- Synthesis of new anthracene derivatives
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An efficient synthesis is described for hexabromoanthracenes 3 and 4 by direct bromination of 9,10-dibromoanthrecene 2. Whereas base-induced elimination of hexabromide 3 with t-BuOK gave 2,3,9,10-tetrabromoanthracene 5, the reaction of hexabromide 4 with DBU afforded 1,3,9,10-tetrabromoanthracene 6 as the sole product. Tetrabromide 5 was also obtained by aromatization of 1,4-dinitroxy-2,3,9,10-tetrabromo-1,2,3,4-tetrahydroanthracene 17. Efficient and convenient synthetic routes are described for the preparation of dinotroxy 17, dimethoxy 23, and dihydroxides 18 and 19 with silver-induced substitution of hexabromides 3 and 4. The hydroxy compounds 19 and 18 were converted to diepoxide 20 and monoepoxide 21, respectively, with sodium methoxide. Base-promoted aromatization of dimethoxide 23 afforded dibromomonomethoxides 26 and 27. Bromoanthracenes and isomeric arene oxides constitute valuable precursors for the preparation of functionalized substituted anthracene derivatives that are difficult to prepare by other routes.
- Cakmak, Osman,Erenler, Ramazan,Tutar, Ahmet,Celik, Nuray
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- Unexpected photooxidation of H-bonded tetracene
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In our attempts of tuning the molecular packing of tetracene with H-bonding, we found that tetracenediamide was much more vulnerable to photooxidation than tetracene in crystals despite their similar sensitivity to photooxidation In solution. Unexpectedly photooxidation of tetracenediamide in solution and in crystals show different regioselectivities. To explain the regioselectivity, a mechanism Involving H-bonding is proposed. This study Indicates that molecular packing in solid state can play an important role In solid-gas reactions.
- Liang, Zhixiong,Zhao, Wei,Wang, Shenglong,Tang, Qin,Lam, Sheung-Chuen,Miao, Qian
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- Polybrominated anthracenes: Selective synthesis of tetrabromoanthracenes as precursors for the corresponding tetracyanoanthracenes
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Selective and efficient methods for the preparation of both 2,7,9,10-tetrabromoanthracene 11 and 2,6,9,10-tetrabromoanthracene 12 are described. Photobromination of 2,9,10-tribromoanthracene 8 resulted in the formation of only one stereoisomeric heptabromide 10. Whilst thermal aromatization of the trans,cis,trans-1,2,3,4,6,9,10-heptabromo-1,2,3,4- tetrahydroanthracene 10 gave mainly 2,6,9,10-tetrabromoanthracene 12, the pyridine-induced elimination yielded 2,7,9,10-tetrabromoanthracene 11 as the only final product. Tetrabromide 11 was transformed into 2,7,9,10- tetracyanoanthracene 14, by copper-assisted nucleophilic substitution reaction, as a potential photoconductive product.
- Akar, Kiymet Berkil,?akmak, Osman
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- Synthesis of monodisperse oligocarbazoles-functionalized anthracenes with intense blue-emitting
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New well-defined monodisperse oligocarbazoles-functionalized anthracenes An-OCZn (n = 1, 2, 3) have been synthesized through Suzuki cross-coupling reaction of the brominated oligocarbazoles and 9,10-bis(4,4,5,5-tetramethyl-1,3, 2-dioxaborolan-2-yl)anthracene. They show good solubility in organic solvents, including dichloromethane, chloroform, toluene, ethyl acetate, and tetrahydrofuran. It should be noted that, in the case of An-OCZn, the formation of the excimer based on anthracene unit is suppressed completely due to the introduction of oligocarbazoles in 9,10-position of anthracene so that an intense blue-emitting has been afforded. In addition, the obtained An-OCZn exhibit good electrochemical and thermal stabilities. Thus, the oligocarbazoles-functionalized anthracenes can be a class of promising candidates for novel blue-emitting materials employed in OLEDs or related devices.
- Zhan, Yong,Cao, Kaiyu,Xue, Pengchong,Lu, Ran
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- Synthesis and characterization of 9,10-[di-p-(7-diethylamino- coumarin-3-yl) thiopheneyl]anthracene as fluorescent material
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A novel N-coumarin derivative, namely 9,10-[di-p-(7-diethylamino-coumarin-3-yl) thiopheneyl]anthracene ((CTh)2A), containing anthracene as the core and 3-thiophene N-coumarin as the substituent was synthesized, and its structure was confirmed by 1H NMR and IR spectroscopies. The optical, electrochemical and thermal properties were investigated. Thermogravimetric analysis and PL spectra reveal the high thermal and good photoluminescence characteristics. The coumarin derivative exhibits blue photoluminescence with high fluorescence quantum yield in solution (up to 40%). The results show that the derivative would serve as promising organic light-emitting diode luminescent material.
