- Synthesis and characterization of novel 4-benzyloxyphenyl 4-[4-(n-dodecyloxy) benzoyloxy]benzoate liquid crystal
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Liquid crystal (LC) compound 4-Benzyloxyphenyl 4-[4-(n-dodecyloxy)benzoyloxy]benzoate (BDBB) was prepared and characterized. Inverse gas chromatography (IGC) was to be a beneficial analysis method for the research of thermodynamic characteristics of the new LC. Acetate and alcohol isomers were used to examine LC selectivity via the IGC technique at temperatures between 333.2 K and 483.2 K. The retention diagrams of n-heptane, n-octane, n-nonane, n-decane, undecane, dodecane, tridecane, n-butyl acetate, isobutyl acetate, ethyl acetate, n-propylbenzene, isopropylbenzene, ethylbenzene, chlorobenzene, and toluene on BDBB were plotted with temperatures of 483.2-493.2 K. Flory-Huggins interaction parameter and weight fraction activity coefficient at infinite dilution were researched for BDBB.
- Balkanli, Emine,?akar, Fatih,Ocak, Hale,Cankurtaran, ?zlem,Bilgin Eran, Belk?z
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- Controlling the formation of heliconical smectic phases by molecular design of achiral bent-core molecules
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Fluids with spontaneous helical structures formed by achiral low molecular mass molecules is a newly emerging field with great application potential. Here, we explore the chemical mechanisms of the helix formation by systematically modifying the structure of a bent 4-cyanoresorcinol unit functionalized with two different phenyl benzoate based aromatic rods and terminated with two alkyl chains of variable length. The majority of these achiral compounds self-assemble, forming a short-pitch heliconical liquid crystalline phase in broad temperature ranges. In some cases, it occurs without any competing low-temperature phase. We demonstrate that the mirror symmetry broken mesophase occurs at the paraelectric-(anti)ferroelectric transition if the tilt angle of the molecules in the smectic layers is around 18-20° and if this transition coincides with a change of the tilt correlation between the layers. In the close vicinity of this transition, a field-induced heliconical phase develops as well as a new heliconical phase with polarization-randomized structure. These investigations provide a blueprint for the future design of achiral molecules capable of spontaneous mirror symmetry breaking by the formation of heliconical liquid crystalline phases.
- Alaasar, Mohamed,Cai, Xiaoqian,Eremin, Alexey,Kurachkina, Marharyta,Lehmann, Anne,Liu, Feng,Nagaraj, Mamatha,Poppe, Marco,Poppe, Silvio,Tamba, Maria-Gabriela,Tschierske, Carsten,Vij, Jagdish K.
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supporting information
p. 3316 - 3336
(2020/03/23)
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- Ferroelectric Liquid Crystals: Synthesis and Thermal Behavior of Optically Active, Three-Ring Schiff Bases and Salicylaldimines
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The chiral ferroelectric smectic C (SmC*) phase, characterized by a helical superstructure, has been well exploited in developing high-resolution microdisplays that have been effectively employed in the fabrication of a wide varieties of portable devices. Although, an overwhelming number of optically active (chiral) liquid crystals (LCs) exhibiting a SmC* phase have been designed and synthesized, the search for new systems continues so as to realize mesogens capable of meeting technical necessities and specifications for their end-use. In continuation of our research work in this direction, herein we report the design, synthesis, and thermal behavior of twenty new optically active, three-ring calamitic LCs belonging to four series. The first two series comprise five pairs of enantiomeric Schiff bases whereas the other two series are composed of five pairs of enantiomeric salicylaldimines. In each pair of optical isomers, the configuration of a chiral center in one stereoisomer is opposite to that of the analogous center in the other isomer as they are derived from (3 S)-3,7-dimethyloctyloxy and (3 R)-3,7-dimethyloctyloxy tails. To probe the structure–property correlations in each series, the length of the n-alkoxy tail situated