- Anhydrous proton conduction in liquid crystals containing benzimidazole moieties
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A homologous series of biphenyl benzoate-based compounds with an alkthio chain bearing a benzimidazole moiety at the termini was synthesized by a nucleophilic substitution reaction. The compounds exhibited smectic A and nematic phases over a temperature range of 173-116 °C during the cooling process. A partially interdigitated bilayer order developed in the smectic assemblies and hydrogen-bonding between the benzimidazole moieties extended along the plane parallel to the smectic layer. Electrochemical characterization revealed that the liquid crystal phases favoured anhydrous proton conduction in the benzimidazole compounds and a proton conductivity of 4.4 × 10-5 S cm-1 was achieved at 173 °C. The temperature dependence of the proton conductivities approximately followed the Arrhenius law and the proton conduction in the benzimidazole liquid crystals was assumed to be dominated by the proton hopping mechanism.
- Tan, Shuai,Wei, Bingzhuo,Liang, Ting,Yang, Xiaohui,Wu, Yong
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- Development of tribenzamide functionalized electrochemical sensor for femtomolar level sensing of multiple inorganic water pollutants
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A novel tribenzamides derivative N-{4-[2-(1,3-Benzoxazolyl)]phenyl}-3,5-N,N′-bis(4-hexyloxybenzoyl)benzamide (BOC6), containing three amide groups, was successfully synthesized and characterized through multiple spectroscopy techniques. The ultrasensitive electrochemical platform was developed by fabrication of glassy carbon electrode (GCE) with synthesized multifunctional tribenzamide appended BOC6 for the removal of water pollutants. The performance of the engineered sensor was studied by its electrochemical characterization with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave anodic stripping voltammetry (SWASV). The modifier played a facilitating role between the GCE surface and the target metal ions by bringing analytes closer to transducer surface resulting in appearance of intense electrochemical signals. Under pre-defined optimized conditions of SWASV, the BOC6 modified electrode was able to attain distinct oxidative current signals of thallium, arsenic, and mercuric ions simultaneously in one voltammogram scan. The sharp electrochemical signal and peak potential shift of thallium (Tl), arsenic (As) and mercury (Hg) oxidation at ?0.79 V, ?0.06 V and 0.22 V respectively, versus reference electrode Ag/AgCl evidence the electrocatalytic role of BOC6/GCE as compared to bare GCE at ?0.68 V, ?0.01 V and 0.3 V, respectively. Moreover, it was found to sense femtomolar concentration of aforementioned toxic ions, much lower than the world health organization (WHO) and environmental protection agency (EPA) guidelines for drinking water [1]. The limit of detections (LODs) obtained on for Tl(I), As(III), and Hg(II) detection were 2.19 fM, 1.97 fM, and 2.52 fM, respectively. Conclusively, the designed electrode was portable, cost effective, resistant to the interference species, highly stable and gives repeatable and reproducible voltammograms of analytes via strong interactions with target ions even in real water samples.
- Ashiq, Muhammad Naeem,Kokab, Tayyaba,Manzoor, Alia,Nisar, Jan,Shah, Aamir Hassan,Shah, Afzal,Siddiqi, Humaira Masood
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- Synthesis and characterization of novel rod-like ester-based liquid crystalline homologous series: Effect of tert-butyl tail on mesomorphism
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A new rod-like homologous series consisting twelve compounds with central ester linkage and terminal tert-butyl group, tert-butyl [4-(4’-n-alkoxybenzoyloxy)benzoates] has been synthesized and characterized through standard spectroscopic techniques like UV, FT-IR, 1HNMR, DSC, POM, and XRD. Methoxy and ethoxy derivatives are nonmesogenic. Nematic mesophase commences as enantiotropy from propyloxy derivative and persists up to the octadecyloxy derivatives. Smectic A mesophase commences as monotropy from propyloxy to the octadecyloxy derivatives. The mesomorphic properties of present series are compared with other structurally related series to evaluate the effect of terminal tert-butyl group on mesomorphism. Two derivatives are subjected to in?vitro antimicrobial activity.
- Thakur, Shavi,Patel, Hemant N.
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- Dependence of mesomorphism on terminal polar group in novel azoester series
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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.
- Kher, Seema N.,Prajapati,Makwana,Chandra, Raviprakash S.
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- Study of Y-shaped liquid crystalline materials with polar nitro substituent
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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.
- Dixit, Sandhya
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- Design and characterization of novel bis-benzamide liquid crystalline materials
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A new homologous series of symmetric, bent-shaped bis-benzamide dimers have been prepared. Several 1,n-bis(p-aminophenoxy)alkanes (n = 3, 5, 9,10,11) were employed as spacers and p-hexyloxy tails have been synthesized and appended to the spacers by amide linking groups. Different important parameters were explored using computational analysis by semi empirical method. The experimental results were correlated with theoretical studies and relationship between molecular structure and mesogenic behavior has been established. The mesomorphic properties of the resultant dimers were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) equipped with a hot stage. Change in mesomorphic properties with change of methylene spacers was observed. Enantiotropic mesogenic behavior was exhibited by D3A6, D10A6 and D11A6 and the needle like and blurred schleiren textures were observed. It was observed that increased methylene spacers chain length decreased the melting temperatures. Thermogravimetric analysis revealed the thermal stability of dimers upto 360 °C.
- Iqbal, Asma,Siddiqi, Humaira Masood,Akhter, Zareen,Qaiser Fatmi, Muhammad
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p. 135 - 141
(2017/09/23)
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- Mesomorphism dependence on terminal polar group in the nonlinear novel azoester series
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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. Novel series consists of ten LC substances. All the homologs are enantiotropically nematogenic without exhibition of smectic property. Transition and melting temperatures, textures of LC are determined by an optical polarizing microscopy equipped with a heating stage. Textures of nematic phase are threaded or schlieren. Transition curves of a phase diagram behaved in normal manner. Nematic–isotropic transition curve exhibited odd–even effect. Analytical and spectral data supported and confirmed the structures of homologues.