- Luo, Qinglong,Zhang, Hui,Zhao, Yuling,Wang, Jun,Yu, Tianzhi
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- Intramolecular hydrogen bond-enhanced electroluminescence performance of hybridized local and charge transfer (HLCT) excited-state blue-emissive materials
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The hybridized local and charge transfer (HLCT) excited state is a successful strategy to produce both high external and internal quantum efficiencies. Based on the HLCT scheme, two isomeric donor-acceptor (D-A)-type excited-state intramolecular proton transfer (ESIPT) chromophores of o-hydroxyphenyl phenanthroimidazole (HPI)-based emissive molecules (mTAHPI and pTAHPI) and their OH-protected derivatives (pTAPI) were designed and explored for organic light-emitting diodes (OLEDs). The photophysical study and density functional theory (DFT) calculations revealed that all molecules possessed the HLCT excited-state characters without exhibiting ESIPT photophysical properties, whereas the nuclear magnetic resonance spectroscopy, single-crystal and physical property analyses discovered the existence of strong intramolecular H bonds and intermolecular interactions in both mTAHPI and pTAHPI. Consequently, their OLEDs displayed blue emissions with a narrow full width at half maximum (65-68 nm) and achieved excellent electroluminescence (EL) performance with a low turn-on voltage of 2.8 V. Particularly, pTAHPI-based devices showed the highest maximum external quantum effciency (EQE) of 8.13% with an ultra-high brightness of 18?100 cd m-2. The maximum singlet exciton utilization efficiency (ηs) of the device was estimated to be as high as 94%, which is among the best results of blue electroluminescence to our knowledge. This journal is
- Li, Wan,Chasing, Pongsakorn,Benchaphanthawee, Wachara,Nalaoh, Phattananawee,Chawanpunyawat, Thanyarat,Kaiyasuan, Chokchai,Kungwan, Nawee,Namuangruk, Supawadee,Sudyoadsuk, Taweesak,Promarak, Vinich
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- Bromodimethylsulfonium bromide: A brominating reagent for the conversion of anthracene into 9,10-dibromoanthracene
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Bromodimethylsulfonium bromide (BDMS) was used as an efficient brominating reagent for the synthesis of 9,10-dibromoanthracene in dichloromethane. The desired products were obtained in excellent yields.
- Zhang, Xin,Liu, Ju-Yan,Wang, Ying,Yue, Min-Min,Yuan, Bin
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- Molecular Scissoring: Facile 3D to 2D Conversion of Lanthanide Metal Organic Frameworks Via Solvent Exfoliation
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Five lanthanide MOFs with pcu topology have been exfoliated into nanoplatelets of two-dimensional structures via sonication in the dimethylacetamide solvent. These nanosheets are fluorescent under two-photon excitation dominated by the ligand, indicating energy upconversion ability.
- Quah, Hong Sheng,Ng, Li Ting,Donnadieu, Bruno,Tan, Geok Kheng,Vittal, Jagadese J.
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- Synthesis and photophysical processes of an anthracene derivative containing hole transfer groups
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A novel luminescent compound 9,10-di-(N-carbazovinylene)anthracene (DCVA) was synthesized by Heck reaction of 9,10-dibromoanthracene and N-vinylcarbazole. The structure was characterized by MS, 1H NMR and Elemental analysis. The photoluminescent properties of DCVA have been carefully investigated by UV-vis absorption and fluorescence emission spectra. The results showed that the luminescent quantum yield of DCVA was 0.73 in THF and it emitted blue-light with the band gap of 3.60 eV estimated from the onset absorption. In addition, the light-emission of DCVA can be quenched by electron acceptor (dimethyl terephthalate), however, the fluorescent intensities of DCVA were slowly increased with the addition of electron donor (N,N-dimethylaniline). Furthermore, the molecular interactions of DCVA with fullerene (C60) and carbon nanotubes (CNTs) were also investigated, which indicated the organic luminescent compound can be used as new fluorescent probe.
- Diao, Haipeng,Feng, Liheng
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- An improved procedure for the preparation of 9,10-dibromoanthracene
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An improved procedure is described for the dibromination of anthracene, affording 9,10-dibromoanthracene with yields >95%.
- Jones,Atherton
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- Multi-fold Sonogashira coupling: A new and convenient approach to obtain tetraalkynyl anthracenes with tunable photophysical properties
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For the first time, a direct single-step one-pot route to access nine new symmetric tetraalkynylated anthracenes via Pd(CH3CN)2Cl2/cataCXiumA catalyzed tetra-fold Sonogashira coupling is reported. Five of these tetraalkynylated anthracenes have been crystallographically characterized, with two of them exhibiting multiple interactions that significantly shorten the inter-planar distances in the solid-state structure. The rich photophysical properties exhibited by these molecules hold immense promise for future applications in sensors and optoelectronic devices. Two of the considered tetraalkynylated anthracenes comprising a D-π-A-π-D motif demonstrate solvatochromism and halochromism, with one of them showing a low bandgap of 1.79 eV. The remaining compounds demonstrate bandgaps in the range of 1.79-2.04 eV.
- Islam, Khadimul,Narjinari, Himani,Bisarya, Akshara,Kumar, Akshai
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p. 9692 - 9704
(2021/11/30)
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- Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
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Alkoxyamide has been reported as a catalyst for the activation ofN-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery of bromonium species from the bromine source to the substrates.
- Mondal, Haripriyo,Sk, Md Raja,Maji, Modhu Sudan
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supporting information
p. 11501 - 11504
(2020/10/12)
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- Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
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A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
- Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
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supporting information
p. 1621 - 1629
(2020/02/04)
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- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
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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.
- Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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p. 2142 - 2150
(2020/03/11)
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- Effect of thiophene substitution on the intersystem crossing of arene photosensitizers
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The effect of thienyl substitution on the intersystem crossing (ISC) of a few arenes was studied using steady state and time-resolved transient absorption and emission spectroscopies, as well as DFT/TDDFT computations. We found that the phenyl and thienyl substituents generally induce red-shifted absorptions for the chromophores, and the DFT/TDDFT computations show that the red-shifted absorption and emission are due to the increased HOMO and the reduced LUMO energy levels. Nanosecond transient absorption spectra indicate the formation of a triplet state, the triplet state lifetime is up to 282 μs, and the singlet oxygen quantum yields (ΦΔ) are up to 60%. DFT/TDDFT computations indicate that introducing the thienyl substituent alters the relative singlet/triplet excited state energy levels, and the energy level-matched S1/T2 states are responsible for the enhanced ISC of the thienyl compounds. This information is useful for the design of heavy atom-free triplet photosensitizers and for the study of the fundamental photochemistry of organic compounds.
- Sadiq, Farhan,Zhao, Jianzhang,Hussain, Mushraf,Wang, Zhijia
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p. 1794 - 1803
(2018/11/23)
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- Method for synthesizing bromo-polycyclic aromatic hydrocarbon compound
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The invention discloses a method for synthesizing bromo-polycyclic aromatic hydrocarbon compounds. The method comprises the following steps: utilizing a polycyclic aromatic hydrocarbon compound shown by a formula I as a substrate, adding base metal bromide into a mixed solution of water and an organic solvent, then slowly adding ZnAl-BrO3--LDHs, reacting for 4 to 8h under 25 to 55 DEG C and treating a reaction mixture by an aftertreatment process to obtain a mono bromo-polycyclic aromatic hydrocarbon compound shown by a formula II or a dual bromo-polycyclic aromatic hydrocarbon compound shown by a formula III after the reaction is finished. A substance amount ratio of the polycyclic aromatic hydrocarbon compound shown by the formula I to the base metal bromide to the ZnAl-BrO3--LDHs is 1 to (0.6 to 1.5) to (0.9 to 1.9). A brominating reagent utilized in the method disclosed by the invention is solid matter and is low in cost, easy to obtain and environmentally friendly. The method has the advantages of moderate reaction condition, convenience in aftertreatment, simpleness in reaction operation, high atom utilization rate, high selectivity, high target product yield and small side reaction. The three formulas are shown in the description.
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Paragraph 0054-0064
(2018/04/01)
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- The relationship between molecular structure and electronic properties in dicyanovinyl substituted acceptor-donor-acceptor chromophores
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In this contribution we describe a combined experimental and theoretical study of the relation between the molecular structure and the electronic properties of conjugated donor-acceptor type chromophores for light-harvesting applications. A series of model systems was synthesized where a central anthracene (electron donor) is connected to dicyanovinyl units (electron acceptor) through a π-conjugated spacer. The study of the redox and optical properties of these chromophores and of reference compounds without dicyanovinyl units allows us correlate the electronic properties to the presence of the electron withdrawing groups and the molecular conformation. Comparison with calculated electronic structure shows that the construction of chromophores that consist of electron donating and accepting units does not always follow the simple rules that are generally used in the design of such molecules. The results show a subtle relation between the charge transfer character and the geometry of the molecules. In some cases this leads to significant contribution of charge transfer excitation to the absorption spectra of some chromophores while such contributions are completely absent in others.
- Tarku?, Simge,Eelkema, Rienk,Grozema, Ferdinand C.
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p. 4994 - 5004
(2017/07/27)
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- Highly Luminescence Anthracene Derivatives as Promising Materials for OLED Applications
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Novel symmetrical anthracene derivatives with bulky carbazolyl-fluorene, diphenylamino-fluorene, or carbazolyl-carbazole units connected to the anthracene frame through an ethynyl bridge were synthesized in excellent yield by using Sonogashira cross-coupling. The ethynyl bridge in the anthracene dyes increases π-electron conjugation and the bulky substituents considerably attenuate intermolecular interactions. The dyes possess high thermal stability, tremendous solubility in common organic solvents, and especially high photoluminescence quantum yield (Φf) in solution in the range of 77–98 %. OLED devices were fabricated. The AFM images of thin films and blends prepared from all compounds show a uniform and flat surface, indicating excellent film-forming properties. Devices incorporating the anthracene derivative with diphenylamino-fluorene end-capping groups exhibited the highest value of current density (J). All of the fabricated OLED devices emitted yellowish-orange light under applied voltage.
- Slodek, Aneta,Filapek, Michal,Schab-Balcerzak, Ewa,Grucela, Marzena,Kotowicz, Sonia,Janeczek, Henryk,Smolarek, Karolina,Mackowski, Sebastian,Malecki, Jan Grzegorz,Jedrzejowska, Agnieszka,Szafraniec-Gorol, Grazyna,Chrobok, Anna,Marcol, Beata,Krompiec, Stanislaw,Matussek, Marek
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supporting information
p. 4020 - 4031
(2016/08/24)
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- 9,10-Dibromo-N-aryl-9,10-dihydro-9,10-[3,4]epipyrroloanthracene-12,14-diones: Synthesis and Investigation of Their Effects on Carbonic Anhydrase Isozymes I, II, IX, and XII
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N-substituted maleimides were synthesized from maleic anhydride and primary amines. 1,4-Dibromo-dibenzo[e,h]bicyclo-[2,2,2]octane-2,3-dicarboximide derivatives (4a-f) were prepared by the [4+2] cycloaddition reaction of dibromoanthracenes with the N-substituted maleimide derivatives. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the new derivatives were assayed against the human (h) isozymes hCA I, II, IX, and XII. All tested bicyclo dicarboximide derivatives exhibited excellent inhibitory effects in the nanomolar range, with Ki values in the range of 117.73-232.87 nM against hCA I and of 69.74-111.51 nM against hCA II, whereas they were low micromolar inhibitors against hCA IX and XII. A series of 9,10-dibromo-N-aryl-9,10-dihydro-9,10-[3,4]epipyrroloanthracene-12,14-diones (4a-f) were synthesized from N-substituted maleimide derivatives and 9,10-dibromoanthracene. Compounds 4a-f were assayed against human carbonic anhydrases (hCA) IX and XII, which are the two tumor-associated isozymes, and hCA I and II, which represent the most common off-targets for the development of selective anticancer CA inhibitors.
