Pyrene
From Wikipedia, the free encyclopedia
| Pyrene | |
|---|---|
 |
|
| IUPAC name | pyrene |
| Other names | benzo(d,e,f)phenanthrene |
| Identifiers | |
| CAS number | [129-00-0] |
| RTECS number | UR2450000 |
| SMILES | C12=CC=C3C=CC=C4 C=CC(C2=C34)=CC=C1 |
| Properties | |
| Molecular formula | C16H10 |
| Molar mass | 202.25 g/mol |
| Appearance | colorless solid
(yellow impurities are often found at trace levels in many samples). |
| Density | 1.271 g/ml |
| Melting point |
145-148 °C (418-421 K) |
| Boiling point |
404 °C (677 K) |
| Solubility in water | 0.135 mg/l |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | irritant |
| NFPA 704 |
 0
1
0
|
| R-phrases | 36/37/38-45-53 |
| S-phrases | 24/25-26-36 |
| Flash point | non-flammable |
| Related compounds | |
| Related PAHs | benzopyrene |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Pyrene is a polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings, resulting in a large, flat aromatic system. It is the smallest peri-fused polycyclic aromatic hydrocarbon - one where the rings are fused through more than one face. It forms during incomplete combustion of organic material and therefore can be isolated from coal tar along with a broad range of related compounds. As a peri-fused PAH, pyrene is much more resonance stabilized than its five-member-ring containing isomer fluoranthene. Thus, it is produced in a wider range of combustion conditions. Pyrene is a colorless solid. Animal studies have shown pyrene is toxic to the kidneys and the liver.
Pyrene and its derivatives is used commercially to make dyes (for example pyranine), pesticides, pharmaceuticals, and plastics. It is also a valuable molecular probe for fluorescence spectroscopy, having a high quantum yield and lifetime (0.65 and 410 nanosecond, respectively, in ethanol at 293K). Its fluorescence emission spectrum is very sensitive to the solvent's polarity, so pyrene has been used as a probe to determine solvent environments. This is due to its excited state having a different, non-planar structure than the ground state. Certain emission bands are unaffected, but others vary in intensity due to the strength of interaction with a solvent.
Pyrene adopts a dimeric structure, with molecules arranged in sandwiched pairs in order to form lattice units. This results in a high degree of symmetry, belonging to the C2h symmetry group. In solution, dimers exhibit high wavelength fluorescence and also excimer formation.
[edit] References
- Birks, J. B. (1969). Photophysics of Aromatic Molecules. London: Wiley.
- Valeur, B. (2002). Molecular Fluorescence: Principles and Applications. New York: Wiley-VCH.
- Birks, J.B. (1975). Eximers. london: Reports on Progress in Physics.
- Fetzer, J. C. (2000). The Chemistry and Analysis of the Large Polycyclic Aromatic Hydrocarbons. New York: Wiley.
