Synthesis and mesomorphic properties of three- and four-ring liquid crystals containing cyclohexyl,phenyl and pyridyl units

Two series of 4-(3-alkoxycarbonylpyridyl-6-ethynyl)phenyl trans-4-n-alkylcyclohexylcarboxylates and 4-(3-alkoxycarbonylpyridyl-6-ethynyl)phenyl 4-(trans-4-n-alkylcyclohexyl)benzoates have been prepared. Their mesmorphic properties were observed and measured by polarizing optical microscopy and differential scanning calorimetry. The relationship between structures and properties is discussed, showing that the ferroelectric phase can be observed when chiral terminal chains exist.     

Synthesis and thermotropic studies of a novel series of nematogenic liquid crystals 2-(6-alkoxynaphthalen-2-yl)-5-cyanopyridines

A novel series of highly birefringent liquid crystalline compounds, 2-(6-alkoxynaphthalen-2-yl)-5-cyanopyridines (nO-NpPyCN, n?=?2–8) that have potential as commercially useful, were synthesised using a short two-step reaction with overall yields between 55% and 85%. Spectral analyses were in accordance with the expected structures. Their thermotropic behaviours were investigated by polarising optical microscopy and differential scanning calorimetry. It was found that the desymmetrised core results in a nematic phase with a broad mesophase range.     

Synthesis and mesomorphic behaviours of a homologous series of 2-(4-alkyloxybenzylidenamino)benzothiazoles

The synthesis and characterisation of a series of new rod-shaped liquid crystal (LC), 2-(4-alkyloxybenzylidenamino)benzothiazoles possessing even number of carbon atoms at the alkyloxy chain (C_nH_2n?+?1O-, n = 2, 4, 6, 8, 10, 12, 14, 16, 18) are reported. The molecular structures of title compounds were elucidated using FTIR and nuclear magnetic resonance spectroscopic techniques. The phase behaviour of these new compounds was characterised and studied by differential scanning calorimetry and polarising optical microscopy. Lower members (n = 2, 4 and 6) did not exhibit mesophase. Octyloxy derivative was monotropic LC. Enantiotropic smectic A phase was observed from n-decyloxy derivatives onward to the last homologous synthesised.     

Synthesis and mesomorphic properties of 1-(4′-ethyl biphenylyl) 2-(4-alkoxy-2,3,5,6-tetrafluorophenyl) acetylenes

A series of l-(4′-ethylbiphenylyl) 2-(4-alkoxy-2,3,5,6-tetrafluorophenyl)acetylenes and their nonfluorinated analogues have been prepared. The polarizing microscope observation shows that the fluorinated target compounds exhibit enantiotropic nematic phases, whereas the nonfluorinated analogues show complicated DSC results. The effect of structure modification of the core on mesogenic phases was discussed by comparing the data of fluorinated target compounds with those of corresponding nonfluorinated analogues.     

Synthesis and mesomorphic properties of resorcyl di[4-(4-alkoxy-2,3-diflorophenyl)ethynyl] benzoate liquid crystals

Two resorcyl di[4-(4-alkoxy-2,3-difluorophenyl)ethynyl] benzoate liquid crystals (A10 and A12) were prepared and their mesomorphic properties were observed. A large polarisation value was obtained with longer terminal chains.     

meso-四(对烷氧苯基)卟啉金属配合物的合成和性能研究(IV)

合成了系列卟啉乙酸合锰配合物9个,其中6个为未见文献报道的新化合物.用UV,1HNMR,IR,MS,元素分析等表征确证了配合物的结构,总结了锰与卟啉类配体配合的IR,UV,1HNMR判据.采用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能,发现8个配合物具有液晶性.考察了烷氧基链长、配位金属离子和分子空间结构对液晶性能的影响.     

Synthesis and mesomorphic properties of four-ring liquid crystals containing cyclohexyl,phenyl and pyridyl units

Two series of chiral and achiral 4-[(3-n-alkoxycarbonylpyridyl)-6-ethynyl]phenyl 4-(trans-4-n-alkylcyclohexyl)benzoate liquid crystals have been synthesized. Their mesomorphic properties were observed and measured by polarizing optical microscopy and DSC. A broad chiral smectic C phase was observed when terminal chains contained a chiral centre.     

