- Photochemical synthesis of pentacene and its derivatives
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A novel α-diketone precursor of pentacene, 6,13-dihydro-6,13- ethanopentacene-15, 16-dione, was prepared and converted successfully to pentacene in 74% yield by photolysis of the precursor in toluene: Irradiation of the diketone solution in toluene with light of 460 nm under an Ar atmosphere caused the solution to change from yellow to fluorescent orange-pink within a few minutes, after which, purple precipitates appeared. After 35 min, the solution changed to colorless and the purple precipitates were filtered to give pentacene in 74% yield. By contrast, in the presence of oxygen, the color of the solution changed from yellow to pale yellow, and only 6,13-endoperoxide of pentacene was quantitatively obtained. The rate of the reaction upon photolysis was measured by observing the decay of n-π* absorption of the precursor at 460 nm, and was found to be similar in both the presence and absence of oxygen. Therefore, the photoreaction of the α-diketone precursor seemed to occur via the singlet excited state. Because the T-T absorption of pentacene was observed upon photolysis of the precursor in the nanosecond transient absorption measurement under an Ar atmosphere, the excited triplet state of the pentacene generated singlet oxygen by sensitization, and it reacted with the ground-state pentacene to give the 6,13-endoperoxide. The α-diketone deposited on glass was also converted successfully to pentacene film by photoirradiation. In addition, diketone precursors of a mixture of 2,8- and 2,9-dibromopentacene and 2,6-trianthrylene were also prepared and their photocon-version was performed.
- Yamada, Hiroko,Yamashita, Yuko,Kikuchi, Makoto,Watanabe, Hikaru,Okujima, Tetsuo,Uno, Hidemitsu,Ogawa, Takuji,Ohara, Keishi,Ono, Noboru
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- Synthesis, structure, and photochemistry of 5,14-diketopentacene
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5,14-α-Diketopentacene, a structural isomer of 6,13-α- diketopentacene, was prepared from pentacene in three steps. In addition to the typical n-π* absorption of the diketone moiety at around 468 nm and the anthracene-like absorption at 333, 349, and 367 nm, a broad absorption was observed at around 386 nm, which could be assigned to an intramolecular charge-transfer absorption from anthracene to the diketone moiety. 5,14-α-Diketopentacene could be converted into pentacene quantitatively by photoirradiation at 405 and 468 nm in toluene with quantum yields of 2.3 and 2.4%, respectively, and these values are higher than the quantum yield of 1.4% obtained for 6,13-α-diketopentacene irradiated at 468 nm. The quantum yields in acetonitrile were lowered to 0.33 and 0.28% with irradiation at 405 and 468 nm. The crystal structure of 5,14-α-diketopentacene showed a CH-π interaction and π-π stacking between neighbouring anthracene and benzene moieties. The lower solubility of 5,14-α-diketopentacene compared with the 6,13-isomer could be explained by this crystal structure.
- Aotake, Tatsuya,Ikeda, Shinya,Kuzuhara, Daiki,Mori, Shigeki,Okujima, Tetsuo,Uno, Hidemitsu,Yamada, Hiroko
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- Pentacene precursors for solution-processed OFETs
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15-Acetoxy- and 15-hydroxy-6,13-dihydro-6,13-ethanopentacenes sublimed over 300 °C and no pentacene was formed below the temperature. The precursors bearing chlorinated epithiomethano bridges suffered complicated decomposition to give oligomeric pentacene derivatives. The precursor bearing an epithio-oxomethano bridge underwent smooth and clean conversion to pentacene by heat or light. An organic field-effect transistor fabricated by the spin-coating method of the precursor followed by light irradiation at 120 °C showed a good FET performance of μ=2.5×10-2 cm2 V -1 s-1 and on/off ratio=3.8×104.
- Uoyama, Hiroki,Yamada, Hiroko,Okujima, Tetsuo,Uno, Hidemitsu
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- A new type of soluble pentacene precursor for organic thin-film transistors
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A new type of soluble pentacene precursor is synthesized, which extrudes a unit of CO upon heating at 150°C, to produce pentacene in nearly quantitative yield. The Royal Society of Chemistry.
- Chen, Kew-Yu,Hsieh, Hsing-Hung,Wu, Chung-Chih,Hwang, Jiunn-Jye,Chow, Tahsin J.
