Structural and dynamical properties have been investigated for the core part of R-MHPOBC in the liquid crystalline phases. The alignment-induced shift of the ¹³C resonance frequencies are analyzed with a theoretical model based on Wigner order parameters and the three components of the chemical shielding tensor for each carbon, which were determined with the local field separated 2-dimensional spinning sideband spectroscopy in the solid state. It has been found that the molecular long axis is located at 7.3deg. and 8.0deg. away from the biphenyl and phenyl para-axes, respectively. The Saupe orientational order parameter of the molecular core has been determined to be 0.75 at 135deg). C. It is most likely that both rings exhibit 180deg. flip about their para axes in the liquid crystalline phases.

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In order to investigate the segmental motion of S-MHPOBC, we measured the ¹³C-NMR spin-lattice relaxation time (T₁), by means of the inversion recovery method. The temperature dependence of T₁ obey the Arrhenius type. T₁ for most of arbons show continuous temperature dependence. On the other hand , in case of the chiral carbon, temperature dependence of T₁ in SmA is different from that in SmC_A^*. This result suggests that the segmental motion of the chiral carbon changes under the influence of some kinds of molecular interaction changing at the phase transition.

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We formulated previously a phenomenological theory of light-induced reorientation of nematic liquid crystals driven by the trans↔cis photoisomerization of photochromic molecules dispersed in liquid crystal media. Extending this theory, we discuss here the influence of light-induced reorientation in the Freedericksz transition.

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The disclination in pi-cell was studied. The boundary-layer model gives a simple expression on the energy difference between the bend/splay states. The disclination motion is determined by the energy difference and the damping factor. It was shown theoretically that (1) the disclination motion is proportional to the electric field and (2) the symmetric splay state is ten times faster in disclination propagation than the asymmetrical splay. During the zero bias, the twist state exists in switching from the bend back to the splay. Its disclination velocity is negligibly small.

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A normal mode analysis was carried out on directors interacting through the Maier-Saupe type interaction, simulated in the 2-dimensional lattice model. The analysis for the director system containing a set of ±1/2 disclinations was compared with the case without disclinations in terms of the vibration patterns of the individual modes. Most modes for the system with the disclinations showed similar vibration patterns to the patterns for the corresponding modes of the system without disclinations, especially at high frequencies, but it was found that some lowest modes could make active the local motions around the disclinations. A similar observation was made on the systems with more disclinations. It was suggested that an application of a specific frequency could activate only the motion of disclinations without disturbing the rest of the ordered region.

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The electrohydrodynamic instability in a homeotropically oriented nematic system occurs after the Freedericksz transition which leads to the Goldstone mode due to additional symmetry. In the system with no magnetic field the transition from a rest state to spatiotemporal chaos via the supercritical bifurcation, that is, soft-mode turbulence occurs. In the presence of magnetic fields the bifurcation point to spatiotemporal chaos shifts to higher value of control parameter with intensity magnetic fields. Above convection thresholds, normal rolls (the wavevector of the pattern k is parallel to the C-director) appear at the frequency of the applied AC-voltage beyond the Lifshitz point (LP), and oblique rolls below LP.

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The response time of the electrooptical characteristics for HAN cells depends on the value of the difference of the flexoelectric coefficients, e₁₁ - e₃₃, where the electric field is applied parallel to the cell surface. To improve flexoelectric effects, an appropriate amount of a ferroelectric llquid crystal was doped in the nematic mixture. The characteristics of the response time were measured and investigated for some mixed liquid crystals. A new quasi-bistable mode using chiral nematic liquid crystals with the flexoelectric effects is proposed, where the electric field is applied along the cell surface.

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The boundary layer display (BLD) with nematic liquid crystals was proposed by J. Cheng et al. in 1982. When a dc voltage is applied, boundary layer moves to one surface layer or the other, depending on the polarity of the dc voltage. J. Cheng et al. came to conclusion that the polarity of the torque in cells were due to ions. However, we assumed that this polarity is unduced by flexoelectric effects in nematics, which is dominant over the effect of ions. Then, numerical simulations were carried out by continuum theory with flexoelectric effects.

