Pyrene Explained

Pyrene is a polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is . This yellow-green solid is the smallest peri-fused PAH (one where the rings are fused through more than one face). Pyrene forms during incomplete combustion of organic compounds.[1]

Occurrence and properties

Pyrene was first isolated from coal tar, where it occurs up to 2% by weight. As a peri-fused PAH, pyrene is much more resonance-stabilized than its five-member-ring containing isomer fluoranthene. Therefore, it is produced in a wide range of combustion conditions. For example, automobiles produce about 1 μg/km.[2]

Reactions

Oxidation with chromate affords perinaphthenone and then naphthalene-1,4,5,8-tetracarboxylic acid. Pyrene undergoes a series of hydrogenation reactions and is susceptible to halogenation, Diels-Alder additions, and nitration, all with varying degrees of selectivity.[2] Bromination occurs at one of the 3-positions.[3]

Reduction with sodium affords the radical anion. From this anion, a variety of pi-arene complexes can be prepared.[4]

Photophysics

Pyrene and its derivatives are used commercially to make dyes and dye precursors, for example pyranine and naphthalene-1,4,5,8-tetracarboxylic acid. It has strong absorbance in UV-Vis in three sharp bands at 330 nm in DCM. The emission is close to the absorption, but moving at 375 nm.[5] The morphology of the signals change with the solvent. Its derivatives are also valuable molecular probes via fluorescence spectroscopy, having a high quantum yield and lifetime (0.65 and 410 nanoseconds, respectively, in ethanol at 293 K). Pyrene was the first molecule for which excimer behavior was discovered.[6] Such excimer appears around 450 nm. Theodor Förster reported this in 1954.[7]

Applications

Pyrene's fluorescence emission spectrum is very sensitive to solvent 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.

Pyrenes are strong electron donor materials and can be combined with several materials in order to make electron donor-acceptor systems which can be used in energy conversion and light harvesting applications.

Safety and environmental factors

Although it is not as problematic as benzopyrene, animal studies have shown pyrene is toxic to the kidneys and liver. It is now known that pyrene affects several living functions in fish and algae.[8] [9] [10] [11]

Its biodegradation has been heavily examined. The process commences with dihydroxylation at each of two kinds of CH=CH linkages.[12] Experiments in pigs show that urinary 1-hydroxypyrene is a metabolite of pyrene, when given orally.[13]

See also

Cited sources

Further reading

Notes and References

  1. 10.1021/cr100428a. Pyrene-Based Materials for Organic Electronics. 2011. Figueira-Duarte. Teresa M.. Müllen. Klaus. Chemical Reviews. 111. 11. 7260–7314. 21740071.
  2. Senkan, Selim and Castaldi, Marco (2003) "Combustion" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim.
  3. Gumprecht . W. H. . 1968 . 3-Bromopyrene . Org. Synth. . 48 . 30 . 10.15227/orgsyn.048.0030 .
  4. 10.1107/S2053229614015290. Bis(pyrene)metal complexes of vanadium, niobium and titanium: Isolable homoleptic pyrene complexes of transition metals. 2014. Kucera. Benjamin E.. Jilek. Robert E.. Brennessel. William W.. Ellis. John E.. Acta Crystallographica Section C: Structural Chemistry. 70. 8. 749–753. 25093352.
  5. Tagmatarchis. Nikos. Ewels. Christopher P.. Bittencourt. Carla. Arenal. Raul. Pelaez-Fernandez. Mario. Sayed-Ahmad-Baraza. Yuman. Canton-Vitoria. Ruben. 2017-06-05. Functionalization of MoS 2 with 1,2-dithiolanes: toward donor-acceptor nanohybrids for energy conversion. npj 2D Materials and Applications. en. 1. 1. 13. 10.1038/s41699-017-0012-8. 2397-7132. free.
  6. Van Dyke . David A. . Pryor . Brian A. . Smith . Philip G. . Topp . Michael R. . Nanosecond Time-Resolved Fluorescence Spectroscopy in the Physical Chemistry Laboratory: Formation of the Pyrene Excimer in Solution . Journal of Chemical Education . May 1998 . 75 . 5 . 615 . 10.1021/ed075p615. 1998JChEd..75..615V .
  7. Förster . Th. . Kasper . K. . Ein Konzentrationsumschlag der Fluoreszenz. . Zeitschrift für Physikalische Chemie . June 1954 . 1 . 5_6 . 275–277 . 10.1524/zpch.1954.1.5_6.275.
  8. Oliveira. M.. Ribeiro. A.. Hylland. K.. Guilhermino. L.. Single and combined effects of microplastics and pyrene on juveniles (0+ group) of the common goby Pomatoschistus microps (Teleostei, Gobiidae). Ecological Indicators. 34. 641–647. 10.1016/j.ecolind.2013.06.019. 2013.
  9. Oliveira. M.. Gravato. C.. Guilhermino. L.. Acute toxic effects of pyrene on Pomatoschistus microps (Teleostei, Gobiidae): Mortality, biomarkers and swimming performance. Ecological Indicators. 19. 206–214. 10.1016/j.ecolind.2011.08.006. 2012.
  10. Oliveira. M.. Ribeiro. A.. Guilhermino. L.. Effects of exposure to microplastics and PAHs on microalgae Rhodomonas baltica and Tetraselmis chuii. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. 163. S19–S20. 10.1016/j.cbpa.2012.05.062. 2012.
  11. Oliveira. M.. Ribeiro. A.. Guilhermino. L.. Effects of short-term exposure to microplastics and pyrene on Pomatoschistus microps (Teleostei, Gobiidae). Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. 163. S20. 10.1016/j.cbpa.2012.05.063. 2012.
  12. 10.3390/ijerph6010278. free. Bacterial Degradation of Aromatic Compounds. 2009. Seo. Jong-Su. Keum. Young-Soo. Li. Qing. International Journal of Environmental Research and Public Health. 6. 1. 278–309. 19440284. 2672333.
  13. 10.3109/00498258309052279. 6659544. Identification of 1-hydroxypyrene as a major metabolite of pyrene in pig urine. Xenobiotica. 13. 7. 415–20. 1983. Keimig. S. D.. Kirby. K. W.. Morgan. D. P.. Keiser. J. E.. Hubert. T. D..

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