- Kher, Seema N.,Prajapati,Chandra, Raviprakash S.,Makwana
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- Dependence of mesomorphism on geometrical shapes of isomeric and nonisomeric series of chalconyl esters
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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).
- Patel, Priya K.,Shah
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p. 168 - 177
(2017/03/08)
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- Identification of highly potent N-acylethanolamine acid amidase (NAAA) inhibitors: Optimization of the terminal phenyl moiety of oxazolidone derivatives
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N-acylethanolamine acid amidase (NAAA) is a cysteine hydrolase that participates in the deactivation of fatty acid ethanolamides, such as palmitoylethanolamide (PEA). NAAA inhibition may provide a potential therapeutic strategy for the treatment of diseases in which higher PEA level is desired. In the present study, we reported the structure-activity relationship (SAR) studies for oxazolidone derivatives as NAAA inhibitors. A series of substituents or alkyl replacements for the terminal phenyl ring of oxazolidone derivatives were examined. The results showed that the inhibition potency of these oxazolidone derivatives towards NAAA depends on the sizes, flexibility, and lipophilicity of the terminal groups. SAR results suggested that small lipophilic 3-phenyl substituents or hydroxy-containing 4-phenyl substituents were preferable for optimal potency. Furthermore, the distal aliphatic replacement is also preferred for high inhibitory potency. Rapid dilution and kinetic analysis suggested that oxazolidone derivatives with different terminal phenyl moieties inhibited NAAA via different mechanisms. This study identified several highly potent NAAA inhibitors, including 1a (F215, IC50 = 0.009 μM), 1o (IC50 = 0.061 μM) and 2e (IC50 = 0.092 μM), and also determined structural requirements of oxazolidone derivatives for potent inhibition against NAAA.
- Li, Yuhang,Chen, Qi,Yang, Longhe,Li, Yanting,Zhang, Yang,Qiu, Yan,Ren, Jie,Lu, Canzhong
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supporting information
p. 214 - 221
(2017/08/16)
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- Mesomorphism dependence on central bridge (-COO-CH2-) and terminal end group (-Br)
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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.
- Marathe, Rajesh B.,Doshi
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p. 122 - 131
(2016/02/19)
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- Dependence of liquid crystallinity on molecular rigidity
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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.
- Rakhasia,Bhoya
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- Study of mesomorphism and its relation to molecular structure with special reference to central bridges viz. -COO- and -CH=CH-COO- of the homologous series
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Two ester homologous series of mesogens, viz., Methyl-p-(p′-n-alkoxy benzoyloxy) cinnamates (X) and Methyl-p-(p′-n-alkoxy cinnamoyloxy) cinnamates (Y) being structurally similar are discussed. Both (X) and (Y) differ in respect of central bridges linking two phenyl rings. Only enantiotropic nematogenic character is observed without exhibition of any smectic character by all members of series (X) and (Y). Thermal stability of series (X) is relatively low as compared to (Y), but nematogenic mesophase lengths are of reverse order. Solid-nematic/solid-isotropic and nematic-isotropic transition curves in the phase diagrams behave in normal manner.
- Sharma,Solanki,Patel,Patel
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p. 137 - 145
(2016/03/01)
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- Mesomorphism of azo-esters and chalcone-esters
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AOne chalcone-ester homologous series of mesogens α-4-[4/-n-alkoxybenzoyloxy phenyl β-4//methoxy benzoyl ethylenes (A) and one azo-ester homologous series of mesogens p-(p/-n-alkoxybenzoyloxy) phenyl azo-p//-methoxy benzene (B) being structurally similar are discussed. Both series (A) and (B) differ in respect of central bridges linking two phenyl rings. Mesomorphic properties start from 6th and 1st member of series (A) and (B) respectively. In series (A), 6th to 12th members show both smectogenic and nematogenic properties, and the 14th and 16th members show only nematogenic property. While in series (B), 1st to 10th members show nematogenic properties, 11th member shows both smectogenic and nematogenic properties, while 12th member shows only smectogenic property. Thermal stability of series (A) is relatively high as compared to series (B). Transition temperatures are observed through hot stage polarizing microscope by the miscibility method. Analytical data support the structure of molecules. Textures of series (A) in nematic are threaded and Schlieren in SmecticSmectic A type, while that of series (B) in nematic are threaded in SmecticSmectic A and smectic C.
- Jain,Sharma, Vinay S.,Chauhan,Patel
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p. 102 - 111
(2016/07/14)
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- Mesomorphism dependence on lateral substitution of functional groups and their position in series: 4(4'-n-alkoxy benzoyloxy)-3-chloro phenyl azo-2"-methoxy benzenes
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Eleven homologues of the title series were synthesized. The methyl-to-pentyl derivatives are nonmesomorphic. The nematic mesophase commences from the sixth member of the series without any smectic phase. An odd-even effect in the nematic-isotropic transition curve is not observed. The nematic mesophase appeared as a threaded or a Schlieren-type texture as observed through a hot-stage polarizing microscope. The nematic-isotropic transition temperatures are between 89°C and 127°C with the mesomorphic range varying from 9°C to 44°C at the hexyl and tetradecyl derivative of the series, respectively. The nematic-isotropic transition curve initially rises and then falls in a normal manner as the series is ascended, but it abnormally rises beyond the 10th homologue. The series is enantiotropic nematic with a middle-ordered melting type. Analytical data support the structures of the molecules. The thermal stability and some other mesomorphic characteristics are compared with structurally similar homologous series. The average nematic-isotropic thermal stability is 105.4°C.
