Chemistry:Higher fullerenes
Higher fullerenes are fullerene molecules consisting of more than 70 carbon atoms. They adopt cage-like structures made up of the fusion of hexagons and pentagons, with a carbon atom at the vertices of each polygon and a bond along each polygon edge. They are all black solids that dissolve sparingly in organic solvents to give deeply colored solutions.
Synthesis
Fullerenes are extracted from the specially prepared soot using organic solvents followed by chromatography.[1] Milligram amounts of higher fullerenes can be obtained with this method in the laboratory. According to the discovery of W. Krätchmer and D. R. Huffman the soot is produced from two high-purity graphite electrodes by igniting an arc discharge between them in an inert atmosphere (helium gas). Alternatively, soot is produced by laser ablation of graphite or pyrolysis of aromatic hydrocarbons.
C76, C78 and C84 are available commercially.
Inventory
| Formula | CAS number[2] | Nis[3] | Symmetry[4][5] |
|---|---|---|---|
| C60 | 99685-96-8 | 1 | Ih |
| C70 | 115383-22-7 | 1 | D5h |
| C72 | 1 | D6h | |
| C74 | 1 | D3h | |
| C76 | 135113-15-4 | 2 | D2* |
| C78 | 136316-32-0 | 5 | D2v |
| C80 | 136316-32-0 | 7 | |
| C82 | 136316-32-0 | 9 | C2, C2v, C3v |
| C84 | 135113-16-5 | 24 | D2*, D2d |
| C86 | 135113-16-5 | 19 | |
| C88 | 135113-16-5 | 35 | |
| C90 | 135113-16-5 | 46 | |
| C3996 | 175833-78-0 |
In the table, Nis represents the number of possible isomers within the "isolated pentagon rule", which states that two pentagons in a fullerene should not share edges. Symmetry is specified for the most experimentally abundant form(s), and * marks symmetries with more than one chiral form.
| Formula | Symmetry | Space group | No | Pearson symbol |
a (nm) | b (nm) | c (nm) | β° | Z | ρ (g/cm3) |
|---|---|---|---|---|---|---|---|---|---|---|
| C76 | Monoclinic | P21 | 4 | mP2 | 1.102 | 1.108 | 1.768 | 108.10 | 2 | 1.48 |
| C76 | Cubic | Fm3m | 225 | cF4 | 1.5475 | 1.5475 | 1.5475 | 90 | 4 | 1.64 |
| C82 | Monoclinic | P21 | 4 | mP2 | 1.141 | 1.1355 | 1.8355 | 108.07 | 2 | |
| C84 | Cubic | Fm3m | 1.5817[7] | 1.5817 | 1.5817 | 90 |
When C76 or C82 crystals are grown from toluene solution they have a monoclinic symmetry. The crystal structure contains toluene molecules packed between the spheres of the fullerene. However, evaporation of the solvent from C76 transforms it into a face-centered cubic form.[6] Both monoclinic and face-centered cubic (fcc) phases are known for better-characterized C60 and C70 fullerenes.
References
- ↑ Katz, 369-370
- ↑ W. L. F. Armarego; Christina Li Lin Chai (11 May 2009). Purification of laboratory chemicals. Butterworth-Heinemann. pp. 214–. ISBN 978-1-85617-567-8. https://books.google.com/books?id=PTXyS7Yj6zUC&pg=PA214. Retrieved 26 December 2011.
- ↑ Manolopoulos, David E.; Fowler, Patrick W. (1991). "Structural proposals for endohedral metal-fullerene complexes". Chemical Physics Letters 187: 1. doi:10.1016/0009-2614(91)90475-O.
- ↑ Diederich, Francois; Whetten, Robert L. (1992). "Beyond C60: The higher fullerenes". Accounts of Chemical Research 25 (3): 119. doi:10.1021/ar00015a004.
- ↑ K Veera Reddy (1 January 1998). Symmetry And Spectroscopy Of Molecules. New Age International. pp. 126–. ISBN 978-81-224-1142-3. https://books.google.com/books?id=oZeFG6QDNekC&pg=PA126. Retrieved 26 December 2011.
- ↑ 6.0 6.1 Kawada, H.; Fujii, Y.; Nakao, H.; Murakami, Y.; Watanuki, T.; Suematsu, H.; Kikuchi, K.; Achiba, Y. et al. (1995). "Structural aspects of C82 and C76 crystals studied by x-ray diffraction". Physical Review B 51 (14): 8723. doi:10.1103/PhysRevB.51.8723.
- ↑ Margadonna, Serena; Brown, Craig M.; Dennis, T. John S.; Lappas, Alexandros; Pattison, Philip; Prassides, Kosmas; Shinohara, Hisanori (July 1998). "Crystal Structure of the Higher Fullerene C". Chemistry of Materials 10 (7): 1742–1744. doi:10.1021/cm980183c.
Bibliography
- Katz, E. A. (2006). "Fullerene Thin Films as Photovoltaic Material". in Sōga, Tetsuo. Nanostructured materials for solar energy conversion. Elsevier. pp. 361–443. doi:10.1016/B978-044452844-5/50014-7. ISBN 978-0-444-52844-5. https://books.google.com/books?id=GmQR1tuk5IgC&pg=PA361.
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