- A Mechanistic Study of Halogen Addition and Photoelimination from π-Conjugated Tellurophenes
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The ability to drive reactivity using visible light is of importance for many disciplines of chemistry and has significant implications for sustainable chemistry. Identifying photochemically active compounds and understanding photochemical mechanisms is important for the development of useful materials for synthesis and catalysis. Here we report a series of photoactive diphenyltellurophene compounds bearing electron-withdrawing and electron-donating substituents synthesized by alkyne coupling/ring closing or palladium-catalyzed ipso-arylation chemistry. The redox chemistry of these compounds was studied with respect to oxidative addition and photoelimination of bromine, which is of importance for energy storage reactions involving X2. The oxidative addition reaction mechanism was studied using density functional theory, the results of which support a three-step mechanism involving the formation of an initial η1 association complex, a monobrominated intermediate, and finally the dibrominated product. All of the tellurophene derivatives undergo photoreduction using 430, 447, or 617 nm light depending on the absorption properties of the compound. Compounds bearing electron-withdrawing substituents have the highest photochemical quantum efficiencies in the presence of an alkene trap, with efficiencies of up to 42.4% for a pentafluorophenyl-functionalized tellurophene. The photoelimination reaction was studied in detail through bromine trapping experiments and laser flash photolysis, and a mechanism is proposed. The photoreaction, which occurs by release of bromine radicals, is competitive with intersystem crossing to the triplet state of the brominated species, as evidenced by the formation of singlet oxygen. These findings should be useful for the design of new photochemically active compounds supported by main-group elements.
- Carrera, Elisa I.,Lanterna, Anabel E.,Lough, Alan J.,Scaiano, Juan C.,Seferos, Dwight S.
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- 2,5-Diaryltellurophenes: Effect of Electron-Donating and Electron-Withdrawing Groups on their Optoelectronic Properties
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The transformation of 1,2-bis(1-arylvinyl)ditellurides into 2,5-diaryltellurophenes by sequential ditelluride exchange and thermal intramolecular cyclization reactions is presented, and the optoelectronic properties of a series of 2,5-diaryltellurophenes with both electron-donating and electron-withdrawing aryl substituents are disclosed. Furthermore, the multicolored emissive tellurophenes in solution at room temperature have been demonstrated.
- Nagahora, Noriyoshi,Yahata, Shuhei,Goto, Shoko,Shioji, Kosei,Okuma, Kentaro
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- Reaction of acetophenone hydrazones with TeCl4: Novel formation of 2,5-diaryltellurophenes and benzotellurophenes
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Reaction of acetophenone hydrazones with TeCl4 in the presence of DBU in CH2Cl2 at rt gave vinyl ditellurides and tellurides, whereas 2,5-diaryltellurophenes were obtained in refluxing DMF. Interestingly, when 1,2-diphenyl
- Okuma, Kentaro,Yahata, Shuhei,Nagahora, Noriyoshi,Shioji, Kosei
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supporting information
p. 405 - 407
(2017/12/26)
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- Synthesis and stille cross-coupling reactions of 2-(tributylstannyl)-and 2,5-bis(trimethylstannyl)tellurophene
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Herein, we describe the synthesis and Stille cross-coupling reactions of 2-(tributylstannyl)-and 2,5-bis(trimethylstannyl) tellurophene. The reactions were most optimal when using aryl iodides as coupling partners, and a mixed catalyst system consisting o
- Sweat, Daniel P.,Stephens, Chad E.
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experimental part
p. 3214 - 3218
(2010/03/03)
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