This article describes the preparation and liquid crystalline properties of a new homologous series of 4-（4-bromopropyloxy）-4＇- （4-alkyloxybenzylidene）anilines in which the phenyl ring is armed by a bromopropylox...This article describes the preparation and liquid crystalline properties of a new homologous series of 4-（4-bromopropyloxy）-4＇- （4-alkyloxybenzylidene）anilines in which the phenyl ring is armed by a bromopropyloxy chain.The thermal behavior and mesomorphic properties of the synthesized compounds were studied with particular attention given to the correlation between their phase transition temperatures and anisotropic change influenced by molecular structure.All the members displayed enantiotropic smectic phase except for the homologue with the longest alkyloxy chain（R = C_（18）H_（37））,exhibiting only monotropic characteristic. The presence of bromine atom from the propyloxy side chain is found to be capable of altering and influencing the mesomorphic properties.展开更多
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 syn...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 texture.It was found that the length of terminal alkanoyloxy chain influenced the mesomorphic properties.展开更多
A new homologous series of isoflavone-based ethers,7-（4-bromoalkyloxy）-3-（4＇-decyloxyprienyl）-4H-1-benzopyran-4-ones were synthesized and characterized.The mesomorphic properties of all homologues were investigat...A new homologous series of isoflavone-based ethers,7-（4-bromoalkyloxy）-3-（4＇-decyloxyprienyl）-4H-1-benzopyran-4-ones were synthesized and characterized.The mesomorphic properties of all homologues were investigated by differential scanning calorimetry（DSC） and polarizing optical microscopy（POM）.Enantiotropic smectic A（SmA） phase was observed for all homologues.The structure-property study was carried out by comparing the mesomorphic behavior of the homologues with those previously reported analogues.The bromine atom from the alkyloxy side chain of the benzene ring fused to the heterocyclic moiety was found to be capable of changing the mesomorphic properties.展开更多
Two types of liquid crystal polymers have been reported. One is enantiotropic and can form a liquid crystal state both on heating and cooling. The other type is monotropic and can form mesophase only in the course of ...Two types of liquid crystal polymers have been reported. One is enantiotropic and can form a liquid crystal state both on heating and cooling. The other type is monotropic and can form mesophase only in the course of cooling from its isotropic melt.展开更多
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 synthe...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 characterized.Whilst 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 phases.It was found that the length of terminal alkanoyloxy chain has an influence on mesomorphic properties.展开更多
A new series of liquid crystals comprising eight heterocyclic isoflavone esters,7-alkanoyloxy-3-[4＇-（3-methylbutyloxyphenyl）]- 4H-1-benzopyran-4-ones exhibiting enantiotropic nematic（N） and smectic C（SmC） phase...A new series of liquid crystals comprising eight heterocyclic isoflavone esters,7-alkanoyloxy-3-[4＇-（3-methylbutyloxyphenyl）]- 4H-1-benzopyran-4-ones exhibiting enantiotropic nematic（N） and smectic C（SmC） phases were synthesized and investigated.The mesomorphic properties of all derivatives were investigated by means of differential calorimetry and polarized optical microscopy. Wide angle X-ray diffraction technique was employed to investigate the molecular packing associated with the intermolecular interaction as well as the correlation between the thermal behaviour of these compounds with their anisotropy properties within a mesophase.展开更多
基金Universiti Sains Malaysia for USM RU(No.1001/PKIMIA/811159) and the research facilities
文摘This article describes the preparation and liquid crystalline properties of a new homologous series of 4-（4-bromopropyloxy）-4＇- （4-alkyloxybenzylidene）anilines in which the phenyl ring is armed by a bromopropyloxy chain.The thermal behavior and mesomorphic properties of the synthesized compounds were studied with particular attention given to the correlation between their phase transition temperatures and anisotropic change influenced by molecular structure.All the members displayed enantiotropic smectic phase except for the homologue with the longest alkyloxy chain（R = C_（18）H_（37））,exhibiting only monotropic characteristic. The presence of bromine atom from the propyloxy side chain is found to be capable of altering and influencing the mesomorphic properties.
基金Universiti Tunku Abdul Rahman for the research facilities and financial support Ministry of Higher Education for the award of MOHE Scholarship
文摘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 texture.It was found that the length of terminal alkanoyloxy chain influenced the mesomorphic properties.
基金Universiti Sains Malaysia for USM RU Grants(No.1001/PKIMIA/811127 and 1001/PKIMIA/811140)Chan T.-N.would like to acknowledge USM for the research fellowship
文摘A new homologous series of isoflavone-based ethers,7-（4-bromoalkyloxy）-3-（4＇-decyloxyprienyl）-4H-1-benzopyran-4-ones were synthesized and characterized.The mesomorphic properties of all homologues were investigated by differential scanning calorimetry（DSC） and polarizing optical microscopy（POM）.Enantiotropic smectic A（SmA） phase was observed for all homologues.The structure-property study was carried out by comparing the mesomorphic behavior of the homologues with those previously reported analogues.The bromine atom from the alkyloxy side chain of the benzene ring fused to the heterocyclic moiety was found to be capable of changing the mesomorphic properties.
基金Project supported by the National Natural Science Foundation of China
文摘Two types of liquid crystal polymers have been reported. One is enantiotropic and can form a liquid crystal state both on heating and cooling. The other type is monotropic and can form mesophase only in the course of cooling from its isotropic melt.
基金Universiti Tunku Abdul Rahman and Malaysia Ministry of Higher Education for the financial supports via LRGS and research facilities
文摘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 characterized.Whilst 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 phases.It was found that the length of terminal alkanoyloxy chain has an influence on mesomorphic properties.
基金Universiti Sains Malaysia for USM RU(No.1001/PKIMIA/81140)
文摘A new series of liquid crystals comprising eight heterocyclic isoflavone esters,7-alkanoyloxy-3-[4＇-（3-methylbutyloxyphenyl）]- 4H-1-benzopyran-4-ones exhibiting enantiotropic nematic（N） and smectic C（SmC） phases were synthesized and investigated.The mesomorphic properties of all derivatives were investigated by means of differential calorimetry and polarized optical microscopy. Wide angle X-ray diffraction technique was employed to investigate the molecular packing associated with the intermolecular interaction as well as the correlation between the thermal behaviour of these compounds with their anisotropy properties within a mesophase.
