摘要:

Metal-free phthalocyanines and nickel phthalocyanines carrying four or eight oligo(ethyleneoxy)thia groups on peripheral positions have been synthesized from new phthalonitrile derivatives. These phthalocyanine derivatives were characterized both thermotropic and lyotropic mesophases by DSC and X-ray.

ISSN:1058-725X    

DOI:10.1080/10587250008024800

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

New pyridinium type thermotropic ionic liquid crystal materials having a 1,3-dioxane ring in their central core: N-substituted-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium halides (6) were synthesized. These componds exhibited a smectic A phase over a very wide temperature range including room temperature [for example6–5: G –24 SmA 152 I (°C)]. The size of the counter anion affected the transition temperatures between the isotropic state and the smectic A phase.

ISSN:1058-725X    

DOI:10.1080/10587250008024801

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The solid state structures of a series of methyl substituted neutral quaterthiophenes have been analysed. Structures have been retrieved from the Cambridge Structural Database and investigated in terms of crystal cohesion and intermolecular interactions. In these thiophene oligomers, it can be shown that crystal packing efficiency and optimisation of S—S, C-H—S and C-H—π interactions constitute the driving force for their solid state geometry and configuration. A detailed discussion of their packing arrangement is reported and shown to be based on either a herringbone or π-π stacking of thiophene units.

ISSN:1058-725X    

DOI:10.1080/10587250008024802

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Several series of fluoro-substituted benzoate liquid crystals have been synthesized. The results showed that the SmA phase is enhanced with the increasing of the degree of fluoro-substitution on thepara- andmeta-postion of the terminal phenyl groups. And the molecules which have same molecular structural formula show nearly the same melting points. It is also discussed about the effect of the ester bond′s direction on the mesomorphic properties.

ISSN:1058-725X    

DOI:10.1080/10587250008024803

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A newvic-dioxime, [N,N′-Bis(3′,4′-didodecyloxyphenyl)diaminoglyoxime](H2L) has been prepared from 3,4-didodecyloxyaniline and(E.E)-dichloroglyoxime. The(E,E)- and(E,Z)-forms of Ni(II) complex have been isolated, but palladium complex could be isolated only as(E,E)-isomer. The mesomorphic properties of these complexes were investigated by polarizing microscopy, differential scanning calorimetry (DSC) and X-ray diffraction analysis. These complexes form columnar hexagonal disordered (Colhd) mesophases. All complexes are very soluble in common organic solvents.1H and13C NMR, IR, MS and UV/Vis data are presented.

ISSN:1058-725X    

DOI:10.1080/10587250008024804

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The proton NMR spectra and DSC thermograms were observed with raising temperature for side chain type thermotropic liquid-crystalline polymer, poly(6-(4′-cyanobiphenyl-4-yloxy) hexylacrylate (PCBA). A pronounced variation was found for the NMR spectra and DSC heating curve depending on the thermal history applied on PCBA before the measurements. In the case of gradual cooling from the isotropic state to the solid state, DSC heating curve showed endothermic peak at the glass transition temperature. The line widths was taken as the parameter characterizing the NMR spectra and their temperature dependence was discussed. A qualitative interpretation on the observed NMR spectra was given in relation to the orientation of mesogenic group. The obtained endothermic peak was considered to come from the change in orientational behavior caused by the gradual cooling to the solid state.

ISSN:1058-725X    

DOI:10.1080/10587250008024805

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We report measurements of the viscoelastic parameters associated with the twist distortion of polymer-stabilized liquid crystal materials (PSLC), made by polymerizing 4,4′-bis-(acryloyloxy)-1,1′-biphenylene (BAB) and 4-butoxybenzyl 4-[6-(methacryloyloxyl-hexyloxy]benzoate (BMB6) to form fibrous networks in a nematic liquid crystal solvent (4′-phenyl-4-cyanobiphenyl, 5CB). By varying the BAB/BMB6 ratio, the twist elastic constant, K22, and viscosity, γ1, were investigated over a range of crosslink densities using electric-field-dependent dynamic light scattering (EFDLS). In PSLC samples, the formation of a highly-crosslinked, phase-separated polymer network can lead to optically heterogeneous behavior of the EFDLS data. Thus, it is necessary to evaluate the ensemble-averaged EFDLS relaxation function through spatial averaging. The results show that the polymer network causes a change in the twist relaxation rate, depending on the cross-link density of the specimens. The twist viscosity was found to increase with decrease in cross-link density, which appears to occur because higher cross-link density causes collapse of the gel fibers and less interaction between the fibers and nematic medium.

