Smectogenic Mesophase Research Articles

“Synthesis and study of novel biological active chalconyl-ester based bent-core LCs: Effect of tail/lateral group”

A newly designed homologues series: 4-bromo-2-(3-(4-dimethyl amino) phenyl) acryloyl)-6-nitrophenyl-3-(4-n-alkoxy phenyl) acrylate has been synthesized and studied through chalconyl vinyl ester linking group at (ortho) position. Novel series consisted thirteen compounds, in which C1 to C5 homologue are nonliquid crystal, while C6 to C18 exhibits SmC and nematic phase at enantiotropically manner. Thus, present novel series is predominantly nematogenic and partly smectogenic mesophase. Mesophase image of present compounds are schlieren like, broken fan and threaded type textures measured by POM equipped with heating stage. All this compounds were characterized by FT-IR and 1H NMR analysis. The mesomorphism is measured by POM, DSC and molecular packing is confirmed by XRD technique. Chalconyl ester based compounds C4 to C12 shows antibacterial as well as antifungal activity compared with corresponding standard drugs. Analytical and spectral data confirmed the molecular structures of the present V-shaped bent core homologous series.

Mesomorphism dependence of a terminal or lateral alkoxy group

ABSTRACTA novel homologous series of thermotropic mesomorphs has been synthesized and studied with a view to understanding and establishing the effect of molecular structure on mesomorphic properties with reference to rigidity and flexibility of the homologues series: RO-C6H4-CH˭CH-CO-C6H4-OC18H37(n). The novel homologous series comprises 13 novel homologues (C1 to C18), from which 11 homologues are enantiotropically mesogenic (C3 to C18). Smectogenic mesophase commences from C7 homologue, and nematogenic mesophase is exhibited by C3 to C18 homologues in enantiotropic manner. Thus, C7 to C18 homologues are enantiotropically smectogenic plus nematogenic. Textures of smectic phase are of the type A or C, and that of nematic phase are threaded or Schlieren as confirmed through an optical polarizing microscope equipped with a heating stage. Transition curve of a phase diagram behaved in a normal manner except N-I transition curve, which shows minor deviating trend (C12 to C18) from expected normal behavior. An odd-even effect is exhibited by N-I and Sm-N transition curves. Analytical, spectral, and thermal data confirm the molecular structures of novel homologues. Thermal stabilities for smectic and nematic are 52.7°C and 66.6°C, respectively, whose total mesophase lengths range from 12.0°C to 28.0°C. Thus, novel series of chalcones is a low melting series whose mesogenic transition temperatures vary between 38.0 and 86.0°C.

Dependence of liquid crystallinity on molecular rigidity

A novel homologous series of liquid crystals (LC) of chalconyl derivatives is synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal properties. The novel series consists of 12 homologues. Nematogenic LC property commences from C3 and continues up to C14 and the smectogenic mesophase is exhibited from C4 to C16. The C3 homologue is a monotropic nematic and the rest of the homologues are enantiotropically smectic and nematic or only smectic (C16). Transition curves Cr-Sm, Sm-N, Cr-I, and N-I behave in normal manner with exhibition of odd-even effect, showing phase behaviors of the series.

Mesomorphism dependence on lateral substitution and central bridge

ABSTRACTA novel ester homologous series was synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal properties with a common laterally substituted –OCH3 group and changing terminal groups. The novel series consists of twelve members. The C1 to C3 members are not liquid crystals and the rest of the members C4 to C16 are smectogenic without exhibition of nematic character. Textures of smectic phase are focal conic fan shaped of the type A or C. The transition temperatures and textures of smectic mesophases were observed through hot stage polarizing microscopy (POM). The transition curves (Cr-I or Cr-M and Sm-I) behaved in normal manner. Analytical and spectral data support the molecular structures. Average thermal stability for smectic is 77.25°C and smectogenic mesophase ranges from 15°C to 33°C. Liquid crystal properties of the present series are compared with structurally similar homologous series. Thus, the series is smectogenic only with three homologs nonmesogenic.

Study of Liquid Crystal Behavior and Dependence on Additional Central Bridge of Ester Homologous Series

A novel homologous series of esters was synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal (LC) properties. The series consists of 11 members, and all exhibit enantiotropically the smectogenic mesophase. The nematogenic mesophase is totally absent. The textures of smectic phases are of the type A or C. The Sm-I transition curve of the phase diagram behaves in abnormal manner. The average Sm-I thermal stability is 124.53°C with mesomorphic phase length between 6.5°C and 52.3°C and is of a middle-ordered melting type. LC properties of the novel series are compared with a structurally similar other known series. Analytical and spectral data of the homologous match the molecular structure.

Mesomorphic Behavior of Chloro Substituted Azoesters. A Novel Homologous Series, 4-(4′-n-Alkoxy Benzoyloxy) Phenyl Azo-3″,4″-dichlorobenzenes

The titled novel homologous series consists of 12 members. Mesomorphic behavior as a nematic phase commences from the first member of the series to the hexadecyloxy homologue. The smectogenic mesophase commences from the hexyloxy homologue to the hexadecyloxy homologue with nematogenic mesophase formation in an enantiotropic manner. The textures of the nematic phase are Schileren or threaded and those of the smectic phase are focal conic fan shaped. Analytical and spectral data matched with the molecular structure of the homologues. A phase diagram shows the phase behavior, and consists of solid-mesomorphic, nematic–isotropic, smectic-nematic transition curves that behave in a normal manner with the exhibition of an odd–even effect. The thermal stabilities for smectic and nematic are 106.0°C and 156.8°C respectively. Smectogenic and nematogenic mesophase temperature ranges vary from 07°C to 24°C, 26°C to 88°C respectively. Isotropic transition temperatures vary between 110°C and 205°C. Thus, the present novel series is predominantly nematogenic and partly smectogenic whose mesomorphic behavior ranges from 34°C to 88°C. Thus, it is middle ordered melting type series.

Dependence of Liquid Crystalline Behaviors on Molecular Flexibility

A novel homologous series of thermotropic liquid crystal (LC) has been synthesized with a view to understand and establish the effect of molecular structure on liquid crystal behaviors of a series. The present LC series consist of twelve homologues (C1 to C16); whose mesomorphic properties commence from octyloxy (C8) homologue of a series. C8, C10 and C12 members of a series are monotropic smectic and C14, C16 members are enantiotropically smectogenic. C1 to C7 homologues are nonmesomorphic. Nematogenic property is totally absent. Transition and melting temperatures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of smectic mesophases are focal conic three or two dimensional networking of the type A or C. Cr-I/Sm and Sm-I or I-Sm transition curves behaved in normal manner. Analytical and spectral data confirms the molecular structures of homologues. Thermal stability of smectogenic mesophase is 100.6 oC and mesomorphic phase length is very short (12.9 °C to 15.3 oC). LC properties of a present novel series are compared with the structurally similar homologous series. Present series is partly smectogenic and partly non mesomorphic with poor degree of mesomorphism and middle ordered melting type without exhibition of nematogenic behavior.

Dependence of Liquid Crystalline Behaviors on Molecular Flexibility

A novel homologous series of thermotropic liquid crystal (LC) has been synthesized with a view to understand and establish the effect of molecular structure on liquid crystal behaviors of a series. The present LC series consist of twelve homologues (C1 to C16); whose mesomorphic properties commence from octyloxy (C8) homologue of a series. C8, C10 and C12 members of a series are monotropic smectic and C14, C16 members are enantiotropically smectogenic. C1 to C7 homologues are nonmesomorphic. Nematogenic property is totally absent. Transition and melting temperatures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of smectic mesophases are focal conic three or two dimensional networking of the type A or C. Cr-I/Sm and Sm-I or I-Sm transition curves behaved in normal manner. Analytical and spectral data confirms the molecular structures of homologues. Thermal stability of smectogenic mesophase is 100.6 oC and mesomorphic phase length is very short (12.9 °C to 15.3 oC). LC properties of a present novel series are compared with the structurally similar homologous series. Present series is partly smectogenic and partly non mesomorphic with poor degree of mesomorphism and middle ordered melting type without exhibition of nematogenic behavior.

Synthesis and Mesomorphic Phase Behavior of Laterally Substituted Novel Azoesters

A novel homologous series of 4(4′-n-alkoxy benzoyloxy)phenylazo 2′′-chloro-3′′-methyl benzenes was synthesized and studied for mesophase behavior dependence on molecular structure. The nematogenic mesophase is exhibited from the first to the last member and the smectogenic mesophase from the hexyloxy to the tetradecyloxy member of the series. The nematic mesophase is of a threaded or Schlieren type, and the smectic mesophase is of a focal conic fan of the type A or C. Mesomorphic properties of the present novel homologous series are compared with other structurally similar homologous series.

Novel Cinnamate Esters—Synthesis and Mesomorphic Properties in Relation to Molecular Structure

A novel homologous series 4-[4′-n-alkoxy cinnamoyloxy] benzyl cinnamates consisting of 11 homologs was synthesized and studied with a view to understanding and establishing the relation between molecular structure and mesomorphic behavior of a substance. Mesomorphic behavior of the series commences from the third homolog and then continues until the last hexadecyloxy homolog. The first and second members of a series are non-mesomorphic. Nematogenic mesophase formation is observed from the propoxy homolog to the hexadecyloxy homolog, but the smectogenic mesophase formation is observed from the hexyloxy homolog to the tetradecyloxy homolog. All mesomorphic transitions are enantiotropic in nature. Transition temperatures were determined by an optical polarizing microscopy equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type and that of the smectic mesophases are focal conic fan shaped of the smectic A or smectic C type. A phase diagram of the series shows a normal behavior of the transition curves with a minor abnormality of the last three homologs for the nematic-isotropic transition curve. The average thermal stability for smectic and nematic mesophases is 176.0°C and 219.3°C, respectively. Analytical and spectral data agree with the molecular structures of homologs. Mesomorphic phase length varies between 22°C and 76°C. Smectic phase length varies from 6°C to 33°C and nematic phase length varies from 22°C to 54°C. Thus, the novel present series is predominantly nematogenic and partly smectogenic. Mesomorphic properties of the novel series are compared with structurally similar other known homologous series.