at the other end of the mesogens has been varied from n-octyloxy to n-dodecyloxy. The measurement of optical activity of these chiral mesogens was carried out by recording their specific rotations. As expected, enantiomers rotate plane polarized light in the opposite direction but by the same magnitude. The thermal behavior of the compounds was established by using a combination of optical polarizing microscopy, differential scanning calorimetry, and powder X-ray diffraction. These complementary techniques demonstrate the existence of the expected, thermodynamically stable, chiral smectic C (SmC*) LC phase besides blue phase I/II (BPI or BPII) and chiral nematic (N*) phase. However, as noted in our previous analogous study, the vast majority of the Schiff bases show an additional metastable, unfamiliar smectic (SmX) phase just below the SmC* phase. Notably, the SmC* phase persists over the temperature range ≈80–115 °C. Two mesogens chosen each from Schiff bases and salicylaldimines were investigated for their electrical switching behavior. The study reveals the ferroelectric switching characteristics of the SmC* phase featuring the spontaneous polarization (PS) in the range 69–96 nC cm?2. The helical twist sense of the SmC* phase as well as the N* phase formed by a pair of enantiomeric Schiff bases and salicylaldimines has been established with the help of circular dichroism (CD) spectroscopic technique. As expected, the SmC* and the N* phase of a pair of enantiomers showed mirror image CD signals. Most importantly, the reversal of helical handedness from left to right and vice versa has been evidenced during the N* to SmC* phase transition, implying that the screw sense of the helical array of the N* phase and the SmC* phase of an enantiomer is opposite.
- Veerabhadraswamy, Bhyranalyar N.,Rao, Doddamane S. Shankar,Yelamaggad, Channabasaveshwar V.
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supporting information
p. 1012 - 1023
(2018/04/23)
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- Optically active, three-ring calamitic liquid crystals: The occurrence of frustrated, helical and polar fluid mesophases
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Herein, we report on the synthesis, characterization, liquid crystalline behavior and chirooptical properties of five (R)-4-{[(4-(octan-2-yloxy)phenyl)imino]methyl}phenyl 4-(n-alkoxy)benzoates and their enantiomers, namely, (S)-4-{[(4-(octan-2-yloxy)phenyl)imino]methyl}phenyl 4-(n-alkoxy)benzoates. These three-ring rod-like mesogens were prepared by acid catalyzed condensation of (R)-/(S)-4-(octan-2-yloxy)anilines with 4-formylphenyl 4-(n-alkoxy)benzoates. Thus, each pair of enantiomers comprises (R)-2-octyloxy and (S)-2-octyloxy chiral tails. In order to understand the structure-property correlations, the length of the paraffinic chain incorporated at the other end has been varied from n-octyloxy to n-dodecyloxy. A detailed study carried out by means of several complimentary techniques reveals the stabilization of liquid crystal phases that hold great promise in applied sciences especially in various device applications. In particular, the occurrence of mesophases such as the blue phase-I/II (BPI or BPII) and chiral nematic (N) and chiral smectic C (SmC) phases has been evidenced unequivocally with the help of polarizing microscopy, differential scanning calorimetry, X-ray diffraction and electrical switching. Besides, the occurrence of an unknown, metastable smectic (SmX) phase below the SmC phase has been noted. This study shows that the length of the terminal tail seems to determine the thermal range of the SmC phase. The enantiotropic SmC phase exhibiting ferroelectric switching behavior occurs over 60 °C thermal range; notably, the spontaneous polarization (Ps) value crosses over 100 nC cm-2. The photophysical properties and chirooptical behavior of the mesogens have been studied with the aid of UV-vis absorption and circular dichroism (CD) spectroscopic methods, respectively; the latter technique has been especially used to ascertain the twist sense of the N and SmC phases formed by a pair of enantiomers. The reversal of the helix-sense (from right to left and vice versa) during the N-SmC phase transition has been observed for the first time.
