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1.
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). 相似文献
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Vinay S. Sharma B. B. Jain H. N. Chauhan R. B. Patel 《Molecular Crystals and Liquid Crystals》2016,630(1):79-86
Two ester homologous series of carboxy (-COO-) and ethylene-carboxy (-CH=CH-COO-) mesogens, viz. α-4-[4’-n-alkoxybenzoyloxy] phenyl β-4’’-methoxy benzoyl ethylenes (1) and α-4-[4’-n-alkoxy cinnamoyloxy phenyl β-4’’-methoxy benzoyl ethylenes (2)] are discussed. Series (1) and (2) differ at their central linking group. Mesophase are observed at four and five number members in both homologue series. Enantiotropic nematogenic property is observed in both series (1) and (2), while some smectic property is exhibited in series (2). Thermal stability of nematic-isotropic in series (1) is relatively low as compared to (2), smectogenic property is totally absent in series (2). In phase diagram, solid-nematic, solid-isotropic, and nematic-isotropic curve follow zigzag path rising and falling. Transition temperatures are observed through hot stage polarizing microscope. Analytical data supports the structure of molecules. Threaded, Schlieren-type textures of homologues are observed through microscope. 相似文献
4.
A 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. 相似文献
5.
Sandhya Dixit 《Molecular Crystals and Liquid Crystals》2018,664(1):77-84
A new homologous series of Y-shaped liquid crystals namely 4-Nitro-[2′4′bis (4″-n-alkoxybenzoyloxy)] phenyl bisazobenzenes have been synthesized and its thermotropic properties studied on the hot stage of a polarizing microscope. The compounds consist four phenyl rings joined through ester and bisazo linkages with alkoxy and nitro as terminal substituents. The structures of synthesized compounds were confirmed by spectroscopic techniques such as FTIR, 1HNMR as well as elemental analysis. The compounds were found to exhibit enantiotropic nematic and smectic mesophases. The role of molecular shape, size and polarity of functional groups in the mesophases formation is discussed. 相似文献
6.
U. H. Jadeja 《Molecular Crystals and Liquid Crystals》2016,637(1):10-18
A novel azoester homologous series of liquid crystalline (LC) compounds: RO?C6H4-COO?C10H6-N:N-C6H4?OC4H9(n) without lateral substitution has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on thermotropic LC substances with reference to tailed-end group. The novel homologous series consists of 13 homologs (C1 to C18) whose nematogenic and smectogenic mesomorphism commences enantiotropically from C6 and C12 members of the series, respectively. The C12–C18 homologs are smectogenic and C6–C18 are nematogenic, of which C12–C18 homologs are smectogenic plus nematogenic. The C1–C5 homologs are nonmesogenic. Transition temperatures and the textures of the homologs were determined and identified by an optical polarizing microscope (POM) equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren and that of the smectic phase are of the type A or C. Transition curves Cr-M/I, Sm-N and N-I of a phase diagram behaved in normal manner except N-I transition temperature of C10 homolog which deviated by 9°C–10°C from normal behavior. N-I transition curve exhibited odd-even effect. Analytical, spectral, and thermal data confirms the molecular structures of homologs. Thermal stability for smectic and nematic are 115.5°C and 138.5°C, respectively whose corresponding mesophaselengths are varied from 10.0°C to 16.0°C and 13.0°C to 24.0°C, respectively. Group efficiency order for smectic and nematic are derived from comparative study of structurally similar analogous series; as smectic: ?OC4H9 (n) > ?CH3 > ?H; Nematic: ?H > ?OC4H9 (n) > ?CH3 相似文献
7.
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. 相似文献
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J. J. Travadi M. S. Vadodaria K. D. Ladva A. V. Doshi 《Molecular Crystals and Liquid Crystals》2016,625(1):63-71
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. 相似文献
9.
Priya K. Patel 《Molecular Crystals and Liquid Crystals》2017,643(1):168-177
A meta substituted chalconyl ester homologous series: RO?C6H4?COO?C6H4(meta)?CO?CH?CH?C6H4?OC12H25(n)(para) is synthesized and studied with a view to understanding the effect of molecular substitution at meta position in a molecular structure on thermotropic liquid crystal properties. The novel homologous series consists of thirteen homologues (C1 to C18). All the homologues except the nonliquid crystal homologues C1, C2, C3 are enantiotropic nematic with the absence of smectic properties. The transition and melting temperatures 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) behave in normal manner except homologues between C10 and C14 of N-I curve, which show negligible deviation from normal and a smooth descending tendency. The N-I transition curve exhibits an odd-even effect up to C10 homologue and then the odd-even effect disappears for higher homologues. Analytical and the spectral data support the molecular structures. Thermal stability for nematic is 107.3°C and the mesophase lengths range between 13.0°C and 35.0°C at the C18 and C12 homologues respectively. Group efficiency order for nematic is derived on the basis of thermal stability as ?OC12H25(n) (linear) > ?OC12H25(n) (nonlinear) > ?OC16H33 (nonlinear). 相似文献
10.