- Patel,Prajapati,Doshi
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- Synthesis of novel ester series and study of its mesomorphism dependence on terminal end group with lateral-OCH3 group
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Novel liquid crystal (LC) materials of ester derivatives were synthesized and studied with a view to understanding and establishing the effects of molecular structure on LC properties. The novel molecules consist of two phenyl rings bonded through-COO-central group and a laterally substituted methoxy group with-OCnH2n+1 as well as-COOCH3 terminal end groups, and yielded 12 homologous members of an ester series. The C1 to C3 members are nonmesomorphic, the C4 to C12 members are enantiotropic nematic only, and the C14 to C16 members are enantiotropically smectogenic in addition to nematogenic. Transition temperatures and the textures of LC state were observed through an optical polarizing microscope (POM) equipped with a heating stage. The textures of nematic phase are threaded or Schlieren, and that of smectic phase are focal conic of the type A or C. Transition curves of a phase diagram behave in normal manner with the exhibition of an odd-even effect (only N-I). Analytical and spectral data support the molecular structures of the novel ester derivatives. The LC properties of the present series are compared with structurally similar other known series. The average thermal stability of the series is 93°C for smectic and 120.88°C for nematic and the mesogenic phase length ranges between 2°C and 46°C.
- Vadodaria,Ladva,Doshi,Travadi
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- Synthesis of novel azoester homologous series of liquid crystalline behavior and the study of mesomorphism dependence on lateral substitution of middle phenyl ring
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The 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.
- Patel,Doshi, Ankita A.,Prajapati,Doshi
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- Mesomorphism dependence on lateral substitution and central bridge
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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.
- Vadodaria,Ladva,Doshi,Travadi
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p. 103 - 111
(2016/02/19)
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- Mesomorphism dependence on molecular rigidity
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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 CCand Cmembers of the series are nonliquid crystals. LC properties commence from the Chomolog and continue up to the Chomolog 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.
- Chauhan,Patel,Pandya,Doshi
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- Dependence of mesomorphism on tail group in combination with a lateral methoxy group
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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.
- Travadi,Vadodaria,Ladva,Doshi
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- Mesomorphism dependence on molecular rigidity with reference to -CH=CH- unit of central bridge
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A novel ester homologous series of rich mesomorphism and low temperatures with unexpected phase behaviors of eleven homologues was synthesized and studied with a view to understanding and establishing the relation between mesomorphic behaviour and the molecular structure of a series 4-(4′-n-alkoxybenzoyloxy)-4″-chlorobenzyl cinnamates. All the members of the novel series are enantiotropically smectogenic and the octyloxy (C8) to hexadecyloxy (C16) homologues are enantiotropically nematogenic, in addition to smectogenic. Odd-even effect is observed for Sm-I/Sm-N transition curve but it is absent for N-I transition curve. Textures of nematic phase are threaded or Schlieren and that of the smectic phase are fan shaped or batonates of smectic-A type phase or Smectic-C type for C16 homologues as judged directly from a heating stage of an optical polarizing microscopy. Analytical and spectral data confirmed the molecular structures of novel homologues. Mesomorphic properties of present series are compared with the structurally similar other known series. The average smectic and nematic thermal stabilities are 92.78°C and 100.8°C, respectively. Mesophase length minimum to maximum for smectic and nematic are 21.0°C to 31.1°C and 8.4°C to 42.6°C respectively. Thus, the present novel series is partly nematogenic and fully smectogenic with considerable degree of mesomorphism and low melting type.
- Marathe,Doshi
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- Mesomorphism Dependence on Molecular Structure
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A novel homologous series of liquid crystal (LC) derivatives of general structure: RO·C6H4·COO·C6H3·OCH3(ortho)CH = CH·COO·(n)C5H11 was synthesized and studied with a view to understanding the effect of molecular structure on liquid crystal behavior with reference to lateral-OCH3 and terminal end group. Homologous series consists of 12 derivatives (C1-C16), the first five (C1-C5), and the last (C16) members are not liquid crystals and the rest of the homologs (C6-C14) are enantiotropically smectogenic without exhibition of the nematic phase. The textures of the smectic phases are focal conic fan shaped or batonets of smectic-A or smectic-C. Average thermal stability for smectic is 81.8°C and mesophase length ranges from 9°C to 31°C. Transition curves of a phase diagram (Sm-I and Cr-Sm/I) behave in a normal manner. The Sm-I transition curve exhibits an odd-even effect. Analytical and spectral data support the molecular structures. The series is smectogenic of a middle ordered melting type. LC properties of the present series are compared with structurally similar known homologous series. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage.
- Travadi,Vadodaria,Ladva,Doshi
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- Dependence of Mesomorphism on Molecular Rigidity with Reference to Lateral Substitution and Central Bridge
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A novel mesogenic ester homologous series is synthesized and studied with a view to understanding and establishing the effect of laterally substituted-OCH3 on mesomorphic behavior. The series consists of twelve members. C1 to C4 members are nonmesogenic, C6 to C12 are smectogenic in addition to nematogenic, and C14 to C16 are only smectogenic. The textures of smectic and nematic phases are A or C type and threaded or Schlieren, respectively. The transition curves in a phase diagram exhibit an odd-even effect and behave in normal manner except for the C14 and C16 derivatives in Sm-I transitions. Thermometric data were determined by an optical polarizing microscope equippedwith a heating stage. Average thermal stability for smectic and nematic are 107.7°C and 121.0°C, respectively. Smectogenic and nematogenicmesophase length ranges from 11.0 to 44.0°C and 12.0°C to 39.0°C, respectively. The mesomorphic properties of present series are comparedwith structurally similar other known series. Thus, present series is predominantly smectogenic and partly nematogenic ofmiddle ordered melting type.
