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New mesomorphic benzothiazol derivatives: Synthesis and characterization

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Chinese Chemical Letters 2013年第10期24卷 926-928页

作者： Teck-Ming Koh sie-tiong ha Guan-Yeow Yeap Hong-Cheu Lin Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak Faculty of Science Universiti Tunku Abdul RahmanJln Universiti Centre for Biodiversity Research Universiti Tunku Abdul RahmanJln Universiti Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia Department of Materials Science & Engineering National Chiao Tung University

In this paper, the synthesis of new mesomorphic benzothiazolyl derivatives, 6-ethoxy-2-[4-（4- alkyloxybenzoyloxy）benzylidenamino]benzothiazoles, is presented. The structures of the title compounds were elucidated using spectroscopic techniques, such as FT-IR, NMR （1H and 13C）, elemental analysis and El-MS. The mesomorphic behaviours of these compounds were determined by differential scanning calorimetric and polarizing optical microscopic techniques. Compounds exhibited nematic and tilted smectic phases upon heating from crystal phase. An obvious odd-even effect was observed in this homologous series.

关键词： Benzothiazole Nematic Smectic C Mesomorphic

Mesomorphic behavior of new azomethine liquid crystals having terminal iodo group

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Chinese Chemical Letters 2011年第3期22卷 260-263页

作者： sie-tiong ha Teck-Leong Lee Guan-Yeow Yeap Masato M.Ito Ayumu Saito Masaaki Watanabe Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia11800 MindenPenangMalaysia Faculty of Engineering Soka University1-236 Tangi-choHachiojiTokyo 192-8577Japan

A series of azomethine esters,3-hydroxy-4-{[（4-iodophenyl）imino]methyl}phenyl alkanoates possessing even number of carbon atoms at the terminal alkanoyloxy chain（C_（n-1）H_（2n-1）COO-,n = 4,6,8,10,12,14） was synthesized.n-Butanoyloxy was found non-mesogenic,whilst n-hexanoyloxy to n-tetradecanoyloxy exhibited enantiotropic smectic A phase with fan-shaped *** was found that the length of terminal alkanoyloxy chain influenced the mesomorphic properties.

关键词： Liquid crystals Azomethine ester Enantiotropic Smectic A

Synthesis and mesomorphic properties of Schiff base esters possessing terminal chloro substituent

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Chinese Chemical Letters 2010年第6期21卷 637-640页

作者： sie tiong ha Lay Khoon Ong siew Ling Lee Hong Cheu Lin Yip Foo Win siew Teng Ong Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Department of Science Faculty of Engineering & ScienceUniversiti Tunku Abdul RahmanJln Genting KlangSetapak53300 Kuala LumpurMalaysia Ibnu Sina Institute for Fundamental Science Studies Universiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia Department of Materials Science & Engineering National Chiao Tung UniversityHsinchu 300TaiwanChina

A homologous series of Schiff base esters,4-chlorobenzylidene-4'-n-alkanoyloxyanilines,containing even number of carbons at the end groups of the molecules(C_(n-1)H_(2n-1)COO-,n=4,6,8,10,12,14,16) were *** mesomorphic properties were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).It was found that the end groups of the molecules had an effect on the mesomorphic properties.n-Butanoyloxy was found non-mesogenic,whilst n-hexanoyloxy exhibited monotropic smectic *** higher members in this homologous series were enantiotropic smectogens.

关键词： Schiff base esters Smectic A Smectic B Liquid crystal

Mesomorphic behaviour of new azomethine liquid crystals having terminal bromo substituent

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Chinese Chemical Letters 2012年第2期23卷 177-180页

作者： sie tiong ha Teck Leong Lee siew Ling Lee Guan Yeow Yeap Yip Foo Win siew Teng Ong Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparMalaysia Ibnu Sina Institute for Fundamental Science Studies Universiti Teknologi Malaysia81310 UTM SkudaiMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia11800 MindenMalaysia Department.of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparMalaysia

A homologous series of azomethine esters,4-n-alkanoyloxybenzylidene-4＇-bromoanilines possessing even number of carbon atoms at the terminal alkanoyloxy chain（C_（n-1）H_（2n-1）COO- n = 8,10,12,14,16,18） was synthesized and *** n-octanoyloxy to n-dodecanoyloxy derivatives exhibited enantiotropic smectic A and smectic B phases,n-tetradecanoyloxy to n-octadecanoyloxy derivatives possessed enantiotropic smectic A and monotropic smectic B properties.n-Decanoyloxy derivatives demonstrated the optimum exhibition for both smectic A and smectic B *** was found that the length of terminal alkanoyloxy chain has an influence on mesomorphic properties.

关键词： Liquid crystals Schiff base ester Enantiotropic Smectic A Smectic B

Heterocyclic benzoxazole-based liquid crystals:Synthesis and mesomorphic properties

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Chinese Chemical Letters 2011年第10期22卷 1191-1194页

作者： sie tiong ha Kok Leei Foo Ramesh T.Subramaniam Masato M.Ito S.Sreehari Sastry siew Teng Ong Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Center for Ionics University Malaya Department of Physics Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia Faculty of Engineering Soka University1-236 Tangi-choHachiojiTokyo 192-8577Japan Department of Physics Acharya Nagarjuna UniversityNagarjuna Nagar 522 510India

New Schiff base liquid crystals containing benzoxazole core and alkanoyloxy chain at the end group of the molecules （C_（n-1）H_（2n-1）COO-,n=14,16,18） was *** present compounds are enantiotropic smectic A liquid *** was also found that the end groups of the molecules and polar chloro substituent at the benzoxazole fragment had effect on the mesomorphic properties.