Synthesis,regioisomerism and characterization of unsymmetrical alkenyl-terminated isoxazole liquid crystals

Two series of unsymmetrical diphenyl-1,3-diketones, each species bearing one terminal alkene, have been synthesized. These diketones have been converted into their respective unsymmetrical diphenylisoxazoles [3(5)-(4-ω-alkenyloxyphenyl)-5(3)-(4-alkoxyphenyl)isoxazoles] which have been isolated as equal mixtures of two regioisomers, due to 3,5- and 5,3-substitution of the isoxazole ring. The mesogenic properties of the isoxazole liquid crystals have been studied by polarizing optical microscopy and DSC. The effect of increasing alkoxy chain length (C6-C10) on the properties of the two series of isoxazoles has been examined. The isoxazoles show enantiotropic smectic C, smectic A and nematic mesophases. A detailed ¹H and ¹³C NMR spectroscopic study has examined both the 1,3-diketones and isoxazoles. Proximity of the terminal alkene to the diphenyl core can greatly affect the complexity of the ¹³C NMR spectra.     

meso-四(对烷氧苯基)卟啉金属配合物的合成和性能研究(IV)

合成了系列卟啉乙酸合锰配合物9个, 其中6个为未见文献报道的新化合物. 用UV, ¹H NMR, IR, MS, 元素分析等表征确证了配合物的结构, 总结了锰与卟啉类配体配合的IR, UV, ¹H NMR判据. 采用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能, 发现8个配合物具有液晶性. 考察了烷氧基链长、配位金属离子和分子空间结构对液晶性能的影响.     

Sulfur makes the difference: synthesis and mesomorphic properties of novel thioether-functionalized imidazolium ionic liquid crystals

Novel thioether-linked imidazolium ionic liquid crystals were synthesized starting from methyl 2-mercaptoacetate. The mesomorphic properties were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. All mesogens displayed smectic A mesophase geometries with strongly interdigitated bilayer structures. Comparison of the thioether-linked imidazolium salts with the corresponding amine- and amide-linked imidazolium salts as well as simple N-alkyl-imidazolium salts showed that both mesophase width and stability increased with increasing softness of the linking unit, thus indicating the beneficial effect of sulfur. Additionally, an increase of the length of the linking unit decreased the interdigitation of the alkyl chains.     

meso-四(邻烷氧基苯基)卟啉合钴的合成、表征和性能研究

合成了meso-四(邻烷氧基苯基)卟啉合钴配合物10个,其中未见文献报道的新化合物8个，研究了其合成、分离、纯化方法,首次得到了该系列化合物的晶体或固体。用¹H NMR、MS、IR、UV、元素分析等表征确证了其结构,报道和解析了该类卟啉钴配合物的¹H NMR特殊波谱现象。用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能,发现6个配合物具有液晶性。研究了烷氧基链长、金属离子和分子空间结构对卟啉液晶性能的影响,烷氧基链长的增加、金属配合物的形成有利于液晶性能的改善。     

Synthesis and properties of new non-symmetric 2,5-bis(4-alkylphenylethynyl)thiophenes

The synthesis and characterisation of new non-symmetric 2,5-bis(4-alkylphenylethynyl)thiophenes are described. Phase transition properties of these non-symmetric homologues are compared to those of the corresponding symmetric analogues. Furthermore, optical, dielectric and elastic data of investigated compounds and nematic mixture are provided. Compounds are characterised by ¹H NMR spectroscopy and mass spectrometry (electron ionization) analysis. They show an enantiotropic nematic behaviour in broad temperature ranges, confirmed by a polarising thermomicroscopy and differential scanning calorimetry. Detailed synthetic procedures are attached, showing a great synthetic versatility of the thiophene ring substitution. Synthesised compounds stand as promising components of highly birefringent liquid crystalline mixtures.     

