Triphenylene

Triphenylene
IUPAC name	triphenylene
Other names	benzo[l]phenanthrene, 9,10-benzophenanthrene, 1,2,3,4-dibenznaphthalene, isochrysene
Identifiers
CAS number	217-59-4 Y
SMILES	C1(C=CC=C3)=C3C(C=CC=C4)=C4C2=C1C=CC=C2
InChI	1/C18H12/c1-2-8-14-13(7-1)15-9-3-4-11-17(15)18-12-6-5-10-16(14)18/h1-12H
Properties
Molecular formula	C18H12
Molar mass	228.29 g mol−1
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

In chemistry, the organic compound triphenylene is a flat polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings. Triphenylene is isolated from coal tar. One molecule of triphenylene has delocalized 18-π-electron systems based on a planar structure. It has the molecular formula C₁₈H₁₂.

Triphenylene 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-bezenoid PAH means that triphenylene is much more resonance stable than its isomers chrysene, benz[a]anthracene, benzo[c]phenanthrene and naphthacene (tetracene). This makes it much more difficult to hydrogenate to the saturated hydrocarbon.

In light of these characteristics, triphenylene may have uses in optics and electronics. Triphenylene is a disc-shaped molecule with a planar structure and three-fold rotation axes. Consisting of colorless needle-like crystals, it emits bluish purple fluorescence by UV irradiation.

In terms of its crystallographic point group, the symmetry of triphenylene is classified as C_3h in Schoenflies notation. Because of these characteristics, 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.

References

• Polycyclic Aromatic Hydrocarbon Structure Index
• Synthesis: Organic Syntheses, Coll. Vol. 5, p.1120 (1973); Vol. 40, p.105 (1960). [1]