Time filter

Source Type

Patel R.B.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Der Pharma Chemica | Year: 2011

The titled new homologous series of twelve mesogens is synthesized by usual established method with, a view to understand and establish the relation between mesogenic properties of the substances and their molecular structure. Methyl to butyl derivatives of the homologous series are nonmesogenic, while pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl derivatives are enantiotropically mesogenic in character. Pentyl, tetradecyl, hexadecyl derivatives are nematogenic only, while, hexyl to dodecyl derivatives are polymesomorphic i.e. smectic and nematic, both mesophases are exhibited enantiotropically by hexyl to dodecyl homologues. Transitions and melting temperatures of homologues are determined by the polarizing microscope with heating stage. Transition temperatures are plotted versus number of carbon atoms in n-alkyl chain of left n- alkoxy terminal end group. A phase diagram is obtained by joining like points. Solid-mesomorphic or solid-isotropic transition curve initially follows zigzag path of rising and falling upto butyl homologue and then falls gradually upto decyl homologue and again rises steeply to a hexadecyl homologue in a rounded shape from decyl to hexadecyl derivative of the series. Smectic-nematic transition curve, behaves in normal manner and merges solid-mesomorphic / isotropic transition curve at the tetradecyl derivative of homologue, with showing up of odd-even effect. Nematic-isotropic transition curve wonderfully show rising tendency as series is ascended with alternation of transition temperatures, showing odd-even effect. Texture of nematic mesophase is of threaded type and that of smectic mesophase is focal conic fan shaped of the type-A. Analytical data support the structure of the molecules.


Patel R.B.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Der Pharma Chemica | Year: 2011

An ester homologous series entitled Ethyl-p-[p/-n-alkoxy cinnamoyloxy] cinnamates is synthesized and studied for liquid crystal behavior and its correlation with molecular structure. Methyl to n-pentyl homologues are non-liquid crystal while, n-hexyl homologue to n-octyl homologue n-decyl, n-dodecyl, n-tetradecyl and n-hexadecyl homologues exhibit liquid crystal properties especially of enatiotropic nematogenic character, even in the monotropic condition. Transition and melting temperatures (Table-1) are determined by hot stage polarizing microscope. A phase diagram (Figure-I) is obtained by plotting transition temperatures (Table-1) versus number of carbon atoms in n-alkyl chain of left n-alkoxy terminal. Solid-isotropic / nematic transition curve follows zigzag path of rising and falling with overall descending tendency as series is ascended in normal manner. Nematic-isotropic transition curve initially falls from n-hexyl homologue to n-decyl homologue in normal manner and passes through minima at decyl derivative but rises abnormally as series is ascended upto last homologue of series. The texture of the nematogenic mesophase is of threaded type. Analytical data support the structures of the molecules. Nematogenic mesophase length is relatively short with absence of smectic mesophase. Mesomorphic properties are compared with structurally similar homologous series.


Patel R.B.,K K Shah Jarodwala Maninagar Science College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Der Pharma Chemica | Year: 2011

A new homologous series of nonamphiphilic liquid crystals viz; n-propyl-p-[p'-n-alkoxy cinnamoyloxy] cinnamates with cis confugration is synthesized and studied with a view to understand the effect of molecular structure on mesomorphic properties of substances which may be useful to the various fields of applications. Methyl to pentyl and hexadecyl homologues are nonmesomorphic, hexyl to octyl, decyl, dodecyl and tetradecyl homologues are mesomorphic i.e. nematogenic in character without exhibition of any smectic character. A phase diagram is drawn from the transition temperatures as determined from hot stage polarizing microscope of homologues against the number of carbon atoms in n-alkyl chain of left n-alkoxy terminal end group. Solid-isotropic or solid nematic transition temperature curve follows a zigzag path of rising and falling throughout the series as series is ascended in normal manner. Nematicisotropic transition curve initially rises and then, shows descending tendency as series is ascended. Thus, it follows usual established trend as expected. Wellknown odd-even effect is observed for nematic-isotropic transition curve. Analytical data support the structures of molecules. The enantiotropic nematic mesophase appeared for all the homologues, is of threaded type as determined from miscibility metod. Thermal stability for nematic is 183.80C and mesomorphic range is short which varies from 8.0°C to 27.°C. mesomorphic properties of titled homologous series (1) are compared with structurally similar homologous series (A),(B) and (C).


Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College | Bhoya U.C.,Saurashtra University | Travadi J.J.,Opp Radhika Hospital
Molecular Crystals and Liquid Crystals | Year: 2012

Eight binary systems consisting of mesomorphs and nonmesomorphs (A 1 or A 2 + B 1 B 2, B 7, B 8) were studied with a view to determine the latent transition temperature (LTT) for the nonmesomorphic component (B) of a binary system by an extrapolation method. Encouraging results supporting earlier views and LTT values were obtained for seven binary systems. Instead of reporting a single value of LTT, the range of temperature or two or three values are reported herewith depending upon the possible paths of extrapolation. LTT reported earlier for nonmesomorphs lie within the range of temperature determined presently. Though the group slope value differs from the earlier reported value, the group efficiency order remains the same. Thus, the present investigation raises the credibility of an extrapolation method to determine LTT and group efficiency order for nematic mesophase. Component A 1 and A 2 are nematogenic, namely, p-(p-n-propyloxy benzoyloxy) anisole (A 1) (90.0 to 116.0) and p-(p-n-butyloxy benzoyloxy) anisole (A 2) (116.0 to 105.5). B 1 to B 8 are Schiff's bases. Transition and melting temperatures are observed through hot stage polarizing microscope for binary mixtures and pure components. © 2012 Copyright Taylor and Francis Group, LLC.


Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College | Odedara D.A.,M D Science College | Patel R.B.,K K Shah Jarodwala Maninagar Science College
Molecular Crystals and Liquid Crystals | Year: 2012

Three binary systems, each consisting of two nonmesogenic compounds, viz. p-tolual-p-phenetidine (M.P. 108.5C) [A] as the common component, and Methyl p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 119.0C) [B 1], Ethyl-p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 94.0C) [B 2], and n-Butyl p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 130.0C) [B 3] as the second component, respectively, are studied with a view to understand the effect of terminal groups on nematic and/or smectic mesomorphism. Latent transition temperatures (LTT) of the constituent components A, B 1, B 2, and B 3 were determined by extrapolation. Binary system (A + B 1) induces a nematogenic mesophase while binary systems (A + B 2) and (A + B 3) both induce a smectic mesophase in addition to a nematic mesophase. Phase diagrams of the binary systems under investigation are plotted for the mole percent of component (A) versus the transition temperatures of each binary system as determined from polarizing optical microscopy. The texture of the nematic mesophase is of threaded type and that of the smectic mesophase is focal-conic fan shaped of the type smectic-A. Components A, B 1, B 2, and B 3 were prepared by established methods. Analytical data support the structure of molecules under investigation. Melting points of the constituent components match with data reported earlier. © 2012 Copyright Taylor and Francis Group, LLC.


Chauhan B.C.,P.A. College | Doshi A.A.,M. S. University of Baroda | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Molecular Crystals and Liquid Crystals | Year: 2013

The synthesis and mesomorphic properties of a new homologous series of azomesogens, 4-(4′-n-alkoxy benzoyloxy)-3-methoxy phenyl azo-3″,4″ dichlorobenzene is detailed. The first four members of the series are nonmesomorphic, and the other eight members are smectogenic in character. The smectic mesophase, which is exhibited montropically, commences from the pentyl to the hexadecyl derivatives. The usual odd-even effect is observed in the isotropic-smectic transition curve. The isotropic-smectic transition curve behaves in a normal manner. The smectic mesophase shows a focal conic fan shaped texture of the smectic A type. An important feature of the series is the absence of the nematic property. The thermal stability and mesomorphic characteristic are compared with two structurally similar homologous series. © 2013 Copyright Taylor and Francis Group, LLC.


Patel R.B.,Kk Shah Jarodwala Maninagar Science College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Der Pharma Chemica | Year: 2011

Homologous series p-(p/-n-alkoxy Cinnamoyloxy) β-benzoyl Styrene is synthesized and studied with a view to understand and to established the relation between molecular structure and liquid crystal property. Homologues are synthesized by reacting p-n-alkoxy cinnamoyl chlorides with p-hydroxy β-benzoyl styrene. Totally twelve homologues are synthesized. Methyl to pentyl homologues are nonmesomorphic while, hexyl to octyl, decyl, dodecyl, tetradecyl and hexadecyl homologues are only nematogenic without exhibition of any smectogenic character even in the monotropic condition. Transition temperatures of the homologues are determined from hot stage polarizing microscope. Solid-isotropic / nematic transition curve in a phase diagram follows a zigzag path of rising and falling and shows overall falling tendency as series is ascended in usual manner. Nematic-isotropic transition curve adopt a descending tendency as series is ascended and behaves in normal manner without showing up of odd-even effect. Melting temperatures are varied between 104.0° C and 179.0° C. Mesomorphic range and nematicisotropic thermal stability are 6.0° Cto 47.0° C and 144.5° C respectively. Analytical data support the structures of molecules. The texture of nematic mesophase is of threaded type as determined by miscibility method. Thus, series under investigation is entirely nematogenic with middle ordered melting type and short range of liquid crystallinity. Mesomorphic properties are compared with structurally similar other homologous series.


Bhoya U.C.,Gujarat University | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Der Pharma Chemica | Year: 2011

A homologous series with -COO- and -N=N-, as central groups have been synthesized by treating p-n-alkoxy benzoyl chlorides with p-methoxy -p/-hydroxy azobenzene. All the homologues of the series are mesomorphic in nature. The nematic type mesophase commences from the very first member of the series. Polymesomorphism is exhibited by tetradecyl homologue i.e. smectic and nematic mesophases appear, one after another. Hexadecyl member is purely smectogenic. On plotting transition temperatures versus number of carbon atoms in nalkyl chain of left n- alkoxy terminal, a phase diagram is obtained. Solid-isotropic /mesomorphic transition curve, shows usual zigzag path of rising and falling. Nematic-isotropic and smectic - isotropic transition curves behave in normal manner with and without odd-even effect respectively. The series is high melting type with considerable mesomorphic range. Thermal stability and other mesogenic properties are comparable with structurally similar known series. Analytical data support the structure. Transition temperatures are determined by hot stage polarizing microscope. Texture of nematic and smectic mesophases confirmed by miscibility method. Nematic mesophase is of threaded type and that of smectic mesophase are focal conic fan shaped of type smectic-A for tetradecyl and smectic-C for hexadecyl homologue.


Bhoya U.C.,Saurashtra University | Vyas N.N.,P.A. College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Molecular Crystals and Liquid Crystals | Year: 2012

A homologous series of 8-(4-n-alkoxybenzoyloxy) quinolines were synthesized by established methods [5,6]. On evaluation by optical microscopy, none of the homologues were found to exhibit mesogenic behavior even in the monotropic condition. Then, each homologue (B) was mixed with a liquid crystal component (A) and binary systems were studied by optical microscopy. Solid-mesomorphic or isotropic-nematic transition temperatures of binary mixtures were determined and plotted to obtain the phase diagram for transition temperatures versus percentage composition of component (A). The nematic-isotropic transition curve was extrapolated to zero mole percentage of component (A) (100%B) to determine the latent transition temperature (LTT) of each nonmesomorphic homologue. The number of carbon atoms in the n-alkyl chain of each homologue versus LTT is plotted and a phase diagram is obtained. The isotropic-nematic transition curve behaves in a normal manner like a curve behaving for a typical nematogenic homologous series, including odd-even effects in its phase diagram. This method is useful to determine the probable temperature at which a nonmesogenic substance can show mesogenic behavior, provided a suitable condition is applied. Also, it is useful to correct the LTT of a homologue from the mesomorphic-isotropic transition curve. © 2012 Copyright Taylor and Francis Group, LLC.


Chauhan M.L.,P.A. College | Pandya R.N.,P.A. College | Doshi A.V.,Matushri Virbaima Mahila Science and Home Science College
Molecular Crystals and Liquid Crystals | Year: 2011

A new homologous series p-(p'-n-alkoxy benzoyloxy) methyl cinnamates is synthesized with a view to understand and establish the relation between mesogenic properties and structure of molecules. Ethyl to octyl, decyl, dodecyl, tetradecyl, and hexadecyl homolgues are enantiotropically nematogenic, while the methyl homologue is nonmesogenic. None of the homologues exhibit a smectogenic mesophase. An odd-even effect is observed in the nematic-isotropic transition curve. The average thermal stability is 105.0C and the nematogenic mesophase ranges from 11.0C to 54.0C. Thus, the series is of a middle ordered melting type with moderate nematogenic range. Analytical data confirm the structure of the compounds, and the mesomorphism was identified by optical microscopy. The mesogenic properties are compared with structurally similar compounds. Copyright © Taylor &Francis Group, LLC.

Loading Matushri Virbaima Mahila Science and Home Science College collaborators
Loading Matushri Virbaima Mahila Science and Home Science College collaborators