1564-64-3Relevant articles and documents
Solvent effects on the formation and decay of an exciplex between the lowest excited singlet state of 9,10-dibromoanthracene and ground-state amine (N,N-dimethylaniline or triethylamine)
Nakayama, Toshihiro,Hamana, Tetsuya,Jana, Pallabi,Akimoto, Seiji,Yamazaki, Iwao,Hamanoue, Kumao
, p. 18431 - 18435 (1996)
Picosecond laser photolysis reveals the formation of an exciplex between the lowest excited singlet state [DBA*(S1)] of 9,10-dibromoanthracene (DBA) and ground-state amine in acetonitrile (CH3CN) and ethanol (EtOH) containing N,N-dimethylaniline (DMA) [and n-heptane (HP) containing DMA or triethylamine (TEA)]. Only in CH3CN-DMA, however, can decomposition of the DBA-DMA exciplex into the DBA radical anion (DBA.-) and the DMA radical cation be seen, indicating very small generation of DBA.- from the DBA-amine exciplex formed in EtOH-DMA and HP-amine (DMA or TEA). Interestingly, no DBA-TEA exciplex is formed in CH3CN and EtOH containing TEA but nanosecond laser photolysis reveals the existence of DBA.- in the former solvent. Furthermore, the rate of DBA → 9-bromoanthracene debromination upon steady-state photolysis in CH3CN-TEA is 1 order of magnitude smaller than that in CH3CN-DMA but 2 or 3 orders of magnitude greater than those in EtOH and HP containing amine. This suggests that diffusion-controlled quenching of DBA*(S1) by TEA in CH3CN and EtOH gives rise to the formation of a nonemissive short-lived encounter complex or ion pair. It thus be concluded that generation of DBA.- from the DBA-amine exciplex or the encounter complex (or the ion pair) is affected by the dielectric constant of a pure solvent.
Matsumoto et al.
, p. 358 (1974)
Construction of Donor-Acceptor Polymers via Cyclopentannulation of Poly(arylene ethynylene)s
Zhu, Xinju,Bheemireddy, Sambasiva R.,Sambasivarao, Somisetti V.,Rose, Peter W.,Torres Guzman, Rubicelys,Waltner, Amanda G.,Dubay, Kateri H.,Plunkett, Kyle N.
, p. 127 - 133 (2016)
A one-step postpolymerization modification that converts three high bandgap poly(arylene ethynylene)s into low bandgap donor-acceptor copolymers is described. The strategy relies on a palladium-catalyzed cyclopentannulation reaction between the main-chain ethynylene functionality and a small molecule aryl bromide (6-bromo-1,2-dimethylaceanthrylene). The reaction installs new cyclopenta[hi]aceanthrylene electron-accepting groups between the electron rich arylenes along the polymer backbone. The modified polymers include poly(9,9-didodecyl-fluorene-2,7-ethynylene), poly(9-dodecyl-carbazole-2,7-ethynylene), and poly(2,5-dioctyloxyphenylene-1,4-ethynylene). The functionalization efficiency was evaluated via isotopic 13C labeling of the polymeric ethynylene carbons and then monitoring the chemical environment of those carbons via NMR spectroscopy. Near complete conversion of the sp carbon species to sp2 carbon species was observed, which demonstrates the high efficiency of the modification strategy. Gel permeation chromatography shows that the hydrodynamic radius of the polymers is reduced considerably going from linear to kinked polymer morphology upon functionalization, and molecular dynamics simulations illustrate the underlying morphological change. The newly formed donor-acceptor polymers showed dramatically different optical and electrochemical properties from the precursor poly(arylene ethynylene) polymers. A new absorption band centered at ～650 nm represents a red-shift of >300 nm for the onset of absorption compared with that of precursor polymers and cyclic voltammetry shows two new low-lying reduction peaks that coincide with the cyclopenta[hi]aceanthrylene moiety.
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Bartlett et al.
, p. 1003 (1950)
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Bromination of phenyl ether and other aromatics with bromoisobutyrate and dimethyl sulfoxide
Li, Jia-Qin,Chen, Xiao-Hui,Wang, Xian-Xun,Cui, Hai-Lei
supporting information, (2021/09/09)
Bromoisobutyrate has been used for the first time as a general brominating source for the direct bromination of a diverse of simple phenyl ethers. Aromatic ethers bearing various substituents could be compatible in this reaction system delivering brominated arenes in moderate to good yields. The reaction system can also be expanded to bromination of phenols and unactivated arene. This process can be regarded as an alternative for the well-established bromination systems for bromoarene synthesis.
Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
, p. 2142 - 2150 (2020/03/11)
A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.