- Travadi,Vadodaria,Ladva,Doshi
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- Mesomorphism Dependence of Chalconyl Derivatives on Position of -CH=CH- Unit
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A novel homologous series of heterocyclic chalconyl esters (C1 to C16) has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal (LC) properties and the degree of liquid crystallinity. The C1 to C6 homologues are not liquid crystals, the C7 homologue is enantiotropic nematic, the C8 to C16 homologues are smectogenic in addition to nematogenic (C8 & C10 monotropic smectic). The texture of nematic phases are threaded or Schlieren and that of the smectic phase are fan-shaped smectic-A or smectic-C type. Transition temperatures and the textures of mesophases were determined by an optical polarizing microscope equipped with a heating stage. Transition curves Cr-I/M, Sm-N/N-Sm, and N-I showing phase behaviors of series in a phase diagram behave in normal manner. Thermal stability for smectic and nematic are 115.66°C and 126.83°C and their mesophase lengths minimum to maximum are 6.3 to 12.9°C and 6.9°C to 17.4°C, respectively. Analytical and spectral data confirms the molecular structures of homologues. LC properties of present novel series are compared with structurally similar other reported series.
- Rakhasia,Bhola,Bhoya
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- Study of the Effect of Lateral Substitution on Mesogenic Behavior with Reference to -CH=CH- Unit
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A novel cinnamate ester homologous series has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal (LC) properties with a focus on the highly polar methoxy group as a lateral substituent. The series consists of twelve homologs; of which C1-C5 are nonmesogenic, and the rest of the homologs are enantiotropically smectogenic or and nematogenic. The texture of nematic phases is threaded or Schlieren and that of the smectic is either smectic A or C, as recognized and determined through an optical polarizing microscope equipped with a heating stage. The Sm-N I and N-I transition curves exhibit odd-even effects and behave in normalmanner. The Cr-IMbehaves in normalmanner. Analytical and spectral data confirm the molecular structures of homologs. The average thermal stabilities for smectic and nematic are 125.3 C and 129.8 C, respectively, whose total mesophase length varies from 13 C to 51 C. Some LC properties of present series are compared with the structurally similar known series.
- Travadi,Vadodaria,Ladva,Doshi
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- Mesomorphism dependence on molecular flexibility
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A novel ester homologous series of liquid crystals with a highly polar laterally substituted –OCH3 group is synthesized and studied with a view to understanding and establishing the effects of molecular structure involving lateral substitution on liquid crystal behavior. The novel series RO·C6H4·COO·C6H3·OCH3(ortho)CH=CH·COO·C2H5 consists of 12 homologs of which C7, C8, C10 are nematogenic and C12, C14, C16 homologs are smectogenic. The rest of the homologs are nonliquid crystals. The textures of nematic phase are threaded and the smectic phase is of the type A or C. Transition temperatures and the textures of mesophases were determined by an optical polarizing microscope equipped with a heating stage. Analytical and spectral data support the molecular structures. The N-I and Sm-I transition curves behave in normal manner without exhibition of an odd-even effect. Average thermal stability for smectic and nematic are 127.3°C and 129°C, respectively. The total mesophase length ranges from 17°C to 57°C and series is of a middle ordered melting type with transition temperatures varying between 82°C and 148°C. The liquid crystal properties of present novel series are compared with, structurally similar known homologous series.
- Travadi,Vadodaria,Ladva,Doshi
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- Mesomorphism dependence on tail group
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A chalconyl homologous novel series of thermotropic liquid crystals (LC) have been synthesized and studied with a view to understand and establish the effects of molecular structure on LC properties in thermotropic behaviors. Homologous series RO-C6H4-COO-C6H4-CO-CH=CH-C6H4-OC14H29 consists of 13 homologs (C1–C18), C1–C6 homologs are nonliquid crystals and the rest of the homologs are enantiotropically nematogenic without exhibition of smectic property. Transition temperatures and the textures of the nematic phase were determined by an optical polarizing microscopy, equipped with a heating stage. Texture of a nematic phase are threaded or schlieren. The Spectral and analytical data confirms the molecular structures of homologs. Thermal stability for nematic is 123.0°C and its mesogenicphaselength ranges between 13°C and 34°C. Cr-N/I and N-I transition curves behaved in normal manner except C14 homolog which shows negligible abnormality for N-I transition temperature or curve with exhibition of odd-even effect. Some LC properties are compared with the structurally similar homologous series. Thus, present homologous series is nematogenic and middle ordered melting type.
- Jain,Patel
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p. 121 - 129
(2016/07/14)
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- Dependence of thermotropic mesomorphism on flexible tail group
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A novel homologous series RO-C6H4-COO-C6H4-CO-CH:CH-C6H4-OC12H25 of chalcones have been synthesized and studied with a view to understand and establish the effects of molecular structure on liquid crystal (LC) properties of a substance. Liquid crystal properties of a novel series commences from C6 homologue and continue upto the last C18 homologue derivative of a series, as enantiotropically nematogenic without exhibition of smectogenic characteristic. The rest of the homologues (C1 to C5) are nonliquid crystals (NLC). Transition temperatures of homologues (C1 to C18) are determined by an optical polarizing microscopy equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Transition curves of a phase diagram behaved in normal manner except for C18 member of a series, which drastically behaved with abnormal manner. N-I transition curve exhibits odd–even effect. Average thermal stability for nematic is 110.25°C and mesophase length ranges from 10°C to 39°C. Analytical and spectral data supported the molecular structures of homologues. LC properties of present novel series are compared with structurally similar other known homologous series. Thus, present novel series of chalcones is partly nematogenic and of middle-ordered melting type.
