- Electron Acceptors Based on Cyclopentannulated Tetracenes
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New cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) based on tetracene have been prepared by a palladium-catalyzed cyclopentannulation reaction. The new compounds have low-energy lowest unoccupied molecular orbitals (LUMOs) and relatively small band gaps. The photooxidative stability was intermediate to previously prepared CP-PAHs based on anthracene and pentacene as found in traditional acene stabilities. Scholl cyclodehydrogenation of pendant aryl groups led to materials that quickly formed endoperoxide products.
- Kulkarni, Gajanan C.,Morales-Cruz, Jean L.,Hussain, Waseem A.,Garvey, Ian J.,Plunkett, Kyle N.
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p. 2572 - 2576
(2018/11/30)
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- Straightforward Synthesis of 2- and 2,8-Substituted Tetracenes
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A simple regiospecific route to otherwise problematic substituted tetracenes is described. The diverse cores (E)-1,2-Ar1CH2(HOCH2)C=C(CH2OH)I (Ar1=Ph, 4-MePh, 4-MeOPh, 4-FPh) and (E)-1,2-I(HOCH2)C=C(CH2OH)I, accessed from ultra-low cost HOCH2C≡CCH2OH at multi-gram scales, allow the synthesis of diol libraries (E)-1,2-Ar1CH2(HOCH2)C=C(CH2OH)CH2Ar2 (Ar2=Ph, 4-MePh, 4-iPrPh, 4-MeOPh, 4-FPh, 4-BrPh, 4-biphenyl, 4-styryl; 14 examples) by efficient Negishi coupling. Copper-catalysed aerobic oxidation cleanly provides dialdehydes (E)-1,2-Ar1CH2(CHO)C=C(CHO)CH2Ar2, which in many cases undergo titanium(IV) chloride-induced double Bradsher closure, providing a convenient method for the synthesis of regiochemically and analytically pure tetracenes (12 examples). The sequence is typically chromatography-free, scalable, efficient and technically simple to carry out.
- Woodward, Simon,Ackermann, Miriam,Ahirwar, Saurabh K.,Burroughs, Laurence,Garrett, Mary Robert,Ritchie, John,Shine, Jonathan,Tyril, Bj?rk,Simpson, Kevin,Woodward, Peter
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supporting information
p. 7819 - 7824
(2017/06/06)
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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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- Benzannulation via ruthenium-catalyzed diol-diene [4+2] cycloaddition: One- and two-directional syntheses of fluoranthenes and acenes
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A new benzannulation protocol is described and applied to the synthesis of polycyclic aromatic hydrocarbons. Ruthenium(0)-catalyzed diol-diene [4+2] cycloaddition delivers cyclohex-1-ene-4,5-diols, which are subject to aromatization upon dehydration or Nicholas diol deoxydehydration. Employing diol and tetraol reactants, benzannulation can be conducted efficiently in one- and two-directional modes, respectively, as illustrated in the construction of substituted fluoranthenes and acenes.
- Geary, Laina M.,Chen, Te-Yu,Montgomery, T. Patrick,Krische, Michael J.
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supporting information
p. 5920 - 5922
(2014/05/20)
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- Photochemical synthesis of naphthacene and its derivatives for irreversible photo-responsive fluorescent molecules
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Highly fluorescent naphthacene derivatives and their photoconvertible precursors were synthesized for irreversibly photo-responsive fluorescent molecules. The fluorescence quantum yields (Φf) of the precursors were less than 0.02, and the precu
- Aotake, Tatsuya,Yamashita, Yuko,Okujima, Tetsuo,Shirasawa, Nobuhiko,Jo, Yukari,Fujimori, Shigeo,Uno, Hidemitsu,Ono, Noboru,Yamada, Hiroko
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p. 1790 - 1793
(2013/05/09)
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- Molecular tunnel junctions based on π-conjugated oligoacene thiols and dithiols between Ag, Au, and Pt contacts: Effect of surface linking group and metal work function
