Kiyoshi Kanie

Stacking of conical molecules with a fullerene apex into polar columns in crystals and liquid crystals

Polar liquid crystalline materials can be used in optical and electronic applications, and recent interest has turned to formation strategies that exploit the shape of polar molecules and their interactions to direct molecular alignment. For example, banana-shaped molecules align their molecular bent within smectic layers, whereas conical molecules should form polar columnar assemblies. However, the flatness of the conical molecules used until now and their ability to flip have limited the success of this approach to making polar liquid crystalline materials. Here we show that the attachment of five aromatic groups to one pentagon of a C60 fullerene molecule yields deeply conical molecules that stack into polar columnar assemblies. The stacking is driven by attractive interactions between the spherical fullerene moiety and the hollow cone formed by the five aromatic side groups of a neighbouring molecule in the same column. This packing pattern is maintained when we extend the aromatic groups by attaching flexible aliphatic chains, which yields compounds with thermotropic and lyotropic liquid crystalline properties. In contrast, the previously reported fullerene-containing liquid crystals all exhibit thermotropic properties only, and none of them contains the fullerene moiety as a functional part of its mesogen units. Our design strategy should be applicable to other molecules and yield a range of new polar liquid crystalline materials.

Oxidative Desulfurization-Fluorination: A Facile Entry to a Wide Variety of Organofluorine Compounds Leading to Novel Liquid-Crystalline Materials

The oxidative desulfurization-fluorination reaction of organosulfur compounds using an N-haloimide and a fluoride source is demonstrated to be an effective and mild fluorinaton method that allows us to synthesize in high yields with high chemoselectivity various types of gem-difluoro compounds, trifluoromethyl-substituted (hetero)aromatics, trifluoromethyl ethers, and N-trifluoromethylanilines. Herein briefly summarized are the synthetic procedures as well as the scope and limitations of the reaction. The applicability of the reaction is demonstrated by the synthesis of a difluorinated glutamic acid and novel liquid-crystalline materials having an N-trifluoromethylamino, trifluoromethoxy, or 1,2-difluoroethylene group. The fluorine-containing liquid-crystalline materials are compared with the corresponding non-fluorinated materials in respect to phase transition behaviors and electro-optical properties and shown to be suitable for not only super twisted nematic (STN) but also for thin film transistor (TFT)-addressed liquid crystals displays. 1. Introduction 2. Fluorination Reactions 2.1 Fluorination of Sulfides and Thiols 2.2 Fluorination of Dithioacetals 2.3 Oxidative Desulfurization-Fluorination of Dithioester and Orthothioester 2.4 Synthesis of Trifluoromethyl Ethers from Dithiocarbonates 2.5 Oxidative Desulfurization-Fluorination of Thionesters and Thioncarbonates 2.6 Synthesis of Trifluoromethylamines from Dithiocarbamates 3. Synthesis and Electro-Optical Properties of Novel Fluorine-Containing Liquid Crystals 3.1 Synthesis and Electro-Optical Properties of N-Trifluoromethylamino-Substituted Liquid Crystals 3.2 Syntheses and Electro-Optical Properties of Liquid Crystals having Trifluoromethoxy Polar Functional Group 3.3 Synthesis and Properties of 3-Substituted Phenyl Trifluoromethyl Ethers 3.4 Synthesis and Electro-Optical Properties of Liquid Crystals with a vic-Difluoro-Olefinic Moiety

Self-assembly of thermotropic liquid-crystalline folic acid derivatives: hydrogen-bonded complexes forming layers and columns

Folic acid derivatives having 2-(3,4-dialkoxyphenyl)ethyl moieties have been found to exhibit thermotropic liquid-crystalline behavior. Smectic and discotic phases are observed for these compounds over wide temperature ranges. X-Ray diffraction and infrared measurements show that the formation of the smectic and discotic phases is due to the ribbon- and disk-like structures of the pterin rings of folic acid, respectively. The smectic phase is changed to a hexagonal columnar phase by the addition of alkali metal salts. This behavior is attributed to the change of the hydrogen-bonded structures from ribbon to disk induced by the ion–dipolar interactions.

Ion-conductive liquid crystals: Formation of stable smectic semi-bilayers by the introduction of perfluoroalkyl moieties†

Liquid-crystalline compounds 1 and 3 having perfluoroalkyl-terminated mesogens at both ends of poly(ethylene oxide) chains have been prepared. These compounds show smectic A (S A ) and C phases over 100 °C. The S A -Iso (isotropic) transition temperatures are higher by about 70 °C than those of the corresponding alkyl-substituted compounds 2 and 4. The incorporation of lithium triflate into 1 and 3 widens the temperature ranges of the S A phases for the resulting complexes. The complexes of 1 and 3 containing 50 mol-% of lithium triflate exhibit columnar phases. The ionic conductivities of the homotropically aligned complexes based on 1 along the direction perpendicular to the molecular director of the S A phases are higher than those of the corresponding compound of 2. The increase of the ionic conductivities as well as the stabilization of the smectic phases for these perfluoroalkyl-terminated compounds may be due to the formation of more stabilized layered structures through the intermolecular interactions among the perfluoroalkyl moieties.

Self-Organized Ion-Conductive Liquid Crystals: Lithium Salt Complexes of Mesogenic Dimer Molecules Exhibiting Smectic A Phases

Abstract Liquid-crystalline dimeric molecules consisting of rigid mesogenic cores and flexible oxyethylene spacers have been prepared. The ethoxy carbonyl and alkoxy groups are attached to the ends of the mesogenic cores. These molecules have been complexed with lithium triflate, resulting in thermal stabilization of the mesophases. Ionic conductivities along the direction perpendicular to the molecular director of the smectic A phases have been measured for these complexes.

Thermotropic liquid-crystalline folic acid derivatives: supramolecular discotic and smectic aggregation

Thermotropic discotic and smectic liquid crystallinity can be induced for folic acid derivatives having octadecyl and undecyl substituents in wide temperatures ranges, respectively; the addition of sodium triflate to smectic liquid-crystalline folic acid leads to a change of the assembled structures from smectic to columnar phases.

Ion-conductive mechanism in liquid crystalline molecules having polyether segment

Abstract A series of liquid crystalline molecules, α,ω-bis{4-[(4′-pentyloxy (or -octyloxy)-4-biphenylyl)-carbonyloxy]phenyl}oligo(oxyethylene)s, was synthesized to prepare oriented oligo(oxyethylene) chains. The complexes with LiCF 3 SO 3 spontaneously formed a smectic phase. Since a rigid rod part cannot solubilize the inorganic salts, the oxyethylene moieties form the ion-conductive layers in the smectic phase. The anisotropic ionic conductivity was measured by an impedance analyzer with gold comb-shaped electrode deposited on a glass substrate between Au teeth. The ionic conductivity between the gold teeth increased to 10 −3 S cm −1 at 142 °C, but it dropped considerably to 10 −4 S cm −1 above that temperature. The temperature corresponded to the isotropization point of the complex. Homeotropic orientation of the liquid crystalline complex enables to make a successive ion-conducting pathway, which is effective to obtain higher ionic conductivity. The effect of the added salts on the ionic conductivity was also analyzed. Higher ionic conductivity was obtained when the liquid crystals were complexed with LiCF 3 SO 3 . There is a suitable ion size for prompt ion migration in the oriented polyether.

A rodlike organogelator: fibrous aggregation of azobenzene derivatives with a syn-chiral carbonate moiety

A chiral azobenzene derivative containing a cyclic syn-carbonate moiety functions as a gelator for various organic solvents; the dipole-dipole interaction drives the fibrous self-assembly of the rodlike gelator.