Highly quadrupolar derivatives of the [closo-B10H10]2- anion: Investigation of liquid crystalline polymorphism in an homologous series of 1,10-bis(4-alkoxypyridinium) zwitterions

2018 ◽  
Vol 865 ◽  
pp. 226-233 ◽  
Author(s):  
Muhammad O. Ali ◽  
Damian Pociecha ◽  
Jakub Wojciechowski ◽  
Irina Novozhilova ◽  
Andrienne C. Friedli ◽  
...  
Keyword(s):  
Homologous Series ◽  
Liquid Crystalline ◽  
Crystalline Polymorphism ◽  
Derivatives Of

Antibacterial Activity and Mesophase Identification of Azomethnine and Azo derivatives

2021 ◽  
Vol 25 (11) ◽  
pp. 119-131
Author(s):  
Shavi Thakur ◽  
H.N. Patel
Keyword(s):  
Homologous Series ◽  
Liquid Crystalline ◽  
Present Series ◽  
Spectroscopic Methods ◽  
Smectic A ◽  
Polarizability Effect ◽  
Benzene Rings ◽  
Azo Derivatives ◽  
Derivatives Of ◽  
Mesomorphic Properties

A new mesogenic homologous series of liquid crystalline azomethnine and azo derivatives of 4ꞌ-nalkoxybenzylidiene- 4-aminoazobenzene has been synthesized and characterized by a combination of elemental analysis and standard spectroscopic methods. In the present series, nematic mesophase commences from n-propyloxy derivative as enantiotropic and persists up to the last member synthesized except in derivative C10. The smectic A (SmA) mesophases commences from n-pentyloxy derivative as enantiotropic and also persists up to ntetradecyloxy synthesized. Imine linkage (-CH═N-) between central and terminal benzene rings helping to understand the polarizability effect as well as nature of mesophase as stability gets reduced due to the presence of nitrogen in the ring. The mesomorphic properties of present series are of great importance to evaluate the effects of central linkage on mesomorphism. The mesomorphic properties of present series were compared with other structurally related mesogenic homologous series to evaluate the effects of central linkage on mesomorphism.

Photoconductive Liquid-Crystalline Derivatives of 6-Oxoverdazyl

2012 ◽  
Vol 134 (5) ◽  
pp. 2465-2468 ◽  
Author(s):  
Aleksandra Jankowiak ◽  
Damian Pociecha ◽  
Jacek Szczytko ◽  
Hirosato Monobe ◽  
Piotr Kaszyński
Keyword(s):  
Liquid Crystalline ◽  
Derivatives Of

scholarly journals Perylene-like Dyes in Liquid Crystalline Media

1996 ◽  
Vol 51 (7) ◽  
pp. 843-850 ◽  
Author(s):  
Ewa Mykowska ◽  
Danuta Bauman
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Fluorescent Dyes ◽  
Liquid Crystal Display ◽  
Isotropic Phase ◽  
Display Devices ◽  
Electrooptical Properties ◽  
Derivatives Of

Abstract The spectral and electrooptical properties of some dichroic fluorescent dyes (derivatives of 3.4,9,10-perylenetetracorboxylic acid and of 3,4,9-perylenetricarboxylic acid) in isotropic solvents and nematic liquid crystals have been studied. The order parameter of the dyes in the anisotropic matrices has been determined by means of optical spectroscopy methods. Moreover, the influence of the dye addition on the nematic-isotropic phase transition temperature of the pure host has been investigated. It was found that some of the dyes studied can be utilized in guest-host liquid crystal display devices.

scholarly journals Synthesis, Characterization and Unusual Dielectric Behaviour of λ-Shaped Mesogenic Homologous Series With Polar Substituents

2011 ◽  
Vol 2 ◽  
pp. 16-25 ◽  
Author(s):  
P. B. Chand ◽  
R. Manohar
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Dielectric Behaviour ◽  
Scanning Calorimetry ◽  
Oh Groups ◽  
Smectic C ◽  
Specific Shape ◽  
Polar Substituents ◽  
Derivatives Of ◽  
Conformer Model

A new λ-shaped mesogenic homologous series with polar bromo and nitro substituent was synthesized by fixing rigid 2-bromo-4-nitrophenylazo groups to a resorcinol moiety. 4-n-alkoxybenzoyl groups esterify both the phenolic -OH groups. In the present series, methoxy and ethoxy derivatives are non-mesogenic, n-propyloxy to n-octyloxy derivatives exhibit enantiotropic nematic mesophase. Smectic C (SmC) mesophase commences from the n- octyloxy derivative as an enantiotropic phase and is retained up to the last member synthesized. The effect of polar bromo and nitro substituent on mesomorphic properties is discussed. In this paper, we also report the unusual dielectric behaviour of n-octyloxy and n-tetradecyloxy derivatives of the present λ-shaped mesogenic homologous series. The dielectric permittivity of the sample was found to be unusually low in SmC phase in comparison to nematic phase. We have explained it on the basis of two-conformer model, which can exist in SmC phase due to specific shape of the molecule. The model has been supported by calculating activation energy of both the possible conformers from Arrhenius plot of relaxation frequency versus temperature. There is a clear difference in the value of activation energy of both the conformers as expected.Keywords: C. Differential scanning calorimetry (DSC); D. Dielectric properties; D. Phase transitionsThe Himalayan Physics  Vol.2, No.2, May, 2011Page: 16-25Uploaded Date: 31 July, 2011

A novel class of mesogens: liquid-crystalline derivatives of linear oligoalkylene amides

1995 ◽  
Vol 5 (12) ◽  
pp. 2247 ◽  
Author(s):  
Uwe Stebani ◽  
G�nter Lattermann ◽  
Reinhard Festag ◽  
Michael Wittenberg ◽  
Joachim Heinz Wendorff
Keyword(s):  
Liquid Crystalline ◽  
Derivatives Of
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