Smectogenic Character Research Articles

A series of liquid crystalline acrylic polymers obtained by a novel electrically induced polymerization method

The synthesis and phase characterization of a homologous series of polymers possessing high molecular weight of acrylic phenyl benzoates has been carried out using a novel polymerization method. The characterization comprises polarized optical microscopy, differential scanning calorimetry and wide-angle X-ray scattering. All polymers are mesogenic, exhibiting either nematic and/or smectic phase depending on chain length. Polymers phases are enantiotropic unlike the starting monomers which are predominantly monotropic. Shorter monomers yield nematogenic and monolayer smectogenic polymers while longer monomers yield polymers with a tilted bilayer smectogenic character. The transition from monolayer to bilayer was observed when a monomer with a terminal chain length of five carbon atoms was polymerized.

SYNTHESIS AND STUDY OF NEW HOMOLOGOUS SERIES: 4-(4’-N-ALKOXY BENZOYLOXY)-NAPTHYL -1-AZO-(2”-METHYL)- 4”-AZO-2”’-METHYL BENZENE

Novel homologous series 4-(4’-n-alkoxy benzoyloxy)- napthyl-1-azo-(2”-methyl)-4”-azo-2”-methyl benzene consisted of 12 members of a series. All the 12 members (ethoxy to hexadecyloxy) are enantiotropically nematogenic without exhibition of any smectogenic character. Transition temperatures and the textures are determinedby an optical polarizing microscopy furnished with a heatingstage. Textures of a nematic phase are threaded or schlieren. Analytical and spectral data supported the molecular structure ofhomologs. Transition curves viz., solid-nematic and nematic-isotropic showing phase behavior of the mesophase in a phase diagrambehave in normal manner. Reversion of transition temperatures is show by N–I transition curve. Hereby, novel series is entirely nematogenic and high to middle ordered melting type. Thus, synthesis of a novel azo ester homologous series is fulfil with a view to understand and establish the effect of molecular structure on Liquid crystal (LC) behaviors of a substance.

Synthesis of homologous series of liquid crystalline behavior and the study of mesomorphism

The azo homologous series of (E)-2-chloro-3-((4-n-alkoxynaphthalene-1-yl) diazenyl) pyridine consisting of 11 homologs was synthesized. All homologs of synthesized homologous series are mesogenic in behavior. All homologs of the homologous series are enantiotropic nematic. The textures of the nematic phase are of the threaded or schlieren type. Transition curves showing phase behavior in a phase diagram behave in normal manner. An odd–even effect is observed for the nematic–isotropic transition curve. Thermal phase transitions were observed through an optical polarizing microscope equipped with a heating stage. Analytical and spectral data support the molecular structures of the homolog molecules. Smectogenic character is totally absent from all the novel homologs.

Homologous series of LC acrylic monomers based on phenyl benzoate core group: synthesis and characterisation

ABSTRACT The synthesis and phase characterisation of a homologous series of monomers of acrylic phenyl benzoates has been carried out. The characterisation comprises polarised optical microscopy, differential scanning calorimetry and powder x-ray diffractometry. All monomers are mesogenic, exhibiting either nematic and/or smectic phase. Shorter monomers are nematogenic while longer monomers show a more smectogenic character. Most of the monomers show monotropic phases.

Dependence of mesomorphism on terminal polar group in novel azoester series

Novel homologous series 4-(4′-n-alkoxy benzoyloxy) napthyl azo 4″–bromo benzenes, consisted of 11 members of a series. All the 11 members (ethoxy to hexadecyloxy) except hexadecyloxy are only enantiotropically nematogenic without exhibition of any smectogenic character. Transition temperatures and the textures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Analytical and spectral data supported the molecular structure of homologs. Transition curves viz., solid-nematic and nematic-isotropic showing phase behavior of the mesophase in a phase diagram behave in normal manner. Alternation of transition temperatures is exhibited by N–I transition curve. Thus, novel series is entirely nematogenic and high ordered melting type. Thus, synthesis of a novel azoester homologous series is carried out with a view to understand and establish the effect of molecular structure on Liquid crystal (LC) behaviors of a substance.

