- “Effect of the linking unit on the calamitic-shaped liquid crystal: a comparative study of two homologous series of benzoate and cinnamate linked compounds”
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Two homologous series based on three linking groups have been synthesized and well characterized by elemental analyses and spectroscopic techniques such as Fourier transform infrared [FT-IR] and proton magnetic resonance magnetic resonance [1H NMR] spectroscopy. The mesomorphic properties of these compounds were observed by using optical polarized microscopy (POM) and confirmed by differential scanning calorimetry (DSC) analysis. In this present investigation, we have synthesized two homologous series viz. (E)-4-(3-(4-(tetra decanoyloxy) phenyl) acryloyl) phenyl-4-n-alkoxy benzoate (Series-1) and 4-((E)-3-(4-(((E)-3-(4-n-alkoxy phenyl) acryloyl) oxy) phenyl)-3-oxo prop-1-en-1-yl) phenyl tetradecanoate (Series-2). Both of the series are differing with respect to the first linking group. All the homologous in following series displays LC properties on heating as well as cooling condition except first four homologous (C1 to C4) in series-1 and six homologous (C1 to C6) in series-2. To get more insights, the HOMO, LUMO studies are carried out which supports intramolecular charge transfer interactions in this class of mesogens.
- Kashyap, Dinesh,Patel, Sunil,Prajapat, Varsha,Sharma, Vinay,Vasava, Dilip
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- Mesomorphism dependence on central bridge and tail ended polar group
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A novel azoester homologous series of laterally and terminally substituted viz, RO–C6H4–CH=CH–COO–C6H3–(CH3) –N=N–C6H4–Cl is synthesized, characterized and studied with a view to understand and establish the relation between molecular structure and thermotropic liquid crystalline property of its homologs. Series consists of twelve homologs. LC properties commence from very first member of a series and continue up to last homolog as enantiotropic nematic with absence of smectic property even in the monotropic condition. Transition temperatures of homologs were determined by polarizing optical microscopy equipped with a heating stage. The transition curves Cr?N and N?I behaved in normal manner. Thermal stability for nematic is 196.7?C whose mesophaselength ranges from 35°C to 131°C.
- Ranchchh, Avani R.,Chavda, Kavita,Bhanderi, Roshani,Patel, Suman,Bhoya
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- Mesomorphism dependence on molecular rigidity and flexibility
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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.
- Ranchchh, Avani R.,Bhoya
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- “Dependence of Mesomorphism in Combination with Fluoro and Chloro Groups”
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A novel azoester homologous series with chloro lateral group and a fluoro terminal end group was synthesized and characterized for mesomorphic properties. It consists of thirteen azo ester derivatives from trans-4-n-alkoxy cinnamic acid with 4-hydroxy-3-chloro phenyl azo-3-chloro-4-fluoro benzene. Mesomorphic property commences from C4homologue as smectic.C1 to C3 member of the series are non-mesomorphic. C4 to C18 homologous are enantiotropic smectic A phase. The nematic mesophase is totally absent. Texture and transition temperatures of the homologues are determined by an optical polarizing microscopy equipped with heating stage. 1H NMR, IR spectra, mass spectra, of some member is included. The spectroscopic analysis supports the molecular structure. A phase diagram is used to illustrate the mesomorphic behaviour across the series. Mesophaselength for smectic is varying from18.0°C to 69.00C. Mesomorphic properties of the novel azoester series are compared with structurally similar series.
- Ranchchh, Avani R.,Tharesha, Bhavna R.,Bhoya
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- Molecular flexibility dependence on mesogenic behaviors of isomeric and nonisomeric series
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A novel homologous series containing vinyl ester and azomethane central bridges and n-alkoxy as well as 3″,4″-dimethyl groups as flexible terminal/lateral groups viz. RO?C6H4?CH = CH?COO?C6H4?N?CH?C6H3-(CH3)2 have been synthesized and studied with a view to establishing the relation between molecular structure and thermotropic liquid crystal (LC) properties with reference to molecular flexibility within the series. The series consists of twelve homologues (C1 to C16). C6 and C7 homologues are smectogenic plus nematogenic and C8 to C16 homologues are only smectogenic, and the rest of the homologues (C1 to C5) are nonmesomorphic. Transition temperatures and the textures of the homologues were determined using an optical polarizing microscope equipped with a heating stage (POM). The textures of a nematic phase are threaded or Schlieren and that of a smectic phase are of the A or C type. Analytical, thermal and spectral data support the molecular structures. Smectic and nematic thermal stabilities are 116.85°C and 147.5°C, respectively. Whose Sm?N/I and N-I mesophase lengths are varied between 15°C to 21°C and 25°C to 62°C, respectively. The novel compounds are compared with structurally-similar series.
- Rakhasia,Ranchchh, Avani R.,Bhoya
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p. 159 - 167
(2017/03/08)
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- Synthesis, characterization, and mesomorphic investigation of vinyl ester-substituted chalcones and effect of lateral ?NO2 and ?OCH3 group
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A novel homologous series of α-4-(4′-n-alkoxy cinnamoyloxy) phenyl β-2″-nitro, 3″–4″ di methoxy benzoyl ethylenes, H2n + 1CnO?C6H4?CH?CH?COO?C6H4?CO?CH?CH?C6H2(NO2) (OCH3)2 (n = 1–8, 10, 12, 14, 16, 18) has been synthesized. All these compounds have been characterized by suitable spectroscopic techniques. C1 homologue is nonmesogenic, while C2 homologue shows enantiotropic nematogenic property and the rest of the homologous (C3?C18) displayed enantiotropically smectogenic plus nematogenic phase. Phase transition temperatures and textures of the LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. The mesomorphic properties of these compounds were confirmed by differential scanning calorimetry (DSC) analysis.
