56800-36-3Relevant academic research and scientific papers
Synthesis and characterization of novel 4-benzyloxyphenyl 4-[4-(n-dodecyloxy) benzoyloxy]benzoate liquid crystal
Balkanli, Emine,?akar, Fatih,Ocak, Hale,Cankurtaran, ?zlem,Bilgin Eran, Belk?z
, p. 71 - 81 (2021/03/16)
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.
Controlling the formation of heliconical smectic phases by molecular design of achiral bent-core molecules
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.
supporting information, p. 3316 - 3336 (2020/03/23)
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.
Ferroelectric Liquid Crystals: Synthesis and Thermal Behavior of Optically Active, Three-Ring Schiff Bases and Salicylaldimines
Veerabhadraswamy, Bhyranalyar N.,Rao, Doddamane S. Shankar,Yelamaggad, Channabasaveshwar V.
, p. 1012 - 1023 (2018/04/23)
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.
Optically active, three-ring calamitic liquid crystals: The occurrence of frustrated, helical and polar fluid mesophases
Veerabhadraswamy,Rao, D. S. Shankar,Prasad, S. Krishna,Yelamaggad
, p. 2011 - 2027 (2015/03/30)
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.
Mesomorphic, micro-Raman and DFT studies of new calamitic liquid crystals; Methyl 4-[4-(4-alkoxy benzoyloxy)benzylideneamino]benzoates
Nandi, Rajib,Singh, Hemant Kumar,Singh, Sachin Kumar,Singh, Bachcha,Singh, Ranjan K.
, p. 248 - 256 (2014/04/17)
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.
Synthesis and mesomorphic investigations of liquid crystalline compounds having a benzothiazole ring
Thaker,Chothani,Patel,Dhimmar,Solanki,Patel, Neeraj,Patel,Makawana
, p. 64 - 76 (2013/06/26)
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).
Photo and electrically switchable behavior of azobenzene containing pendant bent-core liquid crystalline polymers
Srinivasan, M. Vijay,Kannan,Roy
, p. 936 - 946 (2013/03/28)
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.
Synthesis and comparative study on phase transition behavior of triazole-cored liquid crystals armed with cholesterol and double or triple aromatic rings systems
Yeap, Guan-Yeow,Balamurugan, Subramanian,Srinivasan, Murugesan Vijay,Kannan, Palaninathan
supporting information, p. 1906 - 1911 (2013/10/08)
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.
Isophthalic acid based mesogenic dimers: Synthesis and structural effects on mesophase properties
Shanavas,Sathiyaraj,Chandramohan,Narasimhaswamy,Sultan Nasar
, p. 126 - 133 (2013/04/23)
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.
Synthesis, characterization and mesomorphic properties of new rod-like thiophene based liquid crystals
Thaker,Patel,Dhimmar,Solnki,Chothani,Patel,Patel,Makavana
, p. 98 - 113 (2012/10/07)
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.