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The boundary layer display (BLD) with nematic liquid crystals was proposed by J. Cheng et al. in 1982. We assumed that the torque of the director reorientation with polarity which depends on the sign of the applied dc electric field in the BLD cells is induced by flexoelectric effects. Then, some electrooptical characteristics of BLD cells were studied theoretically and experimentally. Good agreements were obtained between the T-V characteristics of numerical calculated results and experimental results.

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We have reported electro-optic characteristics of the light scattering texture induced by applying the burst electric field. Formation of the texture might depend on LC aligning materials. For example, we could not find the texture in case of polyimide (PI) but in case of polyvinylalchol (PVA). In this paper, formation mechanism of the light scattering texture are studied, experimentally. By observing the LC alignment on rubbed PVA films, we find only a few deviation in the direction of the extinction, maximum 10 degrees. Next, we try to iatroduce some deviation of aligning direction into rubbed PI films. We could get the light scattering textures in N^* LC cells with PI films irradiated by polarized UV lights. Then, deviation of aligning directions seems to be necessary to explain the formation mechanism of the light scatering structure.

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The paper is report of micro-doropret growth on a substrate surface at PDLC devices which in growing a phase separation texture as well as the cell membrane and a micro-droplet diameter is 2-3/μm.

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Dynamic Monte Carlo simulation, based on a new algorithm that is specifically designed to deal with long-term phenomena, was carried out for model liquid crystalline systems in order to understand the molecular origin of the anchoring effect and the electric-field induced reorientation dynamics of liquid crystals. Time dependent variation of the "molecular" orientation angle was calculated and compared with the corresponding results obtained for the "director" orientation angle using an elastic continuum theory. Applicability of the dynamic Monte Carlo simulation to the study of various time-dependent phenomena of liquid crystals will be discussed.

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We have developed a new simulation method for a large system within many (〜1000) realistic molecules of liquid crystal. In our Monte Carlo (MC) simulation, the location of a molecule is restricted at a lattice point, and the direction of a molecule is also limited in some discontinuous angle. And the infer-molecular energy is calculated before MC main calculation separately. Therefore our MC method can calculate some physical quantities so rapidly even for a large system. We have calculated the orientational order parameter for some kinds of molecule. And we obtained almost same order of the orientational order parameter with experiments. A part of this study was supported by NEDO.

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Constant temperature molecular-dynamics(MD) simulations of molecules interacting with walls are performed to study the alignment behavior at liquid-crystal/substrate interface. Molecules interact one another via the Gay-Berne potential. Wall is replaced virtual molecules fixed to cell-boundary plane, which react only on the nearest molecule in MD-cell via the Gay-Berne type potential. The system exhibits several phases as the temperature falls, isotropic, nematic, smectic and crystal phase. Existence of walls has an effect on anchoring molecular centre and extends the range of smectic phase Nature of attractive part of wall-potential has an influence on orientation and configuration of molecules in smectic-phase.

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Large-scale molecular-dynamics computation is performed for an atomistic model system that is intended to mimic the interface between a liquid crystal and a rubbed polyimide film by using special-purpose processors MD-Engine. By using this processors(MD-Engine), we could make the molecular-dynamics calctulation speed more than 5 times. The model system, containing total of 11618 atoms, consists of a 400-molecule mixture of 3 types of cyanophenylcyclohexane derivatives and a polyimide film made of 2 Kapton chains. Dynamics is run 4ns duration, and variation of orientation order parameters with time is investigated. As a result, even at higher temperature than N-L point, orientation structure of liquid crystal molecules is found near the interface more than 20 angstroms thick along the orientation of the polyimide film.

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We represented the molecular orientation of a liquid crystalline material by large-scaled MD(Molecular Dynamics) simulations. Even at 150 degrees, liquid crystal phase is induced near the surface of rubbed orientation film. As the temperature is lowered, increases in the order parameter near the surface and the thickness of the induced liquid crystal phase are observed. When an electric field is applied to the liquid crystalline material, long axis of each molecule tends to be parallel to the electric field, where the dipole moment of the molecule does not play an important role.