- Veerabhadraswamy,Rao, D. S. Shankar,Prasad, S. Krishna,Yelamaggad
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p. 2011 - 2027
(2015/03/30)
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- Mesomorphic, micro-Raman and DFT studies of new calamitic liquid crystals; Methyl 4-[4-(4-alkoxy benzoyloxy)benzylideneamino]benzoates
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The mesomorphic properties of newly synthesized homologous series of calamitic liquid crystals; methyl 4-[4-(4-alkoxy benzoyloxy)benzylideneamino] benzoates, H2n+1CnOC 6H4COOC6H4C(H)N C6H 4COOCH3; n = 6, 8, 10, 12, 14, 16 (MABBAB-n) containing ester and Schiff base groups as linker have been studied by temperature dependent micro-Raman study, differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). All members of this series exhibit enantiotropic smectic A (SmA) mesophase with oily streak and focal conic textures. Analyses of Raman marker bands of phenyl rings, Schiff base and ester groups of MABBAB-10 confirm the phase transitions. The Raman study also gives an evidence of breaking of weak intermolecular hydrogen bonds associated with ester groups and formation of new hydrogen bonds through CN bond at Cr → SmA phase transition. The monomer and dimer were optimized and vibrational assignment of MABBAB-10 was also done with density functional theoretical (DFT) technique to understand the experimental results.
- Nandi, Rajib,Singh, Hemant Kumar,Singh, Sachin Kumar,Singh, Bachcha,Singh, Ranjan K.
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supporting information
p. 248 - 256
(2014/04/17)
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- Isophthalic acid based mesogenic dimers: Synthesis and structural effects on mesophase properties
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Two series of mesogens based on isophthalic acid and side arms containing two and three phenyl rings linked through azomethine or ester groups were synthesized via divergent approach. Another type of structurally similar mesogen was synthesized via convergent approach in which the azomethine groups were replaced by ester groups. All the synthesized mesogens and their intermediates were structurally well characterized using FT-IR, 1H NMR, 13C NMR and EI-MASS spectrometry. The mesophase characterization was carried out using hot stage-polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The structural changes made in the mesogens i.e. increase of terminal chain length and replacement of azomethine groups with ester groups decreased the transition temperatures whereas the increase of side arm length improves the phase stability to a wide temperature range. Nematic phase was observed for the mesogens with short terminal chain length whereas the smectic polymorphism was observed on increasing the terminal chain length. The structural modification (three ring) on the side arm core stabilizes the mesophases enantiotropically.
- Shanavas,Sathiyaraj,Chandramohan,Narasimhaswamy,Sultan Nasar
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p. 126 - 133
(2013/04/23)
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- Photo and electrically switchable behavior of azobenzene containing pendant bent-core liquid crystalline polymers
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New class of photo and electrically switchable azobenzene containing pendant bent-core liquid crystalline monomers (AZBM 1, 2, and 3) and their polymers (AZBP 1, 2, and 3) are reported. The synthesized precursors, monomers, and polymers were characterized by FT-IR, 1H, and 13C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro-optical method. Among the three monomers AZBM 1, 2, and 3, AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers (AZMP 1, 2, and 3) show weak AF and F switching behavior. The photo-switching properties of bent-core azo polymers are investigated using UV-vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP-1 and 30 s for AZBP-2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s.
- Srinivasan, M. Vijay,Kannan,Roy
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p. 936 - 946
(2013/03/28)
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- Synthesis and mesomorphic investigations of liquid crystalline compounds having a benzothiazole ring
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Two homologous series of calamitic liquid crystals containing a benzothiazole ring and two different linkages have been prepared, and their liquid crystalline properties are studied and compared with each other and those of similar structure. The mesogens with only the cinnamate linking group showed better thermal properties than those with an ester. Nematic and smectic phases were observed. All the compounds of both the series were characterized by elemental analysis, FT-IR, mass spectrometry, 1H-NMR, and 13C-NMR. Phase transition temperatures and the thermal parameters were obtained from differential scanning calorimetery (DSC). The textural observations were performed using hot-stage Polarizing Optical Microscopy (POM).
