LC Chemistry

Session 2B: LC Chemistry
Monday, Feb. 13, 2017  16:10-17:45
17:00 - 17:15 Paper No.  2017-MON-S0202-O001
Alexej Bubnov
Self-assembling properties of the lactic acid derivatives

Liquid crystalline materials with a chiral part based on lactic acid have been intensively studied for the last decades due to their rich liquid crystalline properties attractive for potential applications but also due to a reasonably low synthetic costs. The main mechanisms to reach the desirable liquid crystalline properties are: (i) tuning the molecular architecture, specifically changing the type and the structure of the molecular core, length of the terminal chains, type and the position of the lateral substituents, (ii) attaching different polymerisable groups for further design of the macromolecular materials that increase the stability of the system and (iii) incorporation of various functional groups (like photosensitive azo group, etc.) in the molecular core. However, it is still almost impossible to achieve the desired properties for a pure single liquid crystalline compound. Mixing of structurally similar or structurally different materials is a powerful tool for tuning the properties of the resulting mixture. This presentation will be devoted to the results obtained on a large variety of lactic acid derivatives of different molecular architecture. Uncommon mesophases and their properties will be highlighted and a potential usefulness of such materials will be discussed.

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17:15 - 17:30 Paper No.  2017-MON-S0202-O002
Yo Shimizu
A rod/disc shape-compatible mesogen : phase transitions of the alkyl homologues in thermal and photonic processes

Liquid crystal has been categorized based on the anisotropic shape of mesogenic molecule to give two types of liquid crystals such as calamitics (rod-like) and discotics (disc-like). Recently a novel and unique liquid crystalline property was found for hexa-tetradecyloxyazobenzene-substituted triphenylenes (1-C14) which exhibits a bimesomorphism of calamitic (smectic) and discotic (columnar) liquid crystalline phases in both thermotropic and photo-induced isothermal conditions and these should be accompanied with change of molecular anisotropic shape between rod and disc1. The phase transitions of the alkyl homologues (1-C11- 1-C16) also exhibit just the same manner in their mesomorphism,2 though different properties of phase transition parameters and phase sequences. In this communication, phase transitions of the alkyl homologues in both thermotropic and photonic process are shown and the phase transition mechanism is discussed.

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17:30 - 17:45 Paper No.  2017-MON-S0202-O003[Canceled]
Sie-Tiong Ha

Despite of recent development in optical-sensitive devices fabricated in various field of industries, such as new emerging blue light-emitting diodes LEDs, optically active chalcone-based material continues to be a promising mesogen. The reasons of this perspective include the versatility of organic synthetic chalcone materials and their nonlinear optical (NLO) property. Herein, we report a new homologous series of non-symmetric liquid crystal dimer in which a thiomethyl-substituted chalcone core unit is covalently tethered to a nitro-substituted Schiff base core unit through an odd-even parity alkyl spacer, -(CH2)n-, with n ranging from 2 to 4, 6, 8, 10, and 12. The molecular structure of title compounds are confirmed using IR, NMR and EI-MS spectrometric techniques. The mesomorphic properties were studied using differential scanning calorimetry and polarized optical microscopy. It is note-worthy that the even-membered homologues (where n = 2, 4, 6, 8, 10, 12) stabilize monotropic nematic phase solely, which is rather surprising given that its odd-membered homologues (where n = 3, 5) has non-mesomorphic properties due to their bent-shaped molecular packing.

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LC Chemistry

Session 5B: LC Chemistry
Tuesday, Feb. 14, 2017  14:20-15:40
15:10 - 15:25 Paper No.  2017-TUE-S0205-O001
Matthias Lehmann
Free Space in Liquid Crystals – Generation, Design and Application

Free space in condensed matter is usually not present, since the self-assembly in ordered liquid crystals maximises the intermolecular interactions by efficient space filling and nanosegregation in order to minimise the total energy of the system. Nevertheless, there are reports of empty space in columnar LCs. Recently it was demonstrated that deuterated molecules added to LCs are located at sites of lowest density. The aim of our research is the generation of free space in the molecular structure of mesogens and its rational employment for a structural control by filling the void with guests. In these new LC materials the position of the different building blocks should be conductable. Therefore, we focus on shape-persistent star mesogens 1 providing void space between their arms. The core can be a discotic unit such as benzene or phthalocyanine and the arms are conjugated oligomers, which guarantee the shape-persistence. The guests can be bound either via a spacer by covalent bonds or by supramolecular interactions. The rational design leads to filled functional LCs with donors and acceptors double nanosegregated within one column confirmed by comprehensive X-ray scattering studies, modelling, fibre simulation, solid-state NMR, temperature-dependent FT-IR and fluorescence spectroscopy of thin solid films.