- G?ksu, Haydar,Topal, Meryem,Keskin, Ali,Gültekin, Mehmet S.,?elik, Murat,Gül?in, Ilhami,Tanc, Muhammet,Supuran, Claudiu T.
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p. 466 - 474
(2016/06/09)
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- Selective Halogenation Using an Aniline Catalyst
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Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent-based approach. Unfortunately, a suitable "catalytic" process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N-halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N-halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.
- Samanta, Ramesh C.,Yamamoto, Hisashi
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supporting information
p. 11976 - 11979
(2015/08/18)
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- H2O2-activated triplet-triplet annihilation upconversion via modulation of the fluorescence quantum yields of the triplet acceptor and the triplet-triplet-energy-transfer efficiency
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Oxidation-activatable triplet-triplet annihilation (TTA) upconversion was achieved with 9,10-bis(diphenylphosphino)-anthracene (BDPPA, nonfluorescent) as an activatable triplet acceptor/emitter, which can be oxidized to BDPPA-O (highly fluorescent) by H2O2 under mild conditions, and thus TTA upconversion was switched on by H2O2.
- Tao, Renjie,Zhao, Jianzhang,Zhong, Fangfang,Zhang, Caishun,Yang, Wenbo,Xu, Kejing
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supporting information
p. 12403 - 12406
(2015/08/03)
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- A practical lewis base catalyzed electrophilic chlorination of arenes and heterocycles
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A mild phosphine sulfide catalyzed electrophilic halogenation of arenes and heterocycles that utilizes inexpensive and readily available N-halosuccinimides is disclosed. This methodology is shown to efficiently chlorinate diverse aromatics, including simple arenes such as anthracene, and heterocycles such as indoles, pyrrolopyrimidines, and imidazoles. Arenes with Lewis acidic moieties also proved amenable, underscoring the mild nature of this chemistry. Lewis base catalysis was also found to improve several diverse aromatic brominations and iodinations.
- Maddox, Sean M.,Nalbandian, Christopher J.,Smith, Davis E.,Gustafson, Jeffrey L.
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supporting information
p. 1042 - 1045
(2015/03/30)
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- Photoactivatable anthracenes
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Fifteen substituted maleimide cycloadducts of anthracene derivatives were synthesized in one or two steps from available precursors in yields ranging from 32 to 63%. They differ in the nature of the group on the maleimide nitrogen atom and of the substituents on the anthracene platform. In all instances, the introduction of a maleimide bridge across positions 9 and 10 of the anthracene skeleton isolates electronically its peripheral phenylene rings and suppresses its characteristic fluorescence. The cycloadducts with a 4-(dimethylamino)phenyl group on the maleimide nitrogen atom undergo retro-cycloaddition upon ultraviolet illumination with quantum yields ranging from 0.001 to 0.01. This structural transformation restores the aromatic character of the central ring of the oligoacene chromophore and activates its emission with fluorescence quantum yields ranging from 0.07 to 0.85. Thus, this particular choice of building blocks for the construction of photoresponsive compounds can translate into viable operating principles for fluorescence activation and, ultimately, lead to the realization of valuable photoactivatable fluorophores for imaging applications.
- Thapaliya, Ek Raj,Captain, Burjor,Raymo, Francisco M.
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supporting information
p. 3973 - 3981
(2014/05/20)
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- Enhanced emission of a pyridine-based luminogen by hydrogen-bonding to organic and polymeric phenols
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Fluorescent bis(pyridinylvinyl)anthracene (An2Py) with two pyridine terminals was synthesized and used to prepare miscible blends with hydroxyl-containing components (organic bisphenol A (BPA) and polymeric poly(vinyl phenol) (PVPh)) through the facile intermolecular hydrogen-bond (H-bond) interactions between the pyridine and the hydroxyl functions. Before blending, the solution of An2Py already emits appreciably due to its aggregation-induced emission enhancement (AIEE) behavior; after blending with the hydroxyl components, the fluorescence can be further intensified due to the restricted molecular rotation, which leads to the blockage of non-radiative decay channels, imposed by the H-bond interactions. The role of the H-bonding on the restricted molecular rotation of the An2Py/BPA (and the An2Py/PVPh) blends was characterized by solution 1H NMR and solid infrared spectroscopy. The effectiveness of the organic BPA and the polymeric PVP as molecular anchors to lock the free rotation of the An2Py luminogen were compared and discussed in this study.
- Chien, Wei-Lun,Yang, Chih-Min,Chen, Tai-Lin,Li, Shu-Ting,Hong, Jin-Long
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p. 6930 - 6938
(2013/05/23)
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- The synthesis of anthracene, and dipyridine salts as cations for DMIT complexes
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The synthesis of a series of cations for the preparation of [Ni(dmit) 2]2 complexes is described. These cations are a series of 9,10-disubstituted anthracene derivatives with phosphane or alkylamine sustituents. Metal catalysed coupling reactions were used to prepare the 9,10-ethynylanthracene derivatives, one of which was subsequently methylated, using iodomethane as methylating reagent, to form cations for [Ni(dmit) 2]2-salts. A range of salts were prepared using ferrocene and anthracene-based cations with [Ni(dmit)2]2- as the dianion.
