Smectic Properties Research Articles

Study of Mesomorphism Changing on Terminal Side Chain with Different Thioalkyl Group

A novel mesomorphic series is RS-C6H4-COO-C6H4-CO-CH=CH-C6H4-OC18H37(n) (para) of chalconyl ester play double role thermotropic as well as lyotropically bioactive is synthesized and studied with a view to understand and establish the effect on mesomorphism when changing on left thioalkyl chain.the relation between mesomorphism and molecular structure on the basis of molecular rigidity and flex Novel series consists of thirteen homologues of which four homologues (C1 to C3) are non liquid crystal and the rest of the homologues (C5 to C18) are thermotropically enantiotropic nematic absences with smectic property. Thermometric transition temperatures and textures of nematogenic phase are determined by an optical polarizing microscopy equipped with a heating stage (POM).Textures of nematicphas schilieren and threaded type. Cr-N/I and N-I transition curves behaves in as manner with negligible abnormality at C18 homologue in phase diagram of a series.Analytical and spectral data conforms the molecular structure of homologues. Thermal stability for nematic is 123.2 °C whose degree of mesomorphism vary minimum from 4.0°C to a maximum of 24.0 °C, and hence novel series is of middle ordered melting type.

Effect of Equipolar Endgroup of a Molecule on Mesomorphic-Isotropic Transition Curve

A Homologous series:RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC18H37(n) (para) of chalconyl novel ester of dual character as thermotropic and lyotropically bioactive is synthesized and studied with a view to understand and establish the relation between mesomorphism and molecular structure on the basis of molecular rigidity and flexibitity through thermotropic liquid crystalline (LC) state. Novel series consists of thirteen homologues of which four homologues (C1 to C4) are non liquid crystal (NLC) and the rest of the homologues (C5 to C18) are thermotropically enantiotropic nematic without exihibition of smectic property. Thermometric transition temperatures and textures of nematogenic phase are determined by an optical polarizing microscopy equipped with a heating stage (POM).Textures of nematic phase are threaded or schilieren. Transition temperatures of novel homologues are relatively lower than the transition temperature of corresponding dimeric trans n-alkoxy cinnamic acid. Cr-N/I and N-I transition curves behaves in normal manner with negligible abnormality at C18 homologue in phase diagram of a series.Analytical and spectral data conforms the molecular structure of homologues. Thermal stability for nematic is 121.88°C whose degree of mesomorphism vary minimum from 4.0°C to a maximum of 34.0 °C, and hence novel series is of middle ordered melting type, Group efficiency order for-OC18H37 tail groups (series-1&Y) is highest irrespective of type of ester group –COO-and CH=CH-CO derived for nematic.

Study of Mesomorphism in Isomeric and Nonisomeric Linear and Nonlinear Chalconyl Series

A novel nonlinear chalconyl homologous series of ester: RO-C6H4-COO-C6H4 (m)-CO-CH:CH-C6H4-OC16H33(n) (para) have been synthesized and studied with a view to understand and establish the relation between thermotropic liquid Crystal (LC) properties and geometrically nonlinear shaped molecular structure. Homologous series consists of thirteen members ( C1 to C18) whose enantiotropic nematogenic mesomorphism commences from C6 homologue without exhibition of smectic property. C1 to C5 homologues are nonmesomorphic. Transition temperatures and textures of homologues were determined by an optical polarising microscopy equipped with a heating stage (POM). Transition curves of a phase diagrams (Cr-N/I and N-I) behaved in normal manner. N-I transition curve exhibited odd-even effect. Textures of a nematic phase are threaded or schlieren. Analytical and spectral data supported molecular structures of homologues. Thermal stability for nematic is 104.5°C whose degree of mesomorphism vary minimum of 13.0°C to maximum of 37.0°C. Group efficiency order for nematic is derived by comparing present novel series with structurally analogous other homologous series. Thus, homologous series of present investigation is nematogenic with absence of smectic property and of middle ordered melting type with considerable degree of mesomorphism.

