Abstract

SYNTHESIS AND STUDY OF A NEW HOMOLOGOUS SERIES OF NOVEL CHALCONE DERIVATIVE

Chauhan M. L.* and Balvani V. N.

Abstract

A new homologous series of non-amphiphilic liquid crystals viz; p-nalkoxy benzoic acid with α-4 Hydroxy benzoyl β -4’ –n-Pentyl phenylethylene configuration is synthesized and studied with a view tounderstand the effect of molecular structure on mesomorphic properties of substances which maybe useful to the various fields of applications. Methyl to pentyl homologues arenonmesomorphic, hexyl to hexadecyl homologues are mesomorphic i.e. nematogenic in character without exhibition of any smectic character. A phase diagram is drawnfrom the transition temperatures as determined from hot stage polarizing microscope ofhomologues against the number of carbon atoms in n-alkyl chain of left n-alkoxy terminal endgroup. Solid-isotropic or solid nematic transition temperature curve follows a zigzag path ofrising and falling throughout the series as series is ascended in normal manner. Nematic-isotropictransition curve initially rises and then, shows descending tendency as series isascended. Thus, it follows usual established trend as expected. Doesn’t known odd-even effect isobserved for nematic-isotropic transition curve. Analytical data support the structures ofmolecules. The enantiotropic nematic mesophase appeared for all the homologues, is of threadedtype as determined from miscibility method. Thermal stability for nematic is 168.5˚C andmesomorphic range is short which varies from 13.0˚C to 30.0˚C. mesomorphic properties of titled homologous series is compared with structurally similar homologous series.

Keywords: Mesomorphism, Mesophase, Mesogen, Smectic, Nematic, Enantiotropy.