Synthesis and study of new mesogenic homologous series : 4-( 4'-n-alkoxybenzoyloxy )-3-methylphenylazo-4"-bromobenzenes

Matushri Virbaima Mahila Science and Home Science College, Kalavad Road, Rajkot-360 00 I, India Manuscript received 14 May 2002, revised 11 May 2004, accepted 22 July 2004 A new homologous series of liquid crystals viz. 4-(4'-n-alkoxybenzoyloxy)-3-methylphenylazo-4"-bromobenzenes comprising of twelve mesogens have been synthesized. It is a high melting series of mesogens. The nematic type mesophase commences from the very first member of the series. Smectic and nematic mesophases are exhibited by tenth homologue. Dodecyl, tetradecyl and hexadecyl derivatives are purely smectogenic. Nematic mesophase shows threaded texture while smectic mesophase shows focal conic fan shaped texture. The usual odd-even effect is observed in nematic-isotropic transition curve. The smectic-isotropic transition curve rises gradually and falls smoothly at the hexadecyl homologue. The mesomorphic range is wide. The thermal stability and mesomorphic characteristics are compared with structurally similar homologous series