Synthesis and mesomorphic properties and optical behaviour analysis of homologous series azobenzene liquid crystal monomer with polar substituents

2019 ◽  
Vol 47 (2) ◽  
pp. 155-168
Author(s):  
Duo Wang ◽  
Ruo-Yan Li ◽  
Yuan-Yuan Quan ◽  
Qing-Qing He ◽  
Mei Tian ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Homologous Series ◽  
Optical Behaviour ◽  
Behaviour Analysis ◽  
Polar Substituents ◽  
Mesomorphic Properties

scholarly journals Dependence of Liquid Crystalline Behaviors on Molecular Flexibility

2015 ◽  
Vol 47 ◽  
pp. 77-86 ◽  
Author(s):  
S.A. Maheta ◽  
G.N. Bhola ◽  
Umed C. Bhoya
Keyword(s):  
Liquid Crystal ◽  
Homologous Series ◽  
Liquid Crystalline ◽  
Molecular Structures ◽  
Melting Temperatures ◽  
Normal Manner ◽  
Optical Polarizing Microscopy ◽  
Transition Curves ◽  
Mesomorphic Properties ◽  
Phase Length

A novel homologous series of thermotropic liquid crystal (LC) has been synthesized with a view to understand and establish the effect of molecular structure on liquid crystal behaviors of a series. The present LC series consist of twelve homologues (C1 to C16); whose mesomorphic properties commence from octyloxy (C8) homologue of a series. C8, C10 and C12 members of a series are monotropic smectic and C14, C16 members are enantiotropically smectogenic. C1 to C7 homologues are nonmesomorphic. Nematogenic property is totally absent. Transition and melting temperatures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of smectic mesophases are focal conic three or two dimensional networking of the type A or C. Cr-I/Sm and Sm-I or I-Sm transition curves behaved in normal manner. Analytical and spectral data confirms the molecular structures of homologues. Thermal stability of smectogenic mesophase is 100.6 oC and mesomorphic phase length is very short (12.9 °C to 15.3 oC). LC properties of a present novel series are compared with the structurally similar homologous series. Present series is partly smectogenic and partly non mesomorphic with poor degree of mesomorphism and middle ordered melting type without exhibition of nematogenic behavior.

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

scholarly journals 1-(4-Alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium organic backbone: A versatile smectogenic moiety

2009 ◽  
Vol 5 ◽  
Author(s):  
William Dobbs ◽  
Laurent Douce ◽  
Benoît Heinrich
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Common Element ◽  
Crystal Fields ◽  
Single Compound ◽  
Imidazolium Ring ◽  
Mesomorphic Properties

The merger of ionic liquid and liquid crystal fields, obtained by using the imidazolium ring as a common element, has allowed us to tailor a new set of materials which associate specific functionalities. These functionalities are consequences of the original properties of the component, ionic liquids, liquid crystals and their association in a single compound. The study of this interesting association led us to elaborate environment-flexible cationic architectures from which mesomorphic properties emerge. Moreover, we have also explored the influence of different anions on the mesomorphic properties.

Mesomorphic properties of a homologous series of chiral liquid crystals containing the α-chloroester group

1995 ◽  
Vol 19 (2) ◽  
pp. 151-157 ◽  
Author(s):  
J. Schacht ◽  
I. Dierking ◽  
F. Gießelmann ◽  
K. Mohr ◽  
H. Zaschke ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Homologous Series ◽  
Chiral Liquid Crystals ◽  
Mesomorphic Properties

Synthesis and Mesomorphic Properties of a Series of Cholesteric Liquid Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 759-762 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Phase Transition Temperatures ◽  
Second Category ◽  
Mesomorphic Properties

A series of cholesterol liquid crystal compounds was synthesized. Phase-transition temperatures and mesomorphic textures of these synthesized compounds were characterized with differential scanning calorimetry and polarized optical microscopy, respectively. In these molecules the terminal ester chains CnH2n-1COO-, where n was the number of carbon atoms in the terminal ester chains, were linked to the cholesterol core. All of the synthesized cholesterol compounds exhibited mesophases for the first heating. However, as temperature decreased from their clearing points, their micrographs can also be divided into two categories, the first category exhibits branch-like mesophase textures for n in the range of 1-10 while the second category exhibits branch-like crystal textures for n in the range of 11-18.

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