Study of deviation from normal liquid crystal behavior of mesomorphic-isotropic transition curve in a chalconyl ester series with equipolar terminal end groups

ABSTRACTA novel chalconyl ester homologous series RO.C6H4.COO.C6H4.CO-CH:CH-C6H4.OC8H17(p) synthesized and studied with a view to understanding and establishing the relation between molecular structure and Liquid Crystal (LC) properties of thermotropic mesomorphs. The novel series consists of eleven homologous (C1 to C16). Enantiotropicnematic type of mesophase formation commences from C3 homologue and continued up to the last C16 homologue of a novel series. Smectogenic character is totally absent for the novel series. Transition temperatures and the textures of nematic phase were determined through an optical polarizing microscopy (POM) equipped with a heating stage. Textures of nematic phase are threaded or Schlieren. Transition curve Cr-N/I and N-I behaved in normal manner except C8 homologue which showed negligible deviation from normal behavior. N-I transition curve exhibited odd–even effect. Analytical and structural data supported the molecular structures of homologues. Average thermal stability for nematic is 98.88°C whose degree of mesomorphismvary from 12.0°C to 37.0°C. Evaluated thermometric data of present novel series are compared with structurally similar series. Group efficiency order for nematic on the basis of thermal stability, early commencement of mesophase and the degree of mesomorphism. Thus, present series is predominantly nematogenic and lower middle ordered melting type the low degree of mesomorphism.

Role of molecular structural flexibility on mesomorphism

ABSTRACTA homologous series of novel chalconyl ester derivatives: RO.C6H4.COO.C6H4.CO.CH:CH.C6H4.OC6H13(n) shave been synthesized and studied for its thermotropic liquid crystal (LC) properties with a view to understanding and establishing the relation between molecular structure and LC properties. The homologous series consists of eleven members whose, mesomorphism commences from C3 of the series and continues up to the C16 homologue. The C1 and C2 homologues are nonliquid crystals. All the LC homologues are enantiotropically nematogenic with absence of smectogenic character. Transition temperatures were determined by an optical polarizing microscope (POM) equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren. Analytical and spectral data confirms the molecular structures of homologues. Transition curve Cr-N/I behaved in normal manner. N-I transition curve exhibits an odd even effect; descended at C10 homologue and then again rises at C12 and descended from and beyond C12 homologue. Thus it partly deviates from normal behaviour. Thermal stability for nematic is 95–89°C and nematogenic upper and lower mesophase lengths are 41.0°C and 07.0°C respectively. Group efficiency order for nematic on the basis of thermal stability is –OC8H17(n)> -OC6H13(n) > -OC10H21(n) and it is a low order melting type series.

Dependence of thermotropic mesomorphism on varying rigidity of central bridge in liquid crystals

ABSTRACTA novel liquid crystalline(LC) homologous series of chalconyl esters: RO-C6H4-COO-C6H4-CH = CH-CO-C6H4F has been synthesized and studied with a view to understanding and establishing the relationship between thermotropic LC properties and molecular structure with reference to varying molecular rigidity due to linking groups. The novel homologous series consists of eleven members (C1 to C16). C1 and C2 homologues are nonliquid crystals (NLC) and the rest of the homologues are enantiotropically nematic (C3 to C16). The smectogenic character, either in enantiotropic or monotropic manner is totally absent for a series. Transition temperatures and textures of nematic phase were determined by an optical polarizing microscope (POM) equipped with a heating stage. Textures of the nematic phase are threaded or Schlieren. The analytical, thermal and spectral data support the molecular structures. Cr-N/I and N-I transition curves behaved in normal manner except for the C14 homologue. N-I transition curve exhibits an odd- even effect with a negligible deviating effect from the C10 homologue. Thermal stability for the nematic is 105.2°C and mesophase lengths range from 06.0°C to 46.0°C at C8 and C14 homologues respectively. The group efficiency order derived for nematic from the comparative study of present novel series with structurally similar analogous series on the basis of thermal stability as under.

Dependence of mesomorphism on molecular rigidity of nonlinear and linear isomeric and nonisomeric chalconyl esters

ABSTRACTThe novel thermotropic liquid crystalline (LC) materials have been synthesized and studied through chalconyl ester nonlinear (meta substituted) homologous series RO-C6H4‒CH˭CH‒COO‒C6H4-CO‒CH˭CH‒C6H4-OC14H29(n) with a view to understand the effect of molecular structure on LC behavior with reference to determine the difference between linear and nonlinear shaped molecules. Novel series consisted of thirteen members, whose nematogenic enantiotropic mesomorphism commences from C6 homologue and continued up to C18 homologue with the absence of smectogenic character. C1 to C5 homologues are nonliquid crystals as determined through an optical polarising microscope (POM) equipped with a heating stage. Transition temperatures of LC homologues alternate and are lower than the corresponding n-alkoxy cinnamic acids. Cr-N/I and N-I transition curve behaved in normal manner. N-I transition curve exhibited odd-even effect in a phase diagram. Textures of nematic phase are threaded or Schlieren or determined by miscibility method and from observing mesophase on the top of the POM. Thermal stability for nematic is 92.5 and mesophase length minimum to maximum is 19.0 to 32.0°C at the C10/18and C6 homologue. Group efficiency order on the basis of thermal stability is Thus, novel series is nematogenic and low melting type. Analytical and spectral data confirmed the molecular structures of homologues.