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The tunneling resistance and electronic structure of metal-molecule-metal junctions based on oligoacene (benzene, naphthalene, anthracene, and tetracene) thiol and dithiol molecules were measured and correlated using conducting probe atomic force microscopy (CP-AFM) in conjunction with ultraviolet photoelectron spectroscopy (UPS). Nanoscopic tunnel junctions (~10 nm2) were formed by contacting oligoacene self-assembled monolayers (SAMs) on flat Ag, Au, or Pt substrates with metalized AFM tips (Ag, Au, or Pt). The low bias (0 exp(βs), where R0 is the contact resistance and β is the tunneling attenuation factor. The R0 values for oligoacene dithiols were 2 orders of magnitude less than those of oligoacene thiols. Likewise, the β value was 0.5 per ring (0.2 A-1) for the dithiol series and 1.0 per ring (0.5 A-1) for the monothiol series, demonstrating that β is not simply a characteristic of the molecular backbone but is strongly affected by the number of chemical (metal-S) contacts. R0 decreased strongly as the contact work function (Φ) increased for both monothiol and dithiol junctions, whereas β was independent of Φ within error. This divergent behavior was explained in terms of the metal-S bond dipoles and the electronic structure of the junction; namely, β is independent of contact type because of weak Fermi level pinning (UPS revealed EF - EHOMO varied only weakly with Φ), but R0 varies strongly with contact type because of the strong metal-S bond dipoles that are responsible for the Fermi level pinning. A previously published triple barrier model for molecular junctions was invoked to rationalize these results in which R0 is determined by the contact barriers, which are proportional to the size of the interfacial bond dipoles, and β is determined by the bridge barrier, E F - EHOMO. Current-voltage (I-V) characteristics obtained over a larger voltage range 0-1 V revealed a characteristic transition voltage Vtrans at which the current increased more sharply with voltage. Vtrans values were generally >0.5 V and were well correlated with the bridge barrier EF - EHOMO. Overall, the combination of electronic structure determination by UPS with length- and work function-dependent transport measurements provides a remarkably comprehensive picture of tunneling transport in molecular junctions based on oligoacenes.
- Kim, Bongsoo,Choi, Seong Ho,Zhu,Frisbie, C. Daniel
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supporting information; experimental part
p. 19864 - 19877
(2012/01/31)
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- A reiterative approach to 2,3-disubstituted naphthalenes and anthracenes
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(formula presented) Simple bis(bromoethynyl)arenediynes are easily prepared by the desilylative halogenation of the corresponding trimethylsilyl derivatives. Cycloaromatization of these halogenated enediynes leads to the otherwise difficult to prepare 2,3-dibromoarenes in good yield. Alkynylation of the resulting haloaromatic compound regenerates the soluble enediyne system, homologated by one aromatic ring. This iterative methodology can be terminated by the cycloaromatization of the unsubstituted enediyne, providing the simple acene hydrocarbon.
- Bowles, Daniel M.,Anthony, John E.
-
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- Kinetics of the reduction of dialkyl peroxides. New insights into the dynamics of dissociative electron transfer
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The concerted dissociative reduction of di-tert-butyl peroxide (DTBP), dicumyl peroxide (DCP), and di-n-butyl peroxide (DNBP) is evaluated by both heterogeneous and homogeneous electron transfer using electrochemical methods. Electrochemical and thermochemical determination of the O-O bond energies and the standard potentials of the alkoxyl radicals allow the standard potentials for dissociative reduction of the three peroxides in N,N-dimethylformamide and acetonitrile to be evaluated. These values allowed the kinetics of homogeneous ET reduction of DTBP and DCP by a variety of radical anion donors to be evaluated as a function of overall driving force. Comparison of the heterogeneous ET kinetics of DTBP and DNBP as a function of driving force for ET allowed the distance dependence on the reduction kinetics of the former to be estimated. Results indicate that the kinetics of ET to DTBP is some 0.8 order of magnitude slower in reactivity than DNBP because of a steric effect imposed by the bulky tert-butyl groups. Experimental activation parameters were measured for the homogeneous reduction of DTBP with five mediators, covering a range of 0.4 eV in driving force over the temperature range -30 to 50°C in DMF. The temperature dependence of the kinetics leads to unusually low preexponential factors for this series. The low preexponential factor is interpreted in terms of a nonadiabatic effect resulting from weak electronic coupling between the reactant and product surfaces. Finally, the data are discussed in the context of recent advances of dissociative electron transfer reported by Saveant and by German and Kuznestov. In total the results suggest that these peroxides undergo a nonadiabatic dissociative electron transfer and represent the first reported class of compounds where this effect is reported.
- Donkers, Robert L.,Maran, Flavio,Wayner, Danial D. M.,Workentin, Mark S.
