- The synthesis, mesomorphic and dielectric investigation of new unsymmetrical bent-core mesogens derived from 3-hydroxybenzoic acid
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Abstract: The synthesis, mesomorphic and dielectric investigation of new unsymmetrical bent-core mesogens derived from 3-hydroxybenzoic acid central core with linked two rodlike units carrying (S)-3,7-dimethyloctyloxy group and an n-alkyloxy chain at both terminals are presented. The liquid crystalline properties of the new unsymmetrical bent-core materials have been investigated by polarizing optical microscopy and differential scanning calorimetry. New compounds with the reversed ester linking unit exhibit a monotropic or enantiotropic columnar mesophase at lower temperatures as compared to analogs with a straight chain depending on the presence of the branched (S)-3,7-dimethyloctyloxy terminal chain. Dielectric measurements for one of the bent-core mesogens, 3-[[4-[[4-(octyloxy)benzoyl]oxy]benzoyl]oxy]benzoic acid 4-[[4-((S)-3,7-dimethyloctyloxy)phenoxy]carbonyl]phenyl ester (OBDPE), have been carried out on the angular frequency range from 25.12 to 50265k?rad/s at different temperatures. Thanks to dielectric measurements, real and imaginary dielectric constant, conductivity mechanism and dielectric relaxation mechanism of OBDPE were obtained. Graphic abstract: [Figure not available: see fulltext.].
- Ocak, Hale,Ahlatc?o?lu ?zerol, Esma,?elikel, Fulya ?a?la,Okutan, Mustafa,Bilgin Eran, Belk?z
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p. 3899 - 3911
(2020/05/26)
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- New chalcone based liquid crystals with allylidene amino linking unit: Synthesis and characterization
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In this study, the synthesis, structural characterization and mesomorphic properties of newly thirteen calamitic shaped compounds derived from allylidene amino chalcone and 4-n-alkoxy benzoyloxy benzoic acid. Comp.H1 to H3 exhibited nonliquid crystalline nature, while comp.H4 to comp.H18 displayed enantiotropical smectic C phase. Phase transition temperatures of present synthesised compounds were determined by optical polarising microscopy (POM), differential scanning calorimetric (DSC) and powder X-ray diffraction (PXRD) techniques. Thermal stabilities of smectic to isotropic phase are 150.0 °C and temperature range of mesophase is in decreasing order from comp.H3 to comp.H18 respectively. The presences of SmC phase are the type of broken fan and needle type in present synthesized series. It is also shown that presence of chalcone amino allylidene central linking group favors a calamitic liquid crystalline behaviour in molecules with lower member to higher member aliphatic side chain in alkoxy group (-OR).
- Sharma, Vinay S.,Sharma, Anuj S.,Jadeja, Upendra H.,Suthar, Deepak
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- New hockey stick shaped amino allylidene (?N?CH?CH?CH) based compounds: Effect of linkage group on mesomorphic properties
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Two nonlinear hockey stick shaped homologous series based on three linking groups have been synthesized and characterized by elemental analyses and spectroscopic techniques. The mesomorphic properties of these compounds were observed by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). In this present investigation, we have synthesized two homologous series viz. 2-((3-phenyl allylidene) amino) phenyl 4-((4-n-alkoxy benzylidene) amino) benzoate (series-1) and 4-((2-((3-phenyl allylidene) amino) phenoxy) carbonyl) phenyl-4-n-alkoxy benzoate (series-2). Both the series are differing with respect to first linking group. In series-1, comp.C4-C18 shows nematic as well as smectic phase while in series-2, comp.C10-C16 shows smectic and nematic phase while comp.C4-C18 shows only nematic phase.
