Synthesis and mesomorphic properties of novel tolane-type liquid crystals

Two series of novel tolane-type liquid crystals （LCs） comprising of hydrogen-bonded organic acids were synthesized. The formation of dimerized H-bond LCs was confirmed by IR spectroscopy, and mesomorphic properties of the LCs were investigated by differential scanning calorimetry （DSC） and polarizing optical microscopy （POM）. It was found that the end groups of the liquid crystals as well as the unsaturated rigid core had effect on the mesomorphic properties.

New mesogenic Schiff base esters comprising benzothiazole moiety:Synthesis and mesomorphic properties

A homologous series of Schiff base esters, 6-methoxy-2-（2-hydroxy-4-alkanoyloxybenzylidenamino）benzothiazoles, compris- ing a benzothiazole moiety as the core was synthesized. All the members of this series exhibited an enantiotropic nematic phase. The azomethine linkage along with the lateral hydroxyl and terminal methoxyl groups were found to exert an effect on the mesomorphic properties. 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Synthesis and mesomorphic properties of new azine-type liquid crystals

A series of symmetrical azine-type liquid crystals were synthesized. The characteristic of these liquid crystals is that they had high clearing point （～320℃） and broad thermal range of nematic phase （～154℃）. It was also found that the end groups of the liquid crystals had effect on the mesomorphic properties.

Synthesis and mesomorphic properties of new Schiff base esters with different alkyl chains

A new series of Schiff base esters, 4-（dimethylamino）benzylidene-4＇-alkanoyloxyanilines containing even number of carbons at the end group of the molecules （Cn-1H2n-1COO, n = 6, 8, 10, 12, 14, 16, 18） were synthesized. The present compounds were monotropic liquid crystals. It was also found that the end groups of the molecules had effect on the mesomorphic properties. C 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Syntheses and Mesomorphic Properties of 2-(4'-Alkoxyphenyl)-6-Substituted Benzothiazoles

Introduction Liquid crystals without a double bond bridge between two rings in the linear molecule are more stable chemically and photochemically. Alkyl cyanobiphenyl was synthesized by Richard in 1973. Later, liquid crystals with the strcture of phenylcyclohexane and cyclohexylcyclohexane also appeared. But the liquid crystals

Mesomorphic Characteristics of Induced Chiral Nematic Phase of[Smectic LCP,PS(4BC/DM)/Nematic LC,E7/Chiral Dopant,CB-15]-Ternary Composite System

The phase transition behavior and aggregating states of [smectic LCP, PS(4BC/DM)/nematic LC, E7/chiral dopant, CB 15] ternary composite system were investigated on the basis of differential scanning calorimetry (DSC) measurement, polarizing optical microscopy (POM) observation and wide angle X ray diffraction (WAXD) patterns. It was demonstrated that if the weight ratio of the chiral dopant was fixed as 4.8wt%, an induced chiral nematic (N *) phase existed in the ternary system when PS(4BC/DM) ratio was below 47.6 wt%. Moreover, smectic like long range ordering appeared in the induced N * phase in a certain temperature range just above the smectic A(S A) N * phase transition when PS(4BC/DM) ratio was between 19.1wt% and 47.6wt%.

Unicity Theorems of Mesomorphic Functions with Three Weighted Sharing Values

In this paper,with the idea of weighted sharing values,we deal with the problem of uniqueness of mesomorphic functions sharing three weighted values.We obtain some theorems which improve the results of H X Yi and W R L.

Mesomorphic Studies on a Series of Nickel (II) Centered Aromatic Complexes Displaying Liquid Crystalline Phases

Two new series (A & B) of three materials each based on the aroyl hydrazinato-nickel (II) complex were synthesized and characterized. The core molecule in these series consists of two 4-benzoyloxy benzylidene moieties and two benzene rings attached at the azomethine moiety. These latter benzene rings have one or two alkoxy chains comprised of either 10, 12, 16 or 18 carbon atoms. The characterization of these two series by polarized optical microscopy and differential scanning calorimetry is described herein. Upon cooling from the Isotropic phase, three of the six materials display a monophasic columnar phase and the other three possess a biphasic nematic and columnar phases. Upon heating, all six materials have a clearance point at high temperatures without displaying mesomorphic behavior. In series B mesogens, it was observed that the longer the hydrocarbon tail length, the lower the clearance point.

Synthesis and mesomorphic properties of n-butyl-4- [4-((4-n-alkoxyl-tetrafluorophenyl)ethynyl)benzyloxy]benzoates

A homologous series of n-butyl-4-[4-((4-n-alkoxyl-tetrafluorophenyl)ethynyl)benzyloxy] benzoates have been synthesized. Their phase transition temperatures have also measured by polarizing textural observation and confirmed by DSC.

Heterocyclic benzoxazole-based liquid crystals:Synthesis and mesomorphic properties

New Schiff base liquid crystals containing benzoxazole core and alkanoyloxy chain at the end group of the molecules （C_（n-1）H_（2n-1）COO-,n=14,16,18） was synthesized.The present compounds are enantiotropic smectic A liquid crystals.It was also found that the end groups of the molecules and polar chloro substituent at the benzoxazole fragment had effect on the mesomorphic properties.