- Sharma, Vinay S.,Patel
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p. 241 - 251
(2017/03/08)
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- Mesomorphic study of novel chalconyl-ester-based nonisomeric series: Synthesis and characterization
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A newly designed homologues series: 3-(3-(4-(Dimethylamino) phenyl) acrylonyl) phenyl 3-(4-n-alkoxyphenyl) acrylate has been synthesized and studied through chalconyl ester linking group at (meta) position. The series consists of 13 compounds, in which C1 to C4 homologue are nonliquid crystal, while C5 to C18 exhibit nematic phase, and C12 to C18 shows smectic and nematic phase with enantiotropically manner. Mesophase image of present compounds are rod like, needle and threaded type textures investigated by POM. All this compounds were characterized by elemental analysis, FT-IR and 1H NMR. The mesomorphism is measured by POM, DSC, and molecular packing is determined by XRD technique. The following synthesized chalconyl ester-based compounds C5 to C12 shows antibacterial as well as antifungal activity compared with corresponding standard drugs. Analytical and spectral data confirmed the molecular structures of homologous series.
- Sharma, Vinay S.,Patel
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- Study the effects of terminal side chain and –nitro group on mesomorphic behaviour of cinnamate-chalconyl based liquid crystal
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The influence of the terminal side chain and lateral nitro on mesomorphism due to the flexibility and polarity of lateral group is investigated. A new homologues series is synthesized to accomplish this aim. The C1 to C3 homologue are nonmesomorphic, while the rest of the homologues exhibit enantiotropic nematic and smectic properties. The texture of the nematic mesophase is of threaded, Schlieren and droplets type. All these compounds were characterized by elemental analyses and spectroscopic techniques of FTIR and 1H Nuclear magnetic resonance (NMR). The phase behaviour was studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction techniques.
- Sharma, Vinay S.,Patel
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- Tuning the mesomorphic properties of nonisomeric chalconyl-ester bases homologous series: The effect of tail group
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The mesomorphic properties of nonlinear chalconyl ester homologous series can be tuned in a predictable fashion with tail groups (-OC16H33) substituents on the terminal side. Novel series consisted thirteen members (C1–C8, C10, C12, C14, C16, C18). C1 to C5 homologues are nonliquid crystal, C6 to C14 homologues shows nematic mesophase enantiotropically, while C16, C18 exhibits smectic as well nematic properties. The texture of the nematic mesophase is of fan shaped, schlieren and nematic droplets type. All these compounds were characterized by elemental analyses and spectroscopic techniques such as [FTIR] and 1H Nuclear magnetic resonance [NMR] spectroscopy. The mesomorphic properties of these compoundswere observed by optical polarized light microscopy (POM) and differential scanning calorimetry (DSC).
- Sharma, Vinay S.,Patel
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- Synthesis and mesomorphic properties of new chalconyl-ester based liquid crystals: The effect of tail group
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A new homologous series viz. 4-(3-(3, 4-dioctadecyloxy) phenyl)-3- oxoprop-1-en-1-yl) phenyl-3-(4-n-alkoxy phenyl) cinnamate) based on two linking groups have been synthesized and characterized. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and confirmed by differential scanning calorimetry (DSC). All synthesized compounds exhibited LC behaviour except compound C1. Thermal stability of smectic and nematic phase of present series are 79.0°C and 120.0°C whose temperature range is vary from 14 to 20°C and 24 to 56°C respectively. The mesomorphic properties of present series were compared with other structurally related mesogenic homologous series to evaluate the effects of tail group on mesomorphism.
- Sharma, Vinay S.,Vekariya, Rajesh H.,Sharma, Anuj S.,Patel
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- Synthetic pathway for a new calamitic series of liquid crystal: Comparison with corresponding linkage group
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Reduction-responsive cystamine-incorporated gelatin microspheres were prepared by an emulsification method. On SEM micrograph, the microsphere, prepared at pH 9.0 and at the carboxyl/amino group molar ratio of 1:1, was sphere-like and its diameter was a few to 100 μm. The gelatin to cystamine ratio of the microsphere was about 1:0.2 (w/w), determined by energy dispersive X-ray spectroscopy. Two endothermic peaks were observed around 92°C and 126°C, which were thought to be the melting point of gelatin-rich phase and that of cystamine-rich phase, respectively. The microsphere released its payload (FITC-dextran) in dithiothreitol (a reducing agent) concentration-dependent manner.
- Sharma, Vinay S.,Vekariya, Rajesh H.,Sharma, Anuj S.,Patel
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p. 143 - 157
(2017/10/27)
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- Mesogenic naphthyl derivatives
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Two new mesogenic homologous series of liquid crystalline naphthalene derivatives with different central linkages: 2- Naphthyl-4-n-alkoxybenzoates (I) and trans-2-Naphthyl -4-n –alkoxycinnamates(II), have been synthesized and characterized by a combination of elemental analysis and standard spectroscopic methods. Twelve compounds have been synthesized in both the series I and II. In series I, methoxy to n-pentyloxy derivatives are non mesogenic, n-hexyloxy to n-hexadecyloxy derivatives exhibit monotropic nematic mesophase. Smectic A mesophase commences from n-decyloxy derivatives as a monotropy and persist up to the last member synthesized. All the 12 compounds of series II exhibit mesomorphism. Methoxy to n-propyloxy derivatives exhibit monotropic nematic mesophse, and n-butyloxy to n-tetradecyloxy derivatives exhibit enantiotropic nematic mesophase. n-Hexayloxy to n-hexadecyloxy derivatives also exhibit enantiotropic smectic A mesophase. The mesomorphic properties of present series were compared with each other and with a structurally related mesogenic homologous series to evaluate the effects of central linkage on mesomorphism.
- Patel,Prajapati
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p. 106 - 115
(2017/03/08)
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- 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
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Two series of chalconyl-based liquid crystals which differ from each other in the position of the first linking group have been synthesized and characterized by elemental analyses and spectroscopic techniques such as Fourier transform infrared and proton magnetic resonance magnetic resonance [1H NMR] spectroscopy. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and differential scanning calorimetry (DSC). We have synthesized two homologous series viz. 3-(3-(4-(Octadecyloxy) phenyl) acrylonyl) phenyl 3-(4-n-alkoxyphenyl) acrylate (series-1) and 3-(3-(4-(Octadecyloxy) phenyl) acryloyl) phenyl 4-n-alkoxy benzoate (series-2). Series-1 has chalconyl-ester central linkage group while in series-2 chalconyl-vinyl ester group is present and tail octadecyloxy side chain is common in both homologous series. All the homologous in present series display LC property in enantiotropical manner except first three homologous in both series.