- Butler, Ian R.,Gerner, Pascal
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supporting information
p. 1 - 5
(2013/05/09)
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- Brominated methanes as photoresponsive molecular storage of elemental Br2
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The photochemical generation of elemental Br2 from brominated methanes is reported. Br2 was generated by the vaporization of carbon oxides and HBr through oxidative photodecomposition of brominated methanes under a 20 W low-pressure mercury lamp, wherein the amount and situations of Br2 generation were photochemically controllable. Liquid CH 2Br2 can be used not only as an organic solvent but also for the photoresponsive molecular storage of Br2, which is of great technical benefit in a variety of organic syntheses and in materials science. By taking advantage of the in situ generation of Br2 from the organic solvent itself, many organobromine compounds were synthesized in high practical yields with or without the addition of a catalyst. Herein, Br2 that was generated by the photodecomposition of CH2Br2 retained its reactivity in solution to undergo essentially the same reactions as those that were carried out with solutions of Br2 dissolved in CH 2Br2 that were prepared without photoirradiation. Furthermore, HBr, which was generated during the course of the photodecomposition of CH2Br2, was also available for the substitution of the OH group for the Br group and for the preparation of the HBr salts of amines. Furthermore, the photochemical generation of Br2 from CH2Br2 was available for the area-selective photochemical bleaching of natural colored plants, such as red rose petals, wherein Br2 that was generated photochemically from CH 2Br2 was painted onto the petal to cause radical oxidations of the chromophoric anthocyanin molecules. The generation of Br 2 from brominated methanes occurred upon photoirradiation under O2. The solutions that contained elemental Br2 were useful for the synthesis of organobromine compounds and the macroscopic photochemical bleaching of colored plants. Copyright
- Kawakami, Kazumitsu,Tsuda, Akihiko
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p. 2240 - 2252
(2012/11/06)
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- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
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Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
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p. 1673 - 1679
(2013/02/22)
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- Assessment of the LiX salt-effect in anthracenyl lithiums
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Based on lithium anthracenes RLi, the formation of mixed complexes from organolithiums and lithium salts RLi·LiX is illustrated. The [RLi(L)]2 dimers formed in presence of different donating solvents L as well as the corresponding mixed lithium bromide complexes [RLi(L)·LiX] were isolated and structurally characterized.
- Stern, Daniel,Finkelmeier, Nils,Stalke, Dietmar
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supporting information; experimental part
p. 2113 - 2115
(2011/04/14)
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- Fluorescent Zn2+ chemosensors, functional in aqueous solution under environmentally relevant conditions
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The synthesis and evaluation of two new ratiometric chemosensors for the quantification of potentially toxic free Zn2+ ions in aqueous solutions are described. Both sensors show high selectivity for Zn2+ over other cations, and are functional at environmentally relevant pH with detection limits of 0.05 μM for free Zn2+.
- Lee, Amanda E.,Grace, Michael R.,Meyer, Adam G.,Tuck, Kellie L.
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scheme or table
p. 1161 - 1165
(2010/04/25)
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- C-9 fluorenyl substituted anthracenes: A promising new family of blue luminescent materials
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Syntheses, optical, and electrochemical properties of novel C-9 fluorenyl substituted anthracenes linked by a tetrahedral sp3-hybridized carbon atom are reported for blue light emitting materials. Remarkably, an unoptimized organic light-emitting diode based on 1-fold fluorene-functionalized anthracene 3 exhibits a radiance of 4100 cd/m2 at 12 V and a maximum EL efficiency of 1.36 cd/A with color purity CIE x, y (0.157, 0.082), which is very close to the National Television System Committee standard blue.
- Wang, Jing,Wan, Wen,Jiang, Haizhen,Gao, Yan,Jiang, Xueyin,Lin, Huaping,Zhao, Weiming,Hao, Jian
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supporting information; experimental part
p. 3874 - 3877
(2010/11/18)
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- Synthesis and properties of blue-light-emitting anthracene derivative with diphenylamino-fluorene
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9,10-Bis-(9′,9′-diethyl-7′-diphenylamino-fluoren-2-yl) -anthracene was synthesized from 9.10-anthracene diboronic acid and (7-bromo-9,9-diethyl-fluoren-2-yl)-diphenyl-amine in a Suzuki coupling reaction. A?theoretical calculation of the three-dimensional structure suggests that it has a non-coplanar structure and inhibited intermolecular interactions. Upon excitation, the photoluminescence maximum of 9,10-bis-(9′,9′-diethyl-7′-diphenylamino-fluoren-2-yl) -anthracene in solution and film were at 454?nm (solution) and 462?nm (film). The full width at half maximum of 9,10-bis-(9′,9′-diethyl-7′-diphenylamino-fluoren-2-yl) -anthracene is 54?nm regardless of whether it is in a solution or a solid state. A multi-layered device using 9,10-bis-(9′,9′-diethyl-7′-diphenylamino-fluoren-2-yl) -anthracene as emitting material exhibits maximum quantum efficiency of 3.3% (power efficiency of 2.1?lm/W, current efficiency of 4.17?cd/A) and a blue Commission Internationale de l'Eclairage chromaticity coordinates (x?=?0.14, y?=?0.17).