ISSN:1058-725X    

DOI:10.1080/10587250008024806

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The ordering in the assembly of biaxial molecules which interact pairwise via the dispersion force is investigated statistical-mechanically, where four kinds of liquid crystalline phase and phase transitions between some pairs of those phases are discussed in comparison with the existing theoretical results from the model of uniaxial molecules. There appear one uniaxial nematic phase, two kinds of biaxial nematic phase and one discotic phase. The phase diagram of temperature versus interaction strength are obtained, where the four phases mentioned above appear in different regions depending on the molecular shape. Some advantages of the present method in investigating the orientational ordering in biaxial liquid crystals, including the discotic phases, are discussed.

ISSN:1058-725X    

DOI:10.1080/10587250008024807

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The crystal structure of 1:1 inclusion complex of hexadecyltrimethylammonium chloride (16TAC) with rac-1,1′-bi-2-naphthol (BNP) [a= 47.968(2),b= 8.757(2),c= 18.249(2)Å, β = 100.772(6)°.C2/c, R = 0.075 for 2578 observed reflections] was determined by the X-ray diffraction method. In the crystal structure there is a strong hydrogen bond between one of the OH groups of BNP and the oxygen of water molecule (O1…OW, 2.665(3)Å). The chloride anion acts as the hydrogen acceptor of the OH group of the water molecule (OW…Cl-, 3.105(3)Å), and of the second OH group of BNP (O2…Cl-, 3.108(2)Å). The short C-H…C distances between hydrogen atoms of the alkyl carbon atom together with one of the methyl groups, and carbon atoms in one of the naphthol rings indicated an existence of C-H…π interactions. The hydrophobic long alkyl chain of the 16TAC molecule contributes to the unique molecular packing arrangement observed in the 16TAC/BNP complex. The alkyl chain of the 16TAC molecule in this crystal is bent at C10 and does not exhibit the complete zig-zag planes as reported on the 16TAC crystal. The BNP molecules are completely trapped between the 16TAC molecules, and the interdigitated arrangement of the 16TAC molecules are clearly observed in theac-plane. The X-ray powder diffraction studies on the mixed powdered samples of 16TAC and BNP suggested that the complex can be obtained by crystallization from the solution and also by mixing powdered samples in a mortar.

ISSN:1058-725X    

DOI:10.1080/10587250008024808

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The crystal and molecular structures of α,ω-bis[4-(4′-butyloxybenzylideneiminophenyl)]octane (4O.8.O4) and the homologue α,ω -bis[4-(4′-pentyloxybenzylideneiminophenyl)]octane (5O.8.O5) have been determined at room temperature, the starting model obtained by direct methods. These two dimesogenic compounds possess besides two crystalline phases (KI, KII) also SmG phases. The crystals KI of the compound 4O.8.O4 belong to the triclinic system with space group P–1, a = 5.484(3), b = 11.826(8), c = 28.03(3) Å, α = 95.77(5), β = 92.39(5), γ = 96.44(5)° with two molecules per unit cell. The compound 5O.8.O5 crystallizes in the monoclinic system with space group P21/n (KI), a = 5.571(2), b = 7.460(2), c = 89.55(3) Å, β = 90.92(2)° with four molecules per unit cell. The structures were refined by full-matrix least-squares calculations to R = 0.069 for 6647/(3340 unique) observed reflections for 4O.8.O4 and to R = 0.106 for 3760/(3329 unique) reflections for 5O.8.O5.

ISSN:1058-725X    

DOI:10.1080/10587250008024809

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor