Showing papers in "Molecular Crystals and Liquid Crystals in 2013"
TL;DR: It is shown that the behavior of living microorganisms is dramatically different in media that are asymmetric, and this study uses the example of Escherichia coli bacteria swimming in a bulk uniaxial liquid environment.
Abstract: Although the influence on bacterial motility of many genetic and biochemical factors has been extensively studied, there have been limited studies of the impact of physical parameters. Indeed, despite the fact that natural environments are often asymmetric (such as stretched supramolecular structures), the majority of behavioral experiments with bacteria have been done in isotropic liquid solutions. In the present work, we show that the behavior of living microorganisms is dramatically different in media that are asymmetric. The example of Escherichia coli bacteria swimming in a bulk uniaxial liquid environment is used to demonstrate this phenomenon. The results of our study provide insight into the behavior of bacteria in conditions encountered in real environments and open new avenues for the control of their movements.
56 citations
TL;DR: In this article, the mesomorphic properties of the α-3-[4′-n-Alkoxy Cinnamoyloxy] phenyl-β-4″-nitro benzoyl ethylene are synthesized and evaluated.
Abstract: Eleven members of a novel homologous series α-3-[4′-n-Alkoxy Cinnamoyloxy] phenyl-β-4″-nitro benzoyl ethylene are synthesized and evaluated for their mesomorphic properties. Seven members of the series are enantiotropically nematogenic without exhibition of smectogenic character, and the other four members are non-mesomorphic in character. Mesomorphic behavior from a phase diagram for solid to nematic and for nematic to isotropic transitions shows the normal behavior. The nematic to isotropic transition curve shows an odd–even effect. Analytical data support the structures of molecules. Nematogenic phase length ranges from 30°C to 62°C. Nematic-isotropic thermal stability is 175.7°C. The mesomorphic properties of the series are compared with the structurally similar isomeric series. Thus, the series is predominantly mesomorphic (nematogenic) and partly non-mesomorphic with middle-order melting points. Transition temperatures and other liquid crystal properties were determined by optical polarizing microsc...
52 citations
TL;DR: In this article, a novel homologous series α-4-[4′-n-alkoxy benzoyloxy] benoyl-β-3″,4″-dimethoxy phenyl ethylenes has been synthesized and studied for liquid crystal properties to understand and establish the relation between molecular structure and liquid crystalline behavior.
Abstract: A novel homologous series α-4-[4′-n-alkoxy benzoyloxy] benzoyl-β-3″,4″-dimethoxy phenyl ethylenes has been synthesized and studied for liquid crystal (LC) properties to understand and establish the relation between molecular structure and liquid crystalline behavior. Twelve members of series were synthesized. All the members except first member of the series are mesomorphic. The hexyloxy to tetradecyloxy homologoues are smectogenic and nematogenic in character. The ethoxy to pentyloxy and the hexadecyloxy homologues exhibit only nematogenic character with the absence of smectogenic mesophase formation. An odd–even effect is observed for the smectic-nematic and the nematic-isotropic transition curves in the phase diagram. The smectic mesophase showed as either the SmA or SmC. The nematic mesophase shows a threaded or Schlieren type texture. Spectral and analytical data confirms the molecular structures of the homologues. The thermal stabilities for the smectic and the nematic are 115.6°C and 156.6°C. The s...
47 citations
TL;DR: In this paper, the synthesis and evaluation of a novel series of 12 homologues is presented, which is entirely nematogenic without the exhibition of smectogenic character, and is of a middle ordered melting type.
Abstract: The synthesis and evaluation of a novel series of 12 homologues is presented. Enantiotropic nematogenic mesomorphism is exhibited from the pentyl to hexadecyl homologues. The other homologues are not liquid crystalline. Smectic mesomorphism is absent in all homologues. Transition temperatures were determined using an optical polarizing microscope equipped with a heating stage. The transition curves of a phase diagram behave in a normal manner. An odd–even effect is observed for the N-I transition curve. The textures of the nematic phase are of the threaded or Schlieren type. Mesomorphic–isotropic transition temperatures range from 152°C to 178°C. The nematogenic phase length varies between 24°C and 51°C. The nematic thermal stability is 163.1°C. Thus, the novel homologous series is entirely nematogenic without the exhibition of smectogenic character, and is of a middle ordered melting type. Analytical and spectral data support the molecular structures. Liquid crystal (LC) properties of the novel series ar...
35 citations
TL;DR: The synthesis and mesomorphic properties of novel homologous series are reported in this article, where all 11 members of the series, except the methoxy and ethoxy derivatives, are enantiotropically mesogenic.
Abstract: The synthesis and mesomorphic properties of novel homologous series are reported. All 11 members of the series, except the methoxy and ethoxy derivatives, are enantiotropically mesogenic. The propoxy to tetradecyloxy homologues exhibits smectognic amd nematogenic behavior, while the hexadecyloxy homologue shows only nematogenic behavior. An odd-even effect is observed for the smectic–nematic and the nematic–isotropic transition curve in the phase diagram. Analytical data support the structure of molecules. The textures of the nematic mesophase are threaded or Schlieren, and that of smectic mesophase are of type-A. The transition temperatures of homologues and other mesomorphic properties are determined using optical polarizing microscopy. The smectic and nematic thermal stabilities are 138.0°C and 163.8°C respectively. The novel series is predominantly nematogenic and partly smectogenic with middle-ordered melting type. The nematic and smectic phase ranges vary between 16°C and 38°C and 6°C and 22°C respe...
34 citations
TL;DR: A novel homologous series α-3-[-4′-n-alkoxy benzoyloxy] phenyl-β-4″-methoxy benoyl ethylene, which consists of 11 members, has been synthesized and the mesomorphic behavior studied in relation to the molecular structure.
Abstract: A novel homologous series α-3-[-4′-n-alkoxy benzoyloxy] phenyl-β-4″-methoxy benzoyl ethylene, which consists of 11 members, has been synthesized and the mesomorphic behavior studied in relation to the molecular structure. The pentyl to hexadecyl homologues are mesomorphic and the remaining homologues are non-mesomorphic. The pentyl, tetradecyl, and hexadecyl derivatives are only enantiotropic nematic, while the hexyl, octyl, decyl, and dodecyl homologue derivatives exhibit smectic mesomorphism in addition to the enantiotropic nematic phase. The transition and melting temperatures were determined by an optical polarizing microscope with a heating stage. Analytical and spectral data confirm the molecular structures. The texture of the nematic phase is of the threaded or Schlieren type and that of the smectic mesophase is a typical smectic A phase. The transition curves of the phase diagram behave in normal manner without showing an odd–even effect. The smectic and nematic thermal stabilities are 129.5°C and...
26 citations
TL;DR: In this article, reduced graphene oxide/polypyrrole (RGO/PPy) conductive composites were prepared by in-situ oxidative polymerization of pyrrole monomer in the presence of RGO under acidic condition.
Abstract: Reduced graphene oxide/polypyrrole (RGO/PPy) conductive composites were prepared by in-situ oxidative polymerization of pyrrole monomer in the presence of RGO under acidic condition. RGO used for the polymerization was previously prepared from natural graphite using modified Hummer's method, subsequently reduced using hydrazine hydrate. The structural, morphology and electrical property of the composites together with graphene oxide (GO) and RGO were characterized using FTIR, XPS, TGA, HRTEM and XRD. It was observed that the RGO and PPy formed a uniform composite with the PPy layers wrapped on the RGO surface. XRD results showed that the RGO/PPy composite was amorphous as neat PPy, suggesting the backbone structure of the PPy was not damaged by the introduction of RGO. Furthermore, the thermal and electrical properties of the composites were much higher than that of pure PPy thank of RGO.
26 citations
TL;DR: In this article, double complementary hydrogen bonds are formed between a nonmesogen suberic acid and mesogenic p-n-alkyl benzoic acid (nBA); the series is referred as SA + nBA.
Abstract: An inter hydrogen bonded homologous series with seven liquid crystalline complexes has been isolated and characterized. Double complementary hydrogen bonds are formed between a nonmesogen suberic acid (SA) and mesogenic p-n-alkyl benzoic acid (nBA); the series is referred as SA + nBA. Hydrogen bond is evinced by FTIR studies, while the mesogenic phases are identified by polarizing optical microscopic studies that are further substantiated by differential scanning calorimetry. Phase diagram is composed of nematic, smectic C, smectic F, and smectic G phases. The variation of tilt angle of various homologues with temperature in smectic C is fitted to a power law and the exponent value (β) is found to be in agreement with mean field predicted value (0.5). Orders of the various phase transitions are established by Cox method. Dielectric studies enable to identify phases and evaluate relaxation processes in smectic C and the corresponding activation energy is derived from the data.