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- Linear Acene Derivatives. New Routes to Pentacene and Naphthacene and the First Synthesis of a Triptycene with Two Anthracene Moieties
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The cycloaddition of o-xylylene to arene 1,4-endoxides was used to construct linear arene derivatives.For example, heating benzocyclobutene 4 with anthracene 1,4-endoxide (10) followed by dehydration and dehydrogenation gave pentacene in three steps and 64percent overall yield.An analogous sequence but with naphthalene 1,4-endoxides gave naphthacenes.Dehydration of the di adducts from 4 and anthracene 1,4:5,8-diendoxides (5) gave a mixture of 5,9,14,18- and 5,8,15,18-tetrahydroheptacenes 3 and 9.The previously unknown triptycene 2 was synthesized from 5,14-dihydropentacene (12), an intermediate in the new pentacene synthesis, in three steps and 29percent overall yield.
- Luo, Jihmei,Hart, Harold
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- Synthesis, stability, and photochemistry of pentacene, hexacene, and heptacene: A matrix isolation study
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The photochemical bisdecarbonylation of bridged α-diketones (Strating-Zwanenburg reaction) to give the oligoacenes pentacene (2), hexacene (3), and heptacene (4) is investigated in solid inert gas matrices at cryogenic temperatures. The photodecomposition
- Mondal, Rajib,Toenshoff, Christina,Khon, Dmitriy,Neckers, Douglas C.,Bettinger, Holger F.
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- An improved synthesis of pentacene: Rapid access to a benchmark organic semiconductor
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Pentacene is an organic semiconductor used in a variety of thin-film organic electronic devices. Although at least six separate syntheses of pentacene are known (two from dihydropentacenes, two from 6,13-pentacenedione and two from 6,13-dihydro-6,13-dihydroxypentacene), none is ideal and several utilize elevated temperatures that may facilitate the oxidation of pentacene as it is produced. Here, we present a fast (~2 min of reaction time), simple, high-yielding (≥90%), low temperature synthesis of pentacene from readily available 6,13-dihydro-6,13-dihydroxypentacene. Further, we discuss the mechanism of this highly efficient reaction. With this improved synthesis, researchers gain rapid, affordable access to high purity pentacene in excellent yield and without the need for a time consuming sublimation.
- Pramanik, Chandrani,Miller, Glen P.
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- A Large Starphene Comprising Pentacene Branches
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Starphenes are attractive compounds due to their characteristic physicochemical properties that are inherited from acenes, making them interesting compounds for organic electronics and optics. However, the instability and low solubility of larger starphene homologs make their synthesis extremely challenging. Herein, we present a new strategy leading to pristine [16]starphene in preparative scale. Our approach is based on a synthesis of a carbonyl-protected starphene precursor that is thermally converted in a solid-state form to the neat [16]starphene, which is then characterised with a variety of analytical methods, such as 13C CP-MAS NMR, TGA, MS MALDI, UV/Vis and FTIR spectroscopy. Furthermore, high-resolution STM experiments unambiguously confirm its expected structure and reveal a moderate electronic delocalisation between the pentacene arms. Nucleus-independent chemical shifts NICS(1) are also calculated to survey its aromatic character.
- Holec, Jan,Cogliati, Beatrice,Lawrence, James,Berdonces-Layunta, Alejandro,Herrero, Pablo,Nagata, Yuuya,Banasiewicz, Marzena,Kozankiewicz, Boleslaw,Corso, Martina,de Oteyza, Dimas G.,Jancarik, Andrej,Gourdon, Andre
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- Photogeneration and thermal generation of pentacene from soluble precursors for OTFT applications
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(Graph Presented) A CO adduct of pentacene with an unsymmetrical structure is synthesized; it is soluble and can be spin-coated into thin films. Pentacene is regenerated in near quantitative yield by either thermal or photoinduced elimination of CO. OTFT devices fabricated by this compound exhibit typical FET characteristics.
- Chuang, Ta-Hsien,Hsieh, Hsing-Hung,Chen, Chang-Ken,Wu, Chung-Chih,Lin, Chao-Chen,Chou, Pi-Tai,Chao, Ting-Han,Chow, Tahsin J.
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- Analysis of molecular aggregation states in pentacene thin films prepared from soluble precursor
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Molecular packing structure in pentacene films prepared from the Afzali's precursor soluble in general organic solvents was characterized by in-plane grazing-incidence X-ray diffraction (GIXD) measurements. The crystallographic ab plane of pentacene was parallel to the surface of a Si substrate. Crystal structure of pentacene near the substrate was identified as the thin-film phase. Copyright
- Akinaga, Takahiro,Yasutake, Shigekazu,Sasaki, Sono,Sakata, Osami,Otsuka, Hideyuki,Takahara, Atsushi
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- Synthesis and thermolysis of a Diels-Alder adduct of pentacene and thiophosgene
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Pentacene has excellent semi-conducting properties but its practical use in organic thin film transistors (OTFTs) gives rise to a lot of problems caused by its sensitivity to oxygen and its very low solubility. In order to solve the problems involved in the use of pentacene, we have synthesized a Diels-Alder adduct of pentacene with thiophosgene.