G. N. Bhola 《Molecular Crystals and Liquid Crystals》2016,630(1):188-196
A novel series of liquid crystal (LC) materials of Schiff's bases viz. RO-C6H4?CH?CH?COO?C6H4?N?CH?C6H4?Br (ortho) is synthesized and studied with a views to understanding and establishing the effect of molecular structure on liquid crystal properties and to provide novel thermotropic LC material to the scientific and technological community of research interest. The novel series consists of thirteen members (C1 to C8, C10, C12, C14, C16 &; C18). All the members of a series are enantiotropic liquid crystals. Smectic (C10?C18) and nematic (C1?C18) property commence from C10 and C1 homologue respectively. Transition temperatures and the textures of homologues were determined using a polarizing optical microscope (POM) equipped with a heating stage. Transition curves Cr-M, Sm-N and N-I of a phase diagram behaved in normal manner. Odd–even effect is absent for Sm-N transition curve, but it is present for N-I curve. Sm-N transition curve is extrapolated to C8 and C6 nonsmectogenic homologues to determine and predict their latent ability for exhibition of smectic property. Analytical and spectral data confirms the molecular structures of homologues. Thermal stabilities of smectic and nematic are 85.4°C and 130.1°C °C whose upper and lower total mesophase length vary from 58.0°C to 06.0°C at the C10 and C1 = C5 = C6 homologue, respectively. Textures of nematic phase are threaded or Schlieren and smectic phase are of type A or C. LC properties of present novel series are compared with structurally series known series. Thus, present novel series is predominantly nematogenic and partly smectogenic with middle ordered melting type and considerable total mesophase length range. 相似文献
11.
Vinay S. Sharma 《Molecular Crystals and Liquid Crystals》2017,643(1):52-61
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. 相似文献
12.
Vinay S. Sharma Rajesh H. Vekariya Anuj S. Sharma R. B. Patel 《Liquid Crystals Today》2017,26(3):46-54
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. 相似文献
13.
Vinay S. Sharma Anuj S. Sharma R. B. Patel 《Molecular Crystals and Liquid Crystals》2017,652(1):158-171
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. 相似文献
14.
A homologous series RO-C6H4-CH:CH-COO-C6H4-CO-CH:CH-C6H4-OC6H13 (n) of novel liquid crystals (LC) has been synthesized and studied with a view to understanding and establishing the relation between molecular structure of a substance and the LC properties or behavior of thermotropic LC materials. Novel series consist of 11 homologues. C1 and C2 homologue derivatives are non-LCs and the rest of homologues (C3 to C16) are nematogenic without exhibition of smectic property. Transition temperatures were determined by an optical polarizing microscopy equipped with a heating stage. Transition curve Cr-N/I of a phase diagram behaved in normal manner. N/I transition curve partly deviated at C6 and C10 homologues from normal descending behavior, and exhibited very narrow and sharp odd-even effects. Textures of nematic phase are threaded or Schlieren. Thermal, analytical, and spectral data confirmed the molecular structures of novel chalconyl ester derivatives. Thermal stability for nematic is 95.77°C and the upper and lower mesophase lengths vary from 35 to 16°C at C5 and C8 homologues respectively. Group efficiency order derived for nematic on the basis thermal stability is -OC10H21 (n) > -OC8H17(n) > -OC6H13(n). 相似文献
15.
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. 相似文献
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Avani R. Ranchchh Kavita Chavda Roshani Bhanderi Suman Patel U. C. Bhoya 《Molecular Crystals and Liquid Crystals》2018,665(1):33-42
AbstractSevere 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. 相似文献
18.
A novel homologous series entitled 4-(4′-n-alkoxy benzoyloxy) phenyl azo 2″, 6″-dimethyl benzenes consisting of 12 members is reported. Liquid crystal behavior as a nematogenic mesophase commences from the pentyloxy homologue monotropically and then continues enantiotropically until the last hexadecyloxy homologue without exhibition of any smectogenic behavior. An odd-even effect is observed for nematic-isotropic transition curve of the phase diagram. The textures of the nematic mesophase are of the threaded or Schlieren type. Analytical and spectral data support the molecular structure of the homologues. Transition temperatures of the novel homologues were determined by an optical polarizing microscopy. Liquid crystal properties of a novel homologous series are compared with other known homologous series. The average thermal stability for the nematic phase is 77.1°C. 相似文献
19.
A novel homologous series: 4-(4′-n-alkoxy benzoyloxy) phenylazo-2″-bromobenzenes is synthesized and studied with a view to understanding and establishing the effects of molecular structure on mesogenic behavior in a series. The mesogenic property commences from fifth homologue to the last homologue. The transition temperatures of the series are relatively low ranging between 68°C and 143°C. The mesogenic range varies between 6°C and 22°C. The novel azoester series is nematogenic without exhibition of any smectogenic property and an average thermal stability of 89.4°C. The mesogenic behavior of the novel series is compared with structurally similar isomeric/nonisomeric other known series. 相似文献