- Towards the Highly Efficient Synthesis and Selective Methylation of C(sp3)-Bridged [6]Cycloparaphenylenes from Fluoren[3]arenes
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An approach to the highly efficient synthesis of C(sp3)-bridged [6]cycloparaphenylenes (C[6]CPPs) from fluoren[3]arenes (F[3]As) was developed. Consequently, F[3]As as a new kind of macrocyclic arenes were synthesized. Followed by the demethylation, triflation and intramolecular aryl–aryl coupling reactions, C[6]CPPs were then conveniently obtained. Interestingly, C[6]CPPs could be selectively methylated to produce their fully outer-methyl-substituted derivatives. The crystal structures showed the hydroxyl-substituted F[3]As had bowl-shaped conformations, and the C[6]CPPs exhibited rigid belt-shaped structures with deep cavities. Moreover, C[6]CPPs exhibited high HOMO energies and narrow energy gaps. An unclosed belt was further obtained, and it not only showed a similar narrow energy gap to those of the aromatic belts, but also displayed strong fluorescence property, which can play a vital role in the design and synthesis of new aromatic belts.
- Chen, Chuan-Feng,Du, Xu-Sheng,Guo, Yan,Han, Ying,Li, Jing,Zhang, Da-Wei
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- Photodecaging from 9-substituted 2,7-dihydroxy and dimethoxyfluorenes: Competition between heterolytic and homolytic pathways
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2,7-Dihydroxy-9-fluorenol (9), 2,7-dimethoxy-9-fluorenol (10), and 2,7-dimethoxy-9-acetoxyfluorene (11) were prepared and their photochemistry was studied in methanol and aqueous methanol solution in the hopes of observing efficient expulsion of the substituents positioned at the 9-position. For all three compounds, the primary photoproducts were 2,7-disubstituted-9-fluorenes and 2,7-disubstituted-9-methoxyfluorenes. A mechanism of reaction is proposed for production of these products, and involves competing homolytic and heterolytic pathways that produce radical and carbocation intermediates. Reaction quantum yields (for substrate disappearance) ranged between 0.21 and 0.31.
- Roxin, Aron,Chase, Alex,Jeffers, Elizabeth,Lukeman, Matthew
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p. 920 - 930
(2012/03/08)
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- Study of Electrochromism of Methoxyfluorene Compounds
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The electrochemical and electrochromic properties of a variety of polysubstituted fluorene compounds have been studied.The 2,7- and 2,3-dimethoxy, 2,3,6,7-tetramethoxy, and 2,3,4,5,6,7-hexamethoxyfluorenes are highly reversible electrochromic materials.One-electron oxidation of these materials yields deeply colored, stable radical cations.The structure-property relationships observed for the electrochemical and absorption behavior of these materials are discussed.
- Grant, Barbara,Clecak, N. J.,Oxsen, Michael
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p. 702 - 705
(2007/10/02)
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