26 citations
TL;DR: In this paper, a host natural matrix (agar) was doped with magnesium triflate (Mg(CF3SO3)2) with the goal of developing electrolytes for the fabrication of solid-state devices.
Abstract: In the present work one host natural matrix – agar – has been doped with magnesium triflate (Mg(CF3SO3)2) with the goal of developing electrolytes for the fabrication of solid-state devices. The resulting samples have been represented by the notation AgarnMg(CF3SO3)2, where n represents the percentage of the magnesium triflate salt proportion in the electrolyte samples. The samples investigated, with n between 0.00% and 37.56%, have been obtained as transparent and thin films. The samples have been characterized by conductivity measurements, thermal analysis, cyclic voltammetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The agar-based electrolytes were also tested as ionic conductor in an electrochromic device with the following configuration: glass/indium tin oxide (ITO)/WO3/agar-based electrolyte/CeO2–TiO2/ITO/glass.
25 citations
TL;DR: In this paper, a nonlinear chalcone derivative, 3-(2,3-dichlorophenyl)-1-(pyridin-2-yl)prop-2,en-1-one (DCPP), has been synthesized and crystallized using dimethylformamide as solvent.
Abstract: New nonlinear chalcone derivative: 3-(2,3-dichlorophenyl)-1-(pyridin-2-yl)prop-2-en-1-one (DCPP), has been synthesized and crystallized using dimethylformamide as solvent. The lattice parameters for the grown crystals were determined by using single crystal x-ray diffraction analysis; the DCPP crystallizes in the monoclinic system with P21 space group. The unit cell parameters of the crystal are: a = 7.4229(2) A, b = 3.9889(1) A, c = 21.2685(6) A, β = 98.212(2), and V = 623.29(3)A3. DCPP crystals were characterized by thermal and FTIR and UV-Vis spectral techniques. DCPP crystals are thermally stable up to 146.9°C. The UV absorption cut off wavelength is observed at 350 nm. DCPP crystals generate second harmonics of Nd:YAG laser operating at 1064 nm wavelength. The second harmonic generation (SHG) efficiency of the powdered DCPP sample was measured using Kurtz and Perry technique. The SHG efficiency is found to be equal to that of urea.
22 citations
TL;DR: In this paper, the propagation of self-confined beams in uniaxial nematic liquid crystals has been studied, both theoretically and numerically, and the model accounts for optical anisotropy and goes beyond the perturbative regime.
Abstract: We discuss, both theoretically and numerically, the propagation of self-confined beams in uniaxial nematic liquid crystals Our model accounts for optical anisotropy and goes beyond the perturbative regime, that is, it allows addressing the unique properties of nematicons, including their tunable nonlinearity, high nonlocality, and ability to spatial self-steer
TL;DR: In this paper, two series of supramolecular hydrogen-bonded liquid crystalline complexes have been designed and synthesized by varying the respective alkyloxy carbon number.
Abstract: Two series of supramolecular hydrogen-bonded liquid crystalline complexes have been designed and synthesized. A successful attempt has been made to form hydrogen bond between Suberic acid (SA) and Pimelic acid (PA) with p-n-alkyloxy benzoic acids (nBAO) by varying the respective alkyloxy carbon number. The first homologous series comprises of Suberic acid and p-n-alkyloxy benzoic acids (SA+nBAO), while the another series is formed between Pimelic acid and p-n-alkyloxy benzoic acids (PA+nBAO), where n represents the alkyloxy carbon number which varies from 5 to 12. These two homologous series are analyzed by polarizing optical microscope, differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), and proton NMR studies. The formation of intermolecular hydrogen bond is evinced through FTIR and 1H-NMR. An interesting feature of PA+nBAO homologues series is the inducement of tilted smectic C phase with increasing carbon chain length. In the SA+nBAO homologues series odd–even effect is ...
TL;DR: In this article, the mesophase and thermal stabilities of the mesogens are discussed with reference to terminal chain length and position of the linking unit, and an enantiotropic nematic phase is confirmed.