- Solanki,Sharma, Vinay. S.,Patel
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p. 216 - 232
(2017/03/08)
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- Mesomorphism dependence on terminal end groups
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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.
- Marathe, Rajesh B.,Doshi
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p. 144 - 151
(2016/02/19)
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- Synthesis and mesomorphism of novel chalconyl esters with a lateral nitro group
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A new chalconyl homologous novel series with lateral nitro group: 4-(3-4-(heptyloxy)phenyl) acryloyl-2/-nitro phenyl 4′-alk oxy benzoate have been synthesized and all the members are differed by the terminal chain length CnH2n+1, where n = 1,2,3,4,5,6,7,8,10,12,14,16,18. Their transition temperatures and mesophase characteristics are studied with the help of polarizing optical microscope (POM). All 13 homolog of series except the C1–C4 are enantiotropically mesogenic. The molecular structures have been confirmed by the analytical techniques of NMR, IR, and elemental analysis.
- Jain,Patel
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- Mesomorphism dependence on central bridges and the efficiency order of the tail group
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A novel homologous series: RO-C6H4?CH?CH?COO?C6H4?CH?N-C6H3 (CH3)2 of ortho-meta Schiff's bases has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on mesomorphic properties and to provide a source of novel liquid crystalline (LC) materials. The series consists of 13 homologues (C1 to C8, C10, C12, C14, C16 & C18). C1 and C3 homologues are nonmesomorphic, C2 and C4monotropicnematic, C6 and C7monotropicsmectic in addition to enantiotropicnematic, C5 is only enantiotropicnematic, C8, C10, C12 are enantiotropically smectogenic plus nematogenic and C14, C16, C18 homologues are enantiotropically smectic only. Textures and transition temperatures were determined using an optical polarizing microscope equipped with a heating stage. Analytical and spectral data confirm the molecular structures. Average smectic and nematic thermal stabilities are 100.16°C and 110.83°C, respectively. Mesomorphic properties of present novel series are compared with structurally similar homologous series.
- Bhola,Bhoya
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p. 154 - 161
(2016/07/14)
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- Mesomorphism dependence on heterocyclic end group
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An ester homologous series containing a heterocyclic end group was synthesized and studied with a view to understanding and establishing the effect of molecular structure on liquid crystal behavior. The novel series consists of 13 homologues. All members of the series are enantiotropically smectogenic without exhibition of nematogenic character. The textures of smectogenic homologues are of the type smectic A or C. The transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. The Sm-I transition curve in a phase diagram behaves partly in an abnormal manner with the exhibition of an odd-even effect. The average thermal stability for smectic is 141.45°C and the mesomorphic phase length ranges from 8.1°C to 30.3°C. Analytical and spectral data confirm the molecular structures. The liquid crystal properties of present series are compared with the structurally similar known homologous series.
- Bhola,Bhoya
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- Dependence of mesomorphism on molecular rigidity of nonlinear and linear isomeric and nonisomeric chalconyl esters
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The novel thermotropic liquid crystalline (LC) materials have been synthesized and studied through chalconyl ester nonlinear (meta substituted) homologous series RO-C6H4?CH?CH?COO?C6H4-CO?CH?CH?C6H4-OC14H29(n) with a view to understand the effect of molecular structure on LC behavior with reference to determine the difference between linear and nonlinear shaped molecules. Novel series consisted of thirteen members, whose nematogenic enantiotropic mesomorphism commences from C6 homologue and continued up to C18 homologue with the absence of smectogenic character. C1 to C5 homologues are nonliquid crystals as determined through an optical polarising microscope (POM) equipped with a heating stage. Transition temperatures of LC homologues alternate and are lower than the corresponding n-alkoxy cinnamic acids. Cr-N/I and N-I transition curve behaved in normal manner. N-I transition curve exhibited odd-even effect in a phase diagram. Textures of nematic phase are threaded or Schlieren or determined by miscibility method and from observing mesophase on the top of the POM. Thermal stability for nematic is 92.5 and mesophase length minimum to maximum is 19.0 to 32.0°C at the C10/18and C6 homologue. Group efficiency order on the basis of thermal stability is (Formula presented.) Thus, novel series is nematogenic and low melting type. Analytical and spectral data confirmed the molecular structures of homologues.
- Jain,Patel
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- Synthesis and study of new homologous series of ester-chalcone exhibiting nematic phases
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A novel homologous series of ester-chalcone have been synthesized and their liquid crystals (LCs) properties are studied. All the homologue shows nematic phase except C1-C4 homologue. Classical nematic textures are observed in this homologous series with the help of polarizing optical microscope (POM) equipped with hot stage. The role of flexible methylene group spaces, degree of polymerization and central linkage on the exhibition of all the homologue is discussed. The novel homologous series has been characterized by the standard methods (1HNMR, IR, and elemental analysis).
- Jain,Patel
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- Mesomorphism dependence on geometric shapes in isomeric molecules
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A novel homologous series of symmetrical dimers RO-C6H4-CH?CH-COO-C6H4-OOC-CH?CH-C6H4-OR of liquid crystalline (LC) characteristics have been synthesized and studied with a view to understand and establish the effects of the molecular structure on the LC property or properties with special reference to geometrical shape in case of isomeric series. Homologous series consisted of 13 dimers (C1 to C18). C1 to C8 are only enantiotropic nematic and the rest of the dimer homologues from C10 to C18 are enantiotropically smectogenic in addition to nematogenic. Textures of the nematic phase are threaded or Schlieren and that of the smectic phase are of the type smectic A or C. Transition temperatures and the textures were determined by an optical polarizing microscopy equipped with a heating stage. Thermal stability for smectic and nematic are 161.0 °C and 237.6 °C, respectively, whose total mesophase (Sm+N) length ranges from 71.0 °C to 126.0 °C. Cr–M, Sm–N, and N–I transition curves of a phase diagram behaved in normal manner except negligible abnormality at C14 dimer of N–I transition curve. N–I transition curve exhibited odd– even effect nearby up to C7 dimer. Analytical and spectral data supported molecular structures of homologue dimers. Thus, present homologue dimer series is predominantly nematogenic and partly smectogenic and high-ordered melting type. LC properties of present novel series are compared with structurally similar series.