- Thaker,Chothani,Patel,Dhimmar,Solanki,Patel, Neeraj,Patel,Makawana
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- Synthesis and comparative study on phase transition behavior of triazole-cored liquid crystals armed with cholesterol and double or triple aromatic rings systems
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Two homologous series of optically active bent-shaped mesogens comprising a cholesterol unit as one of the side arms connected to a 1,2,3-triazole ring while the other arm of the triazole ring is connected to two- and three-ring aromatic systems with varying terminal chain lengths have been synthesized. The molecular structure, thermal and optical activities have been studied extensively in which the compounds from both series exhibit polymorphism ranging from chiral nematic (N*), chiral smectic A (SmA*), chiral smectic C (SmC*) and twist grain boundary (TGBC*) phases. A further comparison between the two series of target compounds has drawn a common remark of which the phase behavior is found to be dependent on the length of the terminal tail and number of aromatic rings in the mesogenic units.
- Yeap, Guan-Yeow,Balamurugan, Subramanian,Srinivasan, Murugesan Vijay,Kannan, Palaninathan
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supporting information
p. 1906 - 1911
(2013/10/08)
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- Trimesic acid-based star mesogens with flexible spacer: Synthesis and mesophase characterization
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A series of trimesic acid-based star mesogens containing an octamethylenoxy spacer and two-ring containing side arms with terminal alkoxy groups were synthesised by a divergent approach. A structurally similar mesogen containing a three-ring side arm was
- Shanavas, A.,Sultan Nasar, A.,Narasimhaswamy, T.
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p. 1426 - 1435,10
(2020/09/02)
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- Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens
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Bent-core mesogens have gained considerable importance due to their ability to form new mesophases with unusual properties. Relationships between the chemical structure of bent-core molecules and the type and physical properties of the formed mesophases a
- Findeisen-Tandel, Sonja,Weissflog, Wolfgang,Baumeister, Ute,Pelzl, Gerhard,Shreenivasa Murthy,Yelamaggad, Channabasaveshwar V.
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supporting information; experimental part
p. 129 - 154
(2012/02/15)
-
- Synthesis, characterization and mesomorphic properties of new rod-like thiophene based liquid crystals
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Two new mesogenic homologous series of Schiff base esters, 2-[4-(4-n-Alkoxy benzoyloxy) benzylidenamino] 3-cyno thiophine (Series-A) and Schiff base cinnamates, 2-[4-(4-n-alkoxy cinnamoyloxy) benzylidenamino] 3-cyano thiophene (Series-B), comprising a thiophene moiety were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as FT-IR, 1H-NMR and 13C-NMR, and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry and optical polarizing microscopy. All the derivatives are mesomorphic in nature showing the nematic phase, and the higher members of Series-A show a smectic C phase whereas Series-B exhibits only the nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related compounds. Taylor and Francis Group, LLC.
- Thaker,Patel,Dhimmar,Solnki,Chothani,Patel,Patel,Makavana
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experimental part
p. 98 - 113
(2012/10/07)
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- A new way to access chiral liquid crystals: Organocatalyst-mediated synthesis of chiral rod-like liquid crystals
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In this article, an asymmetric organocatalytic way to prepare chiral liquid crystals from non-chiral starting materials was described. By using L-proline as the organocatalyst, several new chiral rod-like liquid crystals that are elusive with traditional methods were prepared. In addition, a series of novel enone-containing rod-like liquid crystals were also obtained as side-products. Mesomorphic properties of all new compounds were studied by Polarized Optical Microscope and Differential Scanning Calorimetry. Copyright Taylor & Francis Group, LLC.