Abstract: Novel thiophene mesogens built with two phenyl ring core and alkoxy terminal chains are synthesized by multistep route. The phenyl ring core is connected to thiophene by ester unit at (a) 2-position and (b) 3-position to yield 2-series of mesogens. The structural characterization of them is accomplished by using spectroscopy tools and the mesophase characteristics are evaluated by HOPM and DSC. The 13C chemical shifts of representative mesogens calculated from DFT by quantum chemical calculations are compared with experimental 13C chemical shifts and further utilized for structural assignment of core unit carbons. A good agreement between calculated and experimental values is noticed. An enantiotropic nematic phase is confirmed for all the mesogens and accordingly threaded nematic texture in HOPM is observed and is supported by DSC transition enthalpy values. The mesophase as well as thermal stabilities of the mesogens are discussed with reference to terminal chain length and position of the linking unit ...
TL;DR: In this paper, double hydrogen bond is formed between glutaric acid and p-n-alkyloxy benzoic acids (nBAO), resulting in new complexes referred as GA+n BAO.
Abstract: Homologous series of double hydrogen bonded liquid crystals are designed, synthesized, and characterized. Double hydrogen bond is formed between glutaric acid (GA) and p-n-alkyloxy benzoic acids (nBAO, where n varied from pentyl to dodecyl), resulting in new complexes referred as GA + nBAO. Formation of hydrogen bond is conformed by the Fourier transform infra red spectroscopy. The synthesized mesogens are characterized by polarizing optical microscopy, differential scanning calorimetric studies, ensuing phase diagram from the obtained data. The isolated mesogens are found to exhibit orthogonal and tilted phases, namely, nematic, smectic C, smectic F, and smectic G. In addition to these characteristic phases, a new smectic ordering labeled as smectic X has been identified and characterized. Dielectric studies are performed to confirm the newly formed smectic X phase. Thermal equilibrium and odd even effect are evinced from the individual enthalpy values of the homologues. The magnitudes of experimental op...
TL;DR: In this paper, three banana-shaped monomers containing naphthalene as central units and azobenzene in side arms with terminal alkenes were synthesized and characterized.
Abstract: Three banana-shaped monomers containing naphthalene as central units and azobenzene in side arms with terminal alkenes were synthesized and characterized. DSC, polarizing optical microscopy, and X-ray diffraction measurements prove that all compounds exhibit B6 phase. The trans-azobenzene showed high-intensity π–π* transition at about 365 nm and low-intensity n–π* transition at about 450 nm. The strong photoisomerization behavior in solutions of the molecules displayed that trans to cis isomerization takes 45 sec whereas reverse process takes about 28 h and 30 min. This long thermal back relaxation is useful for creation of optical image storage.
TL;DR: In this article, a novel homologous series α-4-[4′-n-Alkoxy benzoyloxy] benzoyls β-4″-methoxy phenyl ethylenes of 12 homologue substances is presented and comprises of 5 compounds (heptyl to tetradecyl) that exhibit both a smectic and a nematic phases.
Abstract: A novel homologous series α-4-[4′-n-Alkoxy benzoyloxy] benzoyl β-4″-methoxy phenyl ethylenes of 12 homologue substances is presented and comprises of 5 compounds (heptyl to tetradecyl) that exhibit both a smectic and a nematic phases. The pentyl, hexyl, and hexadecyl homologues only exhibit the nematic without exhibition of any smectogenic property. The methyl to butyl homologues are not liquid crystalline. All novel liquid crystal (LC) substances of novel series are enantiotropically mesomorphic. The textures of nematogenic homologues are threaded or Schlieren and that of the smectogenic homologues are typical of the smectic A or C. Analytical and spectral data support the molecular structures. Solid-mesomorphic or isotropic, Sm-N, and N-isotropic transition curves of a phase diagram behave in a normal manner. An odd–even effect is exhibited by the Sm-N and N-isotropic transition curves. Thermal stabilities for the smectic and nematic mesophases are 118.0°C and 157.0°C, respectively. The Sm-N mesophase l...
TL;DR: In this article, the authors proposed the fabrication and the electro-optical characterization of nanoparticle-based multilayer photonic crystals infiltrated with a nematic liquid crystal, which could be very interesting for applications where high sensitivity sensor and selective color tunability is needed with the use of cheap and lowvoltage power supplies.