- Bhola,Bhoya
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p. 112 - 120
(2016/07/14)
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- Role of n-alkoxy terminal end groups on mesomorphism
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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).
- Muniya,Patel
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p. 129 - 136
(2016/09/04)
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- Mesomorphism dependence on halogenated chalconyl esters in terms of molecular flexibility/rigidity
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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
- Sharma, Vinay S.,Patel
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- Dependence of mesomorphism on flexibility of lateral and terminal groups of chalconyl esters
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A novel liquid crystalline homologous series of chalconyl vinyl esters with a lateral bromo substituent RO─C6H4─CH═CH─COO─C6H3─(Br)─CO-CH═CH─C6H4─C12H25(n) has been synthesized and studied with a view to understanding and establishing the relation between the molecular structure and liquid crystal (LC) behavior in terms of molecular flexibility of the lateral and terminal groups. The novel homologous series consists of thirteen (C1–C18) homologues, whose enantiotropic nematic and smectic mesomorphism commences from the C4, (C4–C18) and the C5, (C5–C18) homologue, respectively. The rest of the homologues (C1, C2, C3) are nonliquid crystals (NLC). Mesomorphism and transition temperatures were examined using an optical polarising microscope (POM) equipped with a heating stage. Textures of nematic phase are threaded or Schlieren and those of the Smectic-A or Smectic-C are focal conic. Analytical, thermal and spectral data supported molecular structures of the novel homologues. Thermal for smectic and nematic are 87.5°C and 101.1°C, respectively, whose, total mesophase length ranges from 17°C to 30°C at C14 and C7 homologue, respectively. The mesomorphic transition temperature ranges are between 70°C and 113°C.
- Patel, Priya K.,Shah
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- Study of mesomorphism and its relation to molecular structure through molecular rigidity and flexibility
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Novel liquid Crystalline (LC) substances of chalconyl ester derivatives from Vinyl aromatic carboxylic acids are synthesized and studied with a view to understanding and establishing the relation between molecular structure, RO-C6H4-CH=CH-COO-C6H4-CH=CH-CO-C6H4-F (para) and LC properties of the thermotropic variety. Homologous series consists of eleven members (C1 to C16). C1 and C2 members of novel series are nonliquid crystals (NLC) and the rest of the homologues (C3 to C16) are enantiotropic nematic with absence of smectic property throughout. Transition temperatures and textures of homologues were determined by an optical polarizing microscope (POM) equipped with a heating stage. Textures of nematic phase are threaded or Schlieren. The transition temperatures of novel homologues are relatively lower than the corresponding dimeric trans n-Alkoxy Cinnamic acids from which, novel homologues are synthesized. Thermal, analytical, spectral data confirmed molecular structures of novel homologues. Cr-N/I and N-I transition curves behaved in normal manner except C8 to C14 homologues which deviated from normal descending tendency in N-I transition curve. N-I transition curve exhibited odd-even effect up to C6 homologue and odd member's N-I transition curve occupied lower position than even member's N-I transition curve. Thermal stability for nematic is 118.2°C; with its total mesophase length ranging from 12.0 to 50.0°C. Thus, it is a middle ordered melting type series with absence of smectic property. Group efficiency order derived on the basis of thermal stability using comparative study of present novel series with structurally similar analogous series as mentioned below. Smectic: Series-Y > Series- X = Series-1 and Nematic: Series-X > Series- 1 > Series-Y
- Muniya,Patel
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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 dependence on heterocyclic tail
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A novel homologous series of liquid crystal materials containing a heterocyclic ring was synthesized with a view to understanding and establishing the relation between liquid crystal (LC) properties and a molecular structure; and with a view to curing skin-related diseases following biological activity studies. The series consist of 13 (C1 to C18) members. All the members are liquid crystals. The C4 to C18 members are smectogenic of which C4 and C5 are monotropic and remaining members (C6 to C18) are enantiotropic in nature; whereas all C1 to C18 members are enantiotropically nematogenic. Hence the C1, C2, C3 members are only nematogenic and the rest of the homologues are smectogenic in addition to nematogenic. Transition temperatures were determined by an polarizing optical microscope equipped with heating stage. Analytical and spectral data confirmed the molecular structures of homologues. It is a middle ordered melting type series. LC properties of a series are compared with the structurally known series.
- Bhola,Bhoya
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- Mesomorphism and flexibility of alkyl chains in chalcone esters
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A novel homologous series of chalconyl ester liquid crystals (LCs): RO?C6H4–CH:CH–COO?C6H4–CO?CH:CH?C6H4–OC10H21 (n) (para) has been synthesized and studied with a view to understanding and establishing the relationship between molecular structure and LC properties with reference to flexibility of the terminal chain. The novel series consists of eleven homologs (C1–C16). The C1 and C2 homologs are nonliquid crystals and the rest of the homologs (C3–C16) are enantiotropic nematic without exhibition of smectic mesophase. Transition and melting temperatures were determined by an optical polarizing microscope equipped with a heating stage. Textures of nematic phases are threaded or Schlieren. Cr-N/I transition curve adopts a zigzag path in a normal manner with overall descending behaviors. The N-I transition curve exhibits a sharp and shorter odd-even effect from C3 to C6 and it diminishes from and beyond C6 for higher homologs of longer n-alkyl chain (R) in more or less or negligible deviating manner from normal descending tendency. Thermal stability for the nematic is 116.4°C and mesophase length ranges from 19°C to 67°C at the C3 and C12 homolog respectively. The LC properties of present novel series are compared with structurally similar analogous series to derive group efficiency order.