Study of the effect of a heterocyclic ring end group and an azomethane linkage on mesomorphism

ABSTRACTA novel homologous series RO-C6H4-COO-C6H4-N = CH-C5H4N of liquid crystalline Schiff base esters has been synthesized and studied with a view to correlating molecular structure to the liquid crystal properties on the basis of molecular rigidity and flexibility. All 12 members of series are either monotropic (C1, C3, C5) or enantiotropic (C2, C4, C6 to C16) nematic with the absence of smectogenic character throughout the series. Transition temperatures and LC behavior of the series were determined using an optical polarizing microscope equipped with a heating stage. Transition curves (Cr-N or Cr-I and N-I or I-N) behave in the normal established manner as depicted in a phase diagram. An odd–even effect is exhibited by the N-I transition curve up to the C8 homologue.

Molecular structure and mesomorphism: Effect of tail/lateral group

ABSTRACTChalconyl homologous series of novel mesogenic substances of molecular structure RO-C6H4-COO-C6H4-CO-CH:CH-C6H4-OC16H33 (P) has been studied with a view to understanding and establishing the effects of molecular structure on liquid crystal (LC) properties. A novel homologous series consists of 13 (C1 to C18) members. C1 to C5 and C7 members are non-mesogenic and the even numbered C6 to C18 homologues are enantiotropically nematogenic with absence of smectogenic property. Thermotropic properties such as phase transition temperatures and textures (threaded or Schlieren) were determined by an optical polarizing microscopy equipped with a heating stage. Analytical and spectral data confirm the molecular structure. Transition curves (Cr-N and N-I) showing phase behaviors in phase diagrams behave in a normal manner except C16 and C18 homologues, which partially deviate from normal behavior in N-I transition curve. Thermal stability for nematic on average is 113.14°C and the total mesophase length ranges from 10 to 26°C. The usual odd-even effect is absent for the N-I transition curve. The LC properties of the present novel series are compared with structurally similar known series. The present novel series is predominantly nematogenic without exhibition of smectogenic character, and is of a lower middle-ordered melting-type.

Mesomorphism Dependence on Cis-Trans Configuration and Varying Terminal/Lateral Group

A chalconyl trans vinyl ester homologous series of thermotropic liquid crystals RO-C6H4-CH=CH-COO-C6H4-CH=CH-CO-C6H3 (OCH3)2 meta-para is synthesized and studied with a view to understand and establish the relation between molecular structure and mesomorphism or mesomorphic behaviors. Novel homologous series consists of thirteen homologues (C1 to C18). First five (C1 to C5) homologues are nonmesogenic. Rest of the homologues (C6 to C18) homologues is mesogenic. Monotropically smectogenic character appears from C6 to C10 homologue and C12 to C18 homologues are enantiotropically smectogenic. Nematogenic property is totally absent throughout a series. Textures of smectic phase are of the type smectic A or C. Transition curves of a phase diagram behaved in normal manner. Analytical, spectral and thermal data supports the molecular structures of homologues. Odd-even effect is observed for Sm-I/I-Sm transition curve. Thermal stability for smectic is 93.7 °C and the mesomorphic phase lengths from enantiotropic homologues for smectic from minimum to maximum is 6.0 °C to 28.0 °C at the C12 and C18 homologue respectively. Series is smectogenic without exhibition of nematic property. The group efficiency order on the basis of thermal stability is derived; from comparative study of present series and analogous series.