Abstract: In this study, we propose the fabrication and the electro-optical characterization of nanoparticle-based multilayer photonic crystals infiltrated with a nematic liquid crystal. Two methods of the photonics band gap tunability have been proposed. In the first, we have observed an aligning of the liquid crystal director along the external electric field vector at very low applied voltage, with a blue shift of the photonic band gap of 8 nm at only 8 Vrms. In the second, we put forward the possibility of tuning the photonic band gap of the porous multilayer just by infiltration of appropriate liquid crystals, in accordance with results carried out by a custom simulation software. The presented device could be very interesting for applications where high sensitivity sensor and selective color tunability is needed with the use of cheap and low-voltage power supplies.
TL;DR: In this paper, the optical and thermal properties of a mixture of cholesteryl nanonate, cetyl-dimethyl-ethylammonium bromide, and ethylene glycol are investigated.
Abstract: We report the results of our studies on the optical and thermal properties of the mixture of cholesteryl nanonate, cetyl-dimethyl-ethylammonium bromide, and ethylene glycol, which exhibits very interesting liquid crystalline mesophases like cholesteric (N*) and induced smectic phases, such as SmA, SmC*, SmE, and SmB, sequentially when the specimen is cooled from its isotropic liquid phase. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies. The pitch of the cholesteric phase is discussed. The temperature variation of optical anisotropy, electrical conductivity, ultrasonic velocity, molar, and adiabatic compressibility has also been discussed.
TL;DR: In this paper, the optical properties of carbon-nickel films were investigated at different deposition times from 50 to 600 sec. Reflectance measurements in wavelength range 300-1000 nm were used to compute the refractive index and optical dispersion parameters according to Wemple and DiDomenico single oscillator model (WDD).
Abstract: In this work, the optical properties of carbon–nickel films deposited at different deposition times from 50 to 600 sec were investigated. Reflectance measurements in wavelength range 300–1000 nm were used to compute the refractive index and optical dispersion parameters according to Wemple and DiDomenico single oscillator model (WDD). Dispersion curves of the refractive index of films show anomalous dispersion in absorption region and normal dispersion in transparent region. It is shown that dissipative rate of the electromagnetic wave at 180 sec has a maximum value. It is also shown that at 180 sec films become more disordered.
TL;DR: In this paper, a review of the methods of lignocellulosic plants degumming is presented, especially the method of osmotic degummming combined with ultrasound.
Abstract: In this article the review of the methods of lignocellulosic plants degumming is presented. Generally, for the degumming, the following methods are used: biological, chemical, mechanical and physical – retting in warm and cold water retting, dew retting, chemical treatment by acid and base, use of electromagnetic pulses and most promising – osmotic degumming with ultrasound. The paper presents the newest methods of degumming, especially the method of osmotic degumming combined with ultrasound. This new method, developed by Institute of Natural Fibres and Medicinal Plants, is a typical pro-ecological method, because degumming water after cleaning has to be recycled. The retting water has no odour and biochemical oxygen demand and chemical oxygen demand parameters are not high. For better cost-efficiency, the osmotic degumming method can be applied also for degumming green decorticated fibres.
TL;DR: In this paper, a novel homologous series of liquid crystals, viz., α-4-[4′-nalkoxy cinnamoyloxy] benzoyl -β-4″-chloro phenyl ethylenes, has been synthesized.
Abstract: A novel homologous series of liquid crystals, viz., α-4-[4′-n-alkoxy cinnamoyloxy] benzoyl -β-4″-chloro phenyl ethylenes, has been synthesized. The series consists of twelve homologs. The methyl to butyl derivatives are not liquid crystalline and the rest of the homologs are enantiotropic liquid crystals. The octyl to dodecyl derivatives of the series are enantiotropically smectogenic in addition to nematogenic in character, but the pentyl, hexyl, heptyl tetradecyl, and hexadecyl homolog derivatives of the series are only nematogenic without the exhibition of a smectic phase. The transition temperatures of the novel substances were determined by optical polarizing microscopy equipped with a heating stage. A plot of transition temperatures versus the number of carbon atoms present in the n-alkoxy terminal chain represents the phase behavior of the series. An odd-even effect is observed for the nematic-isotropic transition curve. The textures of the nematic phase are of a threaded or Schlieren type and thos...
