Lyotropic mesomorphism and morphology in non-aqueous solutions of three tetranuclear platinum mesogens with different halogen-bridged groups

WOS: 000176387700003The lyotropic mesomorphism and morphological properties of anew type of lyotropic liquid crystalline system, i.e. a tetranuclear platinum mesogen/apolar organic solvent, have been investigated. The texture transformations in a large temperature interval, especially in the phase transition regions have been studied. The temperature widths of the heterophase regions of the nematic-nematic and nematic-isotropic liquid phase transitions have been determined with a high accuracy. (C) 2002 Published by Elsevier Science B.V

Synthesis and mesomorphic properties of new side chain liquid crystalline oligomers containing salicylaldimine mesogenic groups

New liquid crystalline salicylaldimine-based homopolymers PLC1 and PLC2 have been synthesized from their corresponding monomers 5-(10-undecenyloxy)-2-[[(4-(hexyloxy)phenyl)imino]methyl]phenol (LC1) and 5-(10-undecenyloxy)-2-[[(4-(hexyl)phenyl)imino]methyl]phenol (LC 2) via free radical polymerization. The polymers were characterized by 1H-NMR, differential scanning calorimetry (DSC) and optical microscopy in polarized light (polarizing microscope). The synthesized polymers have low molecular weights, and so are in the oligomeric domain. The oligomers behave very similarly to their monomers that exhibit smectic mesophases. Replacing the hexyloxy chain by a hexyl chain of the mesogenic unit generates an additional SmC mesophase in the temperature range of both the monomer and oligomer. All the observations suggest that the oligomerization of the liquid crystalline salicylaldimine monomers gives rise to decreased transition temperatures whereas it has no influence on the type and stability of the mesophase formed. © 2013 Copyright Taylor and Francis Group, LLC.The work has been supported by Yildiz Technical University Scientific Research Projects Coordination Department under Project Number: 24–01-02–03. We also acknowledge Mrs. N. Coskun for the synthesis of PLC1 and PLC2

Synthesis, characterization and mesomorphic properties of side Chain liquid crystalline oligomer having schiff base type mesogenic group

A new liquid crystalline oligomer OLC was synthesized from its monomer having Schiff-base type mesogenic group MLC via free radical polymerization. The chemical structures of all compounds were confirmed using UV, FTIR, 1H NMR, 13C NMR and MS spectroscopy. Schiff-base type thermotropic system based on side chain oligomer containing long aliphatic branching was studied to determine the change in mesophase behaviour of the Schiff-base type mesogenic groups. A combination of differantial scanning calorimetry (DSC) and polarize optical microscopy (POM) demonstrated that the oligomer behaves similar to its monomer and both of them exhibit enantiotropic SmC and monotropic SmX mesophases. The oligomerization of the liquid crystal monomer gives rise to decreased transition temperatures whereas it has no influence on the type and stability of the mesophase formed. Namely, simply through oligomerization, we can greatly vary transition temperatures of the mesogenic groups. © 2014 VBRI press

Bilayer polymer/fullerene solar cells with a liquid crystal

In this paper the effect of 5-(10-undecenyloxy)-2-[[[4-hexylphenyl] imino] methyl] phenol liquid crystal addition into poly(3-hexylthiophene): fullerene containing solar cells were investigated. Based on current-voltage characteristics, we report on the efficiency enhancement for bilayer heterojunction solar cells using this liquid crystal. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved

Morphology, surface-induced orientational properties and phase transition peculiarities of lyotropic nematic mesophases in pentadecane solutions of tetranuclear platinum mesogens

WOS: 000180053600010We have investigated the surface-induced orientational properties and peculiarities of the phase transitions of a lyotropic system, composed of a,sheet-shaped tetranuclear platinum organyl in pentadecane, and exhibiting two different lyotropic nematic mesophases (N-1 and N-2) Corrugated YBa2Cu3O7-x surfaces with a sinusoidal profile have been used to induce planar orientation of these two nematic lyomesophases, which differ significantly with their orientational behavior. We have also measured the birefringence of these nematic mesophases. Based on high-accuracy determinations of the transition temperatures, we are discussing some peculiarities of the phase transitions between the two nematic mesophases and between N-2 mesophase and isotropic liquid, in particular, the width of the heterophase regions between them. (C) 2002 Elsevier Science Ltd. All rights reserved

Synthesis and mesomorphic properties of new organosiloxane chiral calamitic liquid crystals