Mesomorphism Dependence on Cis-Trans Configuration and Varying Terminal/Lateral Group

A chalconyl trans vinyl ester homologous series of thermotropic liquid crystals RO-C6H4-CH=CH-COO-C6H4-CH=CH-CO-C6H3(OCH3)2meta-para is synthesized and studied with a view to understand and establish the relation between molecular structure and mesomorphism or mesomorphic behaviors. Novel homologous series consists of thirteen homologues (C1to C18). First five (C1to C5) homologues are nonmesogenic. Rest of the homologues (C6to C18) homologues is mesogenic. Monotropically smectogenic character appears from C6to C10homologue and C12to C18homologues are enantiotropically smectogenic. Nematogenic property is totally absent throughout a series. Textures of smectic phase are of the type smectic A or C. Transition curves of a phase diagram behaved in normal manner. Analytical, spectral and thermal data supports the molecular structures of homologues. Odd-even effect is observed for Sm-I/I-Sm transition curve. Thermal stability for smectic is 93.7 °C and the mesomorphic phase lengths from enantiotropic homologues for smectic from minimum to maximum is 6.0 °C to 28.0 °C at the C12and C18homologue respectively. Series is smectogenic without exhibition of nematic property. The group efficiency order on the basis of thermal stability is derived; from comparative study of present series and analogous series.

Study of a new homologous series of liquid crystals: Isopropyl-p-(p/-n-alkoxy cinnamoyloxy) cinnamates

A new homologous series: isopropyl-p-[p/-n-alkoxy cinnamoyloxy] cinnamates was synthesized and studied with a view to understanding and establishing the relation between liquid crystal property and molecular structure. Twelve homologues were synthesized. Methyl to butyl homologues are not liquid crystals, while pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, and hexadecyl derivatives are enantiotropic liquid crystal in nature with nematogenic character. Smectogenic character is totally absent. A phase diagram is obtained by plotting a graph of transition temperatures versus number of carbon atoms is n-alkyl chain of left n-alkoxy terminal end group. Solid-isotropic or solid-nematic transition curve rises steeply from methyl to propyl derivatives and falls to pentyl homologue through butyl homologue, and follows a zigzag path of rising and falling values as the series is ascended. Nematic–isotropic transition curve shows descending tendency as series is ascended in a normal manner with exhibition of odd-even effect. Smectic mesophase does not appear even in the monotropic condition. Phase transition temperatures are determined by hot stage polarizing microscope. Analytical data support the structure of molecules. Texture of nematic mesophase is of threaded type. Mesomorphic properties are compared with structurally similar homologous series.

Synthesis of novel azoester homologous series of liquid crystalline behavior and the study of mesomorphism dependence on lateral substitution of middle phenyl ring

ABSTRACTThe titled azoester liquid crystalline homologous series consists of eleven homologues. The pentyl to tetradecyl derivatives of the series are nematogenic without exhibition of smectogenic character. Rest of the members of the series are nonliquid crystalline in nature. Textures of the nematic mesophase are schlieren or threaded type. Transition curves in the phase diagram showed normal phase behavior. Transition temperatures and liquid crystal behavior observed under an optical polarizing microscope equipped with a heating stage. An odd even effect is observed for nematic-isotropic transition curve. Analytical and spectral data confirms the structures of the molecules. Present homologous series is predominant nematogenic and partly nonmesogenic. Average thermal stability for nematic is 125.33°C and nematogenic mesophase length varies between 12°C to 48°C at tetradecyl (C14) and octyl (C8) derivatives, respectively.

Dependence of Mesomorphism on Terminal End Group of a Molecule

A novel azoester homologous series of liquid crystals consisting of 12 members is majorly nematogenic without the exhibition of smectic mesomorphism, except for the hexadecyloxy derivative. The methoxy and ethoxy members are monotropically nematic and the rest of the homologs are enantiotropically nematogenic. Transition temperatures and mesophase morphology were determined on an optical polarizing microscope equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type. Infra red, 1H NMR, mass spectral data, and elemental analysis data confirm the molecular structures of the novel homologs. The mesophase length varies from 00 to 72°C and the average thermal stability for the nematic phase is 133.5°C. Liquid crystal properties vary from homolog to homolog in present novel series. The liquid crystal behavior of the presently investigated novel series is compared with structurally similar known series. The transition curves (Cr-N/Cr-I and N-I/I-N) behave in a normal manner. The N-I/I-N transition curve exhibit an odd-even effect. The series is majorly nematogenic without exhibition of smectogenic character. Only the C16 homolog is nonmesogenic.

