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Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials

Some laterally fluorinated three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit as the terminal chain were prepared to investigate the effects of terminal substituents on the liquid crystal properties where different opposite terminal groups are introduced. The opposi...

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Main Authors: Kamal, Salwa J., Mohamad Salleh, Noordini, Mahmud, H. N. M. Ekramul, Mat Zahid, Noor Idayu
Format: Article
Published: Taylor & Francis 2022
Subjects:
QD Chemistry
Online Access:http://eprints.um.edu.my/42388/
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spelling my.um.eprints.423882023-10-10T04:27:26Z http://eprints.um.edu.my/42388/ Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials Kamal, Salwa J. Mohamad Salleh, Noordini Mahmud, H. N. M. Ekramul Mat Zahid, Noor Idayu QD Chemistry Some laterally fluorinated three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit as the terminal chain were prepared to investigate the effects of terminal substituents on the liquid crystal properties where different opposite terminal groups are introduced. The opposite terminal side substituent, R, is a polar group that alternatively changes between the electron-donating group (OCH3 or OC4H9) and electron-withdrawing group (Br or NO2), including the terminally unsubstituted compound. The structures of all synthesised compounds were confirmed by Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy, and elemental analysis. Their mesomorphic properties were studied by differential scanning calorimetry, polarised optical microscopy, and small- and wide-angle X-ray scattering. Mesomorphic studies revealed that all derivatives were liquid crystalline materials, except for the unsubstituted terminal derivative (F1). When the electron-donating group is attached to the terminal phenyl ester moiety, the analogues (F2 and F3) were enantiotropically nematogenic. Terminal substitution with the electron-withdrawing bromine atom (F4) induced the nematic-to-nematic (N-N-X) phase transition upon cooling, while the nitro group (F5) exhibited an enantiotropic nematic phase. The terminally nitro-substituted analogue F5 showed the highest bathochromic shift UV-vis absorption bands due to the stronger electron-withdrawing inductive effect of NO2 terminal group. Taylor & Francis 2022-04-09 Article PeerReviewed Kamal, Salwa J. and Mohamad Salleh, Noordini and Mahmud, H. N. M. Ekramul and Mat Zahid, Noor Idayu (2022) Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials. Liquid Crystals, 49 (5). pp. 633-646. ISSN 0267-8292, DOI https://doi.org/10.1080/02678292.2021.1995060 <https://doi.org/10.1080/02678292.2021.1995060>. 10.1080/02678292.2021.1995060
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 QD Chemistry
spellingShingle QD Chemistry
Kamal, Salwa J.
Mohamad Salleh, Noordini
Mahmud, H. N. M. Ekramul
Mat Zahid, Noor Idayu
Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
description Some laterally fluorinated three-benzene-ring molecular core of azo-ester compounds bearing 2-methylbutoxy unit as the terminal chain were prepared to investigate the effects of terminal substituents on the liquid crystal properties where different opposite terminal groups are introduced. The opposite terminal side substituent, R, is a polar group that alternatively changes between the electron-donating group (OCH3 or OC4H9) and electron-withdrawing group (Br or NO2), including the terminally unsubstituted compound. The structures of all synthesised compounds were confirmed by Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy, and elemental analysis. Their mesomorphic properties were studied by differential scanning calorimetry, polarised optical microscopy, and small- and wide-angle X-ray scattering. Mesomorphic studies revealed that all derivatives were liquid crystalline materials, except for the unsubstituted terminal derivative (F1). When the electron-donating group is attached to the terminal phenyl ester moiety, the analogues (F2 and F3) were enantiotropically nematogenic. Terminal substitution with the electron-withdrawing bromine atom (F4) induced the nematic-to-nematic (N-N-X) phase transition upon cooling, while the nitro group (F5) exhibited an enantiotropic nematic phase. The terminally nitro-substituted analogue F5 showed the highest bathochromic shift UV-vis absorption bands due to the stronger electron-withdrawing inductive effect of NO2 terminal group.
format Article
author Kamal, Salwa J.
Mohamad Salleh, Noordini
Mahmud, H. N. M. Ekramul
Mat Zahid, Noor Idayu
author_facet Kamal, Salwa J.
Mohamad Salleh, Noordini
Mahmud, H. N. M. Ekramul
Mat Zahid, Noor Idayu
author_sort Kamal, Salwa J.
title Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
title_short Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
title_full Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
title_fullStr Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
title_full_unstemmed Liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
title_sort liquid crystal and photophysical properties of laterally fluorinated azo-ester materials
publisher Taylor & Francis
publishDate 2022
url http://eprints.um.edu.my/42388/
_version_ 1781704636743286784
score 13.211869

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