- Park, Jong-Won,Kang, Pengtao,Park, Hyuntae,Oh, Hyoung-Yun,Yang, Jung-Hwan,Kim, Yun-Hi,Kwon, Soon-Ki
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scheme or table
p. 93 - 98
(2010/11/16)
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- Mild persubstitution of di- and tetrabrominated arenes with arylthiolate nucleophiles
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A mild selective protocol was used to prepare tetrakis(2-chlorophenylthio) anthracene from tetrabromoanthracene and sodium 2-chlorobenzenethiolate avoiding the thiolate self-attack. The uncatalyzed nucleophilic substitution of a series of mono-, di-, and tetrabrominated arenes by arylthiolate ions was attempted in mild conditions to investigate the scope of the substitution reaction regarding the size of the aromatic system as well as the number of bromine atoms. Successful reactions afforded only the persubstituted products in good purity and yield after a simple workup and chemoselectivity of Br versus Cl substituents was achieved for the tetrabromide.
- Del Rosso, Pablo G.,Almassio, Marcela F.,Bruno, Mattia,Garay, Raúl O.
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supporting information; body text
p. 6730 - 6733
(2011/02/25)
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- Electrophilic aromatic addition reaction (AdEAr) to anthracene
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After finding in a previous study that naphthalene and quinoline can react via electrophilic aromatic addition reaction (AdEAr), we applied this to anthracene. When anthracene was reacted with bromine in methanol in the presence of NaHCO3 and pyridine, 9,10-dihydro-9,10-dimethoxyanthracene (2) was obtained in 82% yield in the absence of substitution products or oxidative demethylation products like anthraquinone. The same reaction in ethanol produced 9,10-diethoxy-9,10-dihydroanthracene (9) in much lower yield (45%). In addition, we investigated the reactivity of addition product 2. Treatment of 2 with DDQ in benzene at 65 °C for 12 h produced 9,10-dimethoxyanthracene (3) in 62% yield, and 2 was rapidly transformed to 9-methoxyanthracene (4) in methanolic NaOH in 10 min. Moreover, the acid-catalyzed aromatization of 2 in 1-propanol at 75 °C for 10 min gave 9-n-propoxyanthracene (8) in 65% yield.
- Jang, Keun Sam,Shin, Hee Young,Chi, Dae Yoon
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p. 5666 - 5671
(2008/09/21)
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- A new ring bromination method for aromatic compounds under solvent-free conditions with NBS/Al2O3
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Alumina supported N-bromosuccinimide was found to be an efficient reagent for ring bromination of a number of aromatic compounds under solvent-free conditions. In the absence of the alumina the reactions are slow and some of the substrates are recovered unchanged. Under the reaction conditions aromatic oximes are converted into the corresponding carbonyl compounds. The method is simple, safe and rapid.
- Imanzadeh, Gholamhassan K.,Zamanloo, Mohammad R.,Eskandari, Habibollah,Shayesteh, Keyvan
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p. 151 - 153
(2007/10/03)
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- An intriguing effect of lithium perchlorate dispersed on silica gel in the bromination of aromatic compounds by N-bromosuccinimide
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A convenient and efficient procedure for electrophilic aromatic bromination has been developed by mixing of N-bromosuccinimide and an aromatic compound at room temperature on the surface of silica gel mixed with solid anhydrous LiClO4. All of the substrates examined underwent clean electrophilic aromatic bromination in reaction times of a few minutes to afford the corresponding bromoarenes under neutral conditions in excellent yield. In the case of thiophenol, no substitution reaction occurred, and the corresponding disulfide was obtained in excellent yield.
- Bagheri, Mojtaba,Azizi, Najmedin,Saidi, Mohammad R.
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p. 146 - 149
(2007/10/03)
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- PS-COD and PS-9-BBN: Polymer-supported reagents for solution-phase parallel synthesis
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(Chemical Equation Presented) 1,5-Cyclooctadiene was deprotonated under LICKOR conditions and reacted with Merrifield resin to afford an immobilized cyclooctadiene in high yield. This polymer is effective as a halogen scavenger, while hydroboration leads to a supported 9-BBN analogue. The latter exhibits similar regioselectivity to 9-BBN in olefin hydroboration.
- Revell, Jefferson D.,Doerner, Barbara,White, Peter D.,Ganesan
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p. 831 - 833
(2007/10/03)
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- Synthesis of unsymmetric anthracene compounds
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A process for forming an unsymmetric anthracene compound comprises a first step of forming a 9-perfluoroalkylsulfonate derivative of anthrone by reacting the anthrone with a perfluoroalkyl sulfonating agent, followed by a second step of contacting the reaction product with an aryl or heteroaryl boronic acid, ester or anhydride, and a palladium catalyst for a period of time sufficient to form an unsymmetric anthracene compound having at least one 9-position aromatic substituent.
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Page/Page column 8
(2010/02/14)
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- Oxidative halogenation of aromatic compounds with metal halides and sodium bismuthate
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A new mild and efficient method for aromatic halogenation with a wide variety of halides in the presence of sodium bismuthate NaBO3 in AcOH is reported. Metal halides of groups Ia, IIa, IIIa, IVa, Va, and the first row of transition elements are suitable for this method.
- Muathen, Hussni A.