- Wang, Li,Liu, Xiao-Jun,Huang, Ping,Gong, Qing-Ping,Li, Yong-Hong,Wang, Bi-Qin,Zhao, Ke-Qing
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scheme or table
p. 53 - 59
(2012/07/14)
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- BENT-CORE LC DECORATED GOLD NANOCLUSTERS
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Novel thiol-terminated bent-core liquid crystals (LCs) are used to decorate gold nanoparticles. Thioacetate or xanthate/xanthogenate functional groups are used to effect the attachment of the LCs to the gold nanoparticles. Such bent-core decorated nanoparticles may be dissolved in bent-core liquid crystal host media to provide polarizable systems which respond quickly to applied electric fields and exhibit other interesting and useful optical and electro-optic behaviour.
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- Liquid crystalline properties of 3-[4-(4′- alkoxybenzoyloxybenzylidene) amino]-1,2,4-triazines: Synthesis and characterization
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A new series of 3-[4-(4′-alkoxybenzoyloxybenzylidene)amino]-1,2,4- triazines, C3H2N3N=CHC6H 4OCOC6H4OCmH2m+1 where m=6, 7, 8, 9, 10, 11, 12, 14, and 16 have been synthesized. These compounds have been characterized by elemental analyses, FT-IR, UV-visible, 1H, and 13C NMR spectroscopy. Mesomorphic properties of these compounds were studied by differential scanning calorimetry and polarizing microscopy. The mesomorphic nature of these compounds is dependent on the alkoxy chain length. The compounds (m=6, 7) do not exhibit mesomorphism while the compounds (m=8, 9, 11, 12, 14) show a monotropic nematic mesophase in cooling cycle. The 3-[4-(4′-decyloxybenzoyloxybenzylidene)amino]-1,2,4-triazine displays an enantiotropic nematic mesophase and the hexadecyloxy compound exhibits the smectic A mesophase. Copyright Taylor & Francis Group, LLC.
- Singh, Bachcha,Pandey, Ashwini,Singh, Sachin Kumar
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experimental part
p. 127 - 137
(2010/09/05)
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- Liquid crystalline properties of unsymmetrical N-(o-hydroxybenzylidene)- N′-(4-n-alkoxybenzoyloxybenzylidene)azines: Synthesis and characterization
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A new series of mesogenic unsymmetrical azines, N-(o-hydroxybenzylidene)- N′-(4-n-alkoxybenzoyloxybenzylidene)azines, HOC6H 4CH=N-N=CHC6H4OCOC6H4O CmH2m+1 (m=7, 8, 9, 10, 11, 12, 14, and 16) have been prepared. They have been characterized by elemental analyses, FT-IR, UV-visible, 1H, and 13C NMR (Nuclear Magnetic Resonance) spectra. The mesomorphic properties of these compounds were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The azines m=7, 10, and 14 exhibit features of enantiotropic nematic (N) mesophase whereas azines m=8, 11 exhibit features of a monotropic nematic phase. The azines m=9, 12, and 16 do not exhibit mesogenic nature. Copyright Taylor & Francis Group, LLC.
