Pyrene is apolycyclic aromatic hydrocarbon (PAH) consisting of four fusedbenzene rings, resulting in a flataromatic system. The chemical formula isC16H10. This yellow-green solid is the smallest peri-fused PAH (one where the rings are fused through more than one face). Pyrene forms duringincomplete combustion of organic compounds.[10]
Pyrene was first isolated fromcoal tar, where it occurs up to 2% by weight. As a peri-fused PAH, pyrene is much moreresonance-stabilized than its five-member-ring containing isomerfluoranthene. Therefore, it is produced in a wide range of combustion conditions. For example, automobiles produce about 1 μg/km.[11]
Oxidation withchromate affords perinaphthenone and then naphthalene-1,4,5,8-tetracarboxylic acid. Pyrene undergoes a series ofhydrogenation reactions and is susceptible to halogenation,Diels-Alder additions, and nitration, all with varying degrees of selectivity.[11] Bromination occurs at one of the 3-positions.[12]
Reduction with sodium affords the radical anion. From this anion, a variety of pi-arene complexes can be prepared.[13]
Pyrene and its derivatives are used commercially to makedyes and dye precursors, for examplepyranine 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.[14] The morphology of the signals change with the solvent. Its derivatives are also valuable molecular probes viafluorescence spectroscopy, having a high quantum yield and lifetime (0.65 and 410 nanoseconds, respectively, inethanol at 293 K). Pyrene was the first molecule for whichexcimer behavior was discovered.[15] Such excimer appears around 450 nm.Theodor Förster reported this in 1954.[16]
STM image of self-assembled Br4Py molecules on Au(111) surface (top) and its model (bottom; pink spheres are Br atoms).[17]
Pyrene's fluorescenceemission 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.[14]
Its biodegradation has been heavily examined. The process commences with dihydroxylation at each of two kinds of CH=CH linkages.[22] Experiments in pigs show that urinary1-hydroxypyrene is a metabolite of pyrene, when given orally.[23]
^Figueira-Duarte, Teresa M.; Müllen, Klaus (2011). "Pyrene-Based Materials for Organic Electronics".Chemical Reviews.111 (11):7260–7314.doi:10.1021/cr100428a.PMID21740071.
^abSenkan, Selim and Castaldi, Marco (2003) "Combustion" inUllmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim.
^Kucera, Benjamin E.; Jilek, Robert E.; Brennessel, William W.; Ellis, John E. (2014). "Bis(pyrene)metal complexes of vanadium, niobium and titanium: Isolable homoleptic pyrene complexes of transition metals".Acta Crystallographica Section C: Structural Chemistry.70 (8):749–753.doi:10.1107/S2053229614015290.PMID25093352.
^Van Dyke, David A.; Pryor, Brian A.; Smith, Philip G.; Topp, Michael R. (May 1998). "Nanosecond Time-Resolved Fluorescence Spectroscopy in the Physical Chemistry Laboratory: Formation of the Pyrene Excimer in Solution".Journal of Chemical Education.75 (5): 615.Bibcode:1998JChEd..75..615V.doi:10.1021/ed075p615.
^Förster, Th.; Kasper, K. (June 1954). "Ein Konzentrationsumschlag der Fluoreszenz".Zeitschrift für Physikalische Chemie.1 (5_6):275–277.doi:10.1524/zpch.1954.1.5_6.275.
^Oliveira, M.; Ribeiro, A.; Hylland, K.; Guilhermino, L. (2013). "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.doi:10.1016/j.ecolind.2013.06.019.
^Oliveira, M.; Gravato, C.; Guilhermino, L. (2012). "Acute toxic effects of pyrene on Pomatoschistus microps (Teleostei, Gobiidae): Mortality, biomarkers and swimming performance".Ecological Indicators.19:206–214.doi:10.1016/j.ecolind.2011.08.006.
^Oliveira, M.; Ribeiro, A.; Guilhermino, L. (2012). "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.doi:10.1016/j.cbpa.2012.05.062.
^Oliveira, M.; Ribeiro, A.; Guilhermino, L. (2012). "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.doi:10.1016/j.cbpa.2012.05.063.
^Keimig, S. D.; Kirby, K. W.; Morgan, D. P.; Keiser, J. E.; Hubert, T. D. (1983). "Identification of 1-hydroxypyrene as a major metabolite of pyrene in pig urine".Xenobiotica.13 (7):415–20.doi:10.3109/00498258309052279.PMID6659544.
