November 4, 1960

Description of the opening.
Carbon is a unique element. It forms countless compounds, serves as an excellent fuel and raw material for obtaining a wide variety of materials and products from them. Due to its structure, it forms a huge number of compounds only with hydrogen, and the total number of all kinds of chemical compounds containing carbon, including in the cells of living beings, exceeds two million.

They did not immediately find the keys to unraveling the behavior of carbon, which has certain structures of atomic chains. This was preceded by decades of scientific research. For a long time, only two crystalline forms of carbon were known - diamond and graphite, which have completely different properties. Diamond - the hardest known substance on Earth - is transparent and has the characteristic properties of an electrical insulator. Graphite is very soft, opaque, conducts current well.

Doctor of Chemistry V.I. Kasatochkin from the Institute of Combustible Fossils, together with scientists of the Institute of Organoelement Compounds, Doctor of Chemical Sciences A.M. Sladkov, Ph.D. a crystalline form of carbon called carbyne. It was made from acetylene. The third form of crystalline carbon has semiconducting properties and photoconductivity.

Carbyne is also found naturally. Recently, crystalline carbon was discovered in the Rhys crater (Bavaria), which was formed as a result of a meteorite falling, with a structure similar to carbine. The same carbon was found by scientists of the Institute of Geochemistry of the USSR Academy of Sciences in the Novy Urey meteorite. These facts indicate that carbyne is very stable and is formed under specific natural conditions. The study of these conditions will help the development of cosmochemistry. Sharp differences in the structure and properties of the three forms of crystalline carbon: diamond, graphite and carbyne - are associated with three possible varieties of the hybrid electronic structure of carbon atoms and, therefore, with differences in the types of interatomic bonds.

According to the theory of transitional forms of carbon, the combination of dissimilar hybrid varieties of atoms in a single polymer structure gives rise to many amorphous forms of this substance. Carbon glass is a typical example of amorphous carbon, which combines all three types of hybrid atoms with three types of bonds - diamond, graphite and carbyne. The number of combinations of hybrid atoms in different ratios is very large. That is why new carbon materials with various properties are emerging now. These materials are based on amorphous carbon.

The attention to these amazing materials all over the world is increasing every year. Large specialized scientific centers are being created. The search for new carbon materials is being persistently pursued. Unusual lightness combined with heat resistance, resistance to aggressive chemical media, and inability to magnetize will undoubtedly allow these substances to take a leading position among other structural materials in the progressive fields of science in the near future.

But few people already remember that carbyne is also called ALEXEY SLADKOV'S CARBON.

Not a space elevator, but electronics

Despite its unique mechanical strength, carbine is unlikely to be used to create ultra-strong macroscopic cables, for example, for "space elevators".

But carbyne can be useful in electronics - depending on the tension, its conductivity and optical absorption spectrum change dramatically. “By tension, you can control which wavelength of light the material is most sensitive to. This is a very useful property for optoelectronic applications, in particular, in telecommunications, ”the scientist noted.

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The one-dimensional (linear) form of carbon has long remained the missing link in the allotropy of carbon. An important stimulus for the resumption of work in this area was the discovery in the 1930s of representatives of the polyacetylene series in nature. In some plants and lower fungi, polyyne compounds containing up to five conjugated acetylene groups were found. Aleksey Mikhailovich Sladkov and Yuri Pavlovich Kudryavtsev, chemists from the laboratory of high-molecular compounds INEOS, were among the first who decided to challenge the authority of their predecessors. Their work led to the discovery of a new linear allotropic form of carbon.

In 1959-1960, in the laboratory of high-molecular compounds INEOS, headed by Academician Korshak, systematic studies of the reaction of oxidative combination of diacetylene compounds were carried out. It was found that in the presence of divalent copper salts, this reaction can be carried out with any diacetylene compounds with the formation of polymers, the elementary unit of which retains the carbon skeleton of the starting diacetylene. In this case, polymeric polyacetylenides Cu (I) are first formed. This variant of the oxidative coupling reaction was named oxidative dehydro-polycondensation. Scientists have suggested that acetylene can be taken as a monomer for such polycondensation. Indeed, when acetylene was passed into an aqueous ammonia solution of the Cu (II) salt, a black precipitate quickly formed. It was this path that led A.M.Sladkov, Yu.P. Kudryavtsev, V.V. Korshak, and V.I. Kasatochkin to the discovery of a linear form of carbon, which was called “ carbyne».

However, the theory allowed the existence of a linear carbon polymer with only double bonds, which was obtained in 1968 by V.P. Nepochatykh: counter synthesis (reduction of polymer glycol) led to the formation of a linear carbon polymer with cumulene bonds, which was called polycumulene. The proof of the presence of double bonds in the resulting substance was the fact that when polycumulene is ozonized, only carbon dioxide is obtained.

There are several reports on the finds of carbino-containing carbon substances made by A.G. Vittaker in Ceylon graphite and graphite of various states of the United States, V.I. Kasatochkin in natural diamond, F.J. Reitinger in graphite from Sri Lanka, G.V. Vdovykin in meteorite.

Detailed methods of preparation, physical and chemical properties of carbine and its application are described in a number of works by Yu.P. Kudryavtsev, S.E. Evsyukov, M.B. Guseva, V.P. Babaev, T.G. Shumilova.

Corbin structure chemistry. Carbyne is a new form of carbon, superior in strength to graphene and carbon nanotubes

Properties

Prehistory of the discovery

Carbine structure

see also

Links

Notes (edit)