A series of symmetrical dimers bearing heterocyclic ring, α,ω-bis(4-pyridine-3-methylideneaminoxy)alkanes, were prepared and all the members are differed by the spacer length, CnH2n, where n = 6, 8, 10 and 12. Their transition temperatures and mesophase characteristics were studied by differential scanning calorimetry and optical polarizing microscopy techniques. DSC thermograms exhibited direct isotropization and recrystallization during heating and cooling cycles, respectively. The crystal phase texture changed to dark region isotropic without displaying any mesophase. The influence of molecular structure on the mesomorphic properties of symmetrical dimers was studied.
Key words: Schiff base, dimer, pyridine, phase transition, synthesis.
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