TL;DR: In this article, the effect of deposition time on structural and electrical properties of tantalum thin films has been investigated in all cases, highly preferred (330) orientation can be observed in X-ray diffraction measurements.
Abstract: Nanoscale grain-size tantalum films with tetragonal crystalline structure were prepared on BK7 glass and 304 steel by low power direct current magnetron sputtering at room temperature. Effect of deposition time on structural and electrical properties of tantalum thin films has been investigated. In all cases, highly preferred (330) orientation can be observed in X-ray diffraction measurements. With increasing the thickness of deposited films from 152 to 388 nm, a weak X-ray photon peak is diffracted from (720) planes of β-Ta. The atomic force microscopy micrographs show the grain size of 20–30 and 100–140 nm for films deposited on glass and steel substrates respectively. Deposition rate was approximately constant. The resistivity of samples on glass substrate is decreased with increasing the time of deposition. Transmittance of deposited films on glass substrate is decreased with increasing the thickness of sample.
TL;DR: The synthesis and mesomorphic properties of a new homologous series of azomesogens, 4-(4′-n-alkoxy benzoyloxy)-3-methoxy phenyl azo-3″,4″ dichlorobenzene is detailed in this article.
Abstract: The synthesis and mesomorphic properties of a new homologous series of azomesogens, 4-(4′-n-alkoxy benzoyloxy)-3-methoxy phenyl azo-3″,4″ dichlorobenzene is detailed. The first four members of the series are nonmesomorphic, and the other eight members are smectogenic in character. The smectic mesophase, which is exhibited montropically, commences from the pentyl to the hexadecyl derivatives. The usual odd-even effect is observed in the isotropic-smectic transition curve. The isotropic-smectic transition curve behaves in a normal manner. The smectic mesophase shows a focal conic fan shaped texture of the smectic A type. An important feature of the series is the absence of the nematic property. The thermal stability and mesomorphic characteristic are compared with two structurally similar homologous series.
TL;DR: In this paper, a spin-coating deposition of a thin film of the conducting polymer poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on the surface of standard monodomain liquid crystal elastomer (LCE) films is described.
Abstract: New bilayered composite systems with tunable and temperature-dependent formation of periodical wrinkles on the surface are the object of this report. The samples were prepared by spin-coating deposition of a thin film of the conducting polymer poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on the surface of standard monodomain liquid crystal elastomer (LCE) films. Several bilayered materials were prepared by changing the thickness of PEDOT:PSS nanofilms. Basic characterization showed very good stability and adhesion between the two components also after performing multiple heat cycles around nematic-to-isotropic transition temperature of the LCE. Interestingly, formation of uniaxially aligned microwrinkles was observed, with most of the wrinkles aligned along perpendicular direction with respect to the nematic director, due to reversible elongation/compression of the LCE during thermal cycles.
TL;DR: In this article, a series of supramolecular hydrogen-bonded liquid crystal, SMHBLC, has been isolated from equimolar ratios of p-n-nonyloxy benzoic acid (9BAO) and seven n-alkyl benzzoic acids (nBA) whose carbon number varied from ethyl to octyl and complementary hydrogen bonds are formed between them.
Abstract: A novel series of supramolecular hydrogen-bonded complexes (supramolecular hydrogen-bonded liquid crystal, SMHBLC) has been isolated from equimolar ratios of p-n-nonyloxy benzoic acid (9BAO) and seven p-n-alkyl benzoic acids (nBA) whose carbon number varied from ethyl to octyl Complementary hydrogen bonds are formed between them They have been investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and further these data are utilized for the construction of phase diagram Characteristic textures of the orthogonal and tilted phases have been recorded and compared A new smectic ordering referred to as smectic X is characterized by various techniques Odd–even effects are evinced in transition temperatures The order of the transitions is distinguished by thermal analysis The magnitude of experimental optical tilt angle in smectic C of all the homologs is fitted to a power law and the value of exponent is found to concur with the mean field theory predicted value
TL;DR: In this paper, 4-alkoxyphenyl-7-triflouromethyl-coumarin-3-carboxylates 7a-g exhibited liquid crystalline SmA phase.