- Muniya,Patel
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- The effect of geometrical shape and molecular rigidity on mesomorphism
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A novel nonlinear homologous series RO?C6H4?CH?CH?COO?C6H4 (meta) ?CO?CH?CH?C6H4?OC12H25(n) (para) consisting of three phenyl rings, two central bridges ?CH?CH?COO? and ?CO?CH?CH? as well as ?OR and ?OC12H25(n) as flexible and constant terminal end groups respectively. The object in view is aimed to understand and establish the effect of molecular structure on LC properties of nonlinear inverted “V” shaped molecules. Novel homologous series consists of thirteen homologues. Transition temperatures and textures were determined by polarizing optical microscopy (POM) equipped with a heating stage. Textures of nematic phases are threaded or schlieren and that of a smectic phases are of the type-A or C. Transition curves of a phase diagram behaved in a normal manner. Sm-N and N-I transition curves exhibited odd-even effect. Analytical, Thermal and Spectral data confirms the molecular structure of homologues.
- Patel, Priya K.,Shah
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- Dependence of molecular structure on mesomorphic behavior with special reference to central bridge
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A novel homologous series of liquid crystalline 4-(4′-n-alkoxy cinnamoyloxy)-4″-methoxy benzyl cinnamates was synthesized and studied with a view to understand and establish the effects of molecular structure on liquid crystal behavior. The series consists of eleven members of the series. None of the homologue derivatives are either nonliquid crystal or smectogenic, i.e. all the eleven members of the novel homologous series are enantiotropcially nematogenic only. Transition and melting temperatures as well as textures of the nematic mesophase were determined on an optical polarizing microscope equipped with a heating stage. The transition curves of the phase diagram show phase behavior in a normal expected manner. An odd-even effect is observed for the nematic-isotropic transition curve. The textures of the nematic mesophase are threaded or Schlieren as determined a by miscibility method. Analytical and spectral data confirm the molecular structures of the homologues. The average thermal stability for nematic is 213.8°C. The isotropic temperatures vary between 190°C and 240°C. The nematogenic mesophase length varies from 17°C to 102°C. Thus, the novel homologous series is entirely nematogenic without the exhibition of smectogenic character. The liquid crystal (LC) properties of the present novel series are compared with structurally similar other known homologous series.
- Patel, Brijesh H.,Doshi, Ankita A.,Doshi
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- Mesomorphism Dependence on Terminally Substituted End Group
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A novel homologous series of liquid crystalline substances has been synthesized and studied with a view to understanding and establishing the relation between liquid crystal properties and molecular structure. The novel ester series consists of eleven enantiotropically smectogenic homologous without exhibition of nematogenic property. Transition temperatures were determined with an optical polarizing microscope equipped with a heating stage. Textures of smectic mesophase are focal conic fan shaped of smectic A or C type. Analytical and spectral data confirms the molecular structures of homologous. Transition curve, Cr-Sm behaved in normal manner. Transition curve Sm-I behaved in a normal manner up to the octyloxy (C8) homolog derivative and then behaved in the unusual manner for the C10, C12, C14, and C16 derivatives. An odd-even effect is observed for the Sm-I transition curve. The series entirely smectogenic with a middle-ordered melting type and a moderate mesophase length. The average thermal stability for smectic is 128.09°C and mesophase length ranges from 8.6°C to 73.2°C. The mesomorphic (LC) behavior of the novel series is compared with structurally similar known homologous series.
- Marathe, Rajesh B.,Doshi
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- Mesomorphism Dependence on Molecular Flexibility and Molecular Rigidity
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A novel liquid crystal (LC) homologues series of ethylene derivatives was synthesized and evaluated for mesomorphic properties. Mesomorphism commences from sixth member of the series. Textures of the nematic phase are threaded or Schlieren and those of the smectic phase are of the focal conic fan type. The N-I and Sm-N transition curves of the phase diagram exhibit odd-even effects and behave in a normal manner. The average thermal stabilities of the smectic and nematic are 113.4°C and 123.2°C with mesogenic phase lengths varying between 3.3°C and 8.1°C and 4.5°C to 13.5°C, respectively. The LC behavior of the novel series is compared with a structurally similar known series.
- Bhola,Bhoya
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- Mesomorphism and molecular structure: Novel homologous series 4-(4′-n-alkoxy cinnamoyloxy)-4″-methoxy benzyl benzoates
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A novel homologous series consists of 11 homologues, studied with a view to understand and establish the relations between mesomorphism and molecular structure of novel substances. All the novel members of a series except methoxy and pentyloxy homologue derivatives are liquid crystalline [LC] in nature. Mesomorphism commences from a second member of a series ethoxy, propyloxy, butyloxy, and hexyloxy to hexadecyloxy homologue derivatives are nematogenic while decyloxy, dodecyloxy, and tetradecyloxy homologue derivatives are smectogenic, in addition to nematogenic. All mesogenic homologues of a series are enantiotropic mesomorphic. Phase transition curve for Smectic-Nematic behave in normal manner without exhibition of odd-even effect, whereas nematic-isotropic transition curve adopts serpentile shape as rising and falling nature with exhibition of very minor odd-even effect. Textures of nematic phase are threaded or schlieren and that of a smectic mesophase is a focal conic fan shaped of the type smectic A or C. Analytical and spectral data supported molecular structures of homologues. The mesomorphic behaviors of present series are compared with a structurally similar other known series. Smectic and nematic thermal stabilities are 182.6 and 246.0°C, respectively. Present series is partly smectogenic and predominantly nematogenic with considerable degree of mesomorphism (maximum 100 °C) and high melting type.
- Patel, Brijesh H.,Doshi
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- Mesomorphism of Novel Symmetric Dimers with Changing Alkoxy Terminal End Group
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A novel homologous series of symmetric dimers has been synthesized. It consists of thirteen (C1 to C8, C10, C12, C14, C16 and C18) dimer ester derivatives from trans cinnamic acid with pyrocatechol. Mesomorphic property commences from C7 homologue as smectic. C1 to C6 members of the series are nonmesomorphic. C7 is monotropic smectic and the rest of the homologues from C8 to C18 are enantiotropic smectic. The nematic mesophase is totally absent. Textures and transition temperatures of the homologues are determined by an optical polarizing microscope equipped with a heating stage. IR, 1H NMR spectra, mass spectra, and differential scanning calorimetry of some members is included. The spectroscopic analyses support the molecular structures. Mesomorphic properties of the novel symmetric dimer series are compared with structurally similar series. The novel series is partly nonmesomorphic and predominantly smectogenic with textures of the A or C type, without the exhibition of the nematic phase.