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15:25 - 15:40 Paper No.  2017-TUE-S0205-O002
Atsushi Seki
Bulk photovoltaic effect in pi-conjugated ferroelectric liquid crystals

An anomalous photovoltaic (APV) effect in ferroelectrics has attracted interest, due to the potential to generate the open-circuit voltage exceeding the band-gap. This specific phenomenon is caused by the internal electric field originated from spontaneous polarization without any junctions. Recently, we have constructed the pi-conjugated ferroelectric liquid crystal (FLC) system based on phenylterthiophene derivatives. Interestingly, bulk photovoltaic effects were observed in their FLC phases. These compounds exhibited carrier transport properties in FLC phases. However, the details of the specific effect have never been clarified. In this presentation, we consider that the spontaneous polarization and carrier mobilities should be key factors for the APV phenomenon. We provide a detailed study on the correlation between APV effect and those properties in some FLC compounds and the enantiomer mixtures.

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LC Chemistry

Poster Session
Tuesday, Feb. 14, 2017  16:10-18:10
Paper No.  2017-TUE-P0201-P001
Takahiro Yamamoto
Self-healing liquid-crystalline composite gels using photothermal effect of anisotropic gold nanoparticles

We have developed self-healing composite gels consisting of liquid crystal, microparticles, and gold nanorods. Upon irradiation of near-infrared light, the temperature of the composite gels rapidly increased. In a reference study using a composite gel not containing gold nanorods, we could not observe any increases in temperature upon irradiation with near-infrared light. Therefore, we can confirm that the observed increase in temperature is attributable to the photothermal effect of gold nanorods. Then, we successfully achieved photoinduced gel-sol transition of composite gels based on the phase transition of liquid crystals induced by the photothermal effect. In addition, we applied the photoinduced gel-sol transition to the mechanism for photothermal healing of surface cracks made on the composite gels.

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Paper No.  2017-TUE-P0201-P002
Tsai-Hui Wang
Incorporation of Molecular Biaxiality for the Generation of Biaxial Nematics from Disc-like Compounds

Current liquid crystal displays (LCDs) utilize uniaxial rod-like materials as active LC materials and uniaxial discotic nematic superstructures as materials in compensating films to improve the viewing-angle and image retention problem. For faster image movement, e.g. in movies, biaxial nematic liquid crystals are predicated by theories to give much shorter response time and wider viewing-angle characteristics than uniaxial ones. In this study, disc-like liquid crystalline materials were designed and synthesized. A sidearm in hexakis(phenylethynyl)benzene was replaced with a biphenyl analogue. The structural modification has been demonstrated to provide partially enhanced - attractions for wider nematic temperature ranges and a new molecular geometry with extrusion for descending significantly melting temperatures. More importantly, the structural modification endows molecular biaxiality which can lead to molecular packing showing biaxiality. The nematic phase has been investigated by polarizing optical microscopy to show optical biaxiality. Moreover, powder X-ray diffraction of magnetic-field-aligned samples indicates the molecular packing of three unique lattice axis, i.e. biaxial molecular packing.

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Paper No.  2017-TUE-P0201-P003
Hirosato Monobe
Charge tansport property of asymetric alkyl-BTBT LC semiconductor possessing fluorine substituted pheny group

In this study, asymmetric alkyl-BTBT semiconductor possessing fluorine substituted phenyl group, 2-dodecyl-7-(4-fluoro-phenyl)-[1]benzothieno[3,2-b][1]benzothiophene and 2-dodecyl-7-(3,4-difluoro-phenyl)-[1]benzothieno[3,2-b][1]benzothio- phene were studied on charge carrier mobility by time-of-flight (TOF) method correlated to the mesomorphism.