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p. 164 - 168
(2007/10/03)
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- Photochemical reactions of hydroarenes with N-bromosuccinimide
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The photochemical reactions of 1,2,3,4-tetrahydronaphthalene (THN), 9,10-dihydrophenanthrene (DHP), 9,10-dihydroanthracene (DHA), and acenaphthene (AN) with N-bromosuccinimide (NBS) were investigated under N2 atmosphere at room temperature. The results show that the relative reactivities of the hydroarenes toward a photochemical reaction with NBS are THN DHP AN DHA, which is consistent with the stabilities of the radicals produced by benzylic hydrogen abstraction from the hydroarenes. Photochemical reactions of THN and DHP mainly afforded dehydrogenated products, while the photobrominations of the dehydrogenated products from AN and DHA with NBS proceeded readily.
- Zong, Zhi-Min,Zhang, Wei-Hong,Jiang, Qun,Lu, Jin,Wei, Xian-Yong
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p. 769 - 771
(2007/10/03)
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- Increasing the selectivity of bromination of aromatic compounds using Br2/SiO2
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Br2/SiO2 possessed considerable practical advantages over traditional reagents for the bromination of aromatic hydrocarbons, e.g., toluene, o-, m-, and p-xylene, anthracene and phenol. In the presence of SiO2, toluene reacted with bromine instantly. Compounds containing electron-donating substituents showed mainly bromination on the rings. The behavior of o-, m-, and p-xylene showed predominant substitution on the rings. The bromination of phenol to p-bromophenol showed good yield at 81%. Naphthalene was monobrominated to 1-bromonaphthalene with a yield of 84% in 2 has the potential to alter reaction selectivity. It may be able to switch a mechanism from radical to polar, or to influence the regioselectivity of the products formed. In the absence of SiO2, selectivity was lost and a mixture of products by substitution of bromine atom on the ring and on the side chain without any preferability was obtained. The nature of silica gel was important for the success of the reaction. Optimal results were obtained with silica gel dried at 250°C for 1 hr.
- Ghiaci,Asghari
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p. 1151 - 1152
(2007/10/03)
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- Halogenations of Anthracenes and Dibenz[a,c]anthracene with N-Bromosuccinimide and N-Chlorosuccinimide
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Halogenation of dibenz[a,c]anthracene (1) by NBS in CCl4 affords the products of 9- and 10-monobromination in the ratio of 9:1. The reaction is accelerated by iodine, and HBr effects rearrangement of 9-bromo product to the sterically less crowded 10-bromo isomer. The mechanism is proposed to involve reversible addition of Br2, followed by elimination of HBr. Reaction of NCS with 1 in CCl4 requires addition of HCl and affords exclusively 9-chlorination. The different reactivities of NBS and NCS are ascribed to the relative amounts of free halogen produced (due to differences in N-X bond strengths involving Br and Cl), and the different sizes of the halogens. Under similar conditions, NCS chlorinates 9-bromoanthracene (2a) to afford 9,10-dichloroanthracene and 9-bromo-10-chloroanthracene in the ratio of 65:35. This reaction ostensibly occurs by addition of Cl2 to 2a, followed by preferential loss of HBr rather than HCl. 9-Methylanthracene (3) affords exclusively 9-(bromomethyl)anthracene with NBS in the absence of iodine, but mainly (67%) 9-bromo-10-methylanthracene in the presence of iodine. Chlorination of 3 with NCS in the presence of HCl also affords mostly (65%) nuclear halogenation. Nuclear bromination of anthracene, 9-methylanthracene, and dibenz[a,c]anthracene by NBS in the absence of added HBr is accelerated by iodine. This effect is probably due to an increase in the amount of bromine produced from NBS in the presence of iodine.
- Duan, Shaoming,Turk, Jeff,Speigle, Joseph,Corbin, Jean,Masnovi, John,Baker, Ronald J.
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p. 3005 - 3009
(2007/10/03)
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- Regioselective bromination of organic substrates by tetrabutylammonium bromide promoted by V2O5-H2O2: An environmentally favorable synthetic protocol
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(matrix presented) Vanadium pentoxide very effectively promotes the bromination of organic substrates, including selective bromination of some aromatics, by tetrabutylammonium bromide in the presence of hydrogen peroxide; mild conditions, high selectivity, yield, and reaction rate, and redundancy of bromine and hydrobromic acid are some of the major advantages of the synthetic protocol.
- Bora, Upasana,Bose, Gopal,Chaudhuri, Mihir K.,Dhar, Siddhartha S.,Gopinath, Rangam,Khan, Abu T.,Patel, Bhisma K.
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p. 247 - 249
(2007/10/03)
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- An environmentally benign synthesis of organic ammonium tribromides (OATB) and bromination of selected organic substrates by tetrabutylammonium tribromide (TBATB)
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Stable crystalline organic ammonium tribromides (OATB), like Me4NBr3, Et4NBr3, Bu4NBr3, cetyltrimethylammonium tribromide, PyHBr3, can be readily synthesised from the reaction of the corresponding bromides with V2O5 and aqueous H2O2. Typically, TBATB, Bu4NBr3, brominates a variety of organic substrates rather easily under mild conditions. An activated aromatic ring is selectively brominated in the presence of an olefinic double bond.
- Chaudhuri, Mihir K.,Khan, Abu T.,Patel, Bhisma K.,Dey, Deepa,Kharmawophlang, Wancydora,Lakshmiprabha,Mandal, Gagan C.
