373596-08-8Relevant articles and documents
The influence of side chains on the structures and properties of functionalized pentacenes
Chen, Jihua,Subramanian, Sankar,Parkin, Sean R.,Siegler, Maxime,Gallup, Kaitlin,Haughn, Chelsea,Martin, David C.,Anthony, John E.
, p. 1961 - 1969 (2008)
We investigated substituent-induced variations in microstructure and physical properties of a family of functionalized pentacenes, materials currently of intensive interest for making organic electronic devices such as thin film transistors, to shed light on the complex relationships between functionalization, film formation, stability, and microstructure. In this study, the pentacenes were modified with alkyl acetylene or alkylsilylethynyl groups with systematic variations in the alkyl chain length. With a proper side chain, this modification can effectively disrupt the herringbone packing seen in neat pentacene, promoting face-to-face arrangements between the acene rings and providing solubility in a variety of convenient solvents. Thin films can be readily formed by solution casting from THF, bromobenzene, toluene and other organic solvents. We have investigated the structure and properties of the functionalized pentacenes using UV-vis spectroscopy, hot stage optical microscopy, differential scanning calorimetry, transmission electron microscopy, X-ray and electron diffraction. The materials show regular variations in their thermal behavior, crystal packing and macroscopic properties as the chemistry of the side-group substituent changes.
High ionization potential conjugated polymers
Kim, Youngmi,Whitten, James E.,Swager, Timothy M.
, p. 12122 - 12130 (2005)
We report the synthesis of a series of poly(p-phenylene ethynylene)s (PPEs) with high ionization potentials and associated high excited-state electron affinities. Their photophysical properties were investigated using steady-state and time-resolved fluorescence techniques. The ionization potentials of the polymer thin films were determined using ultraviolet photoelectron spectroscopy (UPS), and those with the highest ionization potentials displayed high sensitivity for the detection of electron-donating aromatic compounds. The effects of sterics, chemical structure, and electronic properties on the polymers' sensory responses were investigated by fluorescence quenching experiments in both solution and solid thin films. In addition, we report that in some cases the excited-state charge-transfer complexes (exciplexes) of the PPEs with analytes were observed. These latter effects provide promising opportunities for the formation of sensitive and selective chemical sensors.
Anti-[2.2](1,4)pentacenophane: A covalently coupled pentacene dimer
Bula, Rafael,Fingerle, Michael,Ruff, Adrian,Speiser, Bernd,Maichle-Moessmer, Caecilia,Bettinger, Holger F.
, p. 11647 - 11650 (2013)
Two in a row: A pentacene dimer in which both units are covalently linked through a [2.2]paracyclophane bridge, has been synthesized (see picture). The electronic properties of the molecule were elucidated by a combination of experimental and computational methods. Such molecules could lead to materials with improved charge-transport properties. Copyright
Application of zirconacyclopentadienes (metalla-heterocycles) and cross-coupling for the convenient preparative method of 6,13-disubstituted pentacene
Jia, Zhiying,Li, Shi,Nakajima, Kiyohiko,Kanno, Ken-Ichiro,Song, Zhiyi,Takahashi, Tamotsu
, p. 1495 - 1506 (2013/08/23)
Iodination of zirconacyclopentadiene derivative gave diiododiene derivative. The product was lithiated with t-BuLi and treated with diiodonaphthalene successively to afford 6,13-bis(trimethylsilyl)-5,14- dihydropentacene. A 6,13-diiodo-5,14-dihydropentacene was synthesized by iodination of 6,13-bis(trimethylsilyl)-5,14-dihydropentacene with ICl. This diiododihydropentacene was used for the introduction of substituent at 6 and 13 positions by the cross-coupling reactions with Pd catalyst. After aromatization by a combination of DDQ and γ-terpinene or triethylamine, 6,13-disubstituted pentacene derivatives were synthesized.
Unexpected formation of a cyclic vinylene sulfate in the synthesis of ethynyl-substituted acenes
Djukic, Brandon,Perepichka, Dmitrii F.
, p. 6651 - 6653 (2012/07/27)
(E)-2-Styrylanthracene derivatives containing triisopropylsilylacetylene groups at the 9 and 10 positions were synthesized and characterized. The electronic properties have been studied by DFT calculations, spectroscopy and electrochemistry, revealing asymmetric resonance stabilization effects that result in the regioselective formation of an unusual cyclic vinylene sulfate.