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Paper No.  2017-TUE-P0201-P004
Daisuke Yoshizawa
Synthesis and Characterization of Biphenanthrene Derivatives as Chiral Dopants to Induce a Helical Structure in Liquid Crystals

A nematic phase sensitively changes to a chiral nematic phase with a helical structure by doping with a small amount of a chiral molecule. The chiral nematic phase has attracted attention over the years due to its unique properties. Binaphthalene derivatives are preferably used as chiral dopants since they have high ability to induce the helical structure in the nematic phase. However, although many chiral dopants containing binaphthalene backbone have been reported, there are very few studies on biphenanthrene type chiral dopants and the helical twisting ability of them has not been investigated in detail. Here, we synthesized the biphenanthrene type chiral dopants and investigated the helical twisting ability of the chiral dopants in a host nematic phase. The |HTPβ| value of chiral dopants in the host nematic liquid crystal mixture (JC-1041XX/5CB = 1/1) were evaluated by using Cano wedge cell method. As the results, (S)-biphenanthrol ((S)-2-OH) showed opposite temperature dependence of |HTPβ| compared with typical chiral dopants containing the binaphthalene backbone. This result suggested that (S)-2-OH tended to adopt quasi-orthogonal conformation in the low temperature range and its conformation changed to the conformation which showed higher |HTPβ| values with increasing temperature.

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Paper No.  2017-TUE-P0201-P005
Yu Narazaki
Synthesis and Properties of Various 6,6'-Substituted Binaphthy Type Chiral Dopants

Generally, binaphthyl type chiral dopants bridged by alkyl chain at 2,2'-position are known to possess a large ability to twist the molecular alignment in a given nematic host phase, which is represented by helical twisting power (HTP). Moreover, the 6,6'-fluoronated binaphthyl type chiral dopant exhibited a large HTP value and high solubility in a fluorinated nematic liquid crystal. In this study, we synthesized the non-substituted, 6,6'-halogenated and methylated binaphthyl type chiral dopants and investigated influence of size of their substituents or polarity and polarizability of chiral dopants on their HTP values. The 6,6'-chlorinated chiral dopant was found to show the highest |HTP| value among synthesized chiral dopants. The observed |HTP| values were closely correlated with size of their substituents.

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Paper No.  2017-TUE-P0201-P006
Yo Shimizu
One-Pot Synthesis of TiO2 Nanoparticles Encapsulating Liquid Crystalline Phthalocyanine

TiO2 nanoparticles (NPs) has been attracted much attention due to their unique photonic and electronic properties. In particular, hollow TiO2 NPs are interesting category of TiO2 NPs in its applications towards electronics and photonics. Kobiro et al. reported that such TiO2 NPs could be prepared by one-pot synthetic method with high temperature and pressure.1 This technique could cover the preparation of rich diversity of metal oxides NPs named as MARIMOs (Mesoporously Architected Roundly Integrated Metal Oxides). In this work, Kobiro’s one-pot reaction approach was examined to obtain liquid crystalline phthalocyanine (LCPc) encapsulated TiO2 NPs and it was found that this technique is good for the preparation of functionalized TiO2 NPs.

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Paper No.  2017-TUE-P0201-P007
Jhih-Wei Huang
Design and Synthesis of a Selective Probe for Detecting Streptavidin by Using Liquid Crystal Sensor System

In this study, we synthesized a novel probe, 5-((3aS,4S,6aR)-2-oxohexahydro-1H- thieno[3,4-d]imidazol-4-yl)-N-(4'-pentylbiphenyl-4-yl)pentanamide (5CB-Biotin), which can be applied in liquid crystal (LC) sensor system for detecting streptavidin. For the compatibility of the probe in the LC system, the probe was constructed of the main backbone of the nematic LC, 4-cyano-4'-n-pentylbiphenyl (5CB), with a biotin moiety covalently linked to the end as the binding site. When this probe was doped in 5CB to develop a LC/aqueous sensor system, it was found that the specific binding between 5CB-Biotin and streptavidin led to the reorientation of LC, resulting in a bright-to-dark transition of the LC images under polarized light. By using this mechanism, the limit of detection (LOD) for streptavidin is 15 μg/mL and it did not respond to human serum albumin (HSA) and human immunoglobulin G (h-IgG). Besides, we also found that the results of system were not sensitive to the pH value of solutions. Because the specific binding between small molecules and biomolecules has been widely studied, the design strategy for the probe may be applied to develop the LC sensor system suitable for detecting various biomolecules.