- Bhola,Maheta,Bhoya
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p. 129 - 138
(2015/12/30)
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- Novel Cinnamate Esters - Synthesis and Mesomorphic Properties in Relation to Molecular Structure
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A novel homologous series 4-[4′-n-alkoxy cinnamoyloxy] benzyl cinnamates consisting of 11 homologs was synthesized and studied with a view to understanding and establishing the relation between molecular structure and mesomorphic behavior of a substance. Mesomorphic behavior of the series commences from the third homolog and then continues until the last hexadecyloxy homolog. The first and second members of a series are non-mesomorphic. Nematogenic mesophase formation is observed from the propoxy homolog to the hexadecyloxy homolog, but the smectogenic mesophase formation is observed from the hexyloxy homolog to the tetradecyloxy homolog. All mesomorphic transitions are enantiotropic in nature. Transition temperatures were determined by an optical polarizing microscopy equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type and that of the smectic mesophases are focal conic fan shaped of the smectic A or smectic C type. A phase diagram of the series shows a normal behavior of the transition curves with a minor abnormality of the last three homologs for the nematic-isotropic transition curve. The average thermal stability for smectic and nematic mesophases is 176.0°C and 219.3°C, respectively. Analytical and spectral data agree with the molecular structures of homologs. Mesomorphic phase length varies between 22°C and 76°C. Smectic phase length varies from 6°C to 33°C and nematic phase length varies from 22°C to 54°C. Thus, the novel present series is predominantly nematogenic and partly smectogenic. Mesomorphic properties of the novel series are compared with structurally similar other known homologous series.
- Patel, Brijesh H.,Doshi
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- Synthesis and Liquid Crystal Behavior of a Novel Ester Homologous Series
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A novel ester homologous series of 4-[4-n-alkoxy cinnamoyloxy] benzyl benzoates has been synthesized. The series consists of 12 homologues. Liquid crystal properties commence from the sixth member to the last member of the series with the exhibition of an enantiotropic nematic phase without the exhibition of any smectogenic mesophase. The remaining homologues do not exhibit liquid crystal behavior. The texture of the nematic phase is of the threaded or Schlieren type. The solid-nematic or isotropic transition curve adopts a zigzag path and the nematic-isotropic transition curve steeply rises and then falls in the phase diagram and behaves in normal manner. An odd-even effect is absent in the nematic-isotropic transition curve with an alteration of transition temperatures. The average thermal stability for the nematic mesophase is 153.1°C, and the nematogenic temperature ranges vary from 12°C to 50°C. Analytical data confirm the molecular structures of the homologues. The Liquid Crystal properties and transition temperatures were observed through an optical polarizing microscope, equipped with a heating stage. The mesomorphic characteristics of the novel ester series are compared with other, known and structurally similar series. The novel series is predominantly nematogenic with the absence of any smectogenic character, with relatively short mesophase temperature ranges and of the middle ordered melting type.
- Patel,Doshi
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- Synthesis and liquid crystalline properties of novel ethylene derivatives
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A novel homologous series of liquid crystals, viz., α-4-[4′-n- alkoxy cinnamoyloxy] benzoyl-β-4″-chloro phenyl ethylenes, has been synthesized. The series consists of twelve homologs. The methyl to butyl derivatives are not liquid crystalline and the rest of the homologs are enantiotropic liquid crystals. The octyl to dodecyl derivatives of the series are enantiotropically smectogenic in addition to nematogenic in character, but the pentyl, hexyl, heptyl tetradecyl, and hexadecyl homolog derivatives of the series are only nematogenic without the exhibition of a smectic phase. The transition temperatures of the novel substances were determined by optical polarizing microscopy equipped with a heating stage. A plot of transition temperatures versus the number of carbon atoms present in the n-alkoxy terminal chain represents the phase behavior of the series. An odd-even effect is observed for the nematic-isotropic transition curve. The textures of the nematic phase are of a threaded or Schlieren type and those of the smectic A and smectic C phases are typical. Analytical and spectral data agree with the molecular structures. The smectic and nematic thermal stabilities are 132.6°C and 156.7°C, respectively. The smectic phase commences from the octyloxy homolog. Smectogenic phase lengths vary from 26°C to 33°C and the nematogenic phase lengths vary from 6°C to 70°C. The series is predominantly nematogenic and partly smectogenic with considerable mesophase length and a middle-ordered melting type. The liquid crystal properties of the present series are compared with structurally similar homologous series.
- Chauhan,Shah,Doshi
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- Study of the effect of molecular structure on mesomorphic properties through a novel homologous series α-3-[4′-n-alkoxy cinnamoyloxy] phenyl-β-4″-nitro benzoyl ethylenes
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Eleven members of a novel homologous series α-3-[4′-n-Alkoxy Cinnamoyloxy] phenyl-β-4″-nitro benzoyl ethylene are synthesized and evaluated for their mesomorphic properties. Seven members of the series are enantiotropically nematogenic without exhibition of smectogenic character, and the other four members are non-mesomorphic in character. Mesomorphic behavior from a phase diagram for solid to nematic and for nematic to isotropic transitions shows the normal behavior. The nematic to isotropic transition curve shows an odd-even effect. Analytical data support the structures of molecules. Nematogenic phase length ranges from 30°C to 62°C. Nematic-isotropic thermal stability is 175.7°C. The mesomorphic properties of the series are compared with the structurally similar isomeric series. Thus, the series is predominantly mesomorphic (nematogenic) and partly non-mesomorphic with middle-order melting points. Transition temperatures and other liquid crystal properties were determined by optical polarizing microscopy with a heating stage.
