Staff View: Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents

Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents

The effect of introducing a lateral methyl substituent and the two different alkoxy terminal groups on the mesophase behavior of three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit on the opposite terminal side (C1-C6) were explored. Their structures were confirmed b...

Full description

Saved in:

Bibliographic Details
Main Authors:	Kamal, Salwa J., Salleh, Noordini Mohamad, Mahmud, Habibun Nabi Muhammad Ekramul, Abdullah, Iskandar, Gopal, Sanjeev R., Velayutham, Thamil Selvi, Zahid, Noor Idayu Mat
Format:	Article
Published:	Elsevier 2021
Subjects:	QC Physics QD Chemistry
Online Access:	http://eprints.um.edu.my/28700/
Tags:	Add Tag No Tags, Be the first to tag this record!

id	my.um.eprints.28700
record_format	eprints
spelling	my.um.eprints.287002022-08-22T03:08:45Z http://eprints.um.edu.my/28700/ Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents Kamal, Salwa J. Salleh, Noordini Mohamad Mahmud, Habibun Nabi Muhammad Ekramul Abdullah, Iskandar Gopal, Sanjeev R. Velayutham, Thamil Selvi Zahid, Noor Idayu Mat QC Physics QD Chemistry The effect of introducing a lateral methyl substituent and the two different alkoxy terminal groups on the mesophase behavior of three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit on the opposite terminal side (C1-C6) were explored. Their structures were confirmed by several spectroscopic techniques (Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy). The mesomorphic properties of these compounds were studied by differential scanning calorimetry, polarized optical microscopy, and small- and wide-angle X-ray scattering. Except for the un-substituted terminals (C1 and C4), all other derivatives are liquid crystalline, exhibiting enantiotropic nematic liquid crystal phase. The alteration of the alkoxy chain length from methoxy to butoxy at the phenyl ester terminal group (ring A) for each set of laterally-neat and laterally methyl-substituted mesogens decreases the nematic temperature range. A decrease in the mesophase temperature range is also observed when a lateral methyl substituent is incorporated into phenylazo ring of the mesogenic core (ring C). Optical study demonstrated that their absorption spectra are identical in shape due to the structural similarities of the mesogenic core. The corresponding fluorescence spectra exhibited blue-emission with the laterally methyl substituted compounds having a relatively higher fluorescence intensity compared to that of its laterally un-substituted analogues. Furthermore, the laterally methyl-substituted derivatives were subjected to the planar alignment and their dielectric and electro-optic properties were investigated. The nematic phase of the aligned samples shows antiferroelectric switching behavior with spontaneous polarization, P-s similar to 5 mu C/cm(2). (C) 2021 Elsevier B.V. All rights reserved. Elsevier 2021-08-15 Article PeerReviewed Kamal, Salwa J. and Salleh, Noordini Mohamad and Mahmud, Habibun Nabi Muhammad Ekramul and Abdullah, Iskandar and Gopal, Sanjeev R. and Velayutham, Thamil Selvi and Zahid, Noor Idayu Mat (2021) Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents. Journal of Molecular Liquids, 336. ISSN 0167-7322, DOI https://doi.org/10.1016/j.molliq.2021.116308 <https://doi.org/10.1016/j.molliq.2021.116308>. 10.1016/j.molliq.2021.116308
institution	Universiti Malaya
building	UM Library
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Malaya
content_source	UM Research Repository
url_provider	http://eprints.um.edu.my/
topic	QC Physics QD Chemistry
spellingShingle	QC Physics QD Chemistry Kamal, Salwa J. Salleh, Noordini Mohamad Mahmud, Habibun Nabi Muhammad Ekramul Abdullah, Iskandar Gopal, Sanjeev R. Velayutham, Thamil Selvi Zahid, Noor Idayu Mat Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
description	The effect of introducing a lateral methyl substituent and the two different alkoxy terminal groups on the mesophase behavior of three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit on the opposite terminal side (C1-C6) were explored. Their structures were confirmed by several spectroscopic techniques (Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy). The mesomorphic properties of these compounds were studied by differential scanning calorimetry, polarized optical microscopy, and small- and wide-angle X-ray scattering. Except for the un-substituted terminals (C1 and C4), all other derivatives are liquid crystalline, exhibiting enantiotropic nematic liquid crystal phase. The alteration of the alkoxy chain length from methoxy to butoxy at the phenyl ester terminal group (ring A) for each set of laterally-neat and laterally methyl-substituted mesogens decreases the nematic temperature range. A decrease in the mesophase temperature range is also observed when a lateral methyl substituent is incorporated into phenylazo ring of the mesogenic core (ring C). Optical study demonstrated that their absorption spectra are identical in shape due to the structural similarities of the mesogenic core. The corresponding fluorescence spectra exhibited blue-emission with the laterally methyl substituted compounds having a relatively higher fluorescence intensity compared to that of its laterally un-substituted analogues. Furthermore, the laterally methyl-substituted derivatives were subjected to the planar alignment and their dielectric and electro-optic properties were investigated. The nematic phase of the aligned samples shows antiferroelectric switching behavior with spontaneous polarization, P-s similar to 5 mu C/cm(2). (C) 2021 Elsevier B.V. All rights reserved.
format	Article
author	Kamal, Salwa J. Salleh, Noordini Mohamad Mahmud, Habibun Nabi Muhammad Ekramul Abdullah, Iskandar Gopal, Sanjeev R. Velayutham, Thamil Selvi Zahid, Noor Idayu Mat
author_facet	Kamal, Salwa J. Salleh, Noordini Mohamad Mahmud, Habibun Nabi Muhammad Ekramul Abdullah, Iskandar Gopal, Sanjeev R. Velayutham, Thamil Selvi Zahid, Noor Idayu Mat
author_sort	Kamal, Salwa J.
title	Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
title_short	Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
title_full	Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
title_fullStr	Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
title_full_unstemmed	Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents
title_sort	mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: effect of lateral methyl and terminal substituents
publisher	Elsevier
publishDate	2021
url	http://eprints.um.edu.my/28700/
_version_	1744649132656558080
score	13.211869

Mesomorphic, optical, dielectric, and electro-optic properties of azo-ester materials: Effect of lateral methyl and terminal substituents

Similar Items