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Suthar D.M.,K K Shah Jarodwala Maninagar Science College | Doshi A.A.,M. S. University of Baroda | Doshi A.V.,University of Rajasthan
Molecular Crystals and Liquid Crystals | Year: 2013

The titled homologous series consists of 11 members. The methyl and ethyl homologues are nonmesomorphic because of very high melting points, however, the propyl to hexadecyl derivatives are enantiotropic nematic with absence of smectogenic. The texture of nematic mesophase is threaded or Schlieren. The nematic-isotropic transition curve of the phase diagram behaves in a normal manner with the exhibition of an odd-even effect. The transition temperatures of the series and liquid crystal properties are observed through optical polarizing microscopy and a hot stage. The novel materials were characterized by elemental analysis, infrared, and 1H NMR spectroscopy. Analytical data support the molecular structures. The liquid crystal properties of the novel series are compared with structurally similar homologous series. The novel series is entirely nematogenic with absence of smectic character and of a middle-ordered melting type. The nematic-isotropic thermal stability varies between around 120°C and 180°C. © 2013 Copyright Taylor and Francis Group, LLC. Source


Chauhan H.N.,K K Shah Jarodwala Maninagar Science College | Vyas N.N.,P.A. College | Doshi A.V.,Jagdishprasad Jhabarmal Tibrewala University
Molecular Crystals and Liquid Crystals | Year: 2013

A novel homologous series entitled α-4-[4′-n-Alkoxy benzoyloxy] benzoyl β-4″-chloro phenyl ethylenes consists of 12 homologues. The pentyl to tetradecyl homologues are enatiotropically nematogenic and all of the other homologues (methyl to butyl and hexadecyl) are nonmesogenic. The textures of the nematogenic mesophase are threaded or Schlieren in nature. The transition temperatures were determined by an optical polarizing microscope with a heating stage. The phase diagram of the novel series shows a normal behavior with negligible abnormality in trend of the nematic-isotropic transition curve and exhibits an odd-even effect as expected. The nematic thermal stability is 149.4°C on average. The series is nematogenic without any smectogenic character. The mesogenic properties of the novel series are compared with known series that are structurally similar. © 2013 Copyright Taylor and Francis Group, LLC. Source


Suthar D.M.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,University of Rajasthan
Molecular Crystals and Liquid Crystals | Year: 2013

The synthesis and mesomorphic properties of a novel homologous series entitled α-4-[-4′-n-Alkoxy benzoyloxy] phenyl β-4 ″-nitro benzoyl ethylenes are reported. All the 11 members of the series except the methoxy and ethoxy derivatives are mesogenic. The propyloxy to pentyloxy and the hexadecyloxy homologues are only enantiotropically nematogenic and the rest of the mesogenic homologues are enantiotropically smectogenic in addition to nematogenic in character. A phase diagram shows the phase behavior through transition curves is of a normal type. An odd-even effect is observed for the nematic-isotropic transition curve. Analytical and spectral data support the molecular structure of the materials. Transition temperatures and other liquid crystal (LC) properties including average thermal stabilities for smectic and nematic were determined by optical polarizing microscopy. Average thermal stability for smectic and nematic are 125.6°C and 154.6°C, respectively. Smectogenic and nematogenic phase ranges vary between 19°C to 35°C and 14°C to 50°C, respectively. The LC properties of the novel series are compared with two other structurally similar homologous series. The textures of the nematic phase are threaded or schlieren type and those of the smectic phase is of the type A or C. © 2013 Copyright Taylor and Francis Group, LLC. Source


Chaudhari R.P.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,University of Rajasthan
Molecular Crystals and Liquid Crystals | Year: 2013

The synthesis and mesomorphic properties of a novel homologous series is reported. With the exception of the methyl and ethyl homologues, all 11 members of the series exhibit mesomorphism enantiotropically. The propyl to pentyl homologues, and the tetradecyl and hexadecyl homologues are enantiotropic nematic without the exhibition of smectic mesomorphism; while the hexyl to dodecyl homologues exhibit smectic mesomorphism in addition to the nematic phase. The texture of the nematic-mesophase by optical polarizing microscopy is of the threaded or Schlieren type, and that of smectogenic homologues is of the focalconic fan type. A phase diagram of the series shows a typical trend. Analytical and spectral data confirm the molecular structure of the compounds. Transition temperatures and mesomorphic properties are determined by optical polarizing microscopy. Smectic and nematic thermal stabilities are 125°C and 167°C, respectively. The series is predominantly nematogenic and partly smectogenic with middle-order melting type, and the smectic and nematic-mesophase ranges vary from 8°C to 22°C and 9°C to 56°C, respectively. The mesomorphic properties of the novel series are compared with other structurally similar homologous series. © 2013 Copyright Taylor and Francis Group, LLC. Source


Chauhan H.N.,University of Rajasthan | Chauhan H.N.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,University of Rajasthan
Molecular Crystals and Liquid Crystals | Year: 2013

A novel homologous series consists of 12 compounds. The shorter chain homologues do not show liquid crystal phases, but from six carbons onwards, the nematic phase is exhibited enantiotropically, with some members also showing a smectic phase. The phase behavior of the transition curves of the series shows a usual trend. The texture of the nematic phase is the threaded or Schlieren type and that of smectic phase is a smectic A. An odd-even effect is observed for smectic-nematic and nematic-isotropic transition curves. Analytical data confirm the molecular structure. The transition temperatures were determined by an optical polarizing microscopy. The mesogenic properties of the novel series are compared with a structurally similar homologous series. The average smectic-nematic and nematic-isotropic thermal stabilities are 133.4°C and 159.8°C, respectively, with a mesogenic temperature range of 10°C to 62°C. © 2013 Copyright Taylor and Francis Group, LLC. Source

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