Mesogenic Homologous Series Containing Chloro Group as Ortho and Para Substituent

Two mesogenic homologous series 4(4′-n-alkoxy benzoyloxy benzylidene)-4″-chloroanilines and 2”-chloroanilines are synthesized. All the members of both the series are mesogenic in nature. Series having terminal chloro substituent is highly smectogenic. Smectic mesophase commences from the propoxy derivative and dodecyloxy derivative onwards all the members exhibit only smectic mesophase. In the case of the series where chloro group is ortho to azomethme linkage, the smectic mesophase commences from hexadecyl derivative. Melting points and transition temperatures of series having terminal chloro group are higher than that of the ortho substituted one. The thermal stabilities of both the series are compared with other structurally related homologous series.