Synthesis and Liquid Crystal Properties of a Novel Homologous Series 4-(4′-n-Alkoxy benzoyloxy) Benzyl Benzoates

A novel homologous series consisting of 11 homologues is reported. Liquid crystal properties commence from the hexyloxy homologue and continue up to the tetradecyloxy homologue as enantiotropic nematic mesomorphism only. The rest of the homologues (including hexadecyloxy homologue) are not liquid crystalline. None of the homologues show smectogenic mesophase formation. The texture of the nematic mesophase is of a threaded or Schlieren type. The transition temperatures of the homologues were determined by optical polarizing microscopy equipped with a heating stage. Transition curves of a phase diagram behave in normal manner except for the tetradecyloxy homologue which adopts an unexpected trend of propagation. An odd–even effect is absent for nematic-isotropic transition curve. Analytical and spectral data support the molecular structure of the homologues. The average thermal stability of the series is 78.8°C. Mesomorphic/nematogenic phase length varies from 2.0°C to 13.0°C. The liquid crystal behavior of the present series is compared with structurally similar other known series. Thus, the present series is enantiotropically nematogenic only without exhibition of any smectogenic character with a low melting type, whose mesomorphic phase length is relatively short.

Synthesis and Liquid Crystal Behavior of a Novel Ester Homologous Series

A novel ester homologous series of 4-[4’-n-alkoxy cinnamoyloxy] benzyl benzoates has been synthesized. The series consists of 12 homologues. Liquid crystal properties commence from the sixth member to the last member of the series with the exhibition of an enantiotropic nematic phase without the exhibition of any smectogenic mesophase. The remaining homologues do not exhibit liquid crystal behavior. The texture of the nematic phase is of the threaded or Schlieren type. The solid-nematic or isotropic transition curve adopts a zigzag path and the nematic-isotropic transition curve steeply rises and then falls in the phase diagram and behaves in normal manner. An odd–even effect is absent in the nematic-isotropic transition curve with an alteration of transition temperatures. The average thermal stability for the nematic mesophase is 153.1°C, and the nematogenic temperature ranges vary from 12°C to 50°C. Analytical data confirm the molecular structures of the homologues. The Liquid Crystal properties and transition temperatures were observed through an optical polarizing microscope, equipped with a heating stage. The mesomorphic characteristics of the novel ester series are compared with other, known and structurally similar series. The novel series is predominantly nematogenic with the absence of any smectogenic character, with relatively short mesophase temperature ranges and of the middle ordered melting type.

Study of Liquid Crystalline State and Evaluation of its Properties Through a Novel Homologous Series

A novel homologous series α-4-[4′-n-alkoxy benzoyloxy] benzoyl-β-3″,4″-dimethoxy phenyl ethylenes has been synthesized and studied for liquid crystal (LC) properties to understand and establish the relation between molecular structure and liquid crystalline behavior. Twelve members of series were synthesized. All the members except first member of the series are mesomorphic. The hexyloxy to tetradecyloxy homologoues are smectogenic and nematogenic in character. The ethoxy to pentyloxy and the hexadecyloxy homologues exhibit only nematogenic character with the absence of smectogenic mesophase formation. An odd–even effect is observed for the smectic-nematic and the nematic-isotropic transition curves in the phase diagram. The smectic mesophase showed as either the SmA or SmC. The nematic mesophase shows a threaded or Schlieren type texture. Spectral and analytical data confirms the molecular structures of the homologues. The thermal stabilities for the smectic and the nematic are 115.6°C and 156.6°C. The smectogenic and nematogenic mesophase length vary from 7°C to 28°C and from 7°C to 52°C respectively. The transition temperatures were observed through an optical polarizing microscope equipped with heating stage. Thus, the presently investigated novel homologous series is predominantly nematogenic and partly smectogenic with a middle ordered melting type and a considerable mesophase length. The LC properties of the novel series are compared with structurally similar homologous series.

Synthesis and Mesomorphism of Novel Liquid Crystalline: p-(p′-n-Alkoxy Benzoyloxy) Methyl Cinnamates

A new homologous series p-(p′-n-alkoxy benzoyloxy) methyl cinnamates is synthesized with a view to understand and establish the relation between mesogenic properties and structure of molecules. Ethyl to octyl, decyl, dodecyl, tetradecyl, and hexadecyl homolgues are enantiotropically nematogenic, while the methyl homologue is nonmesogenic. None of the homologues exhibit a smectogenic mesophase. An odd–even effect is observed in the nematic–isotropic transition curve. The average thermal stability is 105.0°C and the nematogenic mesophase ranges from 11.0°C to 54.0°C. Thus, the series is of a middle ordered melting type with moderate nematogenic range. Analytical data confirm the structure of the compounds, and the mesomorphism was identified by optical microscopy. The mesogenic properties are compared with structurally similar compounds.