Hydrogen-bonded Liquid Crystals Research Articles

4-Hydroxyphenyl 4-Ferrocenylbenzoate

The reaction of 4-ferrocenylbenzoyl chloride with 1,4-dihydroxybenzene gives 4-hydroxyphenyl 4-ferrocenylbenzoate, which contains a free hydroxyl group and it can be used for the synthesis of ester mono-substituted liquid crystal and hydrogen-bonded supra-molecular liquid crystals [1].[...]

Nematic liquid-crystalline physical gels exhibiting faster responses to electric fields in twisted nematic cells

The liquid-crystalline physical gels, which are prepared by hydrogen-bonded fibrous aggregation of amino acid derivatives in a nematic liquid crystal, exhibit faster electro-optic responses than the single liquid-crystalline component in twisted nematic (TN) cells. They have microphase-separated structures consisting of fibrous solids of hydrogen-bonded molecules and liquid crystal solvents. The effects of the microphase-separated structures on the response speed and the threshold voltage have been examined for these anisotropic gels.

The thermal stability and molecular structural changes of a intermolecular hydrogen bonded liquid crystal compound

In order to investigate the thermal stability of the intermolecular hydrogen bonding and the molecular structure changes during the phase transition process, we studied liquid crystal compound DBS:BD:DBS induced by intermolecular hydrogen bonding between trans-butene diacid (proton donor) and 4-(2,3,4-tridecyloxybenzoyloxy)-4′-stilbazoles (proton acceptor) using the temperature-dependent FT-IR and FT-Raman spectroscopy. The results show that the intermolecular hydrogen bonding is stable in the liquid crystalline phase but becomes slightly decompositive when temperature is higher than its clearing point. As the temperature increasing, the number of the gauche conformation is also increasing, when it is coming to the isotropic phase, the alkyl chain is in disorder state.

Self-Assembling Capsules: From Molecular Recognition to Hydrogen-Bonded Liquid Crystals and Fibers

Self-Assembling Capsules: From Molecular Recognition to Hydrogen-Bonded Liquid Crystals and Fibers

Hydrogen-Bonded Ionic Liquid Crystals Showing Different Mesophases

Binary systems of 1-heptyl-4-(4-pyridyl)pyridinium bromide with different proton acceptors were investigated. The existence of hydrogen bonded liquid-crystalline associates was proven.

Preliminary communication Hydrogen-bonded ionic liquid crystals

Ionic and non-ionic building units were connected via hydrogen bonds. Stable liquid crystalline phases were obtained by a suitable choice of the units. The ionic associates are not miscible with the respective non-ionic associates.

Preliminary communication - The effects of bending sites on unconventionally shaped hydrogen-bonded liquid crystals

Angular mesogenic structures of hydrogen-bonded supramolecules have been constructed from a 1:1 molar ratio of 3(or 4)-decyloxybenzoic acid, MA (or PA), mixing either with trans-4-alkoxy-3'(or 4')-stilbazoles, CnM (or CnP), or with their analogous N -oxides (CnMO and CnPO) to form the hydrogen-bonded (H-bonded) complexes CnPPA, CnPMA, CnMPA, CnPOPA, CnPOMA and CnMOPA. By controlling the relative bending position of the H-bonded complexes, the variety of supramolecules offer new molecular structures of different linearities. By means of these bending effects we are able to tune the shape of the molecular architecture and thus to modify molecular packing as well as mesogenic properties. New liquid crystalline properties are introduced by the nonlinear effects of molecular geometry, and powder X-ray diffraction (XRD) patterns have confirmed their novel molecular architectures.

The Influence of Fluorinated Alkyl Chains on the Stabilization of Hydrogen Bonded Liquid Crystals

Abstract Perfluorinated alkyl chains were introduced into hydrogen bonded associates. Both, mesophase induction and stabilization were observed.

Orthogonal hexatic smectic phase-rare or common?

Abstract The hexatic smectic B (Hex B) phase is commonly encountered among hydrogen-bonded liquid crystal materials. Among enaminoketone and Schiff's base compounds, twenty homologous series (c. 102 compounds) exhibiting orthogonal mono-or bi-layer hexatic phases were identified by combined microscopy and DSC. Phase transitions from crystal B (CrB) of Sf to Hex B as well as from Hex B to Sf, Sa or Sc phases were observed within the range 50 to 190°C. Temperature ranges of the Hex B phase detectable by DSC varied from 0.2 to 20°C. Within two groups of three-ring enaminoketones, the formation of the Hex B phase was found to be controlled by both inductive and mesomeric components of the Hammett constants of the terminal substituents of the molecules.

