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A Novel homologous series of high transition temperature RO-C 6 H 4 -CH=CH-COO-C 6 H 4 -N=CH-CH=CH-C 6 H 5 has been synthesis and studied with a view to understand establish and evaluate the relation between liquid crystal properties and the molecular structure of a substance. A series consists of thirteen homologues. All the homologues are mesogenic. Smectic mesophase commences from C 12 to C 18 homologues. Nematic mesophase appears from C 1 to C 18 homologues. The textures of a nematic phases are of threaded or schlieren and that of the smectic phase are focal conic fan shaped of smectic-A or C type. Transition temperatures and textures were determined by an optical polarizing microscopy equipped with a heating stage. The analytical and spectral data confirms the molecular structures of homologues. Thermal stability for smectic and nematic are 118.5 0 C and 224.77 0 C, whose total mesophase length ranger from 73.0 0 C to 111 0 C. The liquid crystal properties from homologue to homologue varies in the same series. Some liquid crystal properties of present series are compared with the structurally similar known homologous series. Present novel homologous series is partly smectogenic and fully nematogenic and of higher ordered melting type and high thermal stability.

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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 (C 1 to C 16 ); whose mesomorphic properties commence from octyloxy (C 8 ) homologue of a series. C 8 , C 10 and C 12 members of a series are monotropic smectic and C 14 , C 16 members are enantiotropically smectogenic. C 1 to C 7 homologues 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 o C and mesomorphic phase length is very short (12.9 o C to 15.3 o C). 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.