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p. 8163 - 8166
(2007/10/03)
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- Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
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Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
- Liu, Lilian Kao,Lin, Ching-Shan
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- Regioselective Catalytic Halogenation of Arenes, mimicking Vanadium Haloperoxidase Reactions
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Ammonium metavanadate, mimicking vanadate dependent metalloenzymes, efficiently catalyses the halogenation of arenes in moderate to good yields using dilute hydrogen peroxide (30%) as an oxidizing agent, exhibiting remarkable regioselectivity.
- Hegde, Vishnumurthy R.,Pais, Godwin C. G.,Kumar, Rajiv,Kumar, Pradeep,Pandey, Bipin
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- Aryl Proton Transfer Reactions of 9-Arylanthracene and 9-Substituted Anthracene Radical Cations with 2,6-Di-tert-butylpyridine
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Radical cations of anthracenes with substituents at the 9-position (Br, CN, or NO2) or those of 9-arylanthracenes were observed to undergo proton transfer reactions with 2,6-di-tert-butylpyridine (TBP) to generate the corresponding anthracenyl radical.Under the same conditions 2,6-dimethylpyridine (LUT) undergoes combination reactions with the radical cations, and the proton transfer reactions could not be detected.The characteristic features of the reactions producing the anthracenyl radicals are as follows: (a) primary deuterium kinetic isotope effects are observed on substitution of the 10-H with 10-D, (b) the apparent Arrhenius activation energies vary from -2 to -11 kcal/mol, and (c) 10-Br-substituted anthracenes are formed during bromine atom abstraction from bromoform by the free radicals.The intermediate bromo derivatives are further oxidized under the reaction conditions.A two-step mechanism involving a reversible ?-complex formation followed by rate-determining proton transfer is proposed.The results of the reactions with TBP are compared to those obtained from the corresponding reactions of the radical cations with LUT.
- Xue, Jie-you,Parker, Vernon D.
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p. 6564 - 6566
(2007/10/02)
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- Nitrodibromoacetonitrile: An Agent for Bromination and for the Formation of Adducts Formally Derived from Cyanonitrocarbene
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The reactions of nitrodibromoacetonitrile (NDBA) with alkenes, aromatic compounds, amines, and sulphides have been studied.Products were formally derived from bromine or nitrocyanocarbene except for bis(2-bromocyclohexyl)nitroacetonitrile (13), an adduct (2:1) obtained from cyclohexene and NDBA. 2,3-Dimethylbut-2-ene was converted into 3-cyano-4,4,5,5-tetramethyl-4,5-dihydroisoxazole 2-oxide (15) and 2,3-dibromo-2,3-dimethylbutane (16). meso-1,2-Dibromo-1,2-diphenylethane was obtained from trans-stilbene.In a reaction catalysed by copper, benzene and NDBA gave benzoyl cyanide.From anthracene, phenol, and cupric acetylacetonate, 9,10-dibromoanthracene, 4-bromophenol, and cupric bromoacetylacetonate were obtained respectively.Dimethyl sulphide, tetrahydrothiophene, and triethylamine afforded the corresponding sulphonium-(30) and (31) and ammonium cyanomethylide-(33) derivatives and, with the latter, co-formation of triethylammonium bromide.Rationales for the reactions are discussed.
- Boyer, Joseph H.,Manimaran, Thanikavelu
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p. 1381 - 1385
(2007/10/02)
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- Electron Transfer Activation in the Thermal and Photochemical Osmylation of Aromatic EDA Complexes with Osmium(VIII) Tetroxide
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Various types of arenes (Ar) spontaneously form with osmium tetroxide a series of highly colored solutions of electron donor-acceptor or EDA complexes such as in nonpolar solvents.Charge-transfer or CT osmylation is simply effected by the actinic irradiation of the absorption bands (hνCT), and the molecular structures of the OsO4 adducts of benzene (B) and anthracene (A) are elucidated by X-ray crystallography.The metastable ion pair is established as the seminal intermediate in CT osmylation by time-resolved picosecond spectroscopy attendant upon the specific excitation of the EDA complex.According to Scheme II, the rapid collapse of the ion pair (eq 16) with a rate constant k ca. 1E9 s-1 represents the critical transformation in adduct formation.Importantly, this ion-pair mechanism accomodates (a) the osmylation of a wide range of arene donors from the mononuclear benzenes to the electron-rich polycyclic arenes (Table V) under the common umbrella of photoexcitation and (b) the profound effect on the regiochemistry of anthracene (Table VI) by subtle variations in solvent polarity.In the absence of deliberate irradiation (i.e., in the dark), the EDA complexes of OsO4 with electron-rich arenes, especially the polynuclear naphthalene, anthracene and phenanthrene, slowly undergo the direct thermal or DT osmylation to yield the same series of adducts.As such, there is a close relationship between the photoexcited state leading to CT osmylation and the activated complex in DT osmylation.Indeed the formation of the highly unusual adduct A by OsO4 addition to the terminal ring of anthracene binds in common the transition state for DT osmylation and the ion-pair collapse in CT osmylation.Thus the electron-transfer mechanism in Scheme IV employs the adiabatic ion pair (eq 20) to account for the same regiospecificities in DT osmylations.Such a unified view of arene osmylation can be extended to the promoted thermal or PT osmylation via the five-coordinate OsO4(py), as a commonly practiced for bis-hydroxylation of alkenes.
- Wallis, J. M.,Kochi, J. K.
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p. 8207 - 8223
(2007/10/02)
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