- Patel, Priya K.,Shah
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p. 130 - 138
(2016/07/14)
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- Study of novel thermotropic liquid crystals with lateral nitro substituent
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In this article, we report synthesis and characterization of a novel thermotropic liquid crystals, namely, 4-bromo-[3′-nitro-4′(4″-n-alkoxybenzoyloxy)] phenyl azobenzenes. The first member of a homologous series is nonmesogenic in nature. The n-ethyl to n-decyl homologues exhibit enantiotropic nematic mesophases, while the n-dodecylton -hexadecyl homologues exhibit only smectic mesophases. The synthesized compounds were characterized by a combination of elemental analysis and standard spectroscopic methods. The mesogenic behavior of present series is explained by comparing each homologue of the related mesogenic series. The impact of the lateral nitro group on mesomorphism is also discussed.
- Dixit,Intwala
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- Dependence of thermotropic mesomorphism on molecular flexibility of changing tail group
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A novel chalconyl ester homologous series of liquid crystals has been synthesized and studied with a view to understanding and establishing the effect of molecular structure on liquid crystalline properties. Novel series consisted of 13 members (C1–C18) of a series. C1–C4 member of a series is nonliquid crystals and, the rest of the homolog members (C5–C18) are enantiotropically nematogenic with absence of smectogenic property. None of the homolog is monotropically mesomorphic. Transition and melting temperatures were determined by an optical microscope equipped with a heating stage. Textures of nematic phase are threaded or schlieren. Spectral and analytical data of selected members of a series confirms the molecular structures of homologues. Cr-N and N-I transition curves of a phase diagram behaved in normal manner with exhibition of odd-even effect of very short range as observed for N-I transition curve. Thermal stability for nematic is 122.0°C and the nematogenic mesophase ranges from 7.0°C to 38.0°C. Liquid crystal properties of a present series are compared with the structurally similar known homologous series.
- Solanki, Ravindra,Sharma, Vinay,Patel, Roshan
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p. 107 - 115
(2016/07/21)
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- Synthesis, characterization, and mesomorphic investigations of diester-substituted salicylaldimines and their copper (II) complexes
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A novel homologous series of N-[4-[4′-n-alkoxy)benzoyloxy-2-hydroxybenzylidene)-4-carbethoxy anilines, H2n+1CnOC6H4C(O)OC6H3(OH)C(H)NC6H4COOC2H5 (n = 6, 8, 10, 12, 14, 16) and their copper(II) complexes have been synthesized. All these compounds have been characterized by suitable spectroscopic techniques. The mesomorphic properties of these compounds were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The ligands exhibit wide range of enantiotropic smectic A and nematic phases as confirmed by their typical optical texture under polarizing microscope. The square planar copper(II) complexes of the ligands show only an isotropic phase at higher temperature and no mesogenic nature is observed. DFT calculations have been performed using GAUSSIAN-03 program at B3LYP level to obtain the stable electronic structure of the ligand with decyloxy chain length and its copper(II) complex.
- Singh, Sachin Kumar,Singh, Madan Kumar,Singh, Hemant Kumar,Singh, Bachcha
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- A series of 2, 4, 5-trisubstituted oxazole: Synthesis, characterization and DFT modelling
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A new series of 2,4,5-trisubstituted oxazole were synthesized with good yields using simple methodology. All the compounds were thoroughly characterized by IR, NMR (1H and 13C) and mass spectrometry and structures of 2-(4-butyloxyphenyl)-4,5-dimethyloxazole (5b) and 4,5-dimethyl-2-(4-(octyloxy)phenyl)oxazole(5e) were unambiguously determined by X-ray crystallography. Evidently, the crystal structures of these compounds showed C-HaN and C-HaO intermolecular interactions. The electronic structures of these compounds were also studied by DFT at B3LYP/6-311G ++ level of theory.
- Kadam, Vinay S.,Shaikh, Saminaparwin G.,Patel, Arun L.
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p. 181 - 188
(2016/03/12)
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- Mesomorphism dependence on the combined effect of molecular rigidity and flexibility
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A novel liquid crystalline (LC) homologous series of azoesters with a laterally substituted methoxy group RO-C6H4-COO-C6H3-(-OCH3)-N═N-C6H4-COO-C4H9(n) has been synthesized and studied with a view to understanding the effect of molecular structure on thermotropic mesomorphism. The novel homologous series consists of thirteen homologues (C1–C18). The C1–C5 homologues are nonliquid crystals. The C6 and C7 homologues are only enantiotropically nematogenic and the rest of the mesomorphic homologues (C8–C18) are enantiotropically smectogenic and nematogenic. Transition temperatures and the textures of the mesophases were determined using an optical polarizing microscope (POM) equipped with a heating stage. The novel azoester homologues were characterised and confirmed using their analytical, spectral and thermometric data. Transition curves Cr-M/I, Sm-N and N-I behaved in normal manner without (Sm-N) and with (N-I) exhibition of odd-even effect respectively in a phase diagram. Thermal stabilities for smectic and nematic are 100.0°C and 127.7°C whose, mesomorphic phase length vary from 13.0°C to 24.0°C and 11.0°C to 33.0°C, respectively. The mesomorpism is compared with other known series.