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For measuring the optical anisotropy of the PI-LB film, a Four Layers Optical Waveguide (FLOW) method was used. On the glass substrate, a waveguide and the PI-LB film with 31 monolayers are stacked. From the integrated optics theory, the eigen value equation of those guide modes was calculated. By analyzing the propagation of the guide modes, the anisotropic refractive index and the thickness of the PI-LB film are estimated. The results show that the anisotropic refractive index of the PI-LB film to be n_e=1.636407 and n_o=1.578014 and the film thickness of 9.8nm. Considering the average transfer ratio of an LB layer to be 70%, we can calculate the monolayer thickness of 0.45nm. These values are consistent with the results obtained by optical retardation measurements.

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We investigated mixture alignments in cyanobiphenyl liquid crystals. In present study, we observed monolayer alignments in liquid crystal mixtures (10CB-9CB and 12CB-11CB) on molybdenum disulfide (MoS₂) using STM. Two kinds of specific alignments are observed in each mixture such as a unit consisting of three molecules and a unit consisting of five molecules in single row structures. All the alignments have the common feature such that different kinds of molecules align antiparallel each other in a single row.

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We observed the arrangement of cyanobiphenyl liquid crystals (mCB: m=6 to 12) on highly oriented pyrolytic graphite (HOPG) substrates, and 6CB on molybdenum disulfide (MoS₂) by scanning tunneling microscopy (STM). The already reported arrangements were reaffirmed in 8CB, 10CB, 11CB and 12CB. In case of 6CB, the arrangement which had both single-and double-row properties were observed. In case of 7CB and 9CB, the single-row structures were observed for the first time.The characteristic point was that the arrangements were divided into single- and double-row structures accordint to the odd-even effct.

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It is important for the realization of non-rubbed liquid crystal (LC) displays to study the wettability of LCs on polymer surfaces. The estimation of wettability of LC have been done for two kinds of polyimides (PIs). Twisted nematic (TN) LC cells, in which the one side is rubbed and the other side is non-rubbed, are assembled by using a magnetically-aligned method. After the sample cells are completed, they are kept for various periods and the twisted angles of the TN cells are measured. The results show that PI with high wettability of LC gives a large twist angle (large anchoring energy) and long exposure of LC to polymer surfaces may lead the strong adsorption state of LCs.

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We investigated the smectic layer structure in subphases of an antiferroelectric liquid crystal. The structure was analyzed by comparing experimental results measured by transmission ellipsometry with simulations by 4×4 matrix. The material of antiferroelectric liquid crystal was MHPOBC(R), and experiment was carried out by using free standing films. In this measurement, the temprature, incident angle of He-Ne laser beam and the number of the layers of the free standing films were changed.

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Phase sequence of an antiferroelectric liquid crystal,MHPOPB (4-(1-methylhepthyloxycarbonyl)phenyl 4-(4'-octhyloxy-phenylcarbonyloxy)benzoate) ,was investigated by dielectric, electro-optic and circular dichroism measurements. The experimental results showed that introducing the ester bond between the biphenyl-rings leads to a drastic change in the phase sequence of the liquid crystal. Investigation on the mixing system of MHPOPB and MHPOBC are in progress.

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In this study, we investigated the bulk properties of binary mixtures with varying mixing ratio in order to understand thresholdless V-shaped switching behaviors in smectic liquid crystals. The observed jump in the helical pitch with the change of temperature in some ferrielectric phases suggests the existence of the various ferrielectric phases. In case of the mixing ratio 50:50, though the change of the helical pitch with decreasing temperature is continuous and the texture does not change, the conoscopic figure behaves from ferroelectric-like to ferrielectric-like. The behavior of the conoscopic figures in the low temperature region also shows the continuous change from the ferrielectric to the ferroelectric phase by applying an electric field.

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We have observed the two-step decrease in the dielectric constant ε of biass field and the current peaks representing the existence of SmC_α^* phase in several AFLCs. In high optical purity MHPOBC, with increasing temperature in SmC_α^* phase the, first decrease of ε was disappeared and the electric field at which the second-decrease of ε occurs was drastically increased. We discuss the dielectric behavior of the SmC_β^* phase.

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The temperature dependence of ¹³C-NMR spectrum and layer thickness have been investigated on antiferroelectric liquid crystal with tetralin unit. There is no remarkable difference between MHPOBC and tetralin derivative. In addition, we have observed the absorbance vs polarizer angle for the carbonyl and phenyl stretching peak with changing incident angle in order to estimate the direction of carbonyl group.