The Dependence of Mesomorphism on the Terminal Group

A novel azoester homologous series of liquid crystals (LCs) was synthesized and studied with a view to understanding and establishing the effect of molecular structure on LC behavior. The series consists of twelve members. All the members of the series exhibit a nematogenic mesophase. The methoxy and propyloxy derivatives are monotropic and the rest of the homologs are enantiotropic nematogenic. Smectic mesophase formation is completely absent. Transition temperatures and the textures of the nematic phase were observed and determined through an optical polarizing microscope equipped with a heating stage. Transition curves (Cr‒N and N‒I) of a phase diagram behave in a normal manner except for the hexadecyloxy homolog which deviates from normal behavior in the N‒I transition curve. The N‒I transition curve exhibits an odd-even effect. The textures of the nematic phase are threaded or Schlieren in type. The average thermal stability for the nematic phase is 158°C. The nematogenic mesophase length ranges from 27°C to 226°C. The analytical and spectral data confirms the molecular structures of the homologs. The LC properties of the presently investigated novel series are compared with a structurally similar known series. The novel azoester series is entirely nematogenic without exhibition of smectogenic character.

Study of Thermotropic Mesomorphismin Nonlinear and Linear Isomeric and Nonisomeric Series

Chalconyl homologous series: RO-C6H4-COO-C6H4(m)-CO-CH=CH-OC14H29(n) para has been synthesized and studied with a view to establish the relation between the molecular structure and thermotropic Liquid crystalline (LC) properties. Novel nonlinear series consists of thirteen members (C1 to C18) of a series. C6 to C18 members are enantiotropically nematogenic and the rest of the homologues ( C1 to C5 ) are nonliquid crystals (NLC). Smectogenic character is totally absent. Transition temperatures and the textures of the novel homologues were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Transition curves Cr-N/I and N-I behaved in normal manner. N-I transition curve exhibited odd-even effect. Analytical and spectral data confirmed the molecular structures of homologues. Thermal stability is 107.0 and mesomorphic nematogenic degree of mesomorphism vary minimum to maximum are 17.0°C to 35.0°C at the C14 and C8 homologues respectively. Some mesogenic properties of presently investigated homologous series are compared with structurally similar isomeric and nonisomeric homologous series, and their group efficiency order derived. Thus, present novel series is nematogenic with absence of smectogenic character whose nematogenic transition temperatures vary from 74.0°C to 117.0°C.

Molecular Rigidity/Flexibility Dependence of Mesomorphism

A novel chalconyl homologous series of liquid crystalline derivatives; RO - C6H4- CH : CH - COO - C6H4-CO - CH : CH - C6H4 - OC8H17 (n) (para) have been synthesized and studied with a view to correlate the thermotropic liquid crystal (LC) behavioural properties and the molecular structure of a substance. Present novel series consisted of eleven homologue members (C1 to C16) whose, only nematogenic mesomorphism commences from C3 homologue and continued upto C16 homologue in enantiotropic manner with absence of smectogenic character. Transition temperatures and textures of nematic phase were determined using an optical polarizing microscopy equipped with a heating stage (POM). Transition curve Cr-N/I behaved in normal manner. N-I transition curve exhibited odd-even effect and deviated from its normal descending tendency from and beyond C8 homologue and adopted serpantile shape from C8 to C16 homologue in deviating manner. Textures of the nematic phase are threaded or schlieren. Analytical and spectral data supported molecular structures of homologues. Thermal stability for nematic is 112.66 and the degree of mesomorphism vary from 5.00C to 44.00C at the C12 andC4 homologue respectively. It is a middle ordered melting type series, whose relative group efficiency order for nematic derived.

Study of Thermotropic Mesomorphismin Nonlinear and Linear Isomeric and Nonisomeric Series

Chalconyl homologous series: RO-C6H4-COO-C6H4(m)-CO-CH=CH-OC14H29(n) para has been synthesized and studied with a view to establish the relation between the molecular structure and thermotropic Liquid crystalline (LC) properties. Novel nonlinear series consists of thirteen members (C1 to C18) of a series. C6 to C18 members are enantiotropically nematogenic and the rest of the homologues ( C1 to C5 ) are nonliquid crystals (NLC). Smectogenic character is totally absent. Transition temperatures and the textures of the novel homologues were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Transition curves Cr-N/I and N-I behaved in normal manner. N-I transition curve exhibited odd-even effect. Analytical and spectral data confirmed the molecular structures of homologues. Thermal stability is 107.0 and mesomorphic nematogenic degree of mesomorphism vary minimum to maximum are 17.0°C to 35.0°C at the C14 and C8 homologues respectively. Some mesogenic properties of presently investigated homologous series are compared with structurally similar isomeric and nonisomeric homologous series, and their group efficiency order derived. Thus, present novel series is nematogenic with absence of smectogenic character whose nematogenic transition temperatures vary from 74.0°C to 117.0°C.