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p. 7239 - 7248
(2007/10/03)
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- Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
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The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
- Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
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p. 2301 - 2307
(2007/10/03)
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- Indirect Electrochemical Reduction of Some Peroxide Derivatives
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Indirect reduction of derivatives of tert-butyl hydroperoxide by means of aromatic radical anions in DMF results in the formation of tert-butoxy radicals, which abstract a hydrogen atom from DMF.The N,N-dimethylaminocarbonyl radical may couple with the radical anion or be reduced by it; from this competition the reduction potential of the N,N-dimethylaminocarbonyl radical is estimated to be -1.62 V (SCE).
- Kjaer, Niels Them,Lund, Henning
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p. 848 - 852
(2007/10/02)
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- The Nucleophilicity of Superoxide towards Different Alkyl Halides Estimated from Kinetic Measurements
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Values of the rate constant ksub are measured for the substitution reaction between superoxide O2 anion-radical and the alkyl halides butyl chloride, 2-butyl chloride, benzyl chloride, ethyl bromide, butyl bromide, 2-butyl bromide, neopentyl bromide, benzyl bromide, (1-bromo-2,2-dimethylpropyl)benzene and 1-iodoadamantane.These rate constants are compared with the expected rate constant kET for the electron transfer reaction between the same alkyl halides and an aromatic anion radical A anion-radical with the same standard oxidation potential as O2 anion-radical.The ksub/kET ratios show that the mechanism of the substitution reaction amy shift from SN2-like to ET-like on changes in the steric hindrance and the acceptor ability of the alkyl halide.The influence on ksub/kET of the difference in self-exchange reorganization energy λ(0) between O2 anion-radical/O2 and A anion-radical/A is discussed.
- Daasbjerg, Kim,Lund, Henning
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p. 597 - 604
(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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- 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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p. 4833 - 4836
(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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- Twin Benzoannulation of Naphthalene via 1,3-, 1,6-, and 2,6-Naphthodiyne Synthetic Equivalents. New Syntheses of Triphenylene, Benzanthracene, and Naphthacene
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New syntheses of triphenylene (4), benzanthracene (5), naphthacene (6), and the tetramethylated derivatives 17 and 25 are described that feature, as the key step, the formal Diels-Alder cycloaddition between a naphthodiyne synthon (1, 2, or 3) and a furan (10 or 14).Subsequent deoxygenation affords the arene in 16-28percent overall yield from dibromo ditosylate 7, 8, or 9.The latter are prepared in two steps from commercially available 2,3- or 2,7-dihydroxynaphthalene, and, with phenyllithium, serve as synthetic equivalents of 1, 2, and 3.The X-ray structure of the anti isomer of 23 is discussed in some detail.
- Gribble, Gordon W.,Perni, Robert B.,Onan, Kay D.
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p. 2934 - 2939
(2007/10/02)
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- A Convenient Generation of 2,3-Naphthalyne. Linear Annulation of Naphthalene and a New Naphthacene Synthesis
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2,3-Naphthalyne (3) is conveniently generated by treating 2,3-dibromonaphthalene (9) with phenyllithium and is used in a two-step sequence to prepare naphthacene (1) and 1,2,3,4-tetrafluoronaphthacene (17).Thus, the cycloadditions of 3 with 2-methylisoindole (13) and 2-methyl-4,5,6,7-tetrafluoroisoindole (14) afford the naphthacenimines 15 and 16, respectively.Deamination with m-chloroperbenzoic acid (for 15) and dichlorocarbene (for 16) affords 1 and 17 in 44percent and 63percent overall yield from 9, respectively.Similarly, cycloadditions of 3 with furan and N-tert-butylpyrrole give anthracene, after extrusion of the heteroatom bridge.
- LeHoullier, Craig S.,Gribble, Gordon W.
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p. 2364 - 2366
(2007/10/02)
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- Formation and Decay of Radical Anions of Aromatic Compounds Produced by Photoinduced Electron Transfer from the Triphenylstannyl Anion
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Upon steady-light illumination of aromatic compounds (A) in the presence of the triphenylstannyl anion (Ph3Sn-, M+) in tetrahydrofuran, radical anions of the aromatic compounds (A-.(M+)) were produced via electron transfer from Ph3Sn-, M+ to the excited aromatic compounds.After the light was cut off, the radical anions of perylene and tetracene persisted for a long time; for anthracene and pyrene, radical anions formed transiently and decayed rapidly.The decay rates depended on the reduction potentials of A.The decay processes were attributed to back electron transfer from A-.(M+) to the distannane (Ph3SnSnPh3) which is produced by the coupling of Ph3Sn., since the rate constants calculated on the basis of the above reactions were in good agreement with the observed rate constants.Slow decay of A-.(M+) could be realized when the reduction potentials of A are less negative than that of the distannane.
