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.     

Synthesis and mesomorphic properties of 4-n-alkoxy 4'-[4-((4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl)ethynyl)benzyloxy]benzoates

Two series of tolane-based liquid crystals have been prepared that incorporate a tetrafluorophenyl moiety and a flexible methyl ether bond into the core structure. The mesomorphic properties have been studied by polarizing microscopic textural observation and DSC measurements. By comparison with their non-fluorinated analogues, the effect of tetrafluorophenylene on mesomorphic behaviour has been discussed in this paper.     

Synthesis and mesomorphic properties of trifluorobenzoate liquid crystal

Four series of trifluorobenzoate liquid crystals have been synthesized. Their phase transition temperatures have been also measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution and triple bond has been also discussed.     

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 4‐((4‐n‐Alkoxy‐2, 3, 5, 6‐tetrafluorophenyl)ethynyl)phenyl Methoxy‐substituted Benzoates

Two series of 4‐methoxybenzoate liquid crystals were synthesized. Their phase transition temperatures were also measured by texture observation in a polarizing microscope and confirmed by DSC. Their mesomorphic properties and fluoro‐substitute effect were studied in detail.     

Synthesis and mesomorphic behaviour of 4''''-methoxyphenyl 4"-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl) ethynyl] benzylethers

A novel homologous series of 4'-methyoxyphenyl 4"-[(4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl]benzyl ethers have been prepared via Pd-catalysed Heck reactions. Polarizing microscopic textural observation shows that these compounds exhibit enantiotropic nematic phases.     

Synthesis and mesomorphic properties of some fluorinated phenyl 4-[(4-n-alkoxyphenyl)ethynyl]benzoates

Eight homologous series of fluorinated phenyl 4-[(4-n-alkoxyphenyl)ethynyl]benzoates have been synthesized. Textural observations by polarizing microscopy and DSC measurements of the phase transitions show that most of these compounds are thermotropic liquid crystals with nematic and smectic A phases; furthermore, several show monotropic high order smectic phases. The results showed that the SmA phase is enhanced with increasing degree of fluorosubstitution on the para- and meta-positions of the terminal phenyl groups. The mesomorphic properties of these compounds are also affected by the direction of ester bonds. The effect of triple bonds is also discussed.     

Synthesis and mesomorphic properties of some fluorinated phenyl 4-[(4-n-alkoxyphenyl)ethynyl]benzoates

Eight homologous series of fluorinated phenyl 4-[(4-n-alkoxyphenyl)ethynyl]benzoates have been synthesized. Textural observations by polarizing microscopy and DSC measurements of the phase transitions show that most of these compounds are thermotropic liquid crystals with nematic and smectic A phases; furthermore, several show monotropic high order smectic phases. The results showed that the SmA phase is enhanced with increasing degree of fluorosubstitution on the para- and meta-positions of the terminal phenyl groups. The mesomorphic properties of these compounds are also affected by the direction of ester bonds. The effect of triple bonds is also discussed.     

Synthesis and mesomorphic properties of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties.     

Synthesis and mesomorphic properties of 4-[(4n-alkoxy-2,3-difluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

Three series of novel fluorinated liquid crystals containing a 2,3-difluorotolan unit have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution is discussed.     

Synthesis and mesomorphic properties of fluorinated phenyl 4-[(4-n-alkoxy-2,3-difluorophenyl)ethynyl]benzoates

Three series of fluorinated phenyl 4-[(4-n-alkoxy-2,3-difluorophenyl)ethynyl]benzoate liquid crystals have been synthesized. Their phase transition temperatures were measured by texture observation in a polarizing microscope and confirmed by DSC. Their mesomorphic properties and fluoro-substituent effects were studied in detail.     

Synthesis and mesomorphic properties of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties.     

Synthesis and mesomorphic properties of 4-[(4n-alkoxy-2,3-difluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

Three series of novel fluorinated liquid crystals containing a 2,3-difluorotolan unit have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution is discussed.     

The synthesis and phase transition of 4''''-methylphenyl 4"-[(4-alkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates

A homologous series of 4'-methylphenyl 4"-[(4-alkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]-benzoates have been synthesized. Polarizing microscopic textural observation shows that such compounds exhibit enantiotropic nematic phase.     

Synthesis and mesomorphic properties of 3-(4-n-alkyloxyarylaminomethylene)chroman-2,4-diones

The synthesis, characterisation and mesomorphic properties of new liquid crystals are reported. The goal was to obtain amides starting from 7-decanoyloxychromone-3-carboxylic acid and 4-n-alkoxyanilines. However, instead of the expected amides, in each case a mixture of two isomeric E/Z enaminones was isolated, with a ratio 3/1. The mesophase behaviour of the five mixtures was characterised and studied using differential scanning calorimetry and polarising optical microscopy. The transitions are enantiotropic, the peaks being sharp and the mesomorphic range wide. All the compounds exhibit a smectic C phase and the derivatives with shorter chains also exhibit a nematic phase.     

Synthesis and mesomorphic properties of the homologous series of 4'-bromophenyl 4'-[(4-n-alkoxy-2,3,5,6 tetrafluorophenyl)ethynyl]benzoates

A homologous series of 4'-bromophenyl 4'-[(4-n-alkoxy-2,3,5,6-tetrafluoro-phenyl)ethynyl]benzoates has been synthesized. The transition temperatures were studied by polarizing optical microscopy. The compounds exhibit nematic and smectic A phases.     

Synthesis and study of mesomorphic properties of unsymmetrical cyclohexanone-derived bis-chalcones

A series of (2E,6E)-2-(4-n-alkoxybenzylidene)-6-((benzo[d][1,3]dioxol-6-yl)methylene)cyclohexanones were synthesised by stepwise condensation reactions from cyclohexanone. The optical and thermal analysis of the series indicated the mesomorphic properties of some derivatives. The compounds with C7–C16 substituents showed the nematic phases in the range of 90–73°C. The single crystal X-ray analysis confirms the head to tail packing arrangement.     

The synthesis and mesomorphic properties of 4-n-alkoxyphenyl 4-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl)ethyl]benzoates

4-n-Alkoxyphenyl4-[(4-n-alkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates (compound A) are synthesised by a convenient method. These compounds exhibit only enantiotropic nematic phases and have very high clearing points. These compounds (As) can be transformed into corresponding ethane derivatives, via hydrogenation using a palladium catalyst (Pd/C), which exhibit monotropic nematic phases. The effect of the ethylene bridge (–CH₂CH₂–) on the mesomorphic behaviour is discussed.     

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.     

Synthesis and Crystal Structure of 15,16-Bis（（4-nitrophenoxy）methyl）-2,3,5,6,8,9,11,12- octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecine

Double-armed crown ether 15,16-bis((4-nitrophenoxy)methyl)-2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13] pentaoxacyclopentadecine F.W. 570.54 was synthesized by dibromomethyl benzo-15-crown-5 with 4-nitrophenol in the presence of anhydrous K2CO3, characterized by spectroscopic techniques and confirmed by X-ray crystal structure analysis. The title compound crystallizes in monoclinic, space group P21/c with a = 12.840(4), b = 9.425(3), c = 22.447(7), β = 98.128(7)° and Z = 4. The structure exhibits intermolecular hydrogen bonding of C-H···O type.