- Cobalt-Catalyzed Reductive Alkylation of Heteroaryl Bromides: One-Pot Access to Alkylthiophenes, -furans, -selenophenes, and -pyrroles
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A practical and convenient Co-catalyzed alkylation method for the facile introduction of various alkyl chains into organic electronically significant heteroaryl compounds, including thiophenes, furans, selenophenes, and pyrroles, is reported. Under well-optimized reaction conditions, a wide range of alkylated heteroaryl compounds have beeen efficiently prepared in moderate to good isolated yields. Notably, 2- or 3-alkylthiophenes, which play a decisive role in polymer chemistry and organic materials, have been synthesized step-economically for the first time by this reductive-coupling methodology using inexpensive cobalt salts as catalysts. This straightforward synthetic procedure avoids the preparation of moisture-unstable organometallic reagents (RMgX or RZnX) required in conventional alkylation protocols. Various alkyl chains have been introduced into organic, electronically important heteroaryl compounds step-economically through Co-catalyzed reductive alkylation reactions. The resulting alkylheteroarenes are indispensable building blocks for polymer chemistry and π-functional organic materials.
- Cai, Deng-Jhou,Lin, Po-Han,Liu, Ching-Yuan
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supporting information
p. 5448 - 5452
(2015/08/24)
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- Synthesis and self-assembly of 5,5′-bis(phenylethynyl)-2,2′-bithiophene-based bolapolyphiles in triangular and square LC honeycombs
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A series of X-shaped 5,5′-bis(phenylethynyl)-2,2′-bithiophene-based bolaamphiphiles bearing two long lateral alkyl chains and two terminal glycerol groups has been synthesized by using Kumada and Sonogashira coupling reactions as key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by POM, DSC and X-ray scattering. With elongation of the lateral alkyl chains two different kinds of liquid crystalline phases with honeycomb structures, ColhexΔ/p6mm, formed by (defective) triangular honeycomb cells, and Colsqu/p4mm with square cells were observed for these compounds. UV and PL measurements indicate fluorescent properties making them potential candidates for application in fluorescence sensor devices.
- Gao, Hongfei,Cheng, Huifang,Yang, Zonghan,Prehm, Marko,Cheng, Xiaohong,Tschierske, Carsten
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supporting information
p. 1301 - 1308
(2015/02/19)
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- Transition between triangular and square tiling patterns in liquid-crystalline honeycombs formed by tetrathiophene-based bolaamphiphiles
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A series of 5,5′′′-diphenyl tetrathiophenes with polar glycerol groups at each end and two lateral flexible chains self-assemble into a series of liquid-crystalline honeycombs, formed by the π-conjugated rods which enclose polygonal prismatic cells filled by the lateral chains. With increasing chain length a discontinuous transition from triangular to square honeycombs takes place. At this transition a periodic honeycomb composed of a mixture of square and triangular cells in a ratio 1:2 was formed at low temperature, whereas at higher temperature a hexagonal columnar phase composed of triangular and randomly distributed rhombic cells, a new kind of cybotactic nematic phase, and also a cybotactic isotropic phase, both composed of square honeycomb fragments, represent the intermediate states. This provides an example of a dynamic self-assembled system where, depending on the molecular mobility, the transition between two periodic structures with different symmetry either leads to an increase of complexity, or to a chaotic regime with reduced order.
- Cheng, Xiaohong,Gao, Hongfei,Tan, Xiaoping,Yang, Xueyan,Prehm, Marko,Ebert, Helgard,Tschierske, Carsten
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p. 3317 - 3331
(2013/07/26)
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- Dithiophene based X-shaped bolaamphiphiles: Liquid crystals with single wall honeycombs and geometric frustration
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A series of 5,5′-diphenyl-2,2′-dithiophene based X-shaped polyphiles with two long lateral alkyl chains and terminal glycerol groups was synthesized and the liquid crystalline phases formed by these compounds were investigated by polarizing microscopy, DSC and XRD. These compounds form square (p4mm and p4gm) and hexagonal (p6mm) columnar LC phases. In these mesophases the molecules organize into polygonal honeycombs where the π-conjugated cores form the walls, fused at the edges by the hydrogen bonding networks between the glycerol units and filled by the lateral alkyl chains. By elongation of these chains, a series of polygonal honeycomb phases with a "single wall" structure, ranging from triangular via square and pentagonal to hexagonal was observed. Most triangular honeycombs appear to be defective and can be considered as mixtures of triangular cylinders with orientationally randomized rhombic cylinders. The transition from this improper triangular honeycomb to the square honeycomb takes place via a disordered isotropic phase. Addition of water to this isotropic phase gives rise to a true triangular honeycomb LC phase. Replacing one of the long lateral chains by a small methyl group leads to honeycombs formed by double walls instead of single walls. UV investigations indicate π-stacking of the aromatic cores organized in the honeycomb walls, which is of interest for the potential application of these materials in self assembled arrays of organic electronic material. This journal is
- Gao, Hongfei,Ye, Yafei,Kong, Leiyang,Cheng, Xiaohong,Prehm, Marko,Ebert, Helgard,Tschierske, Carsten
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p. 10921 - 10931,11
(2020/09/15)
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- Liquid-crystalline triangle honeycomb formed by a dithiophene-based X-shaped bolaamphiphile
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Soft supramolecular triangles: The molecule shown displays a new liquid-crystalline phase formed by a periodic array of triangular cylinders. The cylinders are fused to form a honeycomb by hydrogen-bonding networks running along the vertices, and the cells are filled by molten alkyl chains. The thickness of the walls separating the compartments is equal to the width of the π-conjugated rods.
- Cheng, Xiaohong,Dong, Xing,Wei, Guanghui,Prehm, Marko,Tschierske, Carsten
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supporting information; scheme or table
p. 8014 - 8017
(2010/02/27)
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