Hydrogen-bonded liquid crystals from alkoxystilbazoles and 3-cyanophenols: structural control of mesomorphism. Molecular structure of the complex between 4-cyanophenol and 4-octyloxystilbazole

Complexes formed between 4-alkoxystilbazoles and 3-cyanophenol show liquid crystal mesophases. Compared to the mesomorphism of similar complexes formed between stilbazoles and 4-cyanophenol, the mesophases are more stable and are enantiotropic.

シグマトロピー転位型および水素結合型トロポノイド液晶化合物の構築

New sigmatropic and intermolecular hydrogen-bonded liquid crystals with a tropone core such as 2- (4-alkoxybenzoyloxy) -5-alkoxytropones, 2- (4-alkoxybenzyloxy) -5-alkoxytropones, 2-acyloxy-5-alkoxytropones, 2, 5-diacyloxytropones, 2- (2-alkenyloxy) -5-alkoxytropones, 5-alkylamino-2- (4-alkoxybenzoyloxy) tropones, and 5-alkoxy-2- (4-alkylaminobenzoyloxy) tropones were prepared to evaluate their properties. Although the fact that the tropone ring is wider than the benzene ring should predict an inferior thermal stability for the troponoid mesophase, this was not the case as the tropone carbonyl group played important roles when these compounds exhibit mesophases ; it worked as an accepter of an intramolecular acyl migration, a polar lateral substituent, and an accepter of an intermolecular hydrogen bond. These behaviors are solely characteristic of troponoids.

Hydrogen-Bonded Liquid-Crystalline Molecular Complexes

In the design of functional organic materials, it is important to use molecular interactions. Hydrogen bonding is one of the key interactions for molecular association and recognition in nature. Recently, new types of hydrogen-bonded liquid-crystalline (LC) complexes have been obtained by molecular recognition between complementary components. For example, molecular recognition by hydrogen bonds between carboxylic acid and pyridyl moieties results in the quantitative formation of well-defined structures of mesogens. In the hydrogen-bonded liquid crystals, dynamic nature of hydrogen bonding gives unique LC structures of complexes such as polymer networks, polymer alloys, and one-dimensional polymers. For LC polymer networks, stable liquid-crystalline phases have been induced by the formation of dynamic intermolecular mesogen consisting of polymer side chain and a small molecule. A wide variety of supramolecular mesogenic materials can be obtained by the molecular aggregation via various hydrogen bonds.

Hydrogen-bonded liquid crystals. Novel mesogens incorporating nonmesogenic bipyridyl compounds through complexation between hydrogen-bond donor and acceptor moieties

Hydrogen-bonded liquid crystals. Novel mesogens incorporating nonmesogenic bipyridyl compounds through complexation between hydrogen-bond donor and acceptor moieties

The Simplest Structure of the Hydrogen-Bonded Mesogen Built from 4-Alkoxybenzoic Acid and 4-Alkylpyridine

Abstract Newly designed hydrogen-bonded liquid crystals having the simplest mesogenic structure have been obtained by self-assembly of 4-alkoxybenzoic acid and 4-alkylpyridine. The complexes show nematic phases near room temperature. The nematic phase is broadened by mixing of several complexes within a homologous series.

Hydrogen-bonded liquid crystals built from hydrogen-bonding donors and acceptors. Infrared study on the stability of the hydrogen bond between carboxylic acid and pyridyl moieties

Hydrogen-bonded liquid crystals built from hydrogen-bonding donors and acceptors. Infrared study on the stability of the hydrogen bond between carboxylic acid and pyridyl moieties

Hydrogen-Bonded Liquid Crystals. A Novel Mesogen Incorporating Nonmesogenic 4,4′-Bipyridine through Selective Recognition between Hydrogen Bonding Donor and Acceptor

Abstract Selective recognition between a benzoic acid derivative and nonmesogenic 4,4′-bibyridine through intermolecular hydrogen bonds results in a novel molecular structure with liquid crystalline properties, in which 4,4′-bipyridine functions as a core unit.