Syntheses, Characterisation And Mesophase Investigation Of A New Class Of Hydrazine-Based Liquid Crystal Dimers
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Date
2016-02
Authors
Abd Rani, Umairah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Four new series of non-symmetric dibenzylidenehydrazine-based liquid
crystal dimers, N-{4[10-(16-decyloxyphenylimino)methyl)phenoxy] alkyloxybenzy
lidene}-N'-(4'-decyloxybenzylidene)hydrazines (SB-(CH2)n-HZ), N-{4[10-(16-decyl
oxyphenyldiazenyl)phenoxy]alkyloxybenzylidene}-N'-(4'-decyloxybenzylidene) hyd
razines (AZ-(CH2)n-HZ), N-[4-{12-[18-((S)-(-)-23-methylbutyloxy)carbonylphenyl]
phenoxy} alkyloxybenzylidene]-N'-(4'-decyloxybenzylidene) hydrazines (BP-(CH2)n
-HZ) and N-(4-alkylxybenzylidene)-N'-[4'-(cholesteryloxycarbonyl)alkyloxybenzylid
ene]hydrazines (Chol-(CH2)m-HZ-(CH2)n) had been synthesised and characterised.
All dimers incorporated dibenzylidenehydrazine as one of the mesogenic arms and
differ in terms of the other side arms and spacer parity. The molecular structures of
these dimers were elucidated by CHN, FT-IR, 1D and 2D-NMR spectroscopy. Their
liquid crystalline properties were investigated using POM, DSC and XRD. Phase
behavior of the dimers was structure and spacer parity dependent. Various
mesophases including nematic (N), cholesteric (N*), smectic A (SmA), chiral
smectic A (SmA*), smectic C (SmC), chiral smectic C (SmC*) and smectic J (SmJ)
were observed when one of the mesogenic side arms was changed. A pronounced
odd-even effect in transitional properties (melting and clearing temperatures as well
as entropy changes) were seen in SB-(CH2)n-HZ, AZ-(CH2)n-HZ and BP-(CH2)n-
HZ upon varying the spacer length.
Description
Keywords
Liquid crystals dimers