92-24-0Relevant articles and documents
Electron Acceptors Based on Cyclopentannulated Tetracenes
Kulkarni, Gajanan C.,Morales-Cruz, Jean L.,Hussain, Waseem A.,Garvey, Ian J.,Plunkett, Kyle N.
, p. 2572 - 2576 (2018/11/30)
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.
Straightforward Synthesis of 2- and 2,8-Substituted Tetracenes
Woodward, Simon,Ackermann, Miriam,Ahirwar, Saurabh K.,Burroughs, Laurence,Garrett, Mary Robert,Ritchie, John,Shine, Jonathan,Tyril, Bj?rk,Simpson, Kevin,Woodward, Peter
supporting information, p. 7819 - 7824 (2017/06/06)
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.
Evaluation of semiconducting molecular thin films solution-processed via the photoprecursor approach: The case of hexyl-substituted thienoanthracenes
Quinton, Cassandre,Suzuki, Mitsuharu,Kaneshige, Yoshitaka,Tatenaka, Yuki,Katagiri, Chiho,Yamaguchi, Yuji,Kuzuhara, Daiki,Aratani, Naoki,Nakayama, Ken-Ichi,Yamada, Hiroko
, p. 5995 - 6005 (2015/06/16)
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.
Benzannulation via ruthenium-catalyzed diol-diene [4+2] cycloaddition: One- and two-directional syntheses of fluoranthenes and acenes
Geary, Laina M.,Chen, Te-Yu,Montgomery, T. Patrick,Krische, Michael J.
, p. 5920 - 5922 (2014/05/20)
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.
Photochemical synthesis of naphthacene and its derivatives for irreversible photo-responsive fluorescent molecules
Aotake, Tatsuya,Yamashita, Yuko,Okujima, Tetsuo,Shirasawa, Nobuhiko,Jo, Yukari,Fujimori, Shigeo,Uno, Hidemitsu,Ono, Noboru,Yamada, Hiroko
, p. 1790 - 1793 (2013/05/09)
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
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
Kim, Bongsoo,Choi, Seong Ho,Zhu,Frisbie, C. Daniel
supporting information; experimental part, p. 19864 - 19877 (2012/01/31)
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.
A reiterative approach to 2,3-disubstituted naphthalenes and anthracenes
Bowles, Daniel M.,Anthony, John E.
, p. 85 - 87 (2007/10/03)
(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.
Kinetics of the reduction of dialkyl peroxides. New insights into the dynamics of dissociative electron transfer
Donkers, Robert L.,Maran, Flavio,Wayner, Danial D. M.,Workentin, Mark S.
, p. 7239 - 7248 (2007/10/03)
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.
Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
, p. 2301 - 2307 (2007/10/03)
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.
Indirect Electrochemical Reduction of Some Peroxide Derivatives
Kjaer, Niels Them,Lund, Henning
, p. 848 - 852 (2007/10/02)
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).