- Jadeja,Patel
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- Mesomorphism in relation to molecular structure with reference to a laterally substituted homologous series
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A novel homologous series 4-(4′-n-alkoxy benzoyloxy) 3-methyl phenyl azo-2″, 6″-dimethyl benzenes consists of 12 homologues. The methyl to hexyl derivatives are non-mesomorphic and the rest of the homologues are mesomorphic. Mesomorphism commences from heptyl homologue in a monotropic manner and continues as an enantiotropic nematic for octyl to dodecyl derivatives, and then monotropic mesomorphism as a nematic mesophase reappears for tetradecyl and hexadecyl derivatives without the exhibition of smectogenic character. The textures of the nematic mesophase are threaded, or are schlieren in type. The nematic-isotropic (or vice versa) transition curve of the phase diagram behaves in a normal manner without the exhibition of an odd-even effect. The average thermal stability for nematic to isotropic transition is 126.5°C. Analytical and spectral data confirm the structure of molecules. The mesomorphic to isotropic transition temperatures vary between 56°C and 130°C. The nematogenic mesophase appeared at the lowest temperature of 41.3°C. Transition and melting temperatures are determined using an optical polarizing microscopy equipped with a heating stage. The present novel series is of a low ordered melting type and predominantly nematogenic, without the exhibition of smectogenic character.
- Khunt,Kotadiya,Bhoya
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- The relation between mesomorphism and molecular structure of a novel azoester series involving laterally substituted chloro groups
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A novel azoester homologous series 4-(4'-n-alkoxy benzoyloxy) phenyl azo 2',6'-dichloro benzene is synthesized and studied with a view to understand and establish the effects of molecular structure on liquid crystal behavior of a substance with reference to steric hindrance. The novel homologous series consists of twelve homologues. Mesomorphism commences from the heptyloxy homologue and continues up to the hexadecyloxy homologue as a monotropic nematic without the exhibition of any smectogenic characteristics. Transition temperatures were determined by an optical polarizing microscopy equipped with a heating stage. Transition curves of the phase diagram behave in a normal manner. The isotropic-nematic transition curve shows an odd-even effect in the very short range of temperature. The texture of nematic mesophase is threaded. Analytical and spectral data support the molecular structures of the homologues. Thermal stability is very low and the degree of mesomorphism is poor. Thus novel series is of low melting type and nematogenic only in a monotropic manner. Mesomorphic properties of the present, novel series are compared with structurally similar other known series.
- Maheta,Bhola,Namera,Bhoya
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p. 104 - 113
(2015/03/18)
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- The mesomorphic properties of chalcone dimer derivatives
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A homologous series of symmetrical dimers viz bis (4-n-alkoxy benzoyloxy) -phenyl β-benzoyl-ethylenes was synthesized and studied with a view to understanding the relation between molecular structure and the mesomorphic behavior. Twelve members of the dimeric series were synthesized, and the methoxy to butyloxy homologues are not liquid crystals, but the pentyloxy to hexadecyloxy are liquid crystals. The pentyl to heptyl dimers are only nematogenic, but the higher homologues show smectogenic mesomorphism prior to nematogenic mesophase formation. The phase diagram of phase transition curves behaves in a normal manner except for the smectic to nematic transition curve which behaves in an unexpected manner. The smectic and nematic thermal stabilities are 103°C and 131.7°C, respectively. The smectogenic and nematogenic phase lengths vary between 17.4°C to 28.3°C and 2.1°C to 29.9°C, respectively. The liquid crystal properties of presently investigated novel chalcone dimers are compared with known monomeric chalcones.
- Kotadiya,Bhoya
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p. 116 - 124
(2015/03/18)
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- Mesomorphism dependence on molecular flexibility in an azoester series
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A novel azoester homologous series with a flouro terminal end group was synthesized and evaluated for mesomorphic properties. The novel homologous series consists of 12 members. The first two-third members of the series are nonmesogenic. The butyloxy to decyloxy homologues are enantiotropic nematogenic and the rest of the mesogenic homologoues are enantiotropic smectogenic only. Transition temperatures and textures of the mesophases were observed through an optical polarizing microscope equipped with a heating stage. The textures of the nematic phase are threaded or Schlieren as judged by a miscibility method and those of the smectic phase are of the type A or C. A phase diagram is used to illustrate the mesomorphic behavior across the series. Analytical and spectral data confirm the molecular structures of the homologues. Thermal stabilities of smectic and nematic mesophases are 114.3°C and 137.0°C respectively. The mesogenic phase lengths for smectic and nematic are vary from 8°C to 26°C and 26°C to 43°C respectively.
- Bhola,Nakum, Kiran,Karia, Kaushal,Bhoya
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p. 125 - 134
(2015/03/18)
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- Effect of a central group on mesomorphism
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A novel homologous series: 4-(4'-n-alkoxy benzoyloxy)-4'-methoxy benzyl benzoates is studied with a view to understanding the effect of a central group on the phenomenon of mesomorphism. The novel homologous series consists of eleven compounds. Mesomorphism commences from the second member of a series. All the mesogenic homologues from ethoxy to hexadecyloxy exhibit nematogenic mesomorphism without the exhibition of smectogenic character. The nematic-isotropic transition curve of the phase diagram behaves in normal manner up to the dodecyloxy homologue and then deviated for the tetradecyloxy and hexadecyloxy homologues. The solid-isotropic or nematic transition curve adopts a normal behavior in a zigzag manner. The nematic-isotropic transition curve shows an odd-even effect and continues up to the octyloxy homologue. Transition and melting temperatures including the textures of mesophases are determined by an optical polarizing microscope, equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type. Analytical data and spectral data support the molecular structures. The mesomorphic behavior of the present series is compared with structurally similar other known series of differing central group (viz. NN and COCHCH) keeping rest of a molecular part unchanged. The nematic thermal stability of the series is 236.8°C of a high melting type present series whose nematogenic mesophase length varies between 27°C and 98°C. Thus, series is only nematogenic without exhibition of a smectic mesophase.
