- Synthesis of aromatic liquid crystals with asymmetric diester based on rod-like multi-ring system by two-step esterification method
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A novel method of two-step esterifications was developed to synthesize compounds with asymmetric double ester groups. By using this method, six rod-like double ester compounds were prepared with p-hydroxy benzaldehyde, p-hydroxy benzoic acid bicyclohexyl carboxylic acid, cyclohexyl benzoic acid and biphenyl carboxylic acid substituted by n-propyl and n-pentyl as main reactants. The structures and properties of target compounds were confirmed by IR, MS, 1H NMR, elemental analysis, differential scanning calorimetry (DSC) and hot stage polarizing optical microscope (HS-POM). Typical yields of the target molecules were more than 70%. All the molecules have mesophases with the textures of nematic type, indicating a rod-like molecule with a longer rigid skeleton can keep its mesophases. There was no clearing point observed for any of the derivatives before they decomposed so that the temperature ranges of the mesophases could not be determined. The energy differences between frontier molecular orbitals (HOMO-LUMO) (Eg) of the compounds were calculated by cyclic voltammetry (CV). The terminal ring system has an obvious influence on the energy levels and the energy gaps (Eg).
- Zheng, Min-Yan,Wei, Yong-Sheng,Geng, Wei,Gu, Yuan-Zi
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- Liquid crystal of ethyl and propyl aromatic aldehyde with azo core and photosensitivity in mesophase
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Eight new stable rod-like aromatic aldehyde liquid crystalline molecules with azo bridge have been prepared, in which single or double six-membered carbon ring carboxylic acid mesogenic cores with shorter alkyl chain of ethyl, n-propyl were condensed with hydroxyl azo benzaldehyde. These compounds have been characterized by their spectral data, DSC and HS-POM. These molecules were expected to exhibit liquid crystal phase so that the influence of UV-light on their textures of mesophase could be detected. The results showed that all these target compounds have the temperature range of mesophase between 101 and 145°C. After irradiating under UV-light, they exihibited photo-sensitivity not only in methanol but also in mesophase.
- Wei, Yong-Sheng,Zheng, Min-Yan,Geng, Wei,Wang, Shan,Shang, Yong-Hui
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p. 1883 - 1888
(2015/03/04)
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- Synthesis of multiring azo-benzoic acid liquid crystalline molecules and their special photosensitive property
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10 new rod-like azo benzoic acid liquid crystals belonged to three series have been prepared, in which trans-cyclohexyl benzene, biphenyl or bi-trans-cyclohexyl carboxylic acid mesogenic cores with ethyl, n-propyl, n-butyl or n-pentyl substituents were connected with azo benzoic acid. Meantime, a simple method was developed in synthesizing compounds bearing both ester and carboxyl groups in one-step reaction. All these compounds have been characterized on the basis of their spectral data, differential scanning calorimeter (DSC) and hot stage polarizing optical microscope (HS-POM). All these compounds have higher thermo-stability. 8 of these compounds have liquid crystalline properties. Their temperature ranges of mesophase have not been obtained, resulting from all the compounds decomposed before their clearing points. Although these compounds are photosensitive in solution under illumination of UV light (365nm), they can't do trans-cis isomerization in their mesophses, indicating the super stabilities of the trans isomer in mesophase.
- Zheng, Min-Yan,Wei, Yong-Sheng,Geng, Wei,Guo, Nai-Ni,Zhang, Ping
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- Multirings aromatic aldehyde liquid crystal with azo linkage and their photosensitivity in mesophase
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Ten new rod-like aromatic aldehyde liquid crystalline molecules with azo linkage were synthesized, in which bi(trans-cyclohexyl), cyclohexyl phenyl, and biphenyl carboxylic acid mesogenic cores with terminal ethyl, n-propyl, n-butyl, and n-pentyl substituents were esterified with azo benzoic aldehyde. These molecules were designed in an attempt to construct a series of new azo liquid crystalline molecules to investigate the influence of ultraviolet (UV) light on their mesophase. All compounds have been characterized on the basis of their spectral data, differential scanning calorimeter (DSC), and hot stage polarizing optical microscope (HS-POM). All these compounds exhibited liquid crystalline phase that belonged to nematic and photosensitive properties. Their temperature ranges of mesophase are from 101°C to 150°C. Under irradiated 365 nm UV light, they showed photosensitivity in the solvent of methanol. Observed under HS-POM, the UV light also did change the textures of these compounds. The result showed that terminal ethyl is enough for these molecules to exhibit wider temperature range of mesophase, and these new molecules have photosensitivities observed under illumination of UV light not only in solution but also in mesophase due to the change of their structures from trans isomer to cis one.
- Zheng, Min-Yan,Wei, Yong-Sheng,Gu, Yuan-Zi,Wang, Shan
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p. 151 - 164
(2014/07/07)
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- SYNTHESIS AND LIQUID CRYSTAL PROPERTIES OF SUBSTITUTED 5-(ARYLCARBONYLOXY)-2-(p-CYANOPHENYL)PYRIMIDINES
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Liquid crystal p-substituted benzoates, biphenylcarboxylates, and benzoyloxybenzoates were obtained on the basis of 5-hydroxy-2-(p-cyanophenyl)pyrimidine.The development of nematogenicity by the esters due to the p-cyanophenyl grouping was noted, and the appearance of the smectic mesophase by the variation of the ring framework of the acid fragment of the molecule was investigated.
- Mikhaleva, M. A.,Igonina, G. A.,Savel'ev, V. A.
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p. 320 - 325
(2007/10/03)
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- SYNTHESIS OF TRANS-4-ALKYL-1-PHENYLCYCLOHEXANES AND THEIR DERIVATIVES
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The alkylation of benzene by 1-alkanoyl-2-chlorocyclohexanes and 1-alkanoyl-1-cyclohexenes leads to the formation of cis- and trans-4-alkanoyl-1-phenylcyclohexanes, the yields of which increase with increase in the reaction temperature. trans-4-Alkyl-1-phenylcyclohexanes were obtained from 4-alkanoyl-1-phenylcyclohexanes and also from the products from the reaction of 4-alkylcyclohexanones with phenylmagnesium bromide.Some mesomorphous derivatives of these hydrocarbons were synthesized.
- Bezborodov, V. S.,Bubel', O. N.,Konovalov, V. A.,Ptashnikov, Yu. L.
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p. 1479 - 1483
(2007/10/02)
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- First Liquid Crystal Azulene Derivatives
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Various azulene derivatives as a new type of coloured liquid crystals have been synthesized.Their mesomorphic behaviour is described. - Keywords: Azulenes, Coloured Liquid Crystals, Nematic Phases
- Praefcke, Klaus,Schmidt, Dietmar
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p. 375 - 378
(2007/10/02)
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