Mesomorphism dependence on central bridge and tail ended polar group

Abstract

Severe operation conditions in the agriculture industry and numerous influencing factors complicate the selection of a contact material for switching devices. Attempts have been made to change the Ag-CdO contact material to a less toxic one. Environmentally friendly copper-base contact materials have been created for devices, which operate in agricultural electric systems, meanwhile being low-cost and with pre-set level of reliability in terms of transient resistance.     

Mesomorphism dependence on terminal end groups

A novel homologous series of liquid crystals (LC) 4-(4′-n-alkoxy cinnamoyloxy)-4′′-bromobenzylbenzoate was synthesized and studied with a view to understanding and establishing the relation between LC properties and the molecular structure. The novel series comprises 11 members, and all the members exhibit mesomorphism as enantiotropic smectic. None of the homologues are nematogenic, even in the monotropic condition. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. The textures of smectic phase are of the type A or C. The transition curves Sm-I and Cr-Sm behave in a normal manner in the phase diagram. An odd-even effect is exhibited by the Sm-I transition curve. Thermal stability for smectic is 102.6°C. Mesomorphism commences from the very first member of the series. The series is entirely smectogenic and of middle-order melting type whose mesomorphic phase length ranges from 7.4°C to 60.9°. Analytical and spectral data confirmed the molecular structures of homologues. The mesomorphic properties of the present series are compared with structurally similar homologous series.     

Mesomorphism dependence on molecular rigidity

A novel ester homologous series of thermotropic liquid crystal (LC) has been studied with a view to understanding and establishing the relation between LC property and the molecular structure. The series consists of 11 members, the C₁–C₅ and C₁₆ members of the series are nonliquid crystals. LC properties commence from the C₆ homolog and continue up to the C₁₄ homolog as enantiotropic nematic and smectic in addition to nematic. Transition temperatures of the homologs were determined by an optical polarizing microscope equipped with a heating stage. Textures of nematic phase are threaded or Schlieren and that of smectic is focal conic of the type-A. Analytical and spectral data confirm the structures of homologs. Thermal stability for nematic is 93 °C and 136 °C, respectively. The N–I and Sm–N transition curves of phase diagram do not exhibit odd-even effect. The N–I transition curve partly behaves in an abnormal manner. The Cr–I and Sm–N transition curves behave in normal manner. The LC behavior of the present series is compared with structurally similar known homologous series.     

Mesomorphism dependence on lateral substitution and central bridge

A 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.     

Synthesis and study of mesomorphic properties in rod-like chalconyl compounds

In order to investigate the influence of the central linking group and effect on flexibility on mesophase behavior of liquid crystal we have synthesized newly homologous series viz. 3-(4-Octyloxyphenyl)-1-(4′-n-alkoxy phenyl) prop-2-en-1-one (Series-l) consists of thirteen homologues (C₁ to C₈, C₁₀, C₁₂, C₁₄, C₁₆, C₁₈). Textures of a nematic phases are threaded or Schlieren type. The textures of smectic and nematic phase are directly judged from the heating and cooling condition. Group efficiency order for mesophases is derived on the basis of thermal stabilities from the comparative study of thermometric data determined from structurally analogous series. A transition curve as depicted in a phase diagram behaves in normal manner. Structural and conformational characterization of these new compounds had achieved by ¹H NMR, ¹³C NMR, IR, and elemental analysis.     

Mesomorphic properties of liquid crystalline compounds with chalconyl central linkage in two phenyl rings

In order to investigate the influence of the central linking group and the effect of flexibility on mesomorphism, we have synthesised a newly homologous series 3-(3-butoxyphenyl)-1-(4-n-alkoxy phenyl) prop-2-en-1-one (series-l) consisting of 13 homologues C₁–C₈, C₁₀, C₁₂, C₁₄, C₁₆ and C₁₈. In the present series, mesophase commences from the C₆ homologue. C₁–C₅ homologues did not exhibit liquid crystalline (LC) property, while C₆–C₁₂ homologues exhibited an enantiotropic nematic phase and the rest of the homologues C₁₄–C₁₈ displayed monotropic SmC and nematic mesophase. The transition temperatures of the synthesised compounds were determined by an optical polarising microscopy equipped with a heating stage. All newly synthesised compounds were confirmed by ¹H-NMR, ¹³C-NMR, IR and elemental analysis.     