Study of Molecular Flexibility Operated Mesomorphism

Homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC14H29(P) of chalconyl novel derivatives have been synthesized and studied with a views to understand and establish the relation between molecular structure and the liquid crystal (LC) properties of thermotropic mesomorphs Series consists of thirteen homologues. Five homologues (C1 to C5) are nonliquid crystal (NLC) and the rest of the homologues (C6 to C18) are enantiotropically nematogenic without exhibition of smectic property. Transition temperatures and textures were determined by an optical polarizing microscope equipped with a heating stage (POM). Transition curves of a phase diagram (N-I and Cr-I/N) behaved in normal manner. N-I transition curve exhibited odd-even effect with negligible abnormality in its behaviour at the C14 homologue. Thermal stability for nematic is 99.75°C.The degree of mesomorphism vary minimum 19°C at the C6 homologue to maximum 28°C at the C8 homologue. Analytical and spectral data confirms the molecular structures of the novel homologues. Evaluated thermal data of present novel series are compared with other structurally similar homologous series. Textures of Nematic phase are threded or schlieren.

Study of Mesomorphism Changing on Terminal Side Chain with Different Thioalkyl Group

A novel mesomorphic series is RS-C6H4-COO-C6H4-CO-CH=CH-C6H4-OC18H37(n) (para) of chalconyl ester play double role thermotropic as well as lyotropically bioactive is synthesized and studied with a view to understand and establish the effect on mesomorphism when changing on left thioalkyl chain.the relation between mesomorphism and molecular structure on the basis of molecular rigidity and flex Novel series consists of thirteen homologues of which four homologues (C1 to C3) are non liquid crystal and the rest of the homologues (C5 to C18) are thermotropically enantiotropic nematic absences with smectic property. Thermometric transition temperatures and textures of nematogenic phase are determined by an optical polarizing microscopy equipped with a heating stage (POM).Textures of nematicphas schilieren and threaded type. Cr-N/I and N-I transition curves behaves in as manner with negligible abnormality at C18 homologue in phase diagram of a series.Analytical and spectral data conforms the molecular structure of homologues. Thermal stability for nematic is 123.2 °C whose degree of mesomorphism vary minimum from 4.0°C to a maximum of 24.0 °C, and hence novel series is of middle ordered melting type.

Effect of Equipolar Endgroup of a Molecule on Mesomorphic-Isotropic Transition Curve

A Homologous series:RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC18H37(n) (para) of chalconyl novel ester of dual character as thermotropic and lyotropically bioactive is synthesized and studied with a view to understand and establish the relation between mesomorphism and molecular structure on the basis of molecular rigidity and flexibitity through thermotropic liquid crystalline (LC) state. Novel series consists of thirteen homologues of which four homologues (C1 to C4) are non liquid crystal (NLC) and the rest of the homologues (C5 to C18) are thermotropically enantiotropic nematic without exihibition of smectic property. Thermometric transition temperatures and textures of nematogenic phase are determined by an optical polarizing microscopy equipped with a heating stage (POM).Textures of nematic phase are threaded or schilieren. Transition temperatures of novel homologues are relatively lower than the transition temperature of corresponding dimeric trans n-alkoxy cinnamic acid. Cr-N/I and N-I transition curves behaves in normal manner with negligible abnormality at C18 homologue in phase diagram of a series.Analytical and spectral data conforms the molecular structure of homologues. Thermal stability for nematic is 121.88°C whose degree of mesomorphism vary minimum from 4.0°C to a maximum of 34.0 °C, and hence novel series is of middle ordered melting type, Group efficiency order for-OC18H37 tail groups (series-1&Y) is highest irrespective of type of ester group –COO-and CH=CH-CO derived for nematic.

Study of Molecular Flexibility Operated Mesomorphism

Homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC14H29(P) of chalconyl novel derivatives have been synthesized and studied with a views to understand and establish the relation between molecular structure and the liquid crystal (LC) properties of thermotropic mesomorphs Series consists of thirteen homologues. Five homologues (C1 to C5) are nonliquid crystal (NLC) and the rest of the homologues (C6 to C18) are enantiotropically nematogenic without exhibition of smectic property. Transition temperatures and textures were determined by an optical polarizing microscope equipped with a heating stage (POM). Transition curves of a phase diagram (N-I and Cr-I/N) behaved in normal manner. N-I transition curve exhibited odd-even effect with negligible abnormality in its behaviour at the C14 homologue. Thermal stability for nematic is 99.75°C.The degree of mesomorphism vary minimum 19°C at the C6 homologue to maximum 28°C at the C8 homologue. Analytical and spectral data confirms the molecular structures of the novel homologues. Evaluated thermal data of present novel series are compared with other structurally similar homologous series. Textures of Nematic phase are threded or schlieren.

