Synthesis and mesomorphic properties of some biphenyl-phenyl triesters as potential longitudinal ferroelectrics

Abstract

A homologous series of “fraternal twin” molecules consisting of relatively short and relatively long mesogenic units connected by a flexible spacer group and flexible chains as the terminal groups was synthesized in an attempt to form a non-chiral longitudinal ferroelectric smectic phase. The shorter of the two mesogenic units consisted of a 4-alkyl/alkoxy substituted biphenyl ester; the longer a terbenzoate group. Mesomorphic properties were determined by hot-stage polarizing microscopy and DSC. Several smectic phases were observed as well as nematic phases. Characterization of the smectic phases by microscopic textures is discussed.     

Synthesis and mesomorphic properties of some ferroelectric liquid crystals of lactate

A semiperfluorinated chain has been introduced into three series of lactate‐based molecules, and their mesomorphic properties have been studied by DSC and optical polarized microscope. An abnormal phenomenon has been found that the introduction of a triple bond in the core of the molecule, which lengthened the molecule, gave rise to a decrease in the thermal stability of chiral smectic C phase and smectic A phase. 2, 3‐Difluoro substituents of the phenylenic structure hinder the formation of the chiral smectic C phase because of the steric effect.     

Synthesis and mesomorphic properties of some homologues of fluorinated 4-chlorobenzoate-tolanes

Three homologues series of 4-chloro-substituted benzoate-tolanes were prepared. Thermal optical microscopy and DSC analysis show that these compounds are liquid crystalline. The effect on the mesomorphic properties of different positions of the perfluorophenyl in the molecular core unit is discussed.     

Synthesis and mesomorphic properties of some cyclohex-2-en-1-one derivatives

Mesomorphic properties of cyclohex-2-en-1-ones belonging to 14 different chemical structural types are compared and discussed. They were prepared by condensation of Mannich salts with 2-substituted acetoacetates or benzyl methyl ketones or acetylacetone in the presence of potassium hydroxide.     

Synthesis and mesomorphic properties of some new chiral thiobenzoates containing three rings

Six new compounds with chiral terminal chains and three rings bridged via the -COS- and -COO- groups have been synthesized. Three of them belong to series A and have two benzene rings and one bicyclo[2,2,2]octane, while the remaining three come from series B, where all three are benzene rings. Series A compounds share a characteristic feature of two smectic phases: SmA* and SmB*, whereas mesogens from the B series exhibit only the one SmA* phase.     

Synthesis and mesomorphic properties of some bisegmented compounds derived from 4,4'-disubstituted biphenyl

New unsymmetrical disubstituted biphenyls have been synthesized. Two different chains (one hydrocarbon and the other fluorinated) are linked through an acetamide bond to 4-methoxy-4'-hydroxybiphenyl. Their mesomorphic properties have been characterized by light microscopy and by differential thermal analysis showing the peculiar contribution of the hydrocarbon chain and the fluorinated tail. The enhancement of the hydrocarbon moiety from one to twelve methylene groups leads to a decrease of the clearing temperatures; furthermore the enantiotropic behaviour is changed to monotropic. The variation of the fluorinated moiety generates strong effects on the transition temperatures. These mesomorphic properties are compared to those of their monocatenar perfluorinated analogues incorporating a connector of the ester or monosubstituted amide type.     

Synthesis and mesomorphic properties of some aryl β-D-C-glycosides

The synthesis of some aryl β-D-C-glycosides bearing long alkoxy chains (grafted on the carbohydrate moiety through the intermediate of an aromatic core) is described. Their mesomorphic properties (studied by microscopic observations under polarized light, DSC and X-ray diffraction) are presented.     

Synthesis and mesomorphic behaviour of some aromatic polyesters

Six new aromatic polyesters were synthesized by the phase-transfer catalytic polycondensation. The polymers obtained were characterized by infra-red, X-ray diffraction, D.S.C., depolarized light intensity and polarizing microscope. Poly(p,p'-hydroquinone-1,4-phenylene dioxyacetate) and poly(p,p'-hydroquinone-1,4,7-trioxaheptamethylene dibenzoate) were found to be thermotropic liquid crystals but related polyesters are not. The results are discussed on the basis of the thermodynamic data obtained.     

Synthesis and mesomorphic behaviour of some aromatic polyesters

Abstract

Six new aromatic polyesters were synthesized by the phase-transfer catalytic polycondensation. The polymers obtained were characterized by infra-red, X-ray diffraction, D.S.C., depolarized light intensity and polarizing microscope. Poly(p,p'-hydroquinone-1,4-phenylene dioxyacetate) and poly(p,p'-hydroquinone-1,4,7-trioxaheptamethylene dibenzoate) were found to be thermotropic liquid crystals but related polyesters are not. The results are discussed on the basis of the thermodynamic data obtained.     

Synthesis of polyphilic hexaazatrinaphthylenes and mesomorphic properties

Methodologies for the synthesis of polyphilic hexaazatrinaphthylenes (HATN) with reduced symmetry based on the sequential condensation reactions of 1,2-bisalkoxy-4,5-diaminobenzenes with either tetrahydroxy-1,4-quinone or hexaketocyclohexane are described. The synthesized HATN possesses improved mesogenic properties and is liquid crystalline at room temperature.     