- Suthar,Doshi
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- Synthesis and evaluation of a novel liquid crystalline homologous series: α-4-[4′-n-alkoxy cinnamoyloxy] benzoyl-β-3′,4′- dimethoxy phenyl ethylenes
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The synthesis and evaluation of a novel series of 12 homologues is presented. Enantiotropic nematogenic mesomorphism is exhibited from the pentyl to hexadecyl homologues. The other homologues are not liquid crystalline. Smectic mesomorphism is absent in all homologues. Transition temperatures were determined using an optical polarizing microscope equipped with a heating stage. The transition curves of a phase diagram behave in a normal manner. An odd-even effect is observed for the N-I transition curve. The textures of the nematic phase are of the threaded or Schlieren type. Mesomorphic-isotropic transition temperatures range from 152°C to 178°C. The nematogenic phase length varies between 24°C and 51°C. The nematic thermal stability is 163.1°C. Thus, the novel homologous series is entirely nematogenic without the exhibition of smectogenic character, and is of a middle ordered melting type. Analytical and spectral data support the molecular structures. Liquid crystal (LC) properties of the novel series are compared with structurally similar homologous series.
- Suthar,Doshi,Doshi
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- Synthesis and mesomorphic properties of novel ethylene derivatives
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A novel homologous series, α-4-[-4′-n-alkoxy cinnamoyloxy] benzoyl-β-4″-methoxy phenyl ethylenes, has been synthesized, which consists of 12 homologues. The pentyl to tetradecyl homologues are enantiotropically mesomorphic, and the rest of the homologues are nonmesomorphic. The pentyl to octyl derivatives exhibit smectogenic character in addition to nematogenic character, but the decyl to tetradecyl homologues exhibit only nematogenic character without the exhibition of a smectic phase. A phase diagram of three transition curves shows a normal phase behavior. Analytical and spectral data confirm the molecular structure of the homologues. The optical microscopic textures are threaded or Schlieren for the nematic phase and the normal smectic A type, respectively. Liquid crystal properties and transition temperatures were determined using a hot stage polarizing microscope. The smectic and nematic thermal stabilities are 159.7°C and 174.1°C, respectively. Thus, the present novel series is predominantly nematogenic and partly smectogenic in nature and is compared with other structurally similar homologous series.
- Chaudhari,Patel,Doshi
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- Synthesis and mesomorphic investigations of liquid crystalline compounds having a benzothiazole ring
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Two homologous series of calamitic liquid crystals containing a benzothiazole ring and two different linkages have been prepared, and their liquid crystalline properties are studied and compared with each other and those of similar structure. The mesogens with only the cinnamate linking group showed better thermal properties than those with an ester. Nematic and smectic phases were observed. All the compounds of both the series were characterized by elemental analysis, FT-IR, mass spectrometry, 1H-NMR, and 13C-NMR. Phase transition temperatures and the thermal parameters were obtained from differential scanning calorimetery (DSC). The textural observations were performed using hot-stage Polarizing Optical Microscopy (POM).
- Thaker,Chothani,Patel,Dhimmar,Solanki,Patel, Neeraj,Patel,Makawana
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- Synthesis and liquid crystal properties of novel ethylene derivatives: α-3-[-4′-n-alkoxy cinnamoyloxy] phenyl β-4″-methoxy benzoyl ethylenes
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Eleven members of a novel homologous series of α-3-[-4′-n- alkoxy cinnamoyloxy] phenyl β-4″-methoxy benzoyl ethylenes were synthesized. The methyloxy, ethyloxy, butyloxy, and hexadecyloxy homologues are nonmesomorphic, while all the other homologues are mesomorphic. The mesomorphic homologues are enantiotropically smectogenic in combination with nematogenic character, except for the propyloxy homologue, which shows only nematogenic character. A phase diagram of the series shows the expected mesomorphic behavior. Transition temperatures of this series are observed through an optical polarizing microscope equipped with a heating stage. An odd-even effect is observed for nematic-isotropic transition curve. Analytical data supports the structures of the molecules. Mesomorphic temperature range varies from 23°C to 51°C. Liquid crystal properties of this series are compared with a structurally similar homologous series. The smectic and nematic thermal stability of the series are 138.8°C and 165.7°C, respectively. The nematic phase shows a threaded or schlieren texture, and the smectic phase is a smectic A phase. Copyright Taylor & Francis Group, LLC.
- Chauhan,Doshi
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- Synthesis of novel mesomorphic homologous series: α-4-[-4′-n- alkoxy cinnamoyloxy] phenyl-β3″ nitrobenzoyl ethylenes
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Eleven novel mesomorphic homologues were synthesized and evaluated for their mesomorphic properties. The methoxy to n-butyloxy homologues are nonmesomorphic, while the other homologues are enantiotropic mesomorphic. The n-pentyloxy, n-hexyloxy, and n-octyloxy homologues are polymesomorphic, i.e., smectic and nematic mesophases are exhibited enantiotropically. Only the nematic mesophase is exhibited by the n-decyloxy to n-hexadecyloxy homologues. Analytical data confirm the structure and textures of molecules. The nematic mesophase shows a threaded-type texture, and that of smectic phase is of smectic A type. The mesomorphic properties are compared with a structurally similar homologous series. The average thermal stability for the smectic and nematic mesophases is 154.6C and 163.8C, respectively, as observed through optical polarizing microscope with heating stage. Copyright Taylor & Francis Group, LLC.
- Chaudhari,Doshi
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- Synthesis and mesomorphism of novel liquid-crystalline isobutyl-p-(p-n- Alkoxy Cinnamoyloxy) cinnamates
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A new homologous series viz. Isobutyl-p-(p-n-alkoxy cinnamoyloxy) cinnamates consisting of 11 homologs has been synthesized with an isobutyl cinnamate end group and a further cinnamate moiety as a linking group. The methyl to butyl homologs are nonmesomorphic, and the pentyl to hexadecyl derivatives are enantiotropic nematogens without exhibition of any smectic phases. The average thermal stability for the nematic phase is 138.1C with a middle ordered melting point. The structures of the novel materials were confirmed by spectroscopic techniques. The liquid crystal phase type was determined by optical polarizing microscopy and all textures are of the threaded type. The mesomorphic behavior of the series is compared with a structurally similar homologous series.