Mesomorphism dependence on central bridge (-COO-CH2-) and terminal end group (-Br)

A novel series of liquid crystalline (LC) ester materials has been synthesized and studied with a view to understanding the effects of molecular structure on LC behavior. The homologous series of eleven members is entirely enantiotropically smectogenic without exhibition of a nematic phase. Transition temperatures and the texture of smectic phase was determined by an optical polarizing microscope equipped with a heating stage (POM). Transition curves (Cr-Sm and Sm-I) showing phase behavior in a phase diagram behave in a normal manner. Textures of smectic phase are focal conic fan shaped of the type Smectic-A or Smectic-C. An odd–even effect is exhibited by the Sm-I transition curve. The average thermal stability for smectic is 91.2°C and the mesogenic phase length ranges between 3.6°C and 39.3°C. Thus, the novel smectogenic homologous series is a middle-ordered melting type whose LC phase is relatively middle ordered. The LC properties of the present series are compared with a structurally similar homologous series. Analytical and spectral data support the molecular structures.     

Mesomorphism dependence on molecular rigidity and substitution of same functional group on lateral or terminal position of tailed phenyl ring

Novel liquid crystal materials (LCs) of low temperature range (53°C to 75°C) have been synthesized through a series of chalconyl derivatives consisting of two phenyl rings bonded through a –CH?CH?CO? central bridge to study the effect of molecular structure on LC properties in general and with a focus on molecular rigidity. The novel homologues series (C₁ to C₁₈) consists of thirteen homologues with general formula RO?C₆H₄?CH?CH?CO?C₆H₄?OC₁₀H₂₁(n) (meta). The C₁, C₂, C₃ homologues are nonliquid crystals (NLC) and the rest of the homologues (C₄ to C₁₈) are either monotropic or enantiotropic liquid crystals. C₄ to C₆ homologues are enantiotropicnematic and the rest of the mesomorphic homologues are (C₇ to C₁₈) monotropicsmectic in addition to monotropicnematic character. Transition and melting temperatures including textures of homologues were determined by an optical polarizing (POM) microscopy equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren, and that of the smectic phase are of the type Smectic A or C as judged directly from the heating top of the microscope. Thermal stability for smectic is very poor and of the nematic is (N-I) 69.3°C whose, total mesophase length ranges between 07.0 to 14.0°C at C₈ and C₄ homologues respectively.     

Mesomorphism dependence on molecular rigidity and flexibility

A novel homologous series of mesogens was synthesized and studied with a view to understanding and establishing the relations between molecular structure and liquid crystal properties. Eleven members of the series were synthesized. Mesogenic behavior commences from the C₆ member and continues up to the C₁₄ member. The rest of the members, C₁ to C₅ and C₁₆, are non-mesogenic. Mesogenic homologues (C₆ to C₁₄) are enantiotropically nematogenic. Textures of nematic phase are threaded or Schlieren. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. Analytical and structural data confirm the molecular structures of homologues. Thermal stability for nematic phase is 198.0°C. Mesomorphic phase length ranges from 11.0°C to 50.0°C. Cr-I/N and N-I transition curves of a phase diagram behave in normal manner from C₁ to C₁₂ members, and higher members C₁₄ and C₁₆ deviated from normal behavior. Mesogenic properties of present novel ester series are compared with the structurally similar series. Odd-even effect is missing for the N-I transition curve. Thus, the present series is partly nematogenic without exhibition of smectic property whose transition temperatures vary between 153°C and 210°C.     

Mesomorphism dependence on molecular rigidity and flexibility

A novel homologous series of liquid crystalline properties is synthesized and studied with a view to understand the effect of molecular structure on its thermotropic properties. Novel homologous series consisted of thirteen homologs. All the homologs are enantiotropically smectogenic with absence of nematic property even in the monotropic condition. Textures of the homologs as observed through an optical hot stage polarizing microscopy. The mesophase temperature range vary minimum from 6.0°C to a maximum 37.0°C at the methyloxy and propyloxy derivatives of a series respectively with its thermal stability (Sm–I) 127.0°C. Transition curves of a phase diagram behaved in normal manner. Odd–even effect is observed for Sm–I transition curve.     