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Paper No.  2017-TUE-P0201-P008
Wei-Lung Liau
Synthesis and Characterization of Liquid Crystal Molecules Based on Anthradithiophene for the Application in Organic Field-Effect Transistors

This study is aimed to synthesize three liquid crystal molecules based on angular anthradithiophene (a-ADT) as core for the application in organic thin film transistors (OTFT). The a-ADT molecules have low HOMO energy level and good stability for the development of OFETs, and the liquid crystals can enhance ordered alignment on OFETs. Thiophenic-octyl group and thiophenic-dodecyl group were introduced onto the core of a-ADT on both sides to yield compounds Bis-C8T-a-ADT and Bis-C12T-a-ADT. On the other hand, thiophenic-dodecyl group was attached to the core of a-ADT on one side to yield compound C12T-a-ADT. The obtained compounds were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) to determine their mesomorphic properties. Compound Bis-C8T-a-ADT showed nematic and smectic A phases while both compounds Bis-C12T-a-ADT and C12T-a-ADT revealed smectic A phase. Their optical and electrochemical properties were measured by UV and CV instruments. All compounds showed low HOMO energy level which meant they have good stability for the development of OFETs. Compound C12T-a-ADT displayed the highest carrier mobility of 0.12 cm2/Vs.

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Paper No.  2017-TUE-P0201-P009
A. Bubnov
New chiral azobenzene-containing monomers for functional liquid crystalline polyacrylates

Due to the photosensitivity, liquid crystalline low molar mass materials or liquid crystalline polymer systems containing azobenzene groups are very promising and unique materials for optical data recording and optoelectronics. Recently, several new series of materials showing the photo-orientation phenomena has been synthesized and studied. However, the relation between the molecular structure and their mesomorphic properties is still not completely clear. In this work we present the design and study of several new azobenzene-containing liquid crystalline monomers with different structure of the molecular core with the aim to find the proper monomer structure for further preparation of functional polyacrylates. The mesomorphic properties of new acrylate monomers have been studies by POM, DSC, SAXS, and dielectric spectroscopy. Depending on the molecule structure the N*, TGBA, SmA* and SmC* phases have been detected. In case of lateral substitution by chlorine atom, phase transition temperatures have been lowered by 40-50 K with respect to the non-substituted compounds. The UV-VIS spectra of these compounds in solutions have been studied. After UV irradiation, the isomer’s E –Z ratios have been determined by high pressure liquid chromatography. The results of the mesomorphic behaviour of new compounds are discussed in terms of the molecular structure changes.

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Paper No.  2017-TUE-P0201-P010
Ya-Ting Yang
Studies of Low Symmetry of Hexa-peri-hexabenzocoronene Derivatives on Synthesis and Applications

To address the effects of molecular symmetry on the phase of columnar liquid crystals, a series of C1 and D3h symmetric hexa-peri-hexabenzocoronene derivatives was prepared.[1] Compounds 3 (C1 symmetry) and 2 (D3h symmetry), as well as a mixture of compounds 3 + 2, all had a significantly lower melting temperature and clearing temperature than D6h symmetry compound 1, and all results show a strong dependence on molecular symmetry.

