Abstract

MESOMORPHISM DEPENDENCE ON MOLECULAR RIGIDITY FLEXIBILITY OF ESTER COMPOUNDS

Patel B. K. and Chauhan M. L.*

Abstract

A Novel homologous series of mesogens have been synthesized and studied with a views to understand and establish the relations between molecular structure and liquid crystal properties of a Compounds. Totally eleven members of series synthesized. Mesogenic behaviors commences from C6 member of a series and continued up to C16 member. The rest of the members C1 to C5 are nonmesogenic. Mesogenic homologues ( C6 to C16) are enantiotropically nematogenic. Textures of nematic phase are threaded or schlieren. Transition temperatures were determined by an optical polarizing microscopy equipped with a heating stage. Analytical and structural data confirms the molecular structures of homologues. Thermal stability for nematic is 166.6 ºC. Mesomorphic phase length range from 9.0 ºC to 36.0 ºC. Cr-I/N and N-I transition curves of a phase diagram behave in normal manner from C1 to C16 members. Mesogenic properties of present novel ester series are compared with the structurally similar series. Odd-even effect is missing for the N-I transition curve. Thus present series is partly nematogenic without exhibition of smectic property whose transition temperatures vary between 190 ºC and 136 ºC.

Keywords: Liquid Crystal, Smectic, Nematic, Mesogen, Mesomorphism.