Study of Mesomorphism in Isomeric and Nonisomeric Linear and Nonlinear Chalconyl Series

A novel nonlinear chalconyl homologous series of ester: RO-C6H4-COO-C6H4 (m)-CO-CH:CH-C6H4-OC16H33(n) (para) have been synthesized and studied with a view to understand and establish the relation between thermotropic liquid Crystal (LC) properties and geometrically nonlinear shaped molecular structure. Homologous series consists of thirteen members ( C1 to C18) whose enantiotropic nematogenic mesomorphism commences from C6 homologue without exhibition of smectic property. C1 to C5 homologues are nonmesomorphic. Transition temperatures and textures of homologues were determined by an optical polarising microscopy equipped with a heating stage (POM). Transition curves of a phase diagrams (Cr-N/I and N-I) behaved in normal manner. N-I transition curve exhibited odd-even effect. Textures of a nematic phase are threaded or schlieren. Analytical and spectral data supported molecular structures of homologues. Thermal stability for nematic is 104.5°C whose degree of mesomorphism vary minimum of 13.0°C to maximum of 37.0°C. Group efficiency order for nematic is derived by comparing present novel series with structurally analogous other homologous series. Thus, homologous series of present investigation is nematogenic with absence of smectic property and of middle ordered melting type with considerable degree of mesomorphism.

Synthesis and Study of Molecular Structure and Its Relation to Liquid Crystal Behavior in a Novel Azoester Series

A novel liquid crystal (LC) homologous series of 12 azoesters was synthesized and evaluated, and nine members of the series exhibited enantiotropically or monotropically nematogenic LC behavior. Smectogenic character is totally absent. The methoxy, tetradecyloxy, and hexadecyloxy homologues are non-liquid crystals (NLC). Textures of nematic phase are threaded, or schlieren. The solid–isotropic/nematic and N-I or vice versa transition curves behave in normal manner. The N-I transition curve exhibits an odd-even effect. The average thermal stability for nematic is 113.25°C. Mesomorphic phase length ranges from 21 to 35°C. The textures of nematic mesophase and transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. Analytical and spectral data confirm the molecular structures of homologues. The LC behavior of the present novel series is compared with a structurally similar known series. The present series is predominantly nematogenic with the absence of smectic property, and is of a middle-ordered melting type.

Mesomorphism Dependence on Terminal and Lateral Polar Groups in the Nonlinear Novel Azoester Series

The synthesis of a novel azoester homologous series was carried out with a view to understanding and establishing the effect of molecular structure on liquid crystal (LC) behavior of a substance. The novel series consists of eleven homologs, and all are enantiotropically nematogenic without exhibition of any smectic property. Transition and melting temperatures, textures of LC were determined by an optical polarizing microscope equipped with a heating stage. The textures of the nematic phase are threaded or Schlieren. Transition curves of a phase diagram behave in normal manner. The nematic-isotropic transition curve exhibits an odd-even effect. Analytical and spectral data support and confirm the structures of the homologues. Average thermal stability for the nematic is 137.2°C. The mesomorphic phase length ranges from 15°C to 50°C. LC behavior of the novel series is compared with a structurally similar known homologous series. The novel azoester homologous series is entirely nematogenic without exhibition of smectogenic character and of a middle-ordered melting type.

Study of Translational Diffusion Anisotropy of Ionic Smectogens by NMR Diffusometry

Thermotropic ionic liquid crystals are considered very promising for a wide range of applications, such as anisotropic conductors as well as electrolytes in dye-synthesized solar cells. Their potential comes from the unique combination of ionic conductivity and high polarizability. In this paper we present a study of the diffusional properties of the ionic smectic A phase formed by the cationic smectogen, N-docecyl-N'-methyl-imidazolium (C12mim), with two different counter ions. Experimental translational diffusion data measured by NMR diffusometry are collected both for cations and anions and discussed in terms of their different anisotropy.

