Yuichiro Haramoto

A new ionic liquid crystal compound with viologen group in the principal structure

Abstract A new ionic liquid crystal system, based on compounds with the viologen group (for example, 1–2: Cr 190 SA 280 dec.) has been synthesized, and is found to exhibit the smectic A phase.

New liquid crystal compounds (+)-4-[5-(2-Methylbutyl)-1,3-dioxan-2-yl]phenyl 4-alkoxybenzoate

Abstract New liquid crystal compounds, (+)-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl] phenyl 4-alkoxybenzoates (5), were synthesized. The mesomorphic behaviour of these compounds is compared with that of (+)-4-(5-alkyl-1,3-dioxan-2-yl)-phenyl 4-(2-methylbutoxy)benzoates (6). While compounds 6 exhibited a chiral smectic C phase, the corresponding compounds 5 did not. This might mean that for the appearance of a chiral smectic C phase in these types of compounds, it is necessary that the carbonyl and the chiral groups exist at nearby positions. Transition temperatures to those isotropic state for compounds 5 were lower than those for compounds 6. This result is common in both cases of (+)-4-alkoxycarbonylphenyl-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl]benzoates (7), and (+)-4-(2-methylbutoxy-carbonyl)phenyl 4-(5-alkyl-1,3-dioxan-2-yl)-benzoates (8).

New pyridinium type ionic liquid crystal compounds with a 1,3-dioxane ring in the principal structure

Abstract A new pyridinium type ionic thermotropic liquid crystal system having two rings in its central core has been synthesized. These compounds exhibited a smectic A phase over a very wide range including room temperature (for example 5-1: Cr -24 SA 150I).

2-(p-Cyanophenyl)-5-Alkyl-1,3-Oxathianes in Liquid Crystal Mixture

Abstract The trans isomer of the 2-(p-cyanophenyl)-5-alkyl-l,3-dithianes, synthesized by the acid-catalyzed thioacetalization of p-cyanobenzaldehyde and dithiols, were separated by means of centrifugal liquid chromatography and recrystallization. Several properties of a liquid crystal mixture containing 2-(p-cyanophenyl)-5-alkyl-1,3-dithianes were measured. The values thus obtained were compared with those for mixtures containing other p-cyanophenyl compounds. The principal feature of the mixture containing 2-(p-cyanophenyl)-5-alkyl-l,3-dithianeiss a low threshold voltage.

New Liquid Crystal Compound: (+)-4-Alkoxycarbonylphenyl 4-[5-(2-methylbutyl)-1,3-oxathian-2-yl]benzoate

Abstract New liquid crystal compound: (+)-4-Alkoxycarbonylphenyl-4-[5-(2-methylbutyl)-1,3-oxathiane-2-yl]benzoates (11) was synthesized. The mesomorphic behavior of this compound is compared with those of (+)-4-(2-methylbutoxycarbonyl)phenyl 4-(5-alkyl-1,3-oxathian-2-yl)benzoates (12), and (+)-4-alkoxy-carbonylphenyl 4-[5-(2-methylbutyl)-1,3-dioxan-2-yl]-benzoates (13), and (+)-4-Alkoxyphenyl 4-[5-(2-methylbutyl)-1,3-oxathian-2-yl]benzoates (14). Transition temperatures to the isotropic state for compound 11 were lower than those for the corresponding compounds 12 or 13. Though compound 11 exhibited the cholesteric phase, compound 12 exhibited the smectic phase. These features seem to originate in the wider molecular width of compound 11. Transition temperatures to the isotropic state for compound 11 are lower than those for 14. In this case, the difference of partial molecular width caused by carbonyl group seem to be main factor.

Liquid crystal properties of new ionic liquid crystal compounds having a 1,3-dioxane ring

New pyridinium type chiral ionic liquid crystal materials having a 1,3-dioxane ring in the central core, (+)- N -2-methylbutyl-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides (6), were synthesized. Mixture A was made by adding 5.9 wt % of compound 6−3 to the ferroelectric liquid crystal mixture Merck 4655-100; its phase transitions and some liquid crystal properties were measured. In spite of a large decrease of Ps for mixture A, its response time A was the same as that of Merck 4655-100. The dielectric constants perpendicular to the molecular axis for the smectic C* and smectic A phases were measured for the mixture and Merck 4655−100: in the smectic C phase, these dielectric constants were almost the same (4.5∼5.5), but in the smectic A phase, the perpendicular dielectric constant of the mixture was 47.0 and that of Merck 4655−100 was 4.5.

Optical Properties of New Ferroelectric Liquid Crystal Materials: (+)-4-(2-Methylbutyloxycarbonyl) 4-(5-alkyl-1,3-dioxan-2-yl)benzoate

Abstract New ferroelectric Liquid Crystal Compounds: (+)-4-(2-Methylbutyloxycarbonyl) 4-(5-alkyl-1,3-dioxan-2-yl)benzoate were synthesized. Some physical properties of these materials were measured and compared with those of (s)-2-methylbutyl p-(p-decyloxybenzylideneamino)cinnamate (DOBAMBC). Theprincipal features of these new ferroelectric liquid crystal compounds are: (1) wider temperature rangeof the ferroelectric liquid crystalline phase; (2) longer helical pitches; and (3) lower rotational viscositycoefficient.

New 1,3-oxathiane type ionic liquid crystal compounds

New pyridinium type thermotropic ionic liquid crystal materials having a 1,3-oxathiane ring in the central core,N-ethyl-4-(5-alkyl-1,3-oxathian-2-yl)pyridinium bromides 8, were synthesized. These compounds exhibited a smectic A phase over a very wide range including room temperature (for example 8c: G –30 SA 21 I).

Redox photochromism of viologen in organized solid state

Abstract N,N′-Diphenylbipyridinium(viologen) having alkylbenzene sulfonate with long alkyl chains (C6-C15) was synthesized by three reaction sequences. The viologens with alkyl chains of C10-C15 exhibit a liquid crystal phase and display smectic-A type. Upon irradiation with near-UV light, viologen films change from pale yellow to blue-green, whose absorption maxima shift remarkably to red and the shapes differ with the length of the alkyl chain of the counter anions. The colour induced by light is maintained above 95% at 30° C and can be bleached at higher temperature. This has made possible, for the first time, the colour development by light and bleaching by heat of transparent anisotropic thin films.

New Liquid-Crystal Polymer with 1,3-Oxathiane Ring

Abstract New polymerizable liquid crystal materials: 4-(5-alkyl-1,3-oxathian-2-yl)-phenylacrylate (9) and 4-(5-alkyl-1,3-oxathian-2-yl)-phenyl methacrylates (9′) have been synthesized and converted into respective polymers. Polymer 9′ having the 1,3-oxathiane ring in their principal structure show a shlieren texture of nematic liquid crystal phase (G 81 N 140 I), therefore this is a new type of liquid crystal polymer having 1,3-oxathiane ring in their principal structure.