- Sharma, Vinay. S.,Vekariya, Rajesh. H.,Sharma, Anuj. S.,Patel
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- Synthesis and mesomorphic properties of calamitic shaped molecules with chalconyl-ester and lateral fluoro substituents
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In this study we have synthesized a new class of compounds incorporating of chalcones and laterally substituted fluoro group. A series of new chalcones with five aromatic rings is synthesized and characterised by elemental analyses and spectroscopic techniques such as Fourier transform infrared [FT-IR] and proton magnetic resonance magnetic resonance [1H NMR] spectroscopy. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and confirmed by differential scanning calorimetry (DSC). It is found that all the prepared materials display enantiotropic LCs phases except first three homologue in present series. The lower homologues (n = 4 to 12) display SmC and nematic phase while, in higher homologues (n = 14 to 18) only SmC phase were seen in heating and cooling condition.
- Sharma, Vinay S.,Sharma, Anuj S.,Vekariya, Rajesh H.,Patel
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- A new series of two-ring-based side chain liquid crystalline polymers: Synthesis and mesophase characterization
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A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl rings and an ester linking unit. All the polymers were characterised by hot-stage polarising optical microscopy, differential scanning calorimetry, variable temperature X-ray diffraction, thermogravimetric analysis, and gel permeation chromato-graphy. The polymers were found to be liquid crystalline. The nematic and smectic A (SA) phases were observed for the homologues with short-terminal chains (C2 and C6), whereas the homologues with longer chains (C8 to C12) exhibited a smectic C phase. The thermal stability of the polymers was found to be in the range of 293 to 326°C and the molecular weights of the polymers were found to vary from 6×103 to 1.3×104.
- Mohan Reddy, Goddeti Siva,Narasimhaswamy, Tanneru,Jayaramudu, Jarugala,Sadiku, Emmanuel Rotimi,Raju, Konduru Mohana,Ray, Suprakas Sinha
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p. 667 - 675
(2013/07/26)
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- Synthesis and characterization of symmetrical eight aromatic ring containing bent-shaped material derived from benzophenone
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A new family of symmetrical eight aromatic ring-containing bent-shaped mesogens in which the central elbow is a ketone has been synthesized and characterized. The effect of the side chain on the mesomorphism has been studied. All the bent derivatives were found to exhibit mesomorphism. The higher homologues of the series exhibit the B1 phase and the lower homologues of the series show the B6 phase. Copyright Taylor & Francis Group, LLC.
- Majumdar,Ghosh,Chakravorty
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scheme or table
p. 63 - 72
(2011/09/13)
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- Chiral smectic *C mesogens having ester and amide central linkages
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Ten members of a chiral homologous series 4-(4'-n-alkoxy benzoyloxy benzoyl)4''- S- (+) 2-methyl butoxy anilides were synthesized in multiple step synthesis. Series exhibits chiral smectic *C and cholesteric mesophases. In this series, n-propyl to n-dodecyl derivatives exhibit smectic *C and cholesteric mesophases. n-Tetradecyl and n-hexadecyl derivatives exhibit only smectic *C phases. The plot of transition temperatures versus number of carbon atoms in alkoxy chain exhibits odd-even effect for cholestric-isotropic transition temperatures. The effect of amide linkage and chirality is discussed in detail. High-temperature cholestric phases exhibit vivid colors. Two compounds were analyzed by calorimetric study (C12 and C14) to confirm the transition temperatures of which was observed under polarizing microscope. The mesogenic behavior of the series compared with other series where amide central linkage differs in its position. The mesogenic thermal stability is compared with other related homologous series. The result indicates that amide linkage enhances smectic as well as cholesteric thermal stability but enhancement in smectic phase is much higher. Compounds are characterized by elemental analysis, IR spectral data, Mass spectral data, DSC, NMR, and microscopic study.
- Tandel,Vora
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p. 103 - 116
(2008/09/20)
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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 AND LIQUID CRYSTALLINE PROPERTIES OF 2-SUBSTITUTED (5-PYRIMIDINYL) BENZOATES AND BENZOYLOXYBENZOATES
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2-Substituted (5-pyrimidinyl) benzoates and benzoyloxybenzoates have been synthesized and their liquid crystalline properties have been studied.In general, these compounds exhibit a characteristic tendency to form a smectic mesophase.
- Kizner, T. A.,Mikhaleva, M. A.,Serebryakova, E. S.
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p. 313 - 315
(2007/10/02)
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