- Aruga, Tamotsu,Ito, Osamu,Matsuda, Minoru
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p. 2950 - 2953
(2007/10/02)
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- (1)H NMR PATTERNS OF ANTIAROMATIC SYSTEMS: PARATROPIC DISPLACEMENT DEPENDENCE UPON LUMO-HOMO ENERGY GAP
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(1)H NMR chemical shifts of antiaromatic species reveal an enhanced paratropic displacement.The high-field shifts exhibited by doubly charged benzenoid polycycles were shown to be strongly related to the LUMO-HOMO energy gap in these antiaromatic systems.As the gap decreases, a larger paratropic shift was observed.
- Minsky, Abraham,Meyer, Amatzya Y.,Rabinovitz, Mordecai
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p. 5351 - 5354
(2007/10/02)
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- PHOTOREARRANGEMENT OF PHOTOCYCLOADDUCTS FROM ARENES AND 1,3-CYCLOHEXADIENE
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The 4?s+4?s photoadduct from an arene and 1,3-cyclohexadiene may undergo a photochemical rearrangement to the 4?s+2?s adduct.
- Wang, To-yuan,Ni, Ji-de,Masnovi, John,Yang, N. C.
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p. 1231 - 1234
(2007/10/02)
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- Crystal Lattice Energies of Solid Anion Radical Salts
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A calorimetric Technique for the determination of the lattice energies of solid anion radical salts has been developed which involves the measurement of the heat of reaction of the solid alkali metal-polyacene salts with water.The enthalpy measured for this reaction is utilized in a thermochemical cycle to obtain the enthalpy of the reaction given by M+?-.(s) ?-.(g) + M+(g), which is the crystal lattice energy of the salt.The lattice energy varies only slightly (from 164.6 to 170.6 kcal/mol) for the sodium salts of anthracene, tetracene, pyrene, and perylene.However, these lattice energies vary dramatically with changes in the size of the cation.When anthracene serves as the anion, a linear relationship is obtained between the crystal lattice energy and the reciprocal of the radius of the cation.For the cations Cs+, Rb+, K+, Na+, and Li+, only Li+ deviates from this linear relationship.From the crystal lattice energies and the heats of solution, a complete energy diagram has been constructed for each of the salts.
- Stevenson, Gerald R.,Wiedrich, Charles R.,Clark, Gary
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p. 374 - 378
(2007/10/02)
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- Evidence for Single Electron Transfer in the Reactions of Alkali Metal Amides and Alkoxides with Alkyl Halides and Polynuclear Hydrocarbons
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Evidence for single electron transfer as the major pathway in reactions previously considered to be classic SN1 and SN2 pathways has been obtained.In this connection, the reaction of KOBu-t with trityl bromide has been shown to proceed through the trityl radical, and the reaction of LiN(i-Pr)2 with a primary alkyl iodide probe gave evidence of proceeding by single electron transfer, as indicated by the cyclized nature of the product as a result of a radical intermediate.
- Ashby, E. C.,Goel, A. B.,DePriest, R. N.
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p. 2429 - 2431
(2007/10/02)
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- Evidence of Single Electron Transfer in the Reduction of Various OrganicSubstrates by Lithium Tetrakis(N-dihydropyridyl)aluminate
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Aromatic ketones, polynuclear hydrocarbons, and alkyl halides with LiAl(PyH)4 by a single electron transfer process.
- Ashby, E.C.,Goel, A.B.
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p. 3934 - 3936
(2007/10/02)
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- Solid state disproportionation enthalpies
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Using calorimetric techniques, we have measured the heats of reaction of several solid anion radical and dianion salts with water. These heats of reaction have been coupled in a thermochemical cycle to yield the first enthalpies of disproportionation for anion radicals in the solid phase. The enthalpies of disproportionation (ΔH° for 2Na+A-·(s) ? Na+2A2-(s) + A(S)) range from -13.6 when A is pyrene to +8.8 kcal/mol when A represents tetracene. The enthalpy of disproportionation for the pyrene salt is the most exothermic anion radical disproportionation yet reported and is largely controlled by the crystal lattice energies of the dianion and anion radical salts.
- Stevenson, Gerald R.,Zigler, Steven S.
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p. 2513 - 2515
(2007/10/02)
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