The effect of position of octadecyloxy tail on the formation of liquid crystal with chalconyl-ester and chalconyl-vinyl ester series: Comparison with corresponding linkage group

Understanding of the electronic structures is indispensable for complete elucidation of the charge carrier behaviors in organic semiconductors. Although recent progress enabling accurate photoemission demonstrations of organic single crystals has greatly promoted such understanding, it had been achieved merely on partially oxidized surfaces by exposure to ambient conditions. In this study, we successfully prepared an oxide-free surface of the pentacene single crystal (PnSC) by cleavage in vacuum. X-ray and ultraviolet photoelectron spectroscopy measurements on the PnSC clean surface revealed improved energetic homogeneity of the C1s level and highest-occupied state in comparison to those of the partially oxidized surface.     

Dependence of thermotropic mesomorphism on lateral nitro group

A novel homologous series RO-C₆H₄-COO-C₆H₃-(NO₂)-CO-CH?CH-C₆H₄OC₁₈H₃₇(n) para of chalconyl ester derivatives have been synthesized and studied with view to understanding the effect of an ortho substituted nitro group on thermotropic liquid crystal (LC) behavior. The novel homologous series consists of thirteen homologues (C₁ to C₁₈). The C₁ to C₄ homologues are nonliquid crystal (NLC) and the rest of the homologues (C₅ to C₁₈) homologues are enantiotropically nematogenic without exhibition of a smectic phase even in the monotropic condition. Transition temperatures were determined by an optical polarizing microscope (POM) equipped with a heating stage. Texture of nematic phase are threaded or Schlieren. Analytical, thermal and spectral data supported molecular structure of homologues. Thermal stability for nematic is 147.1°C whose mesophase lengths vary between 16.0 and 32.0°C the C₇ and C₁₈ homologues, respectively, and their mesogenic exhibition range between 96.0 and 166.0°C. Thus, the present novel series is middle ordered melting type, Group efficiency order is derived from comparative study of structurally similar series. The transition curves of a phase diagram behaved in normal manner except C₁₀ and C₁₆ homologues. Odd-even effect is observed for N-I transition curve. Group efficiency order derived is: -OC₁₂H₂₅ (n) > -OC₁₈H₃₇ (n) > -OC₁₈H₃₇ (n).     

Mesomorphism dependence on halogenated chalconyl esters in terms of molecular flexibility/rigidity

Vinyl carboxy central group containing a novel chalconyl ester homologous series: RO.C₆H₄.CH ? CH.COO.C₆H₄.CH ? CH.CO.C₆H₄.I (para) have been synthesized and studied with a view to understand and establish the relation between thermotropic liquid crystalline (LC) behaviors and the molecular structure. Novel chalconyl ester homologous series consists of thirteen homologs (C₁–C₁₈). C₁–C₃ homologs are nonmesogenic, C₄ homolog is enantiotropic nematogenic and the rest of the homologs (C₅–C₁₈) are enantiotropically smectogenic plus nematogenic. Phase transition temperatures and textures of LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Cr-M/I, Sm-N, N-I transition curves in a phase diagram behaved in normal manner. Sm-N and N-I transition curves exhibited odd-even effect from C₄–C₁₀ or nearby C₁₀ homolog. Textures of nematic phase are threaded or Schlieren and that of the smectic phase are of the type smectic A or C. Analytical and spectral data confirms the molecular structure of homologs. Thermal stabilities for smectic and nematic mesophases are 155.0 and 180.7, respectively, and their corresponding mesophaselengths are varied from minimum to maximum at 17.0°C–39.0°C as well as 15.0°C–30.0°C. Thus, it is middle ordered melting type series. The group efficiency orders derived on the basis of smectic and nematic thermal stabilities are as under: Sm: -C₆H₄.I > -C₆H₄.Cl > -C₄H₃S and N:- C₆H₄.I > -C₆H₄.Cl > -C₄H₃S from comparative study of structurally similar analogous series     