- Patel, Brijesh H.,Vyas,Doshi
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p. 114 - 122
(2015/03/30)
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- A comparative study of mesomorphism in symmetric and nonsymmetric dimers
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A homologous series consisting of 12 homologue symmetrical dimers, viz., bis(4-n-alkoxy benzoyloxy) 2,2-diphenyl propanes was synthesized, studied, and evaluated to establish the relation between molecular structure and mesomorphic properties on comparative basis with nonsymmectric dimers. The methoxy to pentyloxy homologue dimers, the novel symmetric series, are nonmesogenic. Mesomorphism commences from the hexyloxy homologue as smectic and nematic. The hexyloxy to decyloxy dimers possess smectogenic character with nematogenic character and the dodecyloxy to hexadecyloxy homologue dimers exhibit nematogenic character without the exhibition of smectogenic character. All the mesogenic homologues are enantiotropic mesomorphs. The smectic and nematic thermal stability of series is 129.0°C and 147.7°C, respectively, and mesomorphic phase length varies between 18°C for the hexadecyloxy homologue and 56°C for the heptyloxy homologue.
- Kotadiya,Khunt,Bhoya
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p. 135 - 143
(2015/03/30)
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- Mesomorphism Dependence on Molecular Flexibility by -OCH3 and -H Terminal Units
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A novel ester homologous series: 4-(4′-n-Alkoxy benzoyloxy)-4″-methoxy benzyl cinnamates have been synthesized and studied with a view to understanding and establishing the dependence of liquid crystal behavior on molecular structure. The novel series of eleven homologues is entirely nematogenic without exhibition of any smectogenic character from the very first member of the series. Transition and melting temperatures were determined by an optical polarizing microscopy equipped with a heating stage. Transition curves of a phase diagram show the mesomorphism, which behaves in normal manner. An odd-even effect is exhibited by the nematic-isotropic transition curve. The textures of the nematic mesophase are threaded or schlieren in type. Analytical and spectral data confirm the molecular structures of the novel homologues. Thermal stability for the nematic phase is 211.5°C and the degree of mesomorphism varies from 17°C to 72°C and it is a high melting type series. Mesomorphic properties of the series are compared with structurally similar series.
- Patel, Brijesh H.,Patel,Doshi
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- Study of Novel Symmetrical Liquid Crystalline Ester Dimers
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A novel homologous series of 12 symmetrical dimers, viz. 1,1'-Bis[4-(4'-n-alkoxy benzoyloxy)-3-methyl phenyl] cyclohexanes is reported. Nematogenic mesophase commences from the heptyloxy homologue dimer and continues up to the hexadecyloxy dimer in an enantiotropic manner without the exhibition of any smectogenic behavior. The rest of the dimers from methoxy to hexyloxy are nonmesogenic. The textures of the nematic phase are threaded or Schlieren. The transition temperatures and textures of the nematic phase were determined by an optical polarizing microscope equipped with a heating stage. Curves (solid-isotropic/nematic and N-I) of a phase diagram showing mesomorphism behave in normal manner except for a minor deviation at the dodecyloxy derivative. The analytical and spectral data confirm the molecular structure of dimers. The nematogenic mesophase lengths vary between 3.3°C and 26.6°C. The average thermal stability for nematic is 108.26°C; series is partly nematogenic with middle ordered melting type and low degree of mesomorphism. Liquid crystal properties of novel dimer series are compared with the structurally similar other known series.
- Kotadiya,Bhoya
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- Study of Liquid Crystal Behavior and Dependence on Additional Central Bridge of Ester Homologous Series
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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.
- Marathe, Rajesh B.,Doshi
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- Synthesis and Characterization of a Novel Azoester Homologous Series
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An azoester homologous series of 4-(4'-n-alkoxybenzoyloxy) 3-methylphenyl azo-2''-chloro-3''-methyl benzenes consisting of 12 homologues was synthesized. The methoxy to pentyloxy homologues are nonmesogenic, the hexyloxy to dodecyloxy homologues are monotropic nematic and the tetradecyloxy to hexadecyloxy homologues are enantiotropic nematic. The textures of the nemetic phase are of the threaded or schlieren type. Transition curves showing phase behavior in a phase diagram behave in normal manner, with the exception of the last enantiotropic homologue. 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 homologue molecules. Smectogenic character is totally absent from all the novel homologues. The average thermal stability for the nematic phase is 121.5 °C. Mesogenic properties of the present novel series are compared with other structurally similar known series.
- Kotadiya,Khunt,Bhoya
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- Synthesis and Mesomorphic Properties of a Novel Ester Homologous Series: 4-(4'- n -Alkoxy Benzoyloxy) Benzyl Cinnamates
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A novel homologous series 4-(4'-n-alkoxy benzoyloxy) benzyl cinnamates was synthesized and studied with a view to understanding and establishing the relationships between mesomorphism and molecular structure. The novel series consists of eleven members with the commencement of mesomorphism from the pentyloxy homologue onwards to the hexadecyl homologue. The remaining homologues are nonmesomorphic. All the mesomorphic homologues exhibit smectogenic mesomorphism in addition to nematogenic mesomorphism for a definite temperature range in an enantiotropic manner, except for the pentyloxy homologue, which exhibits only a nematogenic mesophase in an enantiotropic manner without the formation of a smectic phase. The texture of the nematic mesophase is of the threaded or Schlieren type and the smectic mesophase is of the type A or C texture, as determined by a miscibility method. Transition temperatures were observed through an optical polarizing microscope equipped with a heating stage. The transition curves of a phase diagram predominantly behave in a normal manner, but partly deviated from normal behavior with the exhibition of an odd-even effect. Analytical and spectral data confirms the molecular structures of all homologues. The mesomorphic behavior of the present series is compared with other structurally similar known series. The mesomorphic temperatures vary between 106°C and 180°C. The mesophase length varies between 33°C to 53°C. Thus, the novel series is predominantly nematogenic and partly smectogenic with relatively high transition temperatures and is of a high melting type. The average thermal stabilities for smectic and nematic phases are 144.1°C and 171.4°C, respectively.