关键词： Schiff bases Benzoxazoles Mesomorphic Smectic A Structure-property relationship

Mesomorphic behavior of new benzothiazole liquid crystals having Schiff base linker and terminal methyl group

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Chinese Chemical Letters 2012年第7期23卷 761-764页

作者： sie tiong ha Kok Leei Foo Hong Cheu Lin Masato M.Ito Kazuma Abe Kenji Kunbo S.Sreehari Sastry Department of Chemical Science Faculty of ScienceCentre for Biodiversity ResearchUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Department of Material Science&Engineering National Chiao Tung UniversityHsinchu 300TaiwanChina Faculty of Engineering Soka University1-236 Tangi-choHachiojiTokyo 192-8577Japan Department of Physics Acharya Nagariuna UniversityNagariuna Nagar 522510India

A homologous series of heterocycles,6-methyl-2-（4-alkoxybenzylidenamino）benzothiazoles,were synthesized and characterized using FT-IR,^1H and ^（13）C NMR and mass spectrometric *** nematic phase was observed for shorter *** A phase only emerged from octyloxy derivative *** terminal methyl group at the benzothiazole fragment and the Schiff base linkage influenced the mesomorphic behavior of the present series.

关键词： Schiff bases Benzothiazole Liquid crystal Smectic A Nematic

Synthesis and mesomorphic evaluation of new calamitic liquid crystals containing benzothiazole core

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Chinese Chemical Letters 2011年第5期22卷 619-622页

作者： Teck Ming Koh sie tiong ha Teck Leong Lee siew Ling Lee Guan Yeow Yeap Hong Cheu Lin Ramesh T.Subramaniam Department of Science Faculty of Engineering & ScienceUniversiti Tunku Abdul RahmanJln Genting KlangSetapak53300 Kuala Lumpur.Malaysia Department of Chemistry National University of SingaporeSingapore 117543Singapore Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Ibnu Sina Institute for Fundamental Science Studies Universiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia11800 MindenPenangMalaysia Department of Materials Science & Engineering National Chiao Tung UniversityHsinchu 300Taiwan Center for Ionics University Malaya Department of Physics Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia

The design and synthesis of new calamitic benzothiazole-based liquid crystals,2-[4-（4-alkyloxybenzoyloxy）-phenyl]ben-zothiazoles are *** target compound was characterized using spectroscopic techniques,such as FT-IR,NMR（~1H and ^（13）C）,microanalysis and *** liquid crystalline behaviours of these compounds were thoroughly examined by differential scanning calorimetry and polarizing optical microscope *** materials exhibited enantiotropic nematic phase with high thermal stability（168℃）.Smectic A phase starts to emerge as monotropic（metastable） phase from C10 member and changes into enantiotropic（stable） phase from C12 and persists up to C16 members.

关键词： Benzothiazole Alkoxy chain Nematic Smectic A Liquid crystal

New mesogenic Schiff base esters comprising benzothiazole moiety:Synthesis and mesomorphic properties

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Chinese Chemical Letters 2009年第9期20卷 1081-1084页

作者： sie tiong ha Teck Ming Koh Guan Yeow Yeap Hong Cheu Lin Jun Kit Beh Yip Foo Win Peng Lim Boey Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia 11800 MindenPenangMalaysia Department of Materials Science & Engineering National Chiao Tung University1001 Ta-Hsueh RoadHsinchu 300Taiwan Faculty of Science Engineering & TechnologyUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat 31900 KamparPerakMalaysia

A homologous series of Schiff base esters, 6-methoxy-2-（2-hydroxy-4-alkanoyloxybenzylidenamino）benzothiazoles, compris- ing a benzothiazole moiety as the core was synthesized. All the members of this series exhibited an enantiotropic nematic phase. The azomethine linkage along with the lateral hydroxyl and terminal methoxyl groups were found to exert an effect on the mesomorphic properties. 2009 sie tiong ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Schiff bases Benzothiazoles Mesomorphic Nematic Structure-liquid crystal property relationship

Synthesis and mesomorphic properties of new Schiff base esters with different alkyl chains

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Chinese Chemical Letters 2009年第7期20卷 767-770页

作者： sie tiong ha Lay Khoon Ong siew Teng Ong Guan Yeow Yeap Joanna Pik Wan Wong Teck Ming Koh Hong Cheu Lin Faculty ofEngineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia 11800 MindenPenangMalaysia Department of Chemistry University of YorkHeslingtonYork YO10 5DDUnited Kingdom.

A new series of Schiff base esters, 4-（dimethylamino）benzylidene-4＇-alkanoyloxyanilines containing even number of carbons at the end group of the molecules （Cn-1H2n-1COO, n = 6, 8, 10, 12, 14, 16, 18） were synthesized. The present compounds were monotropic liquid crystals. It was also found that the end groups of the molecules had effect on the mesomorphic properties. C 2009 sie tiong ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Liquid crystals Schiff base esters Monotropic compounds Mesomorphic properties