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We have investigated collective fluctuation and switching behavior in an antiferroelectric phase designated as the AF phase, which appears in a temperature region above the chiral smectic C_A (SmC_A^*) phase of an antiferroelectric liquid crystal, (S)-4-(1-methylheptyloxy-carbonyl)phenyl 4'-octylbiphenyl-4-carboxylate. It has been confirmed that the relaxation of the Goldstone mode due to antiferroelectric phase mode occurs in the AF phase as well as SmC_A^*. In addition, we have found that the switching behavior of the AF phase depends on the frequency of an applied electric field. The typical tristable switching between AF and SmC^* is observed under a triangular wave of lower frequencies less than 0.1Hz, though the field-induced intermediate phase appears around the frequency range corresponding to the relaxation of the Goldstone mode. We speculate the model responsible for the switching behavior of the antiferroelectric AF phase.

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Anti-ferroelectric(SmC_A^*) and ferroelectric(SmC^*) phases of α-trifluoromethyl-β-methyl-substituted liquid crystalline (LC) molecules, synthesized highly diastereo- and enantioselectively through our chiral titanium complex-catalyzed fluoral-ene reaction, were determined by thermal analysis and electro-optic measurements. Phase transitions were thus found to be critically dependent on the diastereomeric excess for u (R_α,S_β)-diastereomers of the LC molecules. And the liquid crystalline molecules also critically depend on the enantiomeric purities (% ee) not only for u- but also for l-diastereomers to show eventually an unknown phase in the racemic region of either an u- or l-diastereomer.

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We have been analyzed crystal structures containing a chiral alkyl terminus with a single stereogenic center such as methyl-substituted aryl ester and the trifluoromethyl analogue by X-ray diffraction method. In order to investigate the relationship between molecular symmetry and AFLC properties, we are analyzing crystal structures of diastereomeric molecules with double stereogenic centers, 4-(1-trifluoroumethyl 2-methyloctyloxycarbonyl) phenyl 4'-octyloxybiphenyl-4-carboxylate.

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Various fluorine-substituted antiferroelectric liquid crystals were synthesized and their properties such as thermal and electro-optic arntiferroelectricity, response time, tilt angle and spontaneous polarization were examined. From the results, their properties were greatly affected by their fluorine-substituted positions. The relationship between fluorine-substituted liquid crystals and their properties were discussed here.

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Binary mixtures of nematic 5CB with some kinds of non-nematic solutes were found to cause the increase in nematic-isotropic transition temperature, contrary to usually observed decrease. All these 'unusual' solutes found in this work had active hydrogen which can act as hydrogen bond donor. 'Unusual' increase in the clearing temperature was attributed to the hydrogen bonding interaction between 5CB and solutes. The thermal and spectroscopic effects of hydrogen bonding interaction between 5CB and various non-nematic solutes were studied in detail.

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Thermoreversible liquid crystalline gets have been obtained by the introduction of bis(acvlamino)cyclohexane derivative into liquid crystals. This cyclohexane derivative functions as a gelling agent due to the network formation through hydrogen bonds. Two gel states derived from nematic and isotropic states have been obtained for the liquid crystal system.

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Common liquid crystal compounds with short alkyl group show nematic phase and with long alkyl group show smectic phase. But, I have already reported that laterally alkyl or alkenyl substituted alkoxyphenylbicyclohexanes with short alkoxy group unusually showed smectic phase and with long alkoxy group showed nematic phase. In this study, laterally acyl or alkyl substituted alkoxyderivatives were synthesized. Their liquid crystal properties are discussed.

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STN LCDs are extensively used for notebook type PCs, PDAs, and handy telephones. Up to this time, a lot of liquid crystal materials have been synthesized. However, further improvement of properties is required. We here report physical properties of liquid crystal compounds with a difluoroalkenyl group, and compare the properties of difluoroalkenyl group with alkyl group or alkenyl group.

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The synthesis of chiral (E)-1-(4-alkylcyclohexyl)-1,2-difluoro-2-(p-substituted phenyl)ethylenes was studied in purpose of application as chiral additive for STN liquid crystal devices. These compounds were derived from optically active alcohols or carboxylic acids and achiral core counterpart. Ether type compounds showed moderate chiral pitch and high viscosity. Phenyl ester type compounds showed long chiral pitch and low viscosity. Benzoate type compounds exhibited short chiral pitch and low viscosity, and were applicable to chiral additive for STN liquid crystal devices.