Synthesis of quinoxaline-benzoxale conjugates and mesomorphic properties

A new series of non-discotic heterocyclic compounds 1a-e derived from quinoxaline was prepared and their mesomorphic properties investigated. The crystal and molecular structures of nonmesogenic 2,3-bis(3,4-didodecyloxyphenyl)quinoxaline-6-carboxylic acid 4-[(4-butoxy2-hydroxyphenylimino)methyl]phenyl ester 2a (n=4, m=12) were determined by means of X-ray structural analysis. It crystallizes in a monoclinic space group P2(1)/c, with a=21.9193(13) Å, b=8.3693(4) Å, c=30.896(2) Å, and Z=4. The molecule was considered as an elongated or tapered triangle. Both inter- and intra-molecular H-bonds were observed in the crystal lattice, which was attributed to the formation of columnar mesophase in compounds 2. The mesomorphic behavior of compounds 1-2 was studied by thermal analysis and polarized optical microscopy. All compounds 1-2 exhibited hexagonal columnar phases (Col_h), which were also confirmed by powder XRD diffractometer. A N_cell and R_ar value equal to 4.74 and 4.34 within a slice of 9.0 Å thick were obtained for 1b and 2b, indicating that a more disc-like correlated structure by two molecules lying side-by-side was formed in Col_h phases. The fluorescent properties of the compounds 1-4 in CH₃Cl were also examined.     

The synthesis and properties of some mesomorphic cyclohexene derivatives

This paper describes the synthesis and mesomorphic properties of some new liquid crystalline cyclohexene derivatives.     

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, mesomorphic and optical properties of isothiocyanatotolanes

The synthesis, mesomorphic properties and UV absorption spectra of laterally fluorine substituted, and the corresponding unsubstituted, 4'-alkyl-, 4'-alkoxy-, 4'-alkylcyclohexyl-, 4'-alkylbicyclo [2,2,2]octyl- and 4'-alkylcyclohexylethyl-4-isothiocyanatotolanes are described. Multicomponent broad range nematic mixtures with birefringence values higher than 0.4 and moderate viscosities are developed.     

Synthesis of pyran derivatives with mesomorphic properties

N-(4-Arylidene)-4-(3,6-dihydro-4-methyl-2H-pyran-3-yloxy)anilines and N-(4-arylidene)-4-[(5,6-dihydro-2H-pyran-4-yl)methoxy]anilines that have the properties of smectic and nematic liquid crystals were synthesized. The effect of the pyran ring and the length of the aliphatic radical on the type and thermal stability of the meso phase was elucidated.Fortieth Anniversary of the October Revolution Bashkir State University, Ufa 450074. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 897–899, July, 1991.     

Synthesis and mesomorphic properties of some platinum(II) and oxovanadium(IV) complexes

The synthesis and mesomorphic properties of a homologous series of N-(2-hydroxy-4-n-alkoxybenzylidene)-4'-n-decylphenylanilines and their platinum(II) and oxovanadium(IV) complexes are reported. All the ligands and their metal chelates exhibit enantiotropic mesophases, predominantly smectic A and smectic C phases. The transition temperatures and enthalpies have been determined for most of the compounds. The platinum(II) complexes have higher melting points and mesophase thermal stabilities. However, the oxovanadium(IV) complexes have a wider thermal range for the mesophase. Both platinum(II) and oxovanadium(IV) complexes containing only a chain on the biphenyl moiety exhibit a nematic phase.     

Synthesis and mesomorphic properties of novel tolane-type liquid crystals

Two series of novel tolane-type liquid crystals(LCs) comprising of hydrogen-bonded organic acids were synthesized.The formation of dimerized H-bond LCs was confirmed by IR spectroscopy,and mesomorphic properties of the LCs were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).It was found that the end groups of the liquid crystals as well as the unsaturated rigid core had effect on the mesomorphic properties.     

Synthesis and mesomorphic properties of fluoro-containing azobenzene liquid crystals

Four series of azobenzene liquid crystal compounds containing a fluorinated tolan unit have been synthesized. The mesomorphic behaviours of these compounds were characterized by differential scanning calorimetry and optical polarizing microscopy. The compounds of these series exhibit a nematic, a smectic C or a smectic B phase. This investigation revealed that the alkoxy chain at the side of the azobenzene moiety plays a more important role in the formation of smectic phases than the one at the side of the tolan moiety.     

Synthesis and mesomorphic properties of esters derived from alkanediols

New alkane-α,ω-diyl esters, propane-1,3-diyl and butane-1,4-diyl bis[4-(4-alkoxybenzoyloxy)-3-bromobenzoates], were synthesized and were found to form nematic mesophase. The effects of the lateral substituent and the length of the central and terminal hydrocarbon chains on the mesomorphic properties of butane-1,4-diyl bis[4-(4-alkoxybenzoyloxy)-3-bromobenzoates] were studied. Structural factors responsible for mesogenic properties of these compounds were determined by conformation analysis.