- Effect of alkyl chain and linking units on mesophase transitions and molecular order of rod-like thiophene mesogens: 13C NMR investigation
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Thermotropic liquid crystals with π-conjugated cores are increasingly witnessed due to their promising optoelectronic and optophotonic properties. As π-conjugated mesogens are often realized by direct linking of the rings of the core, the mesophase transitions are usually modulated by inserting the required alkyl/alkoxy chains either at a terminal or lateral location. In this work, five mesogens in which thiophene and two phenyl rings are common in the core unit with terminal alkyl/alkoxy chains are investigated to probe the influence of (a) a terminal alkyl chain on the mesophase characteristics, (b) the linking units on the mesophase range and (c) the disparity of thiophene orientational constraints. The mesophase properties reveal that whenever the alkyl chain is located at one end of the molecule, polymesomorphism is observed. The XRD studies reveal layer ordering typical of smectic mesophases with lower temperature and higher order phases, namely SmB and CrE phases. A detailed 13C NMR study of the mesogens in the liquid crystalline phase indicates that the order parameters are governed by the nature of the substitution of thiophene and its linkage with two phenyl rings. Importantly, the 13C NMR data of the terminal chains in the liquid crystalline phase are compared with the recently reported thiophene mesogen in which the n-hexyl chain is located at the lateral position and completely different orientation characteristics were found for the terminal versus lateral chains.
- Santhosh Kumar Reddy,Lobo, Nitin P.,Narasimhaswamy
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supporting information
p. 598 - 612
(2017/12/28)
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- Photochromic dihetarylethenes. 12.* Synthesis of 5-alkyl-2- (1,3,4-oxadiazol-2-yl)thiophenes and their photochromic derivatives
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Photochromic derivatives of 5-alkyl-2-(1,3,4-oxadiazol-2-yl)thiophenes have been synthesized for the first time. Their photochromic and fluorescent properties have been studied.
- Krayushkin,Stoyanovich,Zolotarskaya,Chernoburova,Makhova,Yarovenko,Zavarzin,Martynkin,Uzhinov
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p. 165 - 176
(2007/10/03)
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- Mesomorphic compound, liquid crystal composition, liquid crystal device, display apparatus and display method
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A mesomorphic compound represented by the following formula (I): STR1 wherein R1 and R2 respectively denote a linear or branched alkyl group having 1-18 carbon atoms capable of including one or two or more non-neighboring methylene groups which can be replaced with STR2 wherein X denotes halogen; X1 and X2 respectively denote STR3 Z1 denotes STR4 A1 denotes a single bond, STR5 and Y1 and Y2 respectively denote H, F, Cl, Br, --CH3 or --CF3 with the proviso that Y1 and Y2 are not simultaneously H. The mesomorphic compound is effective for providing a ferroelectric liquid crystal composition showing an improved low-temperature operation characteristic and a decreased temperature-dependence of response speed.
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- Mesomorphic compound, liquid crystal composition containing same and liquid crystal device using same
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A mesomorphic compound represented by the following formula (I): STR1 wherein R1 and R2 respectively denote a linear or branched alkyl group having 1-18 carbon atoms capable of having a substituent; X1 denotes any one of a single bond, --O--, STR2 X2 denotes any one of a single bond, --O--, STR3 Z1 denotes any one of STR4 --CH2 O-- and --CH=C(CN)--; and A1 denotes --A2 -- or --A2 --A3 -- wherein A2 and A3 respectively denote any one of STR5
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- Mesomorphic compound, liquid crystal composition and liquid crystal device using same
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A mesomorphic compound represented by the following formula (I): STR1 wherein R1 and R2 respectively denote a linear or branched alkyl group having 1-18 carbon atoms capable of having a substituent; X denotes any one of a single bond, --O--, STR2 Y denotes STR3 or --CH2 O--; and Z denotes any one of --O--, STR4 .
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- Liquid Crystalline Compounds in the Thiophene Series. 1. Liquid Crystalline Thiophene Carboxylic Esters
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Carboxylic esters have been prepared from 5-alkyl-2-thiophenecarboxylic acid and hydrochinone, biphenol, respectively cholesterol as well as one ester from 2,5-thiophene dicarboxylic acid and p-ethylphenol.Only the esters from biphenol respectively cholesterol have liquid crystalline phases. - Keywords: Liquid Crystalline Thiophene Derivatives, Thiophene Carboxylic Esters
- Kossmehl, Gerhard,Budwill, Detlev
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p. 1669 - 1677
(2007/10/02)
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- Dianions of Methylated Thiophene-2-carboxylic Acids: Their Formation and Reactivity
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Methylated thiophene-2-carboxylic acids can be readily homologated by treatment with LDA (2 equiv) followed by the addition of carbon-containing electrophiles.
- Gould, Norman P.,Lee, Ta-Jyh
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p. 4528 - 4530
(2007/10/02)
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