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New liquid crystal materials were synthesized from carboxyric acids and alcohols having a methyl, a fluoro and a trifluoromethyl group as an asymmetric frame. The materials were mixed with a host nematic liquid crystal. The helical twisting powers of the mixtures were measured using Cano's cell. The relationship between the structure and the helical twisting power of the chiral dopants were discussed.

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The syntheses and ferroelectric liquid crystal (FLC) properties of optically active 2,4-disubstituted γ-butyrolactones, cis-1-4 and trans-1-4, with a different number of methylene group between the core part and the chiral lactone part will be described. The present syntheses are characterized by a highly regioselective C-C double bond isomerization from exo to endo effected by Pd-C to give endo-5-8, from which both cis and trans isomers were prepared in a stereoselective manner. Both cis-1-4 and endo-5-8 showed larger spontaneous polarizations (Ps's) and higher speed responses on the cases of having an even number (n = 0, 2) of methylene group than those of the odd cases (n = 1, ,3). On the other hand, trans-4(n = 3) showed a large Ps and a high speed response.

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The conformation and title properties of typical nematogens, i.e. nCB, 5PCH, MBBA, PAA etc., were calculated using the ,Ab-initio M.O. method with RHF/ 6-31G(D) basis set. Only the most stable conformer of each compound, with some exceptions, was studied. The obtained physical quantities were presented in relation to the axis of moment of inertia.

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In order to study the relationship between the chemical structure and the optical anisotropic properties of liquid crystalline materials, we synthesized and evaluated some liquid crystalline compounds having phenylacetylene unit. Alkenyltolane derivatives showed relatively high optical anisotropy and wide nematic phase. The lirationship between the calculated anisotropy of polarizability(Δ α) and observed optical anisotropy was also investigated.

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In spite of numerous reports of chiroptical liquid crystalline (LC) molecules bearing asymmetric carbons, there is few examples based on axial chirality. Here we have synthesized novel chirotical 1,1'-bi-2-naphthols with LC groups consisting of phenylcyclohexyl or biphenyl moiety as a mesogenic core. Chiral nematic liquid crystalline system was prepared by adding the binaphthol derivative as a chiral dopant into the equi-weighted mixture of two kinds of nematic LCs. Subsequently, acetylene polymerizations was carried out under chiral nematic phase of the liquid crystalline solvent. Polyacetylene film synthesized is found to have helical fibrillar morphology. As a result, the present chiral nematic LC system is demonstrated to be feasible for anisotropic reaction field of acetylene polymerization.

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Oligosilanes with alkoxybiphenyl groups, ROC₁₂H_8[Si(CH₃)₂)_nC₁₂H₈OR, were synthesized by treatment of α,ω-dicholoropermehyloligosilanes with Grignard reagents derived from 4-alkoxy-4'-bromobiphenyls. The oligosilane derivatives with n = 6; R = C₈H₁₇ and n = 6; R = C₁₀H₂₁ show smectic B and E phases, respectively. Furthermore, we investigated liquid crystalline behavior of a series of linear permethyloligosilanes, CH₃[Si(CH₃)₂]_nCH₃ where n = 8, 9, 10, 11, and 12. The permethyloligosilanes show the enantiotropic smectic B phase except the octasilane. In the liquid crystalline state, the silicon chains of these permethyloligosilanes adopt all-trans conformation.

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Thermotropic liquid-crystalline behavior of various organic cations without rigid cores was evaluated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffractometry. The phosphonium salts and the metal-containing ammonium complexes were found to show smectic A phase in which a homeotropic structure was formed spontaneously. It is significant that these compounds possess advantageous feature as thermotropic liquid crystals and show a stable liquid-crystalline phase and a simple phase transition behavior in comparison with commonly available ammonium analogs. Furthermore, to explore the microstructure of the organic cations in a solid state, the second harmonic generation (SHG) was measured in transmission by means of the Maker fringe method. The liquid-crystalline phosphonium salts and metal-containing ammonium complexes were found to be active for SHG. The SHG activity was strongly affected by the molecular alignment in a solid state.

