Ball carbon C60 to graphene: Will there be the next carbon star molecule?

The single (pure) mass of a chemical element exists in different forms of molecules and crystals called the allotrope of this element. The discovery of elemental C 's allotrope " ball carbon " C60 led three scientists to share the 1996 Nobel Prize in Chemistry, only 16 years later, the separation of another allotrope " graphene " of C shared the two scientists 2010 Nobel Prize in Physics. In 1991, C60 was selected as the star of the year by American Science, and graphene certainly became a new star!

Can't help but ask: How many allotropes does Element C have? Will new C star players appear in the future?

If classified according to the phase of the elemental substance, the C allotrope can be roughly discussed as crystal, amorphous and gaseous molecules Cn (n = 1, 2, 3...). However, we are interested in the composition and structure of the well-known isomers that are closely related to our lives and can be crystalline in nature, such as diamond, graphite, spherical carbon and chain carbon compounds. . Among them, we know the earliest diamond and graphite families, and the graphene separated from graphite is the latest.

Diamond crystals are mainly cubic crystal symmetry. In addition, there are hexagonal isomers in nature, and the structure corresponds to cubic and hexagonal zinc sulfide. Both of the C atoms are bonded by the sp3 orbital tetrahedron type. Although this is not a dense packing method of C atoms, diamond is the hardest substance in nature. People have set its Mohr hardness to 10 , which has human production and life important value. Interestingly, the CC distance in diamond is 1.54 angstroms, but not the shortest bond length of CC!

Graphite crystals can be characterized as a three-dimensional structure in which graphene is stacked. Graphene is a monomolecular planar macromolecule in which C atoms are splined into sp2 orbital triangles, and the layers are layered into graphite crystals by van der Waals bonds intermolecular weak interaction forces. Due to the different cycle of stacking, graphite has two main isomers, namely ABABAB . . . Hexagonal stacked alpha- type and pressed ABCABC . . . Three-way stacked β- type structure. Of course, there are a lot of more complicated accumulation methods in nature.

Different from the above two, the C atom of the spherical carbon is distributed on the curved surface of the two-dimensional space, and the connection mode is the triangular cone type of the sp2 - sp3 mixed orbit, which accommodates the harmonious coexistence of the six-membered C- ring and the five-membered C- ring. , thus appearing common "soccer" and so on. Ball carbon is a large family including spheres and ellipsoids. If carbon nanotubes are regarded as long-drawn tubular carbon, it is difficult to answer the question of how many carbons are homogeneous, let alone carbon. The ever-changing organic compounds formed by the elements.

Regardless of the carbon of the ball or the graphene, these star molecules are the masterpieces of the existing natural mother. They have been found to increase people's scientific cognition, and their special properties encourage scientists to continue research, even to explore materials with special properties not found in nature. “Crystal Engineering” means that we challenge nature, not just the gift of her. Superconducting, super strong, super hard, ultra-light, and ultra-dense high-energy materials, etc., we have too many challenges and opportunities for innovation!

Question: Is it impossible to synthesize a substance that is harder than diamond? People are looking forward to this for a long time! It is known from hydrocarbons that the C-C single bond length can be as small as 1.44 angstroms, which is as short as 0.14 angstroms to the diamond C atom. Theoretical calculations have shown that some super tetrahedral alkanes may approach this ultra-short distance when they are linked by a single C-C bond. Then someone was there to "play the game", and it was really impossible to have a carbon allograft to become a new star.

You don't think this is a fantasy, or will you be optimistic about it? I am not sure that you will be happy to participate in it!

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