Why triple bonds protect acenes from oxidation and decomposition
Fudickar, Werner,Linker, Torsten
supporting information, p. 15071 - 15082 (2012/11/06)
An experimental and computational study on the impact of functional groups on the oxidation stability of higher acenes is presented. We synthesized anthracenes, tetracenes, and pentacenes with various substituents at the periphery, identified their photooxygenation products, and measured the kinetics. Furthermore, the products obtained from thermolysis and the kinetics of the thermolysis are investigated. Density functional theory is applied in order to predict reaction energies, frontier molecular orbital interactions, and radical stabilization energies. The combined results allow us to describe the mechanisms of the oxidations and the subsequent thermolysis. We found that the alkynyl group not only enhances the oxidation stability of acenes but also protects the resulting endoperoxides from thermal decomposition. Additionally, such substituents increase the regioselectivity of the photooxygenation of tetracenes and pentacenes. For the first time, we oxidized alkynylpentacenes by using chemically generated singlet oxygen (1O2) without irradiation and identified a 6,13-endoperoxide as the sole regioisomer. The bimolecular rate constant of this oxidation amounts to only 1 × 10 5 s-1 M-1. This unexpectedly slow reaction is a result of a physical deactivation of 1O2. In contrast to unsubstituted or aryl-substituted acenes, photooxygenation of alkynyl-substituted acenes proceeds most likely by a concerted mechanism, while the thermolysis is well explained by the formation of radical intermediates. Our results should be important for the future design of oxidation stable acene-based semiconductors.
Structure, photophysics, and photooxidation of crowded diethynyltetracenes
Zhang, Jingjing,Sarrafpour, Syena,Haas, Terry E.,Mueller, Peter,Thomas, Samuel W.
experimental part, p. 6182 - 6189 (2012/06/29)
This paper describes a previously unreported class of sterically crowded tetracene derivatives that have both phenyl and ethynyl substituents. The steric crowding above and below the tetracene core prevents overlap between the extended π-systems of the acenes. Substituent effects cause these tetra-substituted tetracenes to have absorbance and fluorescence spectra red shifted from either disubstituted derivatives or rubrenes, such that they have spectra similar to diarylpentacenes, but with higher quantum yields of fluorescence and greater photostability. These new molecules also undergo cycloaddition reactions with 1O2, giving regioisomeric mixtures of endoperoxides, and in contrast to longer acenes, the ethynyl substituents show only a modest stabilizing effect to photooxidation. Ethynylated tetracenes also exhibited photochromism, with their endoperoxides undergoing cycloreversion to yield the acene starting material at room temperature in the dark. The Royal Society of Chemistry 2012.
Substituent effects in pentacenes: Gaining control over HOMO-LUMO gaps and photooxidative resistances
Kaur, Irvinder,Jia, Wenling,Kopreski, Ryan P.,Selvarasah, Selvapraba,Dokmeci, Mehmet R.,Pramanik, Chandrani,McGruer, Nicol E.,Miller, Glen P.
supporting information; scheme or table, p. 16274 - 16286 (2009/05/08)
A combined experimental and computational study of a series of substituted pentacenes including halogenated, phenylated, silylethynylated and thiolated derivatives is presented. Experimental studies include the synthesis and characterization of six new and six known pentacene derivatives and a kinetic study of each derivative under identical photooxidative conditions. Structures, HOMO-LUMO energies and associated gaps were calculated at the B3LYP/6-311+G**//PM3 level while optical and electrochemical HOMO-LUMO gaps were measured experimentally. The combined results provide for the first time a quantitative assessment of HOMO-LUMO gaps and photooxidative resistances for a large series of pentacene derivatives as a function of substituents. The persistence of each pentacene derivative is impacted by a combination of steric resistance and electronic effects as well as the positional location of each substituent. Silylethynyl-substituted pentacenes like TIPS-pentacene possess small HOMO-LUMO gaps but are not the longest lived species under photooxidative conditions, contrary to popular perception. A pentacene derivative with both chlorine substituents in the 2,3,9,10 positions and o-alkylphenyl substituents in the 6,13 positions is longer lived than TIPS-pentacene. Of all the derivatives studied, alkylthio- and arylthio-substituted pentacenes are most resistant to photooxidation, possess relatively small HOMO-LUMO gaps and are highly soluble in a variety of organic solvents. These results have broad implications for the field of organic molecular electronics where OFET, OLED, and other applications can benefit from highly persistent, solution processable pentacene derivatives.
A road map to stable, soluble, easily crystallized pentacene derivatives
Anthony, John E.,Eaton, David L.,Parkin, Sean R.
, p. 15 - 18 (2007/10/03)
(figure presented) A series of 6,13-disubstituted pentacenes, in which the substituents are functionalized ethyne units, were synthesized and analyzed by X-ray crystallography. The resulting pentacene derivatives were highly soluble and oxidatively stable and exhibited a significant amount of π-stacking in the crystal.