Molecular Flexibility Operated Mesomorphism

Novel homologous series: RO-C6H4-CH=CH-COO-CH2-C6H4-Br (p) synthesized and studied with a view to understand and establish the effects of molecular structure on liquid crystal (LC) behavior of a series. Series consists of eleven homologues. C1 to C7 members of a novel series are non-liquid crystals. Mesomorphism commences from Octyloxy (C8) homologue and continued upto hexadecyloxy homologue (C16) as enantiotropic nematic without exhibition of smectic property. The textures of a nematic phase are threaded or Schlieren. Transition temperatures (table-2) and textures are determined by an optical polarizing microscopy equipped with a heating stage. Cr-N/I and N-I transition curve behaved in normal manner in phase diagram, showing their phase behavior (figure-1). Odd-even effect is absent for N-I transition curve. Analytical and spectral data confirmed the molecular structures of a series. The LC properties are compared with the structurally similar series. The transition temperatures are relatively lower than the corresponding n-alkoxy benzoic acid. Thus, present novel series is partly nematogenic with absence of smectic property whose mesogenic phase length is low and of low ordered melting type. Thermal stability for nematic is 93.0°C and the mesophaselength ranges from 8 to 21°C.

Molecular Flexibility Operated Mesomorphism

Novel homologous series: RO-C6H4-CH=CH-COO-CH2-C6H4-Br (p) synthesized and studied with a view to understand and establish the effects of molecular structure on liquid crystal (LC) behavior of a series. Series consists of eleven homologues. C1 to C7 members of a novel series are non-liquid crystals. Mesomorphism commences from Octyloxy (C8) homologue and continued upto hexadecyloxy homologue (C16) as enantiotropic nematic without exhibition of smectic property. The textures of a nematic phase are threaded or Schlieren. Transition temperatures (table-2) and textures are determined by an optical polarizing microscopy equipped with a heating stage. Cr-N/I and N-I transition curve behaved in normal manner in phase diagram, showing their phase behavior (figure-1). Odd-even effect is absent for N-I transition curve. Analytical and spectral data confirmed the molecular structures of a series. The LC properties are compared with the structurally similar series. The transition temperatures are relatively lower than the corresponding n-alkoxy benzoic acid. Thus, present novel series is partly nematogenic with absence of smectic property whose mesogenic phase length is low and of low ordered melting type. Thermal stability for nematic is 93.0°C and the mesophaselength ranges from 8 to 21°C.

Synthesis and Phase Behaviors of New Heterocyclic Liquid Crystals: Nematic and Smectic Properties

A series of new rod-shaped liquid crystal, 6-methoxy-2-(4-alkyloxybenzylidenamino) benzothiazoles possessingeven numbers of carbon atoms at the alkyloxy chain (CnH2n+1O-, n = 10, 12, 14, 16, 18) are prepared and characterized. The phase behaviour of these new compounds was studied by differential scanning calorimetry and polarising optical microscopy. All members exhibited mesophase. Influence of alkyl chain length on the mesomorphic properties was studied. Enantiotropic nematic phase was identified in all the members except for n = 18. Lower member (n = 10) exhibited monotropic (metastable) smectic A phase. The enantiotropic smectic A phase was observed from n-dodecyloxy derivatives onward to the last homologous synthesized.

Synthesis and phase transition behaviours of new non-symmetric liquid crystal dimers

A new series of non-symmetric liquid crystal dimers N-(4-(n-(4-(benzothiazol-2-yl)phenoxy)alkyloxy)-4-nitro-benzylideneimine) containing benzothiazole and benzylideneaniline as the mesogenic core units connected by a flexible alkyl spacer, -(CH2)n-, with n ranging from 2 to 6, 8, 10 and 12 have been prepared. Their molecular structures were proposed via spectroscopic techniques. Mesomorphic properties were studied using differential scanning calorimetry and polarising optical microscopy. The results showed that the clearing temperatures decreased upon lengthening of the alkyl spacers. Whilst even member with the shortest alkyl spacer (n = 2) exhibited nematic phase, the rest of even members (n = 4, 6, 8, 10 and 12) possessed smectic and nematic properties. Nematic phase range gradually decreased from n = 2 to n = 12. Odd members are belonged to non-mesogenic compounds except for n = 5 which exhibited monotropic (metastable) nematic phase.

