- Efficient synthesis of alkyl end-capped oligoheterocycles via the use of palladacycle catalyst
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The preparation of mixed thiophene/furan oligomers with alkyl groups at α,α′-position by the method which we discovered recently in our lab is presented. Thus, the mixed thiophene/furan oligomers can be prepared in good yields from monoiodoarene in the pr
- Luo, Fen-Tair,Bajji, Ashok C.
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- Controllable morphology and self-assembly of one-dimensional luminescent crystals based on alkyl-fluoro-substituted dithienophenazines
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A class of dithienophenazine derivatives, 9,10-difluoro-2,5-dialkyldithieno[3,2-a:2′,3′-c]phenazine (F-n, n = 4, 5, 6, 7 and 8), modified with various lengths of linear alkyl chains were synthesized and used as building blocks to assemble luminescent one-dimensional (1D) nano/microcrystals. It was demonstrated that the side-chain length can dramatically influence the self-assembled morphologies of the 1D nano/micromaterials. The self-assembly behaviors of F-n have been studied based on the methods of crystallization in the solution phase and solvent evaporation on a substrate. For F-4, F-6 and F-7 molecules, well-defined 1D twisted microstructures (including ribbons, fibers and bundles) were obtained. F-5 molecules can self-assemble into nearly criss-cross (orthogonal) network patterns interconnected by 1D wires. F-8 molecules with longer alkyl chains predominantly formed flattened wires. Single crystal X-ray structure studies of F-n (n = 4, 5 and 8) demonstrated that alkyl chains with different lengths result in distinctly different intermolecular interactions and molecular packing modes, which provides a reasonable explanation for the alkyl chain length-dependent assembly morphologies and emission of F-n-based nano/micromaterials. It has been demonstrated that anisotropic noncovalent interactions and mirror-symmetrical crystallization dominated the 1D assembly behaviors of this class of molecules.
- Song, Xiaoxian,Yu, Hanbo,Zhang, Yuewei,Miao, Yang,Ye, Kaiqi,Wang, Yue
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p. 1669 - 1678
(2018/03/26)
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- Liquid crystalline alkenyl compounds incorporating an heterocyclic five-membered ring
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Liquid crystal mixtures comprising at least one of the compounds of formula (I) containing a heterocyclic five-membered ring and with a carbon-carbon double bond in the termninal group are new. RJ=CnH2n+1CH=CHCmH2mZ1; n=1-5; m=0-5; and q=0, 1 or 2; A1 and
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- Nematic 2,5-disubstituted thiophenes
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A large number of new liquid crystals incorporating the 2,5-disubstituted thiophene ring have been prepared and their mesomorphic behaviour studied in order to systematically investigate the correlation between the molecular structure and mesomorphism of thiophene derivatives with different shapes, polarisability and polarity. As a consequence of these investigations we have prepared a new class of liquid crystals incorporating a 2,5-disubstituted thiophene ring and a conjugated trans-carbon-carbon double bond in the terminal chain. These novel thiophene derivatives are the first liquid crystals incorporating a 2,5-disubstituted thiophene ring to exhibit a nematic phase at room temperature. This enables the flexoelectric coefficients of a bent-shaped molecule to be measured directly and at room temperature for the first time to the authors' knowledge. Many of these new thiophenes exhibit a high birefringence and a high nematic clearing point and are of potential use as components of nematic mixtures in LCDs.
- Campbell, Neil L.,Duffy, Warren L.,Thomas, Gareth I.,Wild, Janine H.,Kelly, Stephen M.,Bartle, Kevin,O'Neill, Mary,Minter, Vicky,Tuffin, Rachel P.
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p. 2706 - 2721
(2007/10/03)
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- Synthesis and mesomorphic properties of 1,1-difluoroalkyl-substituted biphenylthienyl and terphenyl liquid crystals. A comparative study of mesomorphic behavior relative to alkyl, alkoxy and alkanoyl analogs
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A variety of biphenylthienyl and terphenyl-based liquid crystalline materials were prepared that incorporate a 1,1-difluoropentyl terminal group. The mesogenic properties of these compounds were compared and contrasted with analogs where the CF2 moiety was replaced by a -CH2-, -O- or -CO- group. The 1,1-difluoroalkyl group is unique in its behavior and tends to promote orthogonal smectic phase behavior.
- Kiryanov,Sampson,Seed
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p. 3068 - 3077
(2007/10/03)
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- Nematic thiophenes for STN-LCDS and flexoelectric LCDS
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We report anew class of liquid crystals incorporating a 2,5-disubstituted thiophene ring and one or two conjugated trans-carbon-carbon double bonds in the terminal chain for use as components of nematic mixtures for TN-LCDs and STN-LCDs. The combination of these molecular elements contribute towards generating a high birefringence, a high nematic clearing point as well as a low viscosity for these materials. Several of these compounds exhibit a melting point below room temperature. This is the first time a room temperature nematic phase has been reported for phenyl thiophene derivatives. The new thiophene compounds can be used to induce a high birefringence in nematic mixtures for LCDs with short response times.
- Bartle, Kevin,Campbell, Neil,Duffy, Warren L.,Kelly, Stephen M.,Minter, Vicki,O'Neill, Mary,Tuffin, Rachel P.
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p. 881 - 888
(2007/10/03)
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