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Paper No.  2017-TUE-P0201-P011
Wei-Cheng Hsieh
Wide blue phase range observed in simple binary mixture systems containing biphenyl mesogens with 2-octyloxy tail

Four series of simple and rodlike racemic biphenyl mesogens possessing 2-octyloxy tail and different substituents at inner-core position of phenyl ring were easily prepared. They were confirmed by variable-temperature XRD and the characteristic texture of POM. In general, cubic BPs can be induced by adding appropriate ratio of chiral additive S811 or ISO(6OBA)2 into these biphenyl mesogens during the heating and cooling processes. Interestingly, BPIII (5-6 K) easily dominates in high chirality condition for the blending mixture composed of mono-substituted biphenyl mesogens and S811. In addition, formation temperature of BPIII is near room temperature (36°C) when compound C6OBiPhI-OH is blend with 35 wt% S811 during the cooling process. Stable BPs with more than 20 K present in the blending mixture system composed of ISO(6OBA)2 and no substituted biphenyl mesogens CnOBiPhI-H or difluoro substituted CnOBiPhI-FF. Notably, the widest temperature range of BP (~34 K) can be induced by adding only 10 wt% ISO(6OBA)2 with high HTP into the biphenyl compound C6OBiPhI-H. On the basis of our experimental results and molecular modeling, we demonstrated that the appearance and temperature range of BPs in this simple type of biphenyl mesogen with 2-octyloxy tail are affected by the molecular dipole moment and biaxiality

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Paper No.  2017-TUE-P0201-P012
A. Bubnov
Design of new photosensitive chiral liquid crystalline materials

Ferroelectric liquid crystalline materials exhibiting chiral mesophases are of high interest due to their potential applicability in photonics and electro-optic devices. However, the majority of these materials suffers from layers contraction that occurs at the SmA*-SmC* phase transition that leads to the formation of ‘zig-zag’ defects. Design and utilization of FLC materials with ‘de Vries-like’ type of the phase transition, may resolve this problem. Recently, a new series of ‘de Vries-like’ materials with general structure I that possess a low (> 3%) layer contraction has been designed. In this follow-up study, we optimize the structure of materials I and enhance their functionality by introducing a photosensitive azo group as a spacer between the aromatic units of the central core II. Unlike the previous study, a strong effect of both alkyl chain lengths (R and R’) on mesomorphic behaviour has been detected. These materials can easily be switched by UV-light and that the formed Z isomer is stable in the darkness under heating. The effect of length of both terminal alkyl chains on mesomorphic behaviour will be assessed. Comparison of newly designed FLC materials in terms of E/Z isomerisation rate will be discussed.

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Paper No.  2017-TUE-P0201-P013
Yuji Ogida
Synthesis of Silica Nanoparticles Coated with Mesogens and Measurements of Their Physical Properties

Silica nanoparticles have a chemical and a thermal stabilities but have the disadvantages such as an aggregation and a sedimentation. It is possible to give a functionality to silica nanoparticles by a coating with functional organic compounds. The aggregation of the silica nanoparticles will be also improved by the coating. Therefore, we focused on the silica nanoparticles coated with the liquid crystalline molecules of which molecular orientation can be controlled by an applying electric field. Furthermore, in order to observe the dispersed structure of the silica nanoparticles coated with mesogens in low molecular weight liquid crystals by using a confocal microscope and a fluorescence microscope, the silica nanoparticles coated with fluorescent mesogens have been synthesized. Figure 1 shows the structures of the objective silica nanoparticles.

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Paper No.  2017-TUE-P0201-P014
Yu chang Huang
The effect of functional groups of racemic rodlike schiff base mesogens on the stabilization of blue phase in the binary mixture systems

Four series of rodlike racemic Schiff base mesogens possessing different alkyl chains and two types of linkage (ester and alkynyl) are applied to induce cubic blue phases (BPs) in simple binary mixture systems. BP range could be induced more than 20 K when 20-40 wt% chiral additive S811 is added into the salicylaldimine-based mesogen. The widest BP range (35 K) presents in the blending mixture composed of salicylaldimine-based mesogen OH-TIn possessing alkynyl linkage and 35-40 wt% S811. Notably, the termination temperature of BP is very close to room temperature (35 °C) after 40.0 wt% S811 is added into the salicylaldimine-based mesogens possessing terminal alkyl chain and ester linkage. Interestingly, wide BP range (>30 K) can be induced by adding ISO(6OBA)2 into the Schiff base mesogen possessing ester linkage. BPI and BPII can be confirmed by reflectance spectra. The results indicate that the binary mixture composed of salicylaldimine-based mesogens and S811 easily exhibits super-cooling effect and induces BPI. However, only BPII can be observed in all binary mixtures containing Schiff base mesogen. Based on our experimental results and molecular modeling, we suppose that the values of the molecular biaxiality, polarizability and dipole moment are the main factors to affect BP stabilization.