- Vets, Nathalie,Smet, Mario,Dehaen, Wim
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- Fast and inexpensive synthesis of pentacene with high yield using 6,13-pentacenequinone as precursor
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Pentacene is an important semiconductor in the field of organic electronics. In this work is presented an alternative synthesis procedure to obtain pentacene from 6,13-pentacenequinone as a precursor. Synthesis of pentacene was performed in two reactions, Diels-Adler cycloaddition of 6,13-pentacenequinone followed by 6,13-pentacenequinone reduction to pentacene, employing LiAlH4 as reducing agent. The products were characterized by Fourier Transform Infrared Spectroscopy (FTIR), 1H-Nuclear Magnetic Resonance Spectroscopy (1H-NMR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Ultraviolet–Visible Spectroscopy (UV-VIS). In this work, 6,13-pentacenequinone was synthetized with a high yield (55%) using an alternative method. The optimization process resulted in an overall reduction of reaction time while exhibiting high yield. The method presented here provides an affordable pentacene synthesis route with high purity, which can be further applied for research and development of organic electronic applications.
- Mota, María L.,Rodriguez, Bibiana,Carrillo, Amanda,Ambrosio, Roberto C.,Luque, Priscy A.,Mireles, Marcela,Vivaldo, Israel,Quevedo, Manuel A.
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- Preparation of a Key Tetraene Precursor for the Synthesis of Long Acenes
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The tetraene 7,7-dimethoxy-2,3,5,6-tetramethylenebicyclo[2.2.1]heptane is a key compound for the preparation of a large variety of acenes protected by a carbonyl bridge. We report herein a medium scale preparation in seven steps of this valuable starting material. Diels–Alder addition between 6,6-dimethtyl fulvene and maleic anhydride, followed by carboxylation, ozonolysis of the double bond, reduction of the four ester groups, then chlorination of the alcohol groups and dehydrochlorination give the target compound in 17 % overall yield.
- ?ámal, Michal,Cisa?ová, Ivana,Gourdon, André,Hung, Nguyen Khanh,Jancarik, Andrej,Levet, Gaspard,Rybá?ek, Ji?í
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- Photo precursor for pentacene
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6,13-Dihydro-6,13-ethanopentacene-15,16-dione gave pentacene efficiently both in solid and in solution by irradiation of light.
- Uno, Hidemitsu,Yamashita, Yuko,Kikuchi, Makoto,Watanabe, Hikaru,Yamada, Hiroko,Okujima, Tetsuo,Ogawa, Takuji,Ono, Noboru
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- Solution processed high performance pentacene thin-film transistors
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High performance thin-film transistors were fabricated using a new precursor of pentacene through a multiple spin-heat procedure. High quality pentacene thin films can be prepared by this method and hence a FET device can be made in a top-contact configuration. The device exhibited a remarkable field-effect mobility of 0.38 cm2 V-1 s-1 with an on/off ratio of 106.
- Chao, Ting-Han,Chang, Ming-Jen,Watanabe, Motonori,Luo, Ming-Hui,Chang, Yuan Jay,Fang, Tzu-Chien,Chen, Kew-Yu,Chow, Tahsin J.
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- Thermal generation of pentacene from soluble precursors through expulsion of carbon dioxide
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Highly soluble pentacene precursors possessing ketal bridges across the rings were synthesized. Pure pentacene was produced through thermal dissociation, while carbon dioxide and ethylene were extruded as volatile fragments. Thin solid film of pentacene c
- Huang, Hsin-Hui,Hsieh, Hsing-Hung,Wu, Chung-Chih,Lin, Chao-Chen,Chou, Pi-Tai,Chuang, Ta-Hsien,Wen, Yuh-Sheng,Chow, Tahsin J.