Study of mesomorphism and laterally substituted nitro group

A novel thermotropically mesomorphic, meta-substituted nitro group of chalconyl ester series, RO-C₆H₄-COO-C₆H₃-(NO₂)-CO-CH=CH-C₆H₄OC₁₂H₂₅(n) (para) is synthesized and studied with an aim to establish the relation between molecular structure and the mesomorphism with reference to changing molecular flexibility in presence of nitro lateral group. Novel homologous series consist of thirteen homologs (C₁–C₁₈) whose mesomorphism commences from C₅ homolog as enantiotropic nematogenic with absence of smectic property, even in the monotropic condition. Transition temperatures of novel substances were determined by an optical polarizing microscope, equipped with a heating stage (POM). Textures of a nematic phase are threaded or Schlieren. N-I transition curve exhibited narrow, sharp and short odd-even effect; with deviating trend in a phase diagram. Analytical, spectral and thermal data confirmed the molecular structures of homologs. Thermal stability for nematic is 182.89°C, whose mesophase lengths minimum to maximum ranges from 17°C to 45°C and it is an upper middle ordered melting type series. Group efficiency order for nematic is series 1 > series Y > series X, as derived from comparative study of structurally similar analogous series.     

Dependence of mesomorphism on tail group in combination with a lateral methoxy group

A novel homologous series of esters with a lateral methoxy group and terminal n-heptyl cinnamate group was synthesized and studied to investigate mesomorphic behavior in relation to structure. The twelve membered series consists of methoxy to pentyloxy derivatives that are nonmesomorphic and the rest of the homologs as smectegenically mesomorphic, including C₆ and C₇ monotropic smectic and C₈ to C₁₆ enantiotropic smectic without exhibition of any nematic property. The textures of smectogenic mesophases are focal conic fan shaped or batonates of the type smectic-A or Schlieren-C. An odd-even effect is exhibited by the Sm–I transition curve in the phase diagram. The Cr–Sm and Sm-I transition curves behave in a normal manner. Transition temperatures and textures were determined on an optical polarizing microscope, equipped with a heating stage. Some representative members were characterized by IR, H¹NMR, mass spectra, and elemental analysis. Analytical data support the molecular structures of the homologs. Mesomorphic properties of the present novel series are compared with the structurally similar known series. The present series is smectogenic only, whose thermal average stability is 89.8^°C and of a middle-ordered melting type.     

Mesomorphism Dependence on the Position of Substitution of a Pair of Esters

A novel homologous series of ethylene derivatives of thermotropic liquid crystals has been synthesized. The methoxy to octyloxy derivatives are nematogenic, the decyloxy to tetradecyloxy derivatives are smectogenic, in addition to nematogenic, and the hexadecyloxy homologue is smectogenic only. All the members of the series are enantiotropically mesogenic. Thermotropic behavior was determined by an optical polarizing microscope equipped with a heating stage and Differential Scanning Calorimetry (DSC) study. Analytical and spectral data confirm the molecular structures of homologues (infrared, nuclear magnetic resonance, mass spectra, X-ray, and DSC data). Textures of the nematic phase are threaded or Schlieren and that of smectic phase are focal conic fan-shaped of smectic A or C. Transition curves of the phase diagram behave in a normal manner except one or two deviations from the normal trend. The mesophase range (Sm+N) varies from 3°C to 44°C. The average thermal stability for smectic is 93°C and that for nematic 117.4°C. The LC behavior of the novel series is compared with a structurally similar known series.     

Synthesis and characterization of rigid rode shape homologous series: Effect of tail iodo group

Arylpiperazine derivatives referred in this article possessed antitumor activity, which were synthesized and crystallized through the gradual evaporation process. The molecular structures of 2-(4-(2-(4-phenylpiperazin-1-yl)ethyl)benzyl)isoindoline-1,3-dione (C27H27N3O2, 1), 2-(4-(2-(4-(4-bromophenyl)piperazin-1-yl)ethyl)benzyl)isoindoline-1,3-dione (C27H26BrN3O2, 2) and 2-(4-(2-(4-(4-chlorophenyl)piperazin-1-yl)ethyl)benzyl)isoindoline-1,3-dione (C27H26ClN3O2, 3) were determi-ned and described. π-π interactions were observed in the packing modes of three compounds, and compound 2 and 3 showed halogen interactions between molecules nearby, which were different from compound 1. The dihedral angle values, the bond lengths, bond angles and the parameters demonstrated that involvement of halogen atoms did affect the conformation, configuration and cell parameter of the compounds.     

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

A 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.