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Paper No.  2017-TUE-P0201-P015
Yuta Kitajima
The Synthesis of the Cyclic Siloxane Tetramers with the Side-on Chiral Mesogens and Their Physical Properties

Blue phases are liquid crystal phases with three-dimensional structure and disclination lines, which appear between a cholesteric phase and an isotropic liquid phase. Generally, a blue phases temperature range is very narrow, typically 1 °C because the blue phases are unstable owing to the complicated structure. In this study, the cyclosiloxane derivatives with the side-on chiral mesogens were newly synthesized with the aim of expanding the blue phase temperature range and increasing a clearing point. Moreover, a relationship between the temperature range of mesophases (blue phases) and the spacer length was discussed.

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Paper No.  2017-TUE-P0201-P016
Kishi Yuki
The Synthesis and the ER Effect of the Liquid Crystalline Cyclosiloxane Derivatives with Side-on Mesogens

An electro-rheological (ER) effect is defined as a reversible change of rheological properties of a fluid by an applying electric field. Liquid crystalline (LC) materials are attracted as the materials exhibiting the ER effects in recent years. In this study, the LC cyclosiloxane derivatives using 1,3,5,7-tetramethylcyclotetrasiloxane (cyclosiloxane) as a cyclic core were newly synthesized. In addition, the alkyl chain length in the mesogens of the LC cyclosiloxane derivatives was varied. The phase transition behavior was clarified by using a polarizing optical microscopy and a differential scanning calorimetry. The correlation between the alkyl chain length and the phase transition behavior was discussed, and their ER effect was also discussed.

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Paper No.  2017-TUE-P0201-P017
Toshiyuki Hayashi
Orientational Behavior of Ionic Liquid-Crystalline Polymeric Systems

In liquid-crystalline systems, the introduction of an ionic interaction can lead to the formation of a liquid-crystalline phase with enhanced thermal stability. Furthemore, an ion complexed liquid crystal can be obtained by the ion complexation between different compounds. In this paper, we describe ionic liquid-crystalline polymeric systems through the proton transfer reaction of a sulfonic acid containing polymer (proton donor) with an amine derivative (proton acceptor).

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Paper No.  2017-TUE-P0201-P018
Shunsuke Tanaka
Synthesis of Supramolecular Liquid Crystals containing Nucleic Acid Bases with Siloxane Moiety and Investigation of Their Physical Properties

A supramolecular liquid crystal is a self-assembling chemical system of which component molecules are bonded by non-covalent bonds such as a hydrogen bond, as a result, it exhibits a liquid crystallinity. It is well known that nucleic acid bases form hydrogen-bonded assemblies and each nucleobase specifically forms a Watson-Crick base pair with its complementary partner in DNA double helix structure. We focused on the supramolecular complex containing nucleic acid bases which is expected to exhibit a liquid crystallinity. In this study, a series of adenine and thymine derivatives were synthesized and the phase transition behavior of their complexes was investigated.

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Paper No.  2017-TUE-P0201-P019
Martin Cigl
Reactive mesogens for photosensitive polymers and composites

Driven by the trend of miniaturization there is enormous world-wide effort to develop new so-called “smart materials’ that mechanically deform or change their physical properties in response to external stimuli. Their high potential in industry and medicinal applications includes memory devices [1], responsive surfaces [2] sensors [3] or artificial muscles [4]. Liquid crystalline polymers are very promising class of smart materials combining self-organisation of liquid crystals (LCs) with processability, corrosion resistance and other positive features of polymers. Among them, azobenzene-containing polymer systems present tremendous interest for the development of new materials for optics, photonics and optoelectronics. This interest is associated with photochemical properties of the azobenzene moieties, such as high quantum yield and reversibility of E-Z photoisomerization processes, absence of the side photochemical processes, large changes in molecular anisometry and dipole moment during E-Z isomerization etc. Due to the rapid development of this field there is also an increasing demand for new monomers with suitable properties. Here we discuss the design and synthesis of novel azobenzene-based photosensitive monomers with different polarization of azo bond (see Figure 1 for general structure) and their mesomorphic and spectroscopic properties.