International audienceA new chiral calamitic compound consisting of a phenyl core that is connected through ester linkers to a benzoate carrying a chiral (S)-2-methylbutoxy group at one side and a biphenyl carboxylate with an undecenyloxy chain at other side has been synthesized. Additionally, the siloxane substituted derivatives and a dimer with these two identical chiral calamitics linked by a disiloxane spacer have been obtained via hydrosilylation reaction to study the effect of combining the chiral moiety and siloxane segments within the same structure on liquid crystalline properties. The chiral calamitic compound and derivatives with a siloxane end-group or a siloxane spacer have been characterized using classical spectroscopic methods (1H NMR, 13C NMR, 29Si NMR and MS) and elemental analysis (EA). The liquid crystalline properties of all new compounds were investigated by differential scanning calorimetry, optical polarizing microscopy, X-ray scattering and electro-optic methods. With the introduction of a siloxane end-group to the vinyl-terminated calamitic compound exhibiting enantiotropic chiral nematic phase (N*) and chiral tilted smectic phase (SmC*), the occurrence of stable smectic phase was strongly promoted. In a similar way, the dimer with two identical calamitic mesogens connected by a disiloxane spacer exhibited a wider smectic mesophase interval in addition to the presence of N* mesophase. The new mesogens exhibit a ferroelectric switching with PS of around 200 nC cm−2 in their chiral tilted smectic (SmC*) mesophase range. The transition temperatures of organosiloxanes are considerably lower than that of olefinic precursor. © 2021 Elsevier B.V

Electrical, optical and theoretical characterization of doped and undoped calamitic liquid crystal: (s)-5-octyloxy-2-[[[4-(2-methyl butoxy) phenyl] imino] methyl] phenol

The electrical conductivities of undoped and doped calamitic liquid crystalline compound, (S)-5-octyloxy-2-[[[4-(2-methylbutoxy) phenyl] imino] methyl] phenol (OMPIMP) with tetrabutylammonium tetrafluoroborate as dopant were determined as a function of temperature. Optical studies of undoped and doped OMPIMP thin films were also carried out using spectrophotometer. Optical band gaps of doped and undoped OMPIMP thin films were determined through absorption spectra using Tauc plot. The frontier orbital energies; E-HOMO, E-LUMO and the band gap energies were calculated from the DFT calculations which were carried out by the hybrid B3LYP functional.Yildiz Technical University Scientific Research Projects CoordinationYildiz Technical University [2012-01-01-KAP05, 2012-01-02-KAP08]This research has been supported by Yildiz Technical University Scientific Research Projects Coordination (Project Numbers: 2012-01-01-KAP05 and 2012-01-02-KAP08)

Electrical, optical and theoretical characterization of doped and undoped calamitic liquid crystal: (s)-5-octyloxy-2-[[[4-(2-methyl butoxy) phenyl] imino] methyl] phenol

The electrical conductivities of undoped and doped calamitic liquid crystalline compound, (S)-5-octyloxy-2-[[[4-(2-methylbutoxy) phenyl] imino] methyl] phenol (OMPIMP) with tetrabutylammonium tetrafluoroborate as dopant were determined as a function of temperature. Optical studies of undoped and doped OMPIMP thin films were also carried out using spectrophotometer. Optical band gaps of doped and undoped OMPIMP thin films were determined through absorption spectra using Tauc plot. The frontier orbital energies; E-HOMO, E-LUMO and the band gap energies were calculated from the DFT calculations which were carried out by the hybrid B3LYP functional

Electrical and thermodynamical characterization of thermotropic liquid crystal

The thermodynamic interactions, sorption properties and electrical conductivity measurements of thermotropic liquid crystalline compound, (S)-5-dodecyloxy-2-[[[4-(2-methylbutoxy) phenyl]imino]methyl]phenol (DMPIMP) are experimentally investigated in this work. The retention diagrams of trace amount of solvents such as benzene, propylbenzene, chlorobenzene were passed through the gas chromatography column loaded with DMP IMP coated on Chromosorb W. The retention diagrams of the solvents on DMPIMP were plotted by means of specific retention volumes, V-g(0) at the temperatures in K between 363 and 383 by inverse gas chromatography. Flory-Huggins liquid crystal-solvent interaction parameter, chi(infinity)(12), equation of state liquid crystal-solvent interaction parameter, chi(12)*, the weight fraction activity coefficient, Omega(infinity)(1) and effective exchange energy parameter, X-eff and molar enthalpies related to the DMPIMP-solvent systems were obtained. The DMPIMP films were also characterized by means of its electrical properties depending on doping effect for the films having two different dopant concentrations such as 25 and 50 percent of tetrabutylammonium tetrafluoroborate