77251-75-3Relevant academic research and scientific papers
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
Sharma,Solanki,Patel,Patel
, p. 137 - 145 (2016/03/01)
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.
Study of a new homologous series of liquid crystals: Isopropyl-p-(p/-n-alkoxy cinnamoyloxy) cinnamates
Jain,Jadeja,Sharma,Patel
, p. 146 - 153 (2016/03/01)
A new homologous series: isopropyl-p-[p/-n-alkoxy cinnamoyloxy] cinnamates was synthesized and studied with a view to understanding and establishing the relation between liquid crystal property and molecular structure. Twelve homologues were synthesized. Methyl to butyl homologues are not liquid crystals, while pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, and hexadecyl derivatives are enantiotropic liquid crystal in nature with nematogenic character. Smectogenic character is totally absent. A phase diagram is obtained by plotting a graph of transition temperatures versus number of carbon atoms is n-alkyl chain of left n-alkoxy terminal end group. Solid-isotropic or solid-nematic transition curve rises steeply from methyl to propyl derivatives and falls to pentyl homologue through butyl homologue, and follows a zigzag path of rising and falling values as the series is ascended. Nematic-isotropic transition curve shows descending tendency as series is ascended in a normal manner with exhibition of odd-even effect. Smectic mesophase does not appear even in the monotropic condition. Phase transition temperatures are determined by hot stage polarizing microscope. Analytical data support the structure of molecules. Texture of nematic mesophase is of threaded type. Mesomorphic properties are compared with structurally similar homologous series.
Mesomorphism and molecular structure: Novel homologous series 4-(4′-n-alkoxy cinnamoyloxy)-4″-methoxy benzyl benzoates
Patel, Brijesh H.,Doshi
, p. 78 - 86 (2015/03/14)
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.
Dependence of molecular structure on mesomorphic behavior with special reference to central bridge
Patel, Brijesh H.,Doshi, Ankita A.,Doshi
, p. 38 - 46 (2015/03/18)
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.
Mesomorphism Dependence on Terminally Substituted End Group
Marathe, Rajesh B.,Doshi
, p. 1 - 8 (2015/12/30)
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.
Synthesis and Liquid Crystal Behavior of a Novel Ester Homologous Series
Patel,Doshi
, p. 23 - 31 (2015/10/28)
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.
Novel Cinnamate Esters - Synthesis and Mesomorphic Properties in Relation to Molecular Structure
Patel, Brijesh H.,Doshi
, p. 42 - 51 (2015/10/28)
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.
Synthesis and mesomorphic properties of novel ethylene derivatives
Chaudhari,Patel,Doshi
, p. 95 - 102 (2013/08/23)
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.
Synthesis and evaluation of a novel liquid crystalline homologous series: α-4-[4′-n-alkoxy cinnamoyloxy] benzoyl-β-3′,4′- dimethoxy phenyl ethylenes
Suthar,Doshi,Doshi
, p. 51 - 58 (2013/08/23)
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.
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
Suthar,Doshi
, p. 76 - 83 (2013/08/24)
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.
