Heptacene is an organic compound and a polycyclic aromatic hydrocarbon and the seventh member of the acene or polyacene family of linear fused benzene rings.[1] This compound has long been pursued by chemists[2][3][4] because of its potential interest in electronic applications and was first synthesized but not cleanly isolated in 2006.[5][6] Heptacene was finally fully characterized in bulk by researchers in Germany and the United States in 2017.[7]
The final step is a photochemical decarbonylization with a 1,2-dione bridge extruded as carbon monoxide. In solution heptacene is not formed because it is very unstable being a reactive DA diene and quickly reacts with oxygen or forms dimers. When on the other hand the dione precursor is dissolved in a PMMA matrix first, heptacene can be studied by spectroscopy. Heptacene has been studied spectroscopically at cryogenic temperatures in a matrix.[8] When dissolved in sulfuric acid the heptacene dication is reported to be stable at room-temperature for more than a year in absence of oxygen.[9]
"[Isolated] solid heptacene has a half-life time of several weeks at room temperature."[10]
^Zade, Sanjio S.; Bendikov, Michael (2010). "Heptacene and Beyond: the Longest Characterized Acenes". Angewandte Chemie International Edition. 49 (24): 4012–5. doi:10.1002/anie.200906002. PMID20468014.
^Clar, E. (1942). "Heptacen ein einfacher, "ultragrüner"︁ Kohlenwasserstoff (Aromatische Kohlenwasserstoffe, XXXV. Mitteil.)". Berichte der Deutschen Chemischen Gesellschaft (A and B Series). 75 (11): 1330–1338. doi:10.1002/cber.19420751114.
^Bailey, William J.; Liao, Chien-Wei (1955). "Cyclic Dienes. XI. New Syntheses of Hexacene and Heptacene1,2". Journal of the American Chemical Society. 77 (4): 992–993. doi:10.1021/ja01609a055.
^Boggiano, B.; Clar, E. (1957). "519. Four higher annellated pyrenes with acene character". Journal of the Chemical Society (Resumed): 2681. doi:10.1039/JR9570002681.
^Mondal, Rajib; Shah, Bipin K.; Neckers, Douglas C. (2006). "Photogeneration of Heptacene in a Polymer Matrix". Journal of the American Chemical Society. 128 (30): 9612–9613. doi:10.1021/ja063823i. PMID16866498.
^Einholz, Ralf; Fang, Treliant; Berger, Robert; Grüninger, Peter; Früh, Andreas; Chassé, Thomas; Fink, Reinhold F.; Bettinger, Holger F. (2017). "Heptacene: Characterization in Solution, in the Solid State, and in Films". Journal of the American Chemical Society. 139 (12): 4435–4442. doi:10.1021/jacs.6b13212. PMID28319405.
^Mondal, Rajib; TöNshoff, Christina; Khon, Dmitriy; Neckers, Douglas C.; Bettinger, Holger F. (2009). "Synthesis, Stability, and Photochemistry of Pentacene, Hexacene, and Heptacene: A Matrix Isolation Study". Journal of the American Chemical Society. 131 (40): 14281–14289. doi:10.1021/ja901841c. PMID19757812.
^Einholz, R.; Bettinger, H. F. (2013). "Heptacene: Increased Persistence of a 4n+2 π-Electron Polycyclic Aromatic Hydrocarbon by Oxidation to the 4n π-Electron Dication". Angew. Chem. Int. Ed. 52: 9818–9820. doi:10.1002/anie.201209722. PMID23873781.
^Einholz, Ralf; Fang, Treliant; Berger, Robert; Grüninger, Peter; Früh, Andreas; Chassé, Thomas; Fink, Reinhold F.; Bettinger, Holger F. (2017). "Heptacene: Characterization in Solution, in the Solid State, and in Films". Journal of the American Chemical Society. 139 (12): 4435–4442. doi:10.1021/jacs.6b13212. PMID28319405.