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Paper No.  2017-TUE-P0201-P020
Kosuke Kaneko
Electrorheological Effect of Dual Frequency Nematic Liquid Crystals

This study presents how dual frequency liquid crystals (DFLCs) have a great potential for the development of electrorheological (ER) fluids. DFLCs show positive and negative dielectric anisotropies at different frequencies, which is a promising feature for a driving method of the ER effect. We investigated the dielectric properties of the DFLC mixtures in a wide frequency range (100 Hz-10 MHz) and measured the ER effect caused by changing the frequency. It was also investigated how the DFLC in the nematic phase flows under an applied electric field by using a polarizing optical microscope (POM) in combination with a rheometer. This novel approach offered the possibility of obtaining enhanced response on the ER effect in the turn-on and turn-off processes.

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Paper No.  2017-TUE-P0201-P021
Jeehyun Lee
Synthesis and property of light emitting mesogens with alkylated fluorene and thiophene moieties

Organic semiconducting materials with conjugated-structure have been used in various applications such as OLED, OTFT and OPV. If these materials have a rigid-rod structure, in other words mesogen structure, they can possess orientational characteristic like a liquid crystal. In this work, we have synthesized and characterized the conjugated rigid rod-like molecules and studied the effect of mesophase on luminescence characteristics. In this study, we have synthesized two mesogenic compound which contain an alkylated fluorine unit varying with carbon number of alkyl groups (1: n = 3; 2: n = 8) and bis-p-hexyloxyphenyl- thiophene moieties. The structures of compounds were identified by FT-IR and 1H-NMR spectroscopy. The purity of compounds was confirmed by thin layer chromatography and elementary analysis. The optophysical properties were characterized by UV-Vis and PL spectroscopy. Their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM).

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Paper No.  2017-TUE-P0201-P022
Jeong-Seob So
Synthesis and property of light emitting mesogens with alkylated fluorene and biphenyl moieties

The industry of organic electroluminescence has been grown with the high technology but their life time and light efficiency need to be promoted.1-2 If light emitting molecules have rod or disk-like mesogenic structures and form anisotropic mesophase, it can improve light efficiency and polarized ratio of the OLED device because they can be aligned themselves. In this study, we have synthesized and characterized organic electroluminescence molecules having rigid rod-like structure to understand that how the liquid crystal phase affects the luminescence characterization. We have synthesized two organic light emitting mesogenic compounds which contain bi-alkyl chains in the fluorene moieties. The carbon number of alkyl chains are 3 and 8, respectively. The structure of compounds was identified by FT-IR and 1H-NMR spectroscopy. The purity of compounds was confirmed by thin layer chromatography and elementary analysis. The thermal property and phase behavior were investigated by differential scanning calorimetry (DSC) and cross-polarizing optical microscopy.

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Paper No.  2017-TUE-P0201-P023
Mu-Chun Tu
Novel Cholesteric Liquid Crystal Sensor Materials Containing Dual Sensory Dopant and Host towards Ferric (Fe3+) Ion

We develop novel cholesteric liquid crystal sensor (CLCS) materials containing commercially available cholesteric liquid crystal hosts with a saturated concentration (ca. 30 mol%) of a simple sensor probe (3EOCB) possessing bi-functional moieties, which reveal high selectivities towards particular metal ion, i.e., including ferric ion. Generally, as mixed with most metal ions the CLCS materials show blue-shifted reflections, which demonstrate color changes from blue-green (509 nm) to blue (ca. 484-468 nm) observed by naked-eyes. Due to different coordination mechanisms of particular metal ions with 3EOCB, only ferric and potassium ions illustrate red-shifted color changes, from blue-green to red (ca. 663 nm) and green (ca. 541 nm), respectively. Overall, the blue-shifted reflection wavelengths of CLCS materials towards most metal ions were proportional to the ionic radius of metal ions with the same valence number. The special binding mechanisms of tri-ethylene oxide and CN moieties in probe 3EOCB towards metal ions are proposed to explain the special phenomena of both blue- and red-shifted reflection color changes in the CLCS materials for the first time of metal ion detections. In addition, the largest red-shifted reflection of CLCS are attributed to the synergic effects of dopant 3EOCB and host E7 for ferric ion detection.