- Singh, Bachcha,Pandey, Ashwini
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experimental part
p. 148 - 158
(2010/09/05)
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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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- Synthesis and characterization of unsymmetrical five-ring achrial banana-shaped compounds with a B2 phase
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Two series of unsymmetrical banana-shaped materials have been prepared with laterally substituted hydroxy and nitro groups. All the compounds exhibit liquid crystalline properties. The syntheses and liquid crystalline properties of these compounds are dis
- Majumdar,Chakravorty,Pal
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scheme or table
p. 112 - 125
(2012/08/08)
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- Bent-core liquid crystal (LC) decorated gold nanoclusters: Synthesis, self-assembly, and effects in mixtures with bent-core LC hosts
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We present the first synthesis of a series of thiol-, thioacetate-, and xanthate-terminated bent-core derivatives, as well as the preparation of gold nanoclusters using the thiol-terminated bent-core compounds. The mesomorphic properties of the bent-core compounds have been investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and electro-optic tests. From this series, the mono-xanthate derivatives form rectangular or hexagonal columnar phases, and the mono-thiol derivative with shorter alkyl chains forms a metastable, likely smectic, phase. All other bent-core compounds and intermediates exclusively form disordered or multi-layer lamellar crystalline solid modifications. High-resolution transmission electron microscopy (HR-TEM) images of the bent-core functionalized gold nanoclusters prepared from the thiol-terminated derivatives, taken after slow evaporation of the solvent, provide evidence for the formation of self-assembled nanocluster arrays. Upon dispersion of these gold nanoclusters in two structurally related bent-core LC hosts (one forming a SmCPA, and the second with a terminal double bond displaying a Colr phase), a shift in the surface plasmon resonance was observed indicating a LC host-dependent aggregation of the nanoparticles. Finally, we report initial results on the effects of different concentrations of these nanoclusters on the thermal properties as well as the applied voltage/current response of the parent SmCPA host.
- Marx, Vanessa M.,Girgis, Hidy,Heiney, Paul A.,Hegmann, Torsten
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supporting information; experimental part
p. 2983 - 2994
(2010/02/27)
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- Symmetric bent-core mesogens with m-carborane and adamantane as the central units
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Several members of two homologous series of symmetric bent-shaped compounds with either m-carborane or adamantane (1[n] or 2[n], n = 9-13) in the central position were synthesized and investigated by optical, calorimetric, X-ray diffraction, and electro-o
- Pociecha, Damian,Ohta, Kiminori,Januszko, Adam,Kaszynski, Piotr,Endo, Yasuyuki
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supporting information; experimental part
p. 2978 - 2982
(2010/03/26)
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- Synthesis and characterization of liquid crystalline materials incorporating the novel 4-amino-1,2,4-triazole and isonicotinic acid hydrazide moiety
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We report the synthesis and evaluation of thermal behavior of two new mesogenic homologous series of liquid crystalline compound containg 1,2,4-triazole and isonicotinic acid ring at the terminus of the molecule viz. 4-[(4H-1,2,4-triazol-4-ylimino) methyl] phenyl 4-alkoxybenzoate and 4-(2-isonicotinoylcarbonohydrazonoyl) phenyl 4-alkoxybenzoate. Both series have been characterized by elemental analysis, FT-IR, mass spectrometry, 1H-NMR, and 13C-NMR. Phase transition temperatures and the thermal parameters were obtained from differential scanning calorimetry (DSC). The texture observation was performed under polarizing optical microscopy (PMO) attached with Mettler hot stage. All the derivatives are mesomorphic in nature showing nematic phase and the higher member of both series shows smectic phase. The use of isonicotinic acid and triazole as a terminal group has a very dramatic effect on the melting and clearing points. The mesomorphic behavior has been analyzed in terms of structural property relationship.
