A novel homologous series of liquid crystals, viz., 4-[4’-n-alkoxy Benzoyloxy ] β-Methoxy Ethyl Benzoates has been synthesized. The series consists of eleven homologs. The methyl to butyl derivatives are not liquid crystalline and the rest of the homologs are enantiotropic liquid crystals. The octyl and decyl derivatives of the series are enantiotropically smectogenic in addition to nematogenic in character, but the Pentyl, hexyl,dodecyl, tetradecyl, and hexadecyl homolog derivatives of the series are only nematogenic without the exhibition of a smectic phase. The transition temperatures of the novel substances were determined by optical polarizing microscopy equipped with a heating stage. A plot of transition temperatures versus the number of carbon atoms present in the n-alkoxy terminal chain represents the phase behavior of the series. An odd-even effect is observed for the nematic-isotropic transition curve. The textures of the nematic phase are of a threaded or Schlieren type and those of the smectic A phases are typical. Analytical and spectral data agree with the molecular structures. The smectic and nematic thermal stabilities are 179.0 ºC and 196.28 ºC, respectively. The smectic phase commences from the octyloxy homologue and Nematic mesophase commences Pentyl homologue. Smectogenic phase lengths vary from 15.0 ºC to 17.0 ºC and the nematogenic phase lengths vary from 7.0 ºC to 33.0 ºC. The series is predominantly nematogenic and partly smectogenic with considerable mesophase length and a middle-ordered melting type. The liquid crystal properties of the present series are compared with structurally similar homologous series.
