Triphenylene
In chemistry, the organic compound triphenylene is a flat polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings. Triphenylene can be isolated from coal tar. It is also made synthetically by synthesis and trimerization of benzyne.[1] One molecule of triphenylene has delocalized 18-π-electron systems based on a planar structure. It has the molecular formula C
18H
12.
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| Names | |
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| Preferred IUPAC name
Triphenylene | |
| Other names
Benzo[l]phenanthrene 9,10-Benzophenanthrene 1,2,3,4-Dibenzonaphthalene Isochrysene | |
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| ChemSpider | |
| ECHA InfoCard | 100.005.385  |
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| KEGG | |
| MeSH | C009590 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C18H12 | |
| Molar mass | 228.294 g·mol−1 |
| Melting point | 198 °C; 388 °F; 471 K |
| Boiling point | 438 °C; 820 °F; 711 K |
| -156.6·10−6 cm3/mol | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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| Infobox references | |
Properties
Triphenylene is a disc-shaped molecule with a planar structure and three-fold rotation axes, corresponding to the crystallographic point group D3h. It is a fully benzenoid PAH, meaning its structure is composed only of full benzene rings interconnected by carbon–carbon single bonds. The three benzene rings can be drawn as the three outer rings, with the central ring formed by one face of each and the three carbon–carbon single bonds. Being a fully benzenoid PAH means that triphenylene is much more resonance stable than its isomers chrysene, benz[a]anthracene, benzo[c]phenanthrene, and tetracene. This makes it much more difficult to hydrogenate to the saturated hydrocarbon.[2]
In light of these characteristics, triphenylene may have uses in optics and electronics. Due to its symmetry, six-fold (in the 2, 3, 6, 7, 10, and 11 positions) alkyloxy- or alkylthiol-substituted triphenylenes can be used as a discotic mesogen in liquid crystalline materials.[3] Consisting of colorless needle-like crystals, triphenylene emits bluish purple fluorescence by UV irradiation.
References
- Heaney, H.; Millar, I. T. (1960). "Triphenylene". Organic Syntheses. 40: 105.; Collective Volume, 5, 1973, p. 1120
- Kofman, V.; Sarre, P.J.; Hibbins, R.E.; ten Kate, I.L.; Linnartz, H. (2017). "Laboratory spectroscopy and astronomical significance of the fully-benzenoid PAH triphenylene and its cation". Molecular Astrophysics. 7: 19–26. doi:10.1016/j.molap.2017.04.002. hdl:1887/58655.
- Janietz, Dietmar (2001), "Liquid Crystals at Interfaces", Handbook of Surfaces and Interfaces of Materials, Elsevier, pp. 436–437, doi:10.1016/b978-012513910-6/50014-1, ISBN 978-0-12-513910-6, retrieved 2020-08-23