Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers

Four series of new symmetric and non-symmetric liquid crystal dimers with multi-functional groups have been synthesised and characterised. Physical and spectroscopic characterisations such as elemental analysis (CHN), infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (FT-NMR)...

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Main Author:	Lee, Huey Charn
Format:	Thesis
Language:	English
Published:	2012
Subjects:	QD1-999 Chemistry
Online Access:	http://eprints.usm.my/45593/1/LEE%20HUEY%20CHARN_HJ.pdf
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spelling	my-usm-ep.455932019-10-08T02:53:21Z Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers 2012 Lee, Huey Charn QD1-999 Chemistry Four series of new symmetric and non-symmetric liquid crystal dimers with multi-functional groups have been synthesised and characterised. Physical and spectroscopic characterisations such as elemental analysis (CHN), infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (FT-NMR) have been carried out to elucidate the molecular structures of the dimers. The studies of thermal behaviour and texture observation of the final compounds are performed by means of polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The first and second series of non-symmetric dimers, α-{4-[(4-substituted-phenylimino)methyl]phenoxy}-ω-[4-(4-pentyloxycarbonylphenyl)phenoxy]alkanes consist of twelve homologues which vary in terms of flexible spacers (pentyl and hexyl) and terminal substituents (H, CH3, C2H5, F, Cl, Br). Investigation on the thermal behaviour shows that the dimers without terminal substituent are not mesogenic while the remaining ten homologues exhibit the nematic phase predominantly. The homologues incorporated with odd-numbered pentyl spacers exhibit the monotropic nematic phase while homologues incorporating the even-numbered hexyl spacers show the enantiotropic nematic phase. Additionally, the homologue with a terminal bromine atom and a hexyl spacer also exhibit a smectic A phase during the cooling cycle. Influence of the terminal substituent size in stabilising the liquid crystalline properties is also studied. Analogous to these dimers, another series of non-symmetric dimers with iodine atom as terminal substituent namely α-{4-[(4-iodophenylimino)methyl]phenoxy}-ω-[4-(4-pentyloxycarbonylphe-nyl)phenoxy]alkanes with spacer ranging from C5H10 to C12H24 have been prepared. 2012 Thesis http://eprints.usm.my/45593/ http://eprints.usm.my/45593/1/LEE%20HUEY%20CHARN_HJ.pdf application/pdf en public masters Universiti Sains Malaysia Pusat Pengajian Sains Kimia
institution	Universiti Sains Malaysia
collection	USM Institutional Repository
language	English
topic	QD1-999 Chemistry
spellingShingle	QD1-999 Chemistry Lee, Huey Charn Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
description	Four series of new symmetric and non-symmetric liquid crystal dimers with multi-functional groups have been synthesised and characterised. Physical and spectroscopic characterisations such as elemental analysis (CHN), infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (FT-NMR) have been carried out to elucidate the molecular structures of the dimers. The studies of thermal behaviour and texture observation of the final compounds are performed by means of polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The first and second series of non-symmetric dimers, α-{4-[(4-substituted-phenylimino)methyl]phenoxy}-ω-[4-(4-pentyloxycarbonylphenyl)phenoxy]alkanes consist of twelve homologues which vary in terms of flexible spacers (pentyl and hexyl) and terminal substituents (H, CH3, C2H5, F, Cl, Br). Investigation on the thermal behaviour shows that the dimers without terminal substituent are not mesogenic while the remaining ten homologues exhibit the nematic phase predominantly. The homologues incorporated with odd-numbered pentyl spacers exhibit the monotropic nematic phase while homologues incorporating the even-numbered hexyl spacers show the enantiotropic nematic phase. Additionally, the homologue with a terminal bromine atom and a hexyl spacer also exhibit a smectic A phase during the cooling cycle. Influence of the terminal substituent size in stabilising the liquid crystalline properties is also studied. Analogous to these dimers, another series of non-symmetric dimers with iodine atom as terminal substituent namely α-{4-[(4-iodophenylimino)methyl]phenoxy}-ω-[4-(4-pentyloxycarbonylphe-nyl)phenoxy]alkanes with spacer ranging from C5H10 to C12H24 have been prepared.
format	Thesis
qualification_level	Master's degree
author	Lee, Huey Charn
author_facet	Lee, Huey Charn
author_sort	Lee, Huey Charn
title	Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
title_short	Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
title_full	Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
title_fullStr	Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
title_full_unstemmed	Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers
title_sort	synthesis and mesomorphic properties of symmetric and non-symmetric liquid crystal dimers containing methylene and disulphide spacers
granting_institution	Universiti Sains Malaysia
granting_department	Pusat Pengajian Sains Kimia
publishDate	2012
url	http://eprints.usm.my/45593/1/LEE%20HUEY%20CHARN_HJ.pdf
_version_	1747821534793170944

Synthesis And Mesomorphic Properties Of Symmetric And Non-Symmetric Liquid Crystal Dimers Containing Methylene And Disulphide Spacers

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