Molecular theory of the tilting transition in smectic liquid crystals with weak layer contraction and diffused cone orientational distribution

A molecular field theory of the smectic-A-smectic-C transition has been developed for smectics with a diffused cone orientational distribution of molecules (volcano-like distribution function) in the smectic-A phase and anomalously weak layer contraction in the smectic-C phase. Orientational order parameters and smectic layer spacing have been calculated numerically as functions of temperature and compared with the results obtained using a model with a standard Maier-Saupe-type distribution function that has been considered before. A molecular theory of the electroclinic effect in chiral smectics has also been developed using the recently proposed simple biaxial interaction potential. A comparison has been made between the absolute values and temperature variations of the electroclinic coefficient obtained using the volcano model, the model with Maier-Saupe-type distribution, and the orthodox cone model proposed by de Vries. It has been shown that the model with a conventional "sugar loaf" type orientational distribution function in the smectic-A phase is sufficient to describe the main properties of smectics with anomalously weak layer contraction.

Synthesis of Rod-Like and Y-Shaped Liquid-Crystalline Compounds with Fluorinated Tail Groups

A series of the rod-like and Y-shaped liquid-crystalline (LC) compounds with per- and semifluorinated tails was synthesized with variation of the tail length. The perfluoroalkyl tails enhanced stability of the mesophase both for rod-shaped and Y-shaped LC compounds. The effect of semifluoroalkyl tails is different. For rod-shaped compounds such substituents strongly suppress LC properties. For Y-shaped compounds, smectic properties are stabilized.

Synthesis and mesomorphic properties of chiral smectic A phase liquid crystals of wide temperature range

The synthesis of a novel chiral liquid crystal (LC) is described. Its structure and thermal phase behaviour have been characterised using 1H nuclear magnetic resonance, mass spectroscopy, elemental analysis, differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The compound exhibited a chiral smectic A (SmA*) phase over a wide temperature range. Its electro-optical properties, including voltage–transmittance relationship, electroclinic effect and switching time have also been assessed, shedding light on the correlation between electro-optical properties and chemical structure. The potential of the SmA* compound for use in electro-optical applications that exploit the electroclinic effect is also discussed.

ChemInform Abstract: Molecular Structure and Smectic Properties: The Substituent Effect on the Smectic A Phase in Biphenyl Ester Systems

The substituent effect on the thermal properties of smectic A phase for two related compounds; 4-octyloxybiphenyl-4-yl 4-Y-benzoates and 4-Y-phenyl 4-octyloxybiphenyl-4′-carboxylate with Y = N(CH3)2, OH, OCH3, CH3, C6H5, SCH3, H, CHO, halogens, COCH3, SO2CH3, CO2CH3, CN and NO2, has been examined. The smectic A–nematic transition temperature (TSA–N) and the ratio of TSA–N to the nematic–isotropic transition temperature are discussed in terms of Hammett's constants for the substituents and change in polarity around the ester group and the substituent. The non-ideal solution behaviour of TSA–N in binary phase diagrams consisting of methoxy and cyano derivatives is also examined.

ChemInform Abstract: Synthesis and Mesomorphic Properties of trans-[1,4-Bis(5-R-pyrimidin-2-yl)]-cyclohexanes and 1,2-Bis(5-R-pyrimidin-2-yl)ethanes.

New trans-bis(5-R-pyrimidin-2-yl)-1,4-cyclohexanes and-1,2-ethanes (R=C7H15, C6H4OR1, where R1=H, COCH3, C4H9, C5H11, C8H17) have been synthesized. Only nematic mesophases are found from a study of their mesomorphic properties, except for bis[5-(4-octyloxyphenyl)- and-(4-acetoxyphenyl)pyrimidin-2-yl)-cyclohexanes, which also exhibit smectic properties.