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- Solvent Modulation of Aromatic Substituent Effects in Molecular Balances Controlled by CH-π Interactions
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CH-π aromatic interactions are ubiquitous in nature and are capable of regulating important chemical and biochemical processes. Solvation and aromatic substituent effects are known to perturb the CH-π aromatic interactions. However, the nature by which the two factors influence one another is relatively unexplored. Here we demonstrate experimentally that there is a quantitative correlation between substituent effects in CH-π interactions and the hydrogen-bond acceptor constants of the solvating molecule. The CH-π interaction energies were measured by the conformational study of a series of aryl-substituted molecular balances in which the conformational preferences depended on the relative strengths of the methyl and aryl CH-π interactions in the folded and unfolded states, respectively. Due to the favorable methyl-aromatic interactions, the balances were found to exist predominantly in the folded state. The observed substituent effect in the conformational preferences of the balances was controlled by the explicit solvation/desolvation of the aryl proton. The interpretation of the conformational free energy as a function of substituents and solvation using Hunter's solvation model revealed that a linear relationship exists between the sensitivity of aromatic substituent effects (i.e., the ρ values derived from Hammett plots) and the hydrogen-bond acceptor propensity (βs) of the solvent molecule: ρ = 0.06βs - 0.04.
- Emenike, Bright U.,Spinelle, Ronald A.,Rosario, Ambar,Shinn, David W.,Yoo, Barney
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- Alpha-diimine ligand compound, complex and preparation method of polyolefin lubricating oil base oil
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The present invention provides an alpha-diimine ligand compound having a structure represented by a formula (I), and further provides an alpha-diimine complex obtained from the ligand compound. In addition, the invention also provides a preparation method of polyolefin lubricating oil base oil taking the alpha-diimine complex as a catalyst and the prepared lubricant base oil. According to the ligand compound and the complex provided by the invention, a large steric hindrance group is introduced into a ligand skeleton, and the skeleton rigidity is increased, so that the chain walking capabilityof the complex as a catalyst is improved. The polyolefin lubricating oil base oil provided by the invention has high long-chain branch content and branching degree, can be used as medium-high viscosity lubricating oil base oil, simplifies the production process, reduces the production cost, is very suitable for industrial-scale production, and has excellent economic and social benefits.
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Paragraph 0155-0158
(2020/07/24)
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- Synthetic method of pentacene and derivative thereof
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The invention belongs to the field of organic synthesis and particularly relates to a synthetic method of pentacene and a derivative thereof. The synthetic method provided by the invention comprises the following steps: starting from an o-methylbenzaldehyde compound and a p-(di)iodobenzene compound which are simple and easy to obtain, firstly synthesizing 2,2'-(1,4-phenylene bis(methylene) dibenzaldehyde and 2,2'-(1,3-phenylene bis(methylene)) dibenzaldehyde compounds through direct arylation reaction of transition metal palladium-catalyzed temporary guiding group-guided benzyl C(sp3)-H; thengenerating benzene cyclization reaction of an aromatic aldehyde compound in a 1,1,1,3,3,3-hexafluoroisopropanol solvent by using a Lewis acid catalyst to obtain the pentacene and the derivative thereof. The synthetic method provided by the invention is less in step, simple and easy to implement, readily-available in raw materials involved, mild in reaction condition and higher in yield.
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Paragraph 0036-0037
(2018/07/06)
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- Evaluation of semiconducting molecular thin films solution-processed via the photoprecursor approach: The case of hexyl-substituted thienoanthracenes
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Organic electronic devices are expected to be easily scalable and highly cost-effective, presuming the good solution processability of high-performance organic semiconductors. However, there are cases where an organic compound with promising semiconducting properties lacks adequate processability and does not form well-performing thin films through conventional solution-based deposition techniques. The photoprecursor approach, in which a soluble photoprecursor is solution-deposited on a substrate and then converted to a target material by in situ photoreaction, can be an effective means to evade such a problem. Herein, we describe a comparative evaluation of thin films deposited by three different methods; i.e., vacuum deposition, photoprecursor approach, and direct spin coating. Two highly crystalline molecular semiconductors, hexyl-substituted anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (C6-ATT) and anthra[1,2-b:5,6-b′]dithiophene (or bent anthradithiophene, C6-BADT), are employed in this study along with the corresponding newly synthesized α-diketone-type photoprecursors. In the case of C6-ATT, thin films prepared through the photoprecursor approach are as good as those obtained by vacuum deposition in terms of surface smoothness and space-charge-limited-current (SCLC) mobility, while direct spin coating affords highly inhomogeneous films. For C6-BADT, on the other hand, employment of the photoprecursor approach is not as effective, albeit it is still advantageous as compared to direct spin coating. These results highlight the power and limitations of the photoprecursor approach, and will serve as a basis for the preparation of practically useful organic devices through this unique approach.
