Effect of a lateral methyl group on azo-mesogens containing the naphthalene moiety

Two mesogenic homologous series, 2-[4-(4-n-alkoxybenzoyloxy)-2-methylphenyl azo]-naphthalenes (I) and 2-[4-(4-n-alkoxybenzoyloxy)-3-methylphenylazo]nap hthalenes (II) with a lateral methyl group have been synthesized. Both seri es are purely nematogenic. The mesomorphic properties of both series are co mpared with each other and also with the properties of other structurally r elated series to evaluate the effect of the lateral methyl group on mesomor phism. The chiral nematic (N*) mesophase was induced in the system by dopin g with a derivative of naturally occurring chiral menthol.