- Patel, H. Brijesh,Doshi
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- Synthesis and Study of Novel Mesogenic Homologous Series: 4-(4′- n -alkoxy benzoyloxy)- n -propyl Cinnamates
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A novel homologous series of liquid crystals viz. 4-(4′-n-alkoxy benzoyloxy) n-propyl cinnamates comprising of 11 homologues has been synthesized. It is a middle ordered melting type of series with exhibition of smectic and nematic mesophases. The first to fifth members of the series are non-mesomorphic. Mesomorphic behavior commences from the sixth homologue. The octyloxy (C8) and decyloxy (C10) homologues are polymesomorphic. The smectic-nematic and nematic-isotropic transition curves behave in a normal manner except for the hexadecyl derivative, which slightly deviates from normal behavior (N-I). An odd-even effect was not observed for the N-I or Sm-N transition curves. The texture of nematic phase is threaded or Schlieren and that of the smectic phase is focal conic fan shaped of the smectic-A type. Transition temperatures and textures of mesophases were observed through an optical polarizing microscope equipped with a heating stage. Thermal stability and mesomorphic characteristics are compared with a structurally related series. Analytical and spectral data support the structure of the molecules.
- Chauhan,Doshi,Sheth
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p. 157 - 165
(2015/12/30)
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- Mesomorphism dependence on positional substitution of same polar group on same phenyl ring in isomeric homologous series
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Novel homologous series 4-(4′-n-alkoxy benzoyloxy) napthyl azo 2″ - nitro benzenes, consisted of eleven members of a series. All the eleven members (methoxy to tetradecyloxy) homologs 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. Odd-even effect and alternation of transition temperatures are exhibited by N-I transition curve. N-I thermal stability is 129.7°C and Nematic mesophase vary from 12 to 64°C. Thus, novel series is entirely nematogenic and middle ordered melting type. Mesomorphic behavior of a novel series are compared with the structurally similar homologous series.
- Prajapati,Doshi
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- Mesomorphism Dependence on Terminal/Lateral Substitution of Nonlinear Azoester Molecules
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A novel azo ester homologous series of liquid crystals (LCs) 2(4′-n-alkoxy benzoyloxy) napthyl 1 azo-3″ nitrobenzenes consists of eleven members of a series with enantiotropic nematogenic mesophase formation and without exhibition of smectogenic property by all the eleven homologs. The nematogenic mesophase textures are threaded or Schlieren. Solid-nematic and nematic-isotropic transition curves of the phase diagram behave in normal manner except for the decyloxy, dodecyloxy, and tetradecyloxy homologs. Analytical and spectral data confirm the molecular structures of homologues. Thermal stability for the nematic phase is 132.6°C, and the degree of mesomorphism varies between 34°C and 79°C and the series if of a middle-ordered melting type. An odd-even effect is observed for the N-I transition curve with alternation of transition temperatures. The LC behavior of the series is compared with other structurally similar known homologous series to establish the relation between mesomorphism and molecular structure.
- Prajapati,Doshi
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- Mesomorphism Dependence on Terminal and Lateral Polar Groups in the Nonlinear Novel Azoester Series
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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.
- Prajapati,Doshi
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- Synthesis and Study of Molecular Structure and Its Relation to Liquid Crystal Behavior in a Novel Azoester Series
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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.
- Makwana,Doshi
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- Dependence of Liquid-Crystal Behavior of a Substance on Molecular Structure
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A novel azoester homologous series of liquid crystals (LCs) consisting of 12 members has been synthesized and evaluated. All members of the series exhibit the nematic mesophase enantiotropically without the exhibition of a smectic mesophase. The textures of the nematic phase are threaded or Schlieren in type. The transition curves in the phase diagram behave in a normal manner. The N-I transition curves exhibit an odd-even effect. The analytical and spectral data support the molecular structures of the homologs. The transition temperatures and mesophase morphology were determined by an optical polarizing microscope equipped with a heating stage. The azoester compounds consist of three phenyl rings with a meta substituted -Cl group at the middle phenyl ring and -OR and -OCH3 as terminal end groups. The average nematic thermal stability is 195°C and the nematogenic mesophase length ranges from 9°C to 186°C. The LC behaviors of the series are compared with a structurally similar series. The novel series is entirely nematogenic and of a high melting point type.
- Makwana,Doshi
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- Study of Mesomorphism Through a Novel Homologous Series and Its Relation to Molecular Structure
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A novel homologous series 4-(4'-n-alkoxy benzoyloxy)-3-chloro phenyl azo,3',4'-dichlorobenzenes was synthesized with a view to understand and establish the relation between mesomorphism and the molecular structure. The novel series consists of 12 members, which showed commencement of monotropic nematic mesophase formation from the butoxy homologue and continued up to the hexadecyloxy homologue without exhibition of a smectic mesophase. The textures of the nematic mesophase are threaded or Schlieren in type. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. Isotropic-nematic transition curve of the phase diagram behaved in normal manner with exhibition of odd-even effect. Solid-isotropic transition curve behaved descending tendency by adopting zigzag path up to the pentyloxy homologue; which include methoxy to propoxy homologues as nonmesomorphic derivatives. Thermal stability for the nematic is just a few degrees (1°C to 2°C). Analytical and spectral data support the molecular structures. The mesomorphic properties of present novel series are compared with structurally similar other known homologous series.
- Doshi,Chauhan
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