Abstract: New liquid crystalline 4-alkoxyphenyl-coumarin-3-carboxylates 6a–e, 7a–g, 8a–e, and 9a–e were prepared by reacting various coumarin-3-carboxylic acids 5a–d with 4-(alkoxy) phenols 4a–g in the presence of 1(3-dimethylaminopropyl-3-ethylcarbodiimide/dimethyl amino pyridine (EDCI/DMAP) as a coupling agent. The structures of the new coumarin derivatives were confirmed by spectral analysis and the liquid crystalline property was established by polarizing optical microscope and by differential scanning calorimetric techniques. The diethyl amine and morpholine were taken as electron-donating and –CF3 as electron-withdrawing groups at the seventh position of the coumarin-3-carboxylic acids to check the mesomorphic property in all new 4-alkoxyphenyl-coumarin-3-carboxylates. Among them, only 4-alkoxyphenyl-7-triflouromethyl-coumarin-3-carboxylates 7a–g exhibited liquid crystalline SmA phase.
TL;DR: In this article, the alignment behavior of chromonic molecules using different hydrophobic substrates has been investigated, and it has been shown that ribbons textures develop, indicating a slow water evaporation and/or a strong aggregation among molecules.
Abstract: We present our recent effort on chromonic liquid crystal alignment. In particular, we report the alignment behavior of chromonic molecules using different hydrophobic substrates. Different materials have been used to this purpose but in all cases ribbons textures develop, indicating a slow water evaporation and/or a strong aggregation among molecules, that, as reported in a recent paper, give rise to threads connected through salt bridge bonds. Thin films of materials usually employed for thermotropic liquid crystals alignment induce schlieren textures that after 10 days evolve into ribbon textures; thin films of materials with a low surface energy orient molecules in homeotropic configuration, but the alignment is lost after two weeks as in the case of degenerate planar alignment.
TL;DR: A novel homologous series, α-4-[4′-n-Alkoxy benzoyloxy] benoyl β-4″-chloro phenyl ethylenes consists of 12 homologues.
Abstract: A novel homologous series entitled α-4-[4′-n-Alkoxy benzoyloxy] benzoyl β-4″-chloro phenyl ethylenes consists of 12 homologues. The pentyl to tetradecyl homologues are enatiotropically nematogenic and all of the other homologues (methyl to butyl and hexadecyl) are nonmesogenic. The textures of the nematogenic mesophase are threaded or Schlieren in nature. The transition temperatures were determined by an optical polarizing microscope with a heating stage. The phase diagram of the novel series shows a normal behavior with negligible abnormality in trend of the nematic-isotropic transition curve and exhibits an odd–even effect as expected. The nematic thermal stability is 149.4°C on average. The series is nematogenic without any smectogenic character. The mesogenic properties of the novel series are compared with known series that are structurally similar.
TL;DR: In this paper, the optical and thermal properties of binary mixture of compounds, viz., Berberine (BBE) and Glacial acetic acid (GAA), were investigated.
Abstract: We report the results of our studies on the optical and thermal properties of binary mixture of compounds, viz., Berberine (BBE) and Glacial acetic acid (GAA). The mixture shows very interesting coexistent nematic biphase (N+I) and nematic phase for different concentrations of BBE sequentially when the specimen is cooled from its isotropic phase. The order parameter (S) of the coexistent nematic biphase is estimated with the help of optical anisotropy from the measured refractive index and density data. The temperature variation curve of experimentally found order parameter is well fitted with the Maier–Saupe theoretical curve. The temperature variation of electrical conductivity is also discussed. Formation of above molecular orientations has been confirmed by optical studies.
TL;DR: In this paper, a method for the determination of anti-oxidative properties against singlet oxygen (1O2), which plays an important role in skin aging, was presented.
Abstract: Carotenoids have attracted attention in food and healthcare industries owing to their ability to quench ROS. Here, we present a method for the determination of anti-oxidative property against singlet oxygen (1O2), which plays an important role in skin aging. We quantified the bimolecular 1O2 quenching rate constant, and the amount of 1O2 molecules that can be quenched by a single anti-oxidative molecule before degradation, for five materials. We have defined the anti-oxidative property against 1O2 as the product of these two constants. It was revealed that anti-oxidative properties of astaxanthin and lycopene were the highest among the materials investigated.