- Patel,Patel,Doshi
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- Synthesis, characterization and mesomorphic properties of new rod-like thiophene based liquid crystals
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Two new mesogenic homologous series of Schiff base esters, 2-[4-(4-n-Alkoxy benzoyloxy) benzylidenamino] 3-cyno thiophine (Series-A) and Schiff base cinnamates, 2-[4-(4-n-alkoxy cinnamoyloxy) benzylidenamino] 3-cyano thiophene (Series-B), comprising a thiophene moiety were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as FT-IR, 1H-NMR and 13C-NMR, and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry and optical polarizing microscopy. All the derivatives are mesomorphic in nature showing the nematic phase, and the higher members of Series-A show a smectic C phase whereas Series-B exhibits only the nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related compounds. Taylor and Francis Group, LLC.
- Thaker,Patel,Dhimmar,Solnki,Chothani,Patel,Patel,Makavana
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- PHENYLALKYLCARBOXYLIC ACID DELIVERY AGENTS
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The present invention provides phenylalkylcarboxylic acid compounds and compositions containing such compounds which facilitate the delivery of biologically active agents.
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Page/Page column 32
(2008/12/07)
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- New mesogenic homologous series of schiff base cinnamates comprising naphthalene moiety
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New mesogenic homologous series of Schiff base cinnamates comprising a naphthalene moiety were prepared by condensing different 4(4'-n-alkoxy cinnamoyloxy) benzaldehydes with 2-amino naphthalene. All the synthesized compounds were characterized by combination of elemental analysis and spectroscopic techniques. All the homologues synthesized exhibit mesomorphism. The mesomorphic properties of the present series are compared with other structurally related series.
- Prajapati,Thakkar, Viral,Bonde, Nilesh
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- Cinnamic acid derived oxazolinium ions as novel cytotoxic agents.
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Substituted cinnamoyl chlorides, 11, were converted into (2-hydroxyethyl)-oxazolinium chlorides 14, N,N-bis-(2-chloroethyl)amides 16 and (2-chloroethyl)-oxazolinium chlorides 17. Although derivatives 14 which possess electron-donating substituents (Me or MeO) were more potent than those substituted by electron-withdrawing groups (NO(2), Cl or CF(3)), the difference in cytotoxic actin was not significant. Modification of the lipophilic character in a series of alkoxy-substituted derivatives 14 led to more active compounds, where 14t that possesses a 4-octyloxy-phenyl-substituent was the most potent and displayed cytotoxic activity in the microM range. It is assumed that the oxazolinium salts act as alkylating agents, and undergo nucleophilic attack on the methylene adjacent to the ring oxygen where the oxazolinium ring parallels the aziridinium ring intermediate found in classical alkylating agents.
- Hedvati, Lilach,Nudelman, Abraham,Falb, Eliezer,Kraiz, Boris,Zhuk, Regina,Sprecher, Milon
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p. 607 - 616
(2007/10/03)
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- Mesogenic Homologous Series : 4-Isopropoxyphenyl-4′-n-alkoxycinnamates and Binary Systems Comprising the Homologues of this Series
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Twelve members of the homologous series-A have been synthesised. First two members are non-mesogenic. The nematic mesophase commences as a monotropic phase from n-propoxy derivative. equation presented Series-A (where n = 1 to 16) n-Propoxy to n-heptyloxy derivatives exhibit only nematic phase. n-Octyloxy and n-decyloxy derivatives exhibit smectic and nematic phases. n-Dodecyloxy to n-hexadecyloxy derivatives exhibit only smectic phase. Seven binary systems comprised of homologues of series-A have been studied. The non-mesogens induce mesomorphism in a few binary systems. Other binary systems, where both the components are mesogens, exhibit normal behaviour of mesogenic binary systems. Results indicate that eventhough homologues of series-A contain branched alkyl chain, the binary systems do not exhibit pronounced decrease in melting behaviour.
- Vora,Vyas
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p. 507 - 511
(2007/10/03)
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- New potent antagonists of leukotrienes C4 and D4. 1. Synthesis and structure-activity relationships
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(p-Amylcinnamoyl)anthranilic acid (3a) had moderate antagonist activities against LTD4-induced smooth muscle contraction on guinea pig ileum and LTC4-induced bronchoconstriction in anesthetized guinea pigs. Modifications were made in the hydrophobic part (cinnamoyl moiety) and the hydrophilic part (anthranilate moiety) of 3a. A series of 8-(benzoylamino)-2-tetrazol-5-yl-1,4-benzodioxans and 8-(benzoylamino)-2-tetrazol-5-yl-4-oxo-4H-1-benzopyrans were revealed to be potent antagonists of leukotrienes C4 and D4. Among both series, ONO-RS-347 (18k) and ONO-RS411 (19h) were the most potent and orally active antagonists, respectively. Structure-activity relationships are discussed.
- Nakai,Konno,Kosuge,Sakuyama,Toda,Arai,Obata,Katsube,Miyamoto,Okegawa,Kawasaki
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- Study of Anisotropic Phase Transitions of Some New Mesogenic Esters: Methyl p-(p'-n-Alkoxycinnamoyloxy) benzoates
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A new series of mesogenic esters, methyl p-(p'-n-alkoxycinnamoyloxy) benzoates (n-alkyl = CH3 to C18H37) has been synthesized.These esters show variations in textures and transitions as the series is ascended.The first member of the series is homeotropically-mesomorphic while the second exhibits mesophase in monotropic condition.The third member shows enantiotropic nematic mesophase of homeotropic variation; the fourth, fifth and sixth members exhibit enantiotropic smectic and nematic mesophases at definite transition temperatures.Heptyl to octadecyl derivatives exhibit only smectic phase with definite transition to isotropic liquid.While all the nematic phases are homeotropic, the smectic mesophases show focal conic Grandjean plates with fan shape texture belonging to smectic-A type.The mesomorphic-isotropic transitions show a gradual fall with the increase in alkyl chain length; the mesomorphic region of fan shape structures with reference to temperature range, decreases as the number of carbon atoms increases.The mesomorphic range is quite wide and the thermal stabilities are correlated with the structural characteristics of the molecules.
- Lohar, J. M.,Mahsru, Urvashi
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p. 125 - 128
(2007/10/02)
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