A5073538173- Liquid Crystal Research Advancements
- Molecular spectroscopy and chirality
- Photonic Crystals and Applications
- Surfactants and Colloidal Systems
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Quantum Chemical Studies
- Plant Reproductive Biology
- Synthesis and Properties of Aromatic Compounds
- Photonic and Optical Devices
- Nonlinear Optical Materials Research
- Nonlinear Dynamics and Pattern Formation
- Advanced Materials and Mechanics
- Material Dynamics and Properties
- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- Photochromic and Fluorescence Chemistry
- Porphyrin and Phthalocyanine Chemistry
- Photoreceptor and optogenetics research
- Photorefractive and Nonlinear Optics
- Solid-state spectroscopy and crystallography
- Polydiacetylene-based materials and applications
- Force Microscopy Techniques and Applications
- Organic Light-Emitting Diodes Research
- Supramolecular Self-Assembly in Materials
Tokyo Institute of Technology
2009-2024
Toyota Central Research and Development Laboratories (Japan)
2015-2018
Toyota Physical and Chemical Research Institute
2015-2018
Otto-von-Guericke University Magdeburg
2014-2018
University of Warsaw
2006-2016
Toyota Motor Corporation (Switzerland)
2015
Meguro Parasitological Museum
2015
University of Wisconsin–Madison
1981-2012
The University of Tokyo
2008-2011
Japan Synchrotron Radiation Research Institute
2008-2010
The synthesis of a banana-shaped molecule is reported and it found that the smectic phase which forms biaxial with molecules packed in best direction into layer. Because this characteristic packing, spontaneous polarization appears parallel to layer switches on reversal an applied electric field. This first obvious example ferroelectricity achiral ascribed C2v symmetry molecular packing.
Structures and properties of liquid crystalline phases formed by bent-core molecules are reviewed. At least eight designated as B1–B8 have been found, being unambiguously distinguished from usual calamitic due to a number remarkable peculiarities. In addition phases, smectic A-like biaxial nematic also The most attractive aspects this new class crystals in polarity chirality, despite achiral molecules. mesogens the first ferroelectric antiferroelectric realized without introducing chirality....
At least two antiferroelectric liquid crystalline phases were discovered in MHPOBC. These appear below the usual ferroelectric Sm C * phase. Because of alternation molecular tilt directions as well dipole orientations successive layers, optic axis is along layer normal. This strong stabilization normal brings about so-called third stable state responsible for tristable switching. The structure was strongly supported by selective reflections oblique incidence; a full-pitch band does not...
It is proposed to apply the direct measurement of spontaneous polarization using triangular waves ferroelectric liquid crystals. The use allows us easily subtract background contribution due conductive and capacitive current accurately determine polarization, since a bump realignment appears on straight base line. Moreover, experiment with pulsed clearly reveals no existence threshold voltage for deforming helix some characteristic properties dynamic reaction field applied.
The phase, designated as Sm C A * , which shows tristable switching was investigated in 8 H 17 O– - -COO– -COO CH(CH 3 )C 6 13 (MHPOBC) by means of thermal analyses, a miscibility test and microscope observation. phase transition from to is not observable AC calorimetry but small peaks comparable the A-Sm are discernible DSC. According racemic MHPOBC with standard compound, this new found exist between I be miscible B hex . Therefore, assignment one known phases ruled out, that totally...
A new switching process was observed in surface stabilized ferroelectric liquid crystals. The is associated with a third stable state addition to the well-known bistable states. appearance of characteristic materials large spontaneous polarization and caused by minimizing induced charges. between each exhibits sharp dc-threshold hysteresis, suggesting possible application for device.
Ferroelectric liquid crystals are materials that have a remnant and electrically invertible polar order. Columnar with ferroelectric nature potential use in ultrahigh-density memory devices, if electrical polarization occurs along the columnar axis. However, having an axial nonzero at zero electric field its invertibility not been demonstrated. Here, we report response for crystal adopting core-shell architecture accommodates array of cyano groups confined by hydrogen-bonded amide network...
Any polar-ordered material with a spatially uniform polarization field is internally frustrated: The symmetry-required local preference for to be nonuniform, i.e., locally bouquet-like or "splayed." However, it impossible achieve splay of preferred sign everywhere in space unless appropriate defects are introduced into the field. Typically, materials like ferroelectric crystals liquid crystals, such not thermally stable, so that globally frustrated and remains uniform. Here, we report class...
Helical structures were confirmed for both the SmA b and SmBlue phases of banana-shaped molecular systems from observations microscopic fringe pattern selective reflection blue color, respectively. X-ray optical microscopy indicate that helical axes in are normal parallel to smectic layer, In these two phases, 13 C NMR spectra show C=O peaks, suggesting different configurations ester group, whereas only one peak appears isotropic crystal phases. This indicates groups mesogenic core not same...