- Quinton, Cassandre,Suzuki, Mitsuharu,Kaneshige, Yoshitaka,Tatenaka, Yuki,Katagiri, Chiho,Yamaguchi, Yuji,Kuzuhara, Daiki,Aratani, Naoki,Nakayama, Ken-Ichi,Yamada, Hiroko
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p. 5995 - 6005
(2015/06/16)
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- Synthesis and optical reactivity of 6,13-α-diketoprecursors of 2,3,9,10-tetraalkylpentacenes in solution, films and crystals
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Tetraalkylpentacenes having alkyl chains at 2,3,9,10-positions (Et-PEN, Pr-PEN and Hex-PEN) were prepared from their precursors Et-PDK, Pr-PDK and Hex-PDK, respectively. Photoreactions proceeded both in solutions, thin-films, and crystals, thus the properties of Et-PDK in films can be studied despite the instability of the pentacenes in solution. Et-PEN showed significantly different aggregation-nature compared with the parent pentacene. The hole mobilities of Et-PEN and Pr-PEN in films were 3.4 × 10-6 and 8.1 × 10-7 cm2 V-1 s-1, respectively, determined by space-charge-limited current measurement, comparable with the order 10-6 cm2 V-1 s-1 of the electron mobility of Alq3.
- Katsuta, Shuhei,Saeki, Hiroyuki,Tanaka, Katsuki,Murai, Yuki,Kuzuhara, Daiki,Misaki, Masahiro,Aratani, Naoki,Masuo, Sadahiro,Ueda, Yasukiyo,Yamada, Hiroko
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p. 986 - 993
(2014/02/14)
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- SYNTHESIS AND APPLICATIONS OF SOLUBLE PENTACENE PRECURSORS AND RELATED COMPOUNDS
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The present disclosure relates to methods and systems for synthesis of bridged-hydropentacene, hydroanthracene and hydrotetracene from the precursor compounds pentacene derivatives, tetracene derivatives, and anthracene derivatives. The invention further relates to methods and systems for forming thin films for use in electrically conductive assemblies, such as semiconductors or photovoltaic devices.
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- Thermal generation of pentacenes from soluble 6,13-dihydro-6,13- ethenopentacene precursors by a Diels-Alder-retro-Diels-Alder sequence with 3,6-disubstituted tetrazines
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3,6-Substituted tetrazines 2 (a: R2 = 2-pyridyl or b: CO 2Me) react with 2,3,9,10-(R1)4-dihydro-6,13- ethenopentacene 3 in solution at elevated temperature to the corresponding pentacene 1 (a: R1 = H, b: OBn, c: F).
- Bula, Rafael P.,Oppel, Iris M.,Bettinger, Holger F.
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experimental part
p. 3538 - 3542
(2012/06/15)
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- Compounds comprising a linear series of five fused carbon rings, and preparation thereof
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The present application discloses methods for the production of organic compounds comprising a linear series of five fused carbon rings. Such compounds are useful in the production of electronic components, devices and materials. For example the methods disclosed permit the production of 2,9- and 2,10-disubstituted pentacene compounds that present particularly advantageous properties for the manufacture of semiconductor materials, or ink jet fabrication, and may be used in devices such as for example thin film transistors and solar cells. Also disclosed are compounds that are excellent candidates for use in the manufacture of semiconductor materials, and other components of electronic systems, by virtue of their solubility, crystal packing geometries, and electronic properties.
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- Process for preparing pentacene derivatives
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A process for preparing substituted pentacene compounds comprises the step of cyclizing substituted bis(benzyl)phthalic acids using an acid composition comprising trifluoromethanesulfonic acid, the substituted bis(benzyl)phthalic acids being represented by the following general formulas: wherein each R (that is, each of the groups R1 through R8) is independently an electron-donating group, a halogen atom, a hydrogen atom, or a combination thereof.
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- NEW BICYCLO COMPOUND, METHOD FOR PRODUCING FUSED AROMATIC COMPOUND USING THE SAME AND METHOD FOR FORMING FILM OF THE SAME
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There is provided a method for producing highly purified fused aromatic ring compounds with high yield by a simpler method. A method for producing a fused aromatic ring compound comprising irradiating the bicyclo compound containing at least one bicyclo ring represented by formula (1) in a molecule with light to detach a leaving group X from a residual part to form an aromatic ring: wherein R1 and R3 each denotes a group to form an aromatic ring or a heteroaromatic ring which may be substituted, together with a group to which each thereof is bonded; R2 and R4 each denotes a hydrogen atom, an alkyl group, an alkoxy group, an ester group or a phenyl group; and X is a leaving group, which denotes a carbonyl group or -N=.