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Paper No.  2017-TUE-P0201-P024
Yan-Song Zhang
Fabrication and characterization of wide-band reflection films via multiple gradient UV-polymerization

A wide-band cholesteric liquid crystal imprinted cell is fabricated by controlling photo-polymerization has been performed. The wide-band Bragg reflection cholesteric liquid crystal (CLC) cells have been reported using UV bleachable dye, temperature variance photo-polymerization process, etc.[1-5] In this study, imprinting and broadening of reflection band of CLC cells were achieved via controlling UV polymerization. Intensity gradient of UV light was achieved by adjusting the distance between UV lamp and the sample cell. Imprinted template was prepared by photopolymerization of mixed nematic LC, chiral dopant, bifunctional monomer and photoinitiator. Intensity of UV light may affect the polymerization rate leads to the formation of imprinted helical construction with different pitches. Pitch gradient inside systems usually broaden the reflection band of sample cells effectively. After polymerization, the residual LC mixture was then removed by using solvent. Refilling of NLC increases refractive indexes leads to the enhancement of reflection light strength of sample cells. Stacking of two imprinted cells with different pitches broadens reflection band effectively. In this study, comparison of this new designed process with traditional UV polymerization process was carried out. Spectral characterizations and optical reflection of the fabricated sample cells were performed using UV-vis spectrometer equipped with an optical fiber probe.

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Paper No.  2017-TUE-P0201-P025
Chun-Chieh Han
Lateral fluoro-substitution and chiral effects on supramolecular liquid crystals containing rod-like and H-bonded bent-core mesogens

The first series of liquid crystalline supramolecular diads C/D containing asymmetric rod-like and H-bonded bent-core mesogens were designed and synthesised, among which supramolecular diad PIII*/AII* with two chiral centers on both H-acceptor/H-donor and non-lateral fluoride substitution possessed a wide blue phase (BPI) range of 13.7°C.

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Paper No.  2017-TUE-P0201-P026
Ashwathanarayana Gowda
Ethylenedioxythiophene: Novel central unit for bent-core liquid crystals

We have discovered that ethylenedioxythiophene (EDOT) can be used as a central unit for the synthesis of bent-core liquid crystals (BC LCs). Four series of compounds include three ring- and five ring compounds were prepared from EDOT. The mesophase behaviour of all the compounds was characterized using a combination of polarising optical microscopy, differential scanning calorimetry and X-ray diffraction measurements. EDOT-based three-ring compounds with acetylene linkage were found to be nonliquid crystalline, while all the four derivatives of five-rings series with acetylene linkage, including a branched alkoxy chain derivative, display enantiotropic nematic phase over wide temperature range. EDOT bearing three-ring Schiff base bent-core compounds are non-mesomorphic but all the Schiff bases containing five-ring exhibit enantiotropic mesophase behaviour. The higher homologues show long range nematic phase along with a smectic C phase at lower temperature. While the lower homologues exhibit only N phase. The bent angle of these compounds is about 153°-155°, which falls in between typical rod-like and banana liquid crystals[1–4]. The detailed XRD investigations of all the mesogens corroborate the presence of nematic phase and SmC phase.

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Paper No.  2017-TUE-P0201-P027
Jae-Hyun Bae
A Photonic Reflective Device utilizing Polymer-Stabilized Liquid-Crystalline Blue Phase II

We demonstrate a photonic reflective device using polymer-stabilized liquid-crystalline blue phase II over a temperature range of several ten degrees including room temperature. Vivid colors are due to three-dimensional photonic crystalline structure of BPII. The fabricated reflective-type device utilizing the reflectance–voltage performance of the polymer-stabilized BPII showed very small hysteresis and fast response times. [1] Our work demonstrates the possibility of practical application of the polymer-stabilized BPII to photonic crystals. Details will be discussed in ACLC 2017.

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