Molecular orientational structures in MHPOBC were studied by means of conoscope observation. Contrary to a ferroelectric response the an electric field smectic C * phase, conoscopic figure antiferroelectric A phase does not shift its center and is biaxial with optic plane perpendicular direction. This change only due dielectric contribution, indicating existence inherent threshold induced transition phase. In between phases, kind ferrielectric was clearly distinguished figure; applied...
The smectic layer thickness and the switching behavior in MHPOBC have been studied as a function of temperature; SmC α * is tilted phase antiferroelectric at least higher-temperature region but becomes ferrielectric with decreasing temperature. gradual appearance characteristics suggests emergence Devil's staircase. To explain antiferroelectricity A , two types molecular interactions are proposed: one interaction between spontaneous polarizations neighboring layers which effective other...
We have prepared a novel series of banana-shaped molecules with central bent core based on 2,7-dihydroxynaphthalene group, the side wings containing Schiff's moiety, and alkoxy flexible tails carbon numbers n = 6, 8, 10, 12, 14, 16. Among these, 8−16 formed smectic phase. Its layer possessed liquidlike association similar to SmA or SmC phase, although texture that developed from isotropic melt was unconventional. Small fractal domains initially grew then coalesced into several large domains....
An amide-appended corannulene derivative (3) with tribranched paraffinic side chains self-assembles into a hexagonal columnar liquid crystalline (LC) mesophase over wide temperature range from 154 to −10 °C. In contrast LC assemblies of planar polycyclic aromatic hydrocarbons, the assembly nonplanar 3 responds an applied electric field and can align homeotropically electrode surface. Even after is switched off, this alignment memorized for long period time unless material heated above...
Spontaneous formation of two types helical structure is observed in smectic phases consisting banana-shaped achiral molecules for the first time. Local optical resolution occurs to form spatially resolved helices both handednesses.
This paper reviews nearly $20\phantom{\rule{0.3em}{0ex}}\text{years}$ of research related to antiferroelectric liquid crystals and gives a short overview possible applications. ``Antiferroelectric crystals'' is the common name for smectic formed chiral elongated molecules that exhibit number (Sm) tilted structures with variation strong-tilt azimuthal direction from layer (i.e., nonsynclinic structures). The phases have varying crystallographic unit periodicity few...
Pillars of salts: By combining planar cations and anionic structures based on π-conjugated acyclic dipyrroles containing an anion, charge-by-charge assemblies could be formed (see picture). Not only crystals but also soft materials, such as supramolecular gels thermotropic liquid crystals, made by this method.
New chiral dimers consisting of a rod-like and cholesterol mesogenic units are reported to form twist-bend nematic phase (NTB *) with heliconical structure. The compressibility the NTB made bent was found be as large in smectic phases, which is consistent nanoperiodic structure phase. atomic force microscopy observations revealed periodicity about 50 nm, significantly larger than one previously for non-chiral compounds (ca. 10 nm).
Color conversion, long‐wavelength light emission by absorbing short‐wavelength light, is an attractive approach for developing a broad‐color expression technology and widely used in solid‐state lighting, dye‐lasers, colorful displays. Up to now, many papers have been published reporting various mechanoluminescent materials emitting color of ultraviolet, blue, green, orange, red. However, the strategies previous reports focused on color‐tuning material itself through newly inorganic...
The emergence of the blue phases I and II that are thought to exist in highly chiral systems has been found nematic liquid crystals (N* LCs) when they doped with achiral bent-core (banana mesogens). same effect was also observed by adding racemic 4-(1-methylheptyl oxycarbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC), while terephthal-bis(p-butylaniline) (TBBA) not effective. difference attributed different conformations, i.e., MHPOBC is known have a bent shape, but TBBA. doping more...
Lasing via a phase retardation defect mode is reported for the first time. The Figure shows far‐field pattern of laser emission realized by inserting an anisotropic nematic liquid crystal (LC) layer between polymer cholesteric LC layers. system mimics cuticle Plusiotis resplendens , beetle, using birefringence to achieve reflectance greater than 50 % provided simple photonic bandgaps.
Achiral banana-shaped molecules with dodecyloxy tail groups, P-12-O-PIMB, N-12-O-PIMB, and S-12-O-PIMB, have exhibited unusual smectic phases which possess chiral helical structures. In this work, we mixed these the molecule forming a nematic liquid crystal found an exclusive effect of achiral dopant that twisting power phase in mixtures is significantly increased increase content molecules. This characteristic field seems to offer rational evidence for twist conformation such molecules,...