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In a ferroelectric liquid crystal,a special type of phase-matching for optical second harmonic generation (SHG) is possible,where two counter-propagating fundamental waves create second harmonic waves at the edge of the selective reflection band. A remarkable enhancement of second harmonic generation by helicoidal distributed feedback action was observed ,which is proportional to a fourth power of the sample thickness, and is much larger compared with the conventional phase matched SH signal in rclative thick samples.

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Host-guest LC systems containing novel photoresponsive 3,3'-disubstituted azobenzenes were designed and their properties were studied. We found that these azobenzenes prefers rod-like structures in both trans and cis conformations by introducing appropriate substituents. The relation between molecular structures and compatibility with LC hosts was studied experimentally by means of highly doped LC systems. The thermodynamic properties of these systems were also evaluated. Computational calculation for optimizing molecular structure was performed by using MOPac PM3 method.

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We have investigated a photo-stimulated phase transition in 4-cyano-4'-5alkyl-biphenyl (5CB) containing a chiral material (0.1, 0.5, 1.0 weight % in 5CB). By illuminating a light to a mixture at a constant temperature just below a phase transition temperature from a nematic to an isotropic phase, a mixture shows photo-stimulated phase transitions. The phase of a mixture changes from nematic to isotropic phase, and then again to nematic phase with increasing a light illumination time. Photo-stimulated phase transitions (nematic-isotropic-nematic) depend on a light illumination time (photon energy) and a concentration of a chiral material.

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Photochemical phase transition behavior of mixtures of donor-acceptor (D-A) type azobenzene liquid crystals (LCs) and 4-pentyl-4'-cyanobiphenyl (5CB) has been explored. Various kinds of the D-A type azobenzene LCs were prepared. trans-Azobenzene in the mixture stabilizes an LC phase, while cis isomer destabilizes the LC phase. Photoirradiation of very thin film (〜 200 nm) of the mixtures at 405 nm and 436 nm resulted in disappearance of the LC phase due to trans-cis photoisomerization of the azobenzenes, and the LC phase recovered when the irradiated sample was kept in the dark because of cis-trans thermal isomerization and reorientation of the mesogens. The thermal I-LC phase transition rate varied with structures of D and A: the LC phase recovered in 500 ms in a mixture of an azobenzene (with A = -NO₂ and D = -N<) and 5CB at 37℃.

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A homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-chloroanilines [AHC(n; n= 1-8)] was synthesized. AHC(1-3) exhibited a monotropic nematic phase and AHC(4-8) a nematic phase. The temperature dependence of infrared(IR) spectra of ABCs has been observed in the spectral range of 1800-600 cm^-1. Some of the IR bands changed in intensity and wavenumber as AHCs undergo the phase-transition. Their changes can be explained by the change of the molecular conformation through the phase-transition. AHC(1-5, 7, 8) were yellow when freshly prepared and deepened to pale-orange by ultra-violet irradiation. At room temperature, the colored species thermally faded in the dark with time. The kinetics analysis of the thermal fading exhibited a good fit to a double-exponential equation, consisting of a two-state transient decay (rate constants: k₁ and k₂).

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If a phthalocyanine (Pc) is substituted by non-electro-donating group of alkylthio chains instead of electro-donating group of alkoxy chains, the Q-band may red-shift on the electronic spectra. Hence, The energy difference between HOMO and LUMO levels becomes smaller, so that we can expect better electric conductivity. Accordingly, we synthesised eight long alkylthio-groups-substituted Pc derivatives, octakis(alkylthio)phthalocyanines, and their copper(II) complexes to investigate the mesomorphic properties. Each of them shows a Dh mesophase. Furthermore, we measured the electronic spectra and conductivities and compared with those of the octakis(alkoxy)phthalocyanine derivatives. The influence of the sulfur atoms on these properties will be discussed.

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We investigated the carrier transport of liquid crystalline material, 4-(hexyloxy)-4'-octylbipchenyl. This material exhibits smectic phases, in which hole transport was observed. The hole mobilities are 10^-3cm²/Vs in smectic B and smectic E phases. These are the almost same as that of 2-(4'-octylphenyl)-6-dodecyloxynaphthalene(8-PNP-O12) which we have studied. This fact suggests that π -electron overlap caused by molecular alignment is more important than the extent of π-conjugate system in the carrier transport of liquid crystalline materials.

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