Effect of Laterally Substituted Methoxy Group on the Mesomorphic Behavior of Novel Ester Derivatives

To understand how molecular structure affects liquid crystal behavior with reference to the lateral methoxy group, a novel homologous series of liquid crystal derivatives was synthesized and analyzed. The homologous series consists of 12 derivatives (C₁–C₁₆), of which the first five homologs (C₁–C₅) are not liquid crystals, while the remaining homologs (C₆–C₁₆) are enantiotropically smectogenic liquid crystals without exhibiting the nematic phase. The average thermal stability of the smectic phase is 77.85°C, and the mesophase length ranges from 4 to 17°C. The molecular structures were verified by analytical and spectral data. The liquid crystal properties of the novel series were compared with those of structurally similar known homologous series. The transition temperatures were determined by an optical polarizing microscope equipped with a heating stage.