- Robust Direct (Hetero)arylation Polymerization in Biphasic Conditions
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The synthesis of conjugated polymers from direct (hetero)arylation polymerization (DHAP) has been achieved for the first time using biphasic water/toluene conditions. This protocol is robust enough to form polymers even when air is introduced in the system. General reactivity is demonstrated for a single set of polymerization conditions with thienyl- or phenyl-based substrates, whether they are electron-rich or electron-poor. Complete characterization from differential scanning calorimetry and 1H NMR and UV-vis-NIR spectroscopies is presented, demonstrating this DHAP protocol offers comparable or better properties than the very best values published thus far. High molecular weights are obtained, showcasing the perfect equilibrium of reactivity and selectivity attained with this method. Moreover, this efficient and versatile methodology, which also uses low-cost, "wet" reagents, is scalable and done at ambient pressure.
- Grenier, Fran?ois,Goudreau, Karine,Leclerc, Mario
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- Synthesis and photovoltaic properties of copolymers based on bithiophene and bithiazole
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Three simple structured D-A copolymers, PBTBTz-1, PBTBTz-2, and PBTBTz-3, containing bithiophene (BT) donor unit and bithiazole (BTz) acceptor unit with different alkyl chain length were synthesized by the Pd-catalyzed Stille-coupling method. The copolymers were characterized by thermogravimetric analysis, UV-vis absorption, electrochemical cyclic voltammetry, and photovoltaic measurements. The results indicate that the introduction of BTz unit to the polythiophene main chain effectively decreases highest occupied molecular orbital levels of the copolymers and increases the open circuit voltage (Voc) of polymer solar cells (PSCs) based on the copolymers as donor, and the alkyl chain length influences the photovoltaic properties of the polymers significantly. The PSCs based on PBTBTz-2 and PBTBTz-3 show higher Voc up to 0.77 and 0.81 V, respectively. The power conversion efficiency of the PSC based on PBTBTz-2:PC70BM = 1:1(w/w) reached 2.58% with short circuit current of 8.70 mA/cm2, under the illumination of AM1.5, 100 mW/cm2.
- Zhang, Maojie,Fan, Haijun,Guo, Xia,Yang, Yang,Wang, Shanshan,Zhang, Zhi-Guo,Zhang, Jing,Zhan, Xiaowei,Li, Yongfang
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- Synthesis and optical properties of 1,1-binaphthyl-thiophene alternating copolymers with main chain chirality
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A series of axially chiral 1,1-binaphthyl-thiophene copolymers were synthesized by Migita-Kosugi-Stille polycondensation and electrochemical polymerization. The polymers exhibit circular dichroism not only in the ultraviolet region but also in the visible region, both in solution and film states. Optical and electrochemical properties of the polymers are in good agreement with theoretical results obtained by density functional theory calculations. Although effective conjugation of the polymers was cleaved at the orthogonally oriented two naphthalene rings in the 1,1-binaphthyl unit, the electrochemically synthesized polymer film shows good electrochemical redox behavior with repeatable changes in optical absorption and circular dichroism. The changes in circular dichroism may reflect a change in the dihedral angle of the binaphthyl unit caused by reorientation of conjugated main chains between oxidized and neutral states. The Royal Society of Chemistry 2012.
- Kawabata, Kohsuke,Goto, Hiromasa
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- Structure of Thiophene-Based Regioregular Polymers and Block Copolymers and Its Influence on Luminescence Spectra
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Two approaches toward control of the luminescence wavelength of polythiophenes have been explored: (i) block copolymers in which oligothiophene blocks alternate with oligosilanylene blocks and (ii) regioregular polythiophenes in which oligothiophene sequences are delimited by n-octyl substituents placed in a "head-to-head" fashion on adjacent rings.Both methods aim at restricting the ?-conjugation to the oligothiophene sequences.The block copolymer approach is very effective, whereas the (solution) luminescence spectra of the regioregular polymers are strongly red-shifted with respect to absorption and confined to a narrow range of wavelengths.This is due to the quinoid character of the excited singlet state, in which there is a strong electronic driving force toward coplanarity of adjacent thiophene rings, which offsets the steric hindrance of the octyl substituents and increases the size of the conjugating ?-system.This explanation is supported by calculations and by spectral data of substituted bithiophenes.
- Hutten, Paul F. van,Gill, Richard E.,Herrema, Jan K.,Hadziioannou, Georges
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- Synthesis of 5-alkyl[3,4-c]thienopyrrole-4,6-dione-based polymers by direct heteroarylation
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Don't stand Stille: A direct heteroarylation polycondensation reaction was used for the synthesis of high-molecular-weight thienopyrroledione-based polymers (see scheme) in an impressive yield (up to 96 %) and in only a few synthetic steps. This new method is an alternative to the standard Stille coupling reaction and thus avoids formation of toxic tin by-products. Copyright
- Berrouard, Philippe,Najari, Ahmed,Pron, Agnieszka,Gendron, David,Morin, Pierre-Olivier,Pouliot, Jean-Remi,Veilleux, Justine,Leclerc, Mario
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- Effective tuning of HOMO and LUMO energy levels by p-n diblock and triblock oligomer approaches
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A novel series of oligomers consisting of thiophene as a p-type unit and oxadiazole as an n-type unit were separately synthesized. On the basis of the characterization of photophysical and electrochemical properties, the structure-property relationships of the oligomers were investigated. Cyclic voltammogram studies showed that changing the number of thiophene and oxadiazole units could effectively modulate the electronic properties of the p-n diblock and triblock oligomers. The effect of molecular regiochemistry on electronic properties is also investigated. The observed electronic properties were consistent with theoretical calculations. These systems serve as excellent examples, demonstrating the band gap control principle in the p-n heterostructure oligomers.
- Wan, Jun-Hua,Feng, Jia-Chun,Wen, Gui-An,Wei, Wei,Fan, Qu-Li,Wang, Chuan-Ming,Wang, Hong-Yu,Zhu, Rui,Yuan, Xiang-Dong,Huang, Chun-Hui,Huang, Wei
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p. 2565 - 2571
(2007/10/03)
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- New p-n diblock and triblock oligomers: Effective tuning of HOMO/LUMO energy levels
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A new series of oligomers consisting of thiophene as p-type unit and oxadiazole as n-type unit were synthesized, and their photophysical and electrochemical properties were evaluated. Cyclic voltammography studies demonstrated that the electronic properties of the p-n diblock oligomers could be modulated by changing the number of thiophene and oxadiazole rings. The molecular regiochemical effect to the electrochemical and optical properties was also investigated.
- Wan, Jun-Hua,Feng, Jia-Chun,Wen, Gui-An,Wang, Hong-Yu,Fan, Qu-Li,Wei, Wei,Huang, Chun-Hui,Huang, Wei
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p. 2829 - 2833
(2007/10/03)
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- Organometallic chemistry for controlled synthesis of various conjugated polymers
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Two synthetic approches based on organometallic chemistry for a controlled synthesis of polythiophenes derivatives are discussed: (i) activation of oxidative coupling by SiME3 groups (ii) organometallic coupling of stannyl derivatives and bromo compounds catalyzed by Pd°complexes.
- Bouachrine,Lere-Porte,Moreau,Torreilles
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p. 1176 - 1179
(2007/10/03)
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