Synthesis and mesomorphic properties of bent-shaped molecule with low bent-angle central core and long alkylthio tail

Two homologous series of bent-shaped molecules composed of low bent-angle naphthalene central core and long alkoxy tail or alkylthio tail, N（1,7）-n-OPIMB and N（1,7）-n-SP1MB （n = 20, 22）, respectively, were synthesized. The mesomorphic properties were investigated by differential scanning calorimetry （DSC）, polarizing optical microscopy （POM） and X-ray diffraction （XRD）. Compared to the direct transition from the isotropic phase to the chiral B4 phase examined in N（1,7）-n-OPIMB, N（1,7）-n-SPIMB exhibited a rare Iso-Ncol-Colh-B4 phase sequence. The combination of the asymmetric low bent-angle 1,7-naphathalene central core and the flexible long alkylthio tail is considered to play an important role in the formation of such a novel phase sequence.

Synthesis and Mesomorphic Properties of Some ω＇-Alkoxy-ω-benzoxypolyfluorotolane Compounds

Abstract Four homologue series of 4-cyano- and 4-nitro-substituted benzoate-tolanes were synthesized and characterized by IR, NMR, MS spectra and elemental analysis. Their phase transition behaviors were investigated by DSC and polarized optical microscope. The effects on the mesomorphic properties of different positions of the perfluorophenyl in the molecular core unit, the terminal cyano-substituted systems and the terminal nitro-substituted ones were discussed.

Synthesis and mesomorphic properties of 4-(4-bromopropyloxy)-4'-(4-alkyloxybenzylidene)anilines

This article describes the preparation and liquid crystalline properties of a new homologous series of 4-（4-bromopropyloxy）-4＇- （4-alkyloxybenzylidene）anilines in which the phenyl ring is armed by a bromopropyloxy chain.The thermal behavior and mesomorphic properties of the synthesized compounds were studied with particular attention given to the correlation between their phase transition temperatures and anisotropic change influenced by molecular structure.All the members displayed enantiotropic smectic phase except for the homologue with the longest alkyloxy chain（R = C_（18）H_（37））,exhibiting only monotropic characteristic. The presence of bromine atom from the propyloxy side chain is found to be capable of altering and influencing the mesomorphic properties.

New mesomorphic benzothiazol derivatives: Synthesis and characterization

In this paper, the synthesis of new mesomorphic benzothiazolyl derivatives, 6-ethoxy-2-[4-（4- alkyloxybenzoyloxy）benzylidenamino]benzothiazoles, is presented. The structures of the title compounds were elucidated using spectroscopic techniques, such as FT-IR, NMR （1H and 13C）, elemental analysis and El-MS. The mesomorphic behaviours of these compounds were determined by differential scanning calorimetric and polarizing optical microscopic techniques. Compounds exhibited nematic and tilted smectic phases upon heating from crystal phase. An obvious odd-even effect was observed in this homologous series.

Synthesis and mesomorphic properties of trifluorobenzoate liquid crystal

Four series of trifluorobenzoate liquid crystals have been synthesized. Their phase transition temperatures have been also measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution and triple bond has been also discussed.

Phase behaviors of binary mixtures composed of electron-rich and electron-poor triphenylene discotic liquid crystals

Disk-like liquid crystals（DLCs） can self-assemble to ordered columnar mesophases and are intriguing onedimensional organic semiconductors with high charge carrier mobility.To improve their applicable property of mesomorphic temperature ranges,we exploit the binary mixtures of electronic donor-acceptor DLC materials.The electron-rich2,3,6,7,10,11-hexakis（alkoxy）triphenylenes（C4,C6,C8,C10,C12） and an electron-deficient tetrapentyl triphenylene-2,3,6,10-tetracarboxylate have been prepared and their binary mixtures have been investigated.The mesomorphism of the1：1（molar ratio） mixtures has been characterized by polarizing optical microscopy（POM）,differential scanning calorimetry（DSC）,and small angel x-ray scattering（SAXS）.The self-assembled monolayer structure of a discogen on a solid-liquid interface has been imaged by the high resolution scanning tunneling microscopy（STM）.The match of peripheral chain length has important influence on the mesomorphism of the binary mixtures.

Phase Transition Investigations of a Series of Aromatic Naphthalene-2-yl-4-(Alkoxy) Benzoate and Naphthalene-1-yl-4-(Alkoxy) Benzoate Materials

The mesogenic properties of a homologous series of aromatic ester materials are investigated. Single tail and double tail materials were synthesized to compare with other series we prepared and published earlier. The phase sequences and transition temperatures were obtained by polarized light microscopy and differential scanning calorimetry. Only the single tail materials with the ester attached to naphthalene at position 2 display mesogenicbehavior. Two materials (ZH 29 & ZH 32) possess a monophasic nematic phase and another two materials (ZH 14 & ZH 35) display biphasic nematic and smectic (A) phases.