- Thaker,Patel, Pranay
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- Synthesis of symmetric liquid crystal dimers based on 1,2-bis{-[-(4- alkoxybenzoyloxy)benzylidene]amino)phenoxy}ethane and investigation of phase behaviour by varying alkoxy terminal chain length
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With the objective to study the effect of alkoxy terminal chain length on mesomorphic properties of liquid crystals, We have synthesized ester and Schiff base dimers from diamine derivative containing 1,2-dioxyethylene as short spacer with aldehyde deriva
- Lee, Chang Sin,Kim, Tae Hyeong,Ramaraj,Ryu, Seok Gn,Song, Hyun Hoon,Lee, Soo-Min,Yoon, Kuk Ro
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experimental part
p. 117 - 129
(2010/03/03)
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- Synthesis, computational modelling and liquid crystalline properties of some [3]ferrocenophane-containing Schiff's bases and β-aminovinylketone: Molecular geometry-phase behaviour relationship
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Rotationally fixed [3]ferrocenophane extends the variety of possible molecular geometries in its derivatives in comparison with unbridged ferrocenes. In this respect molecular geometry-liquid crystalline properties relationship studies in [3]ferrocenophane mesogens are of considerable interest. Different positional isomers of mono- and di-substituted [3]ferrocenophanes which are obtained by incorporating one or two promesogenic building blocks into the cyclopentadienyl rings are reported in this article. A series of mono-substituted [3]ferrocenophane-containing Schiff's bases was synthesized by condensing isomeric p-aminophenyl [3]ferrocenophanes with appropriate aldehydes. Isomers of di-substituted [3]ferrocenophane amines gave rise to a series of azomethines with two promesogenic substituents in the cyclopentadienyl rings. Besides, a β-enaminoketone was prepared from 3-(p-aminophenyl)[3]ferrocenophane. Nematic and smectic mesophases were observed in the synthesized compounds under a polarizing optical microscope. The [3]ferrocenophane-containing β-enaminoketone showed complex mesomorphic behaviour connected with occurrence of the keto-enamine and imino-enol tautomeric equilibrium in this compound. On the base of computational models obtained by semi-empirical quantum chemistry calculations the molecular geometry-phase behaviour relationships were examined. It was demonstrated that mesomorphism of [3]ferocenophane azomethines depends on the spatial orientation of the substituents with respect to the propanediyl bridge in a case of mono-, and as well as to each other in a case of di-substituted derivatives.
- Kadkin, Oleg N.,Han, Haksoo,Galyametdinov, Yuri G.
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p. 5571 - 5582
(2008/03/18)
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- Intercalated liquid-crystalline phases formed by symmetric dimers with an α,ω-diiminoalkylene spacer
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Four series of symmetric, dimeric molecules with flexible α,ω-diiminoalkylene spacers have been synthesised and characterised by polarising optical microscopy, differential scanning calorimetry, and X-ray diffraction. The effects on the mesomorphism of th
- Sepelj, Maja,Lesac, Andreja,Baumeister, Ute,Diele, Siegmar,Nguyen, H. Loc,Bruce, Duncan W.
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p. 1154 - 1165
(2008/02/04)
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- Synthesis, characterization, and mesomorphic properties of new liquid-crystalline compounds involving ester-azomethine central linkages, lateral substitution, and a thiazole ring
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In continuation with our work on liquid crystals with unconventional molecular structures, two homologous series that have 1,4-disubstitution and 1,3,4-trisubstitution in the central phenyl ring, such as 2[(4-n-alkoxy- benzyloxy) phenyl azomethine]-5-methyl thiazole and 2-[(4-n-alkoxy-benzyloxy)-2- hydroxy salicyladimine]-5-methyl thiazole, have been synthesized. They have been characterized by elemental analysis, FT-IR, 1HNMR, 13CNMR, and mass spectrometry. The liquid-crystalline behavior of these compounds was observed by differential scanning calorimetry (DSC) and polarizing microscopy. All the compounds of the 1,4-disubstituted series show an enantiotropic nematic phase only, whereas the compounds of the 1,3,4-trisubstituted series show smectic and nematic phases. Some mesogens with a lateral hydroxy group were also synthesized to evaluate the effect of this group on melting point, transition temperatures, and mesophase morphology.
- Thaker,Patel, Pranay,Vansadia,Patel
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- Symmetrical dimer liquid crystals with tilted smectic phases
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Three, series of symmetrical dimer liquid crystals, i.e. bis(dodecyloxybenzoyloxybenzoyloxy)alkanes (BC12) and bis(dodecyloxy- and hexadecyloxybenzoyloxyphenyl) alkanedicarboxylates (QC12 and QC16) with a spacer ranging from two to eight methylene units,
- Achten, Remko,Marcelis, Antonius T.M.,Koudijs, Arie,Sudhoelter, Ernst J.R.