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- Studies in the Cycloproparene Series: Electron Transfer Induced Dimerizations of Cyclopropanaphthalene
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Attempts to characterize the radical anion from 1H-cyclopropanaphthalene (1) by conventional electron transfer techniques has led instead to detection of the pentacene radical anion (10).- and the pentaphene analogue (11).- by ENDOR spectroscopy.Reactions of (1) with potassium in tetrahydrofuran on a preparative scale depend upon the surface, and 6,13-dihydropentacene (8), 6,7-dihydropentaphene (9), pentacene (10), 2-methylnaphthalene (12) and 1,2-di(2'-naphthyl)ethane (13) are formed.
- Cooney, Mark J.,Halton, Brian,Baumgarten, Martin,Gherghel, Lileta
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p. 1167 - 1174
(2007/10/02)
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- Effects of Substituents and Solvents on the Electronic Spectra of 9,10-Dihydro-9,10-o-benzenoanthracene-1,4-diones: Intramolecular Charge Transfer
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Electronic spectra of substituted 9,10-dihydro-9,10-o-benzenoanthracene-1,4-diones (triptycenequinones) in various solvents and that of benzo- and dibenzotriptycenequinones were investigated in this paper.Intramolecular charge-transfer (CT) bands were observed in triptycenequinone system as a result of intramolecular interaction between benzene ring and benzoquinone moiety.Substituents on the benzene rings strongly affected the CT bands.Electron-donating groups gave absorption maxima at long wavelength.Naphthalene ring gave similar but stronger CT bands than benzene ring.Hammett ?+ value of substituents gave good linear relationship with the energy of the CT bands.Calculations of reduced charge matrix of triptycenequinones by extended Hueckel theory showed the charge of aromatic ring(s) were transferred to benzoquinone moiety accompanying HOMO-LUMO excitation.Especially, absorption maxima of the methyl-substituted triptycenequinones gave good correlation with the amounts of charge transferred from benzene ring to benzoquinone moiety.These analysis confirmed clearly CT character of the absorption maxima of triptycenequinones.However, solvent effect of these CT bands maxima is not so clear as the substituent effect.
- Kitaguchi, Nobuya
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p. 800 - 807
(2007/10/02)
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- Isobenzofuran-Aryne Cycloadducts: Formation and Regioselective Conversion to Anthrones and Substituted Polycyclic Aromatics
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Several substituted anthracenes, benzanthracenes, dibenzanthracene, and more complex ring system derivatives are formed by the cycloaddition of 1,3-bis(trimethylsilyl)isobenzofuran (2) with arynes generated by LTMP-induced dehydrohalogenation of readily accessible haloaromatics.The cycloadducts undergo a novel acid-induced conversion to anthracenones.For several substrates this reaction is highly regioselective, allowing position specific introduction of another substituent at this stage.Reduction/dehydration of the anthrones provides an expeditious route to various polycyclic aromatic hydrocarbons.
- Netka, Jill,Crump, Stephen L.,Rickborn, Bruce
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p. 1189 - 1199
(2007/10/02)
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- TRANSFORMATIONS THERMIQUES DES PHOTOOXYDES MESO DES ACENES-VI. CAS DES PHOTOOXYDES DE PENTACENES
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Thermolysis of the meso-pentacenic photooxides 1P, 1dP and 1tP, in solution, brings about various isomerizations which appear strongly affected by the phenyl substituents.Thus the pentacene photooxide 1P gives only the bicyclic acetal 9P, beside pentacenequinone 5P in high ratio.With the photooxides 1dP of 6,13-diphenylpentacene and 1tP of 5,7,12,14-tetraphenylpentacene, the main products are the naphthocyclobutenic diethers 8dP and 8tP, which are formed in competition with the bicyclic acetals 9dP and 9tP and, in the first case, with an isomer of a new kind, the bis-naphthofuranic diether 13dP.These discrepancies are interpreted in terms of the effect of phenyl groups on the successive steps of the previously established isomerization process of meso-acenic photooxides. Comparative analysis of the chemical shifts of the central carbon atoms, in (13)C NMR, allows the unambiguous assignment of the structure of each isomer.
- Sparfel, D.,Gobert, F.,Rigaudy, J.
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p. 2225 - 2235
(2007/10/02)
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