Synthesis and mesomorphic properties of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates

A new series of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl)benzoates have been prepared. Polarizing microscopic textural observation shows that they are liquid crystals with nematic phase.     

meso-四(邻烷氧基苯基)卟啉合锌的合成、表征和性能研究

用邻烷氧基苯甲醛与吡咯缩合合成meso-四(邻烷氧基苯基)卟啉, 再与醋酸锌配合反应合成了meso-四(邻烷氧基苯基)卟啉合锌配合物10个, 其中未见文献报道的配合物9个, 得到该系列配合物的晶体或固体. 用¹H NMR, MS, IR, UV, 元素分析等表征确证了该系列配合物的结构. 用差示扫描量热法和偏光显微镜研究了该系列配合物的液晶性能, 发现6个配合物具有液晶性, 其液晶行为表现为升温单变液晶.     

Synthesis and mesomorphic properties of n-butyl-4- [4-((4-n-alkoxyl-tetrafluorophenyl)ethynyl)benzyloxy]benzoates

A homologous series of n-butyl-4-[4-((4-n-alkoxyl-tetrafluorophenyl)ethynyl)benzyloxy]benzoates have been synthesized.Their phase transition temperatures have also measured by polarizing textural observation and confirmed by DSC.     

meso-四(对烷氧苯基)卟啉金属配合物的合成和性能研究(II)

合成了Zn、Pb两个系列卟啉金属配合物12个,其中6个为未见文献报道的新化合物,用元素分析、IR、UV、^1HNMR、MS确证了其结构。总结了Zn、Pb与卟啉类配体配合的IR、UV、^1HNMR判据。研究了这两个系列化合物的液晶性能,发现9个化合物具有液晶性。     

meso-四(对烷氧基苯基)卟啉配合物的合成、表征和液晶性研究

The method of Adler was improved to prepare a series of 5,10,15,20-tetrakis(4-alkoxyphenyl)porphyrins and their complexes containing Fe³⁺, Mn³⁺, Pb²⁺, Co²⁺, Cu²⁺, Zn²⁺. Among them there were seven new compounds. All these compounds were identified through ¹H NMR, MS, IR, UV and Element analysis. The correlation between the structure of compounds and their ¹H NMR, MS, IR, UV spectra was discussed and their specific spectra were explained. We found nine metalloporphyrins exhibited liquid crystal behaviour through DSC and polarized-light microscope. They had one to three mesophases and certain phase transition temperature, ΔH and temperature range of L.C(ΔT).     

Synthesis of 6,8-substituted 4-(hydroxyphenylamino)- and 4-(aminophenylamino)-2-methylquinolines

A procedure has been developed for the synthesis of 4-(hydroxyphenylamino)- and 4-(aminophenylamino)-2-methylquinolines having a substituent in the 6(8)-position of the quinoline ring from the corresponding 4-chloro-2-methylquinolines and o-, m-, and p-aminophenols and o-, m-, and p-phenylenediamines.     

Synthesis and mesomorphic properties of four ring,rod-like fluorene derivatives – the influence of the lateral substitution on mesomorphic properties of 2,7-bis(4-alkylphenyl)-fluorenes

ABSTRACT

This work presents new rod-like compounds being fluorene derivatives linked with other parts of the core at 2 and 7 positions – its synthesis and properties. The fluorene moiety is located in the central position of the four rings molecular core. The chain system in most cases was symmetrical and limited to pentyl or hexyl chains. To study the influence of the lateral substituents on mesomorphic properties two types of substituents have been incorporated, centrally located various short alkyl groups at fluorene’s 9,9 positions and outer core fluorosubstitutions located at side phenyl rings. All synthesised compounds exhibit liquid crystalline properties, where for laterally non-substituted and fluorosubstituted derivatives the dominant phases are smectics, while the nematics phases (nematic and chiral nematic – observed mostly on cooling cycle) occurs for compounds having alkyl substituents at 9,9 positions of fluorene. The synthetic methodology and mesomorphic properties of title compounds will be presented in detail as well as photophysical properties such as UV-visible absorption spectra and fluorescence spectra.