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p. 177/[1219]-184/[1226]
(2007/10/03)
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- Novel nitronyl nitroxides: Synthesis and properties
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The synthesis of several new nitronyl nitroxides with mesogenic groups is reported (6a, b, 11, 14a, b). Microscopic investigations revealed that in some cases (6b, 14b) highly ordered mesogenic phases are formed.
- Greve, Stefan,Vill, Volkmar,Friedrichsen, Willy
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p. 677 - 684
(2007/10/03)
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- Synthesis and mesomorphic characterisation of chiral homologues
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Chiral liquid crystals have attracted considerable interest as they exhibit a good variety of modulated phases. We have synthesised a homologous series viz., 4-(4!-n-alkoxy benzoyloxy) benzylidene-4!!-1-(s)-methyl propoxy anilines, incorporating a terminal chiral centre, inorder to obtain better understanding of the relationship between molecular structure and appearance of SmC*phase in the molecules. It is observed that, in the present series the lower members upto butyl are pure nematogens, while pentyl to hexadecyl derivatives exhibit classical smectic as well as nematic mesophases. An additional smectic C* phase is observed in the middle octyl to dodecyl homologues. The homologues have been characterised by IR, NMR and DSC. Their mesomorphic properties have been compared with structurally related homologous series.
- Dave, Jayrang S.,Menon, Meera R.,Patel, Pratik R.
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p. 575 - 587
(2007/10/03)
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- Synthesis of new mesogenic homologous series with broken alkoxy chain
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A new mesogenic homologous series with broken alkoxy chain at the terminus of long polarizable molecules having following general formula have been synthesized. RO-C6H4-COO-C6H4-CH=N-C 6H4-COOCH2CH2OCH2CH 3 Where, R=-CnH2n+1; n=1 to 8, 10, 12, 14 and 16. All the members exhibit enantiotropic mesomorphism. Methoxy derivative is purely nematogenic. Ethoxy to n-hexyloxy derivatives exhibit enantiotropic smectic-A as well as nematic mesophases. n-Heptyloxy to n-hexadecyloxy derivatives exhibit only enantiotropic smectic A mesophases. The thermal stabilities and the commencement of smectic phase of the present series are compared with those of other structurally related series.
- Prajapati,Sharma,Chudgar
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p. 815 - 823
(2007/10/03)
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- The synthesis, mesomorphism and mesophase structure of anisotropic imines and their complexes with rhenium(I)
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Highly anisotropic imine ligands have been synthesised and complexed to Re(I). Two series of ligands and complexes were obtained with various chain lengths, showing smectic and nematic phases for the ligands and only a nematic phase for the complexes. The
- Liu, Xiao-Hua,Henirich, Benoit,Manners, Ian,Guillon, Daniel,Bruce, Duncan W.
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p. 637 - 644
(2007/10/03)
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- Mesomorphic Behavior of N,N'-Bis-3,3'-diaminodiphenylsulfones
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A new series of sulfur ligated siamese twin mesogens, N,N'-bis-3,3'diaminodiphenylsulfones has been studied for the thermotropic phase transition behavior.A stable or metastable nematic phase is exhibited by the methoxy
- Matsunaga, Y.,Yuri, T.
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p. 145 - 150
(2007/10/02)
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- APPLICATION OF LIQUID CRYSTALS FOR GAS-LIQUID CHROMATOGRAPHY.
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A liquid crystalline homologous series of N- left bracket 4-(4-alkoxybenzoyloxy)benzylidene right bracket -4-cyanoanilines was applied as a stationary liquid phase for the gas-liquid chromatographic separation of various positional isomers. It is shown that the nematic phase has higher selectivity for several positional isomers compared with the other mesomorphic phases.
- Sakagami,Nakamizo
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p. 1157 - 1158
(2007/10/02)
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