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2 International Letters of Chemistry, Physics and Astronomy

2 2015

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Dependence of Mesomorphism on Molecular Rigidity

Rola R. R., Bhola G. N., Bhoya U. C.

International Letters of Chemistry, Physics and Astronomy

2015

Vol. 47

67--76

A novel smectogenic homologous series of twelve homologues synthesized and studied with a view to understand and establish the effect of molecular structure on liquid crystal properties (LC) and LC behaviors of thermotropic homologues. First (C1) to last (C16) member of a series exhibited only enantiotropically smectogenic property without showing nematic property which is absent even in the monotropic condition. Transition and melting temperature including textures of homologues were determined by an optical polarizing microscopy equipped with a heating stage, texture of a smectic phase are of the type A or C. Smectogenic phase length ranger between 5.1oC to 22.6oC. SmecticIsotropic (Sm-I) thermal stability is 153.55oC. Analytical, spectral and thermal data supported molecular structures of homologues. LC behaviors of present novel series are compared with the structurally similar homologous series. Transition curves viz. Cr-Sm and Sm-I transition curves of a phase diagram behaved in normal manner.

Dependence of Liquid Crystalline Behaviors on Molecular Flexibility

Maheta S. A., Bhola G. N., Bhoya U. C.

International Letters of Chemistry, Physics and Astronomy

2015

Vol. 47

77--86

A novel homologous series of thermotropic liquid crystal (LC) has been synthesized with a view to understand and establish the effect of molecular structure on liquid crystal behaviors of a series. The present LC series consist of twelve homologues (C1&enspto C16); whose mesomorphic properties commence from octyloxy (C8) homologue of a series. C8, C10&enspand C12 &enspmembers of a series are monotropic smectic and C14, C16&enspmembers are enantiotropically smectogenic. C1&enspto C7 &ensphomologues are nonmesomorphic. Nematogenic property is totally absent. Transition and melting temperatures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of smectic mesophases are focal conic three or two dimensional networking of the type A or C. Cr-I/Sm and Sm-I or I-Sm transition curves behaved in normal manner. Analytical and spectral data confirms the molecular structures of homologues. Thermal stability of smectogenic mesophase is 100.6 oC and mesomorphic phase length is very short (12.9 oC to 15.3 oC). LC properties of a present novel series are compared with the structurally similar homologous series. Present series is partly smectogenic and partly non mesomorphic with poor degree of mesomorphism and middle ordered melting type without exhibition of nematogenic behavior.