Influence of Linking Group Orientation on Mesomorphism of Two Aromatic Ring Mesogens

A new homologous series of alkyl 4-{[(4-chlorophenyl)imino]methyl}benzoates were prepared, and all the members are differentiate by the alkoxy chain length, CnH2n+1O, where n=2–7, 9, 11, 13, 15. Their phase transition behaviors and mesophase characteristics were studied by differential scanning calorimetry (DSC) and optical polarizing microscopy techniques. DSC thermograms show direct isotropization and recrystallization during heating and cooling processes, respectively. The crystal phase changed directly to dark area textures (isotropic phase) without displaying any mesophase. The mesomorphic properties of compounds studied are strongly dependent on the orientation of the ester linkage. Reversed ester linkage has caused depression of mesomorphic property in the compounds studied