Influence of difluoro lateral substitution on the mesomorphic and optical absorption of schiff base mesogens

A new series of difluoro-substituted analogues, 4-(((2,6-difluorophenyl)imino)methyl)phenyl 4-(x-alkyloxy)benzoates (DFPIMB-n), was synthesized to assess how lateral substitution and terminal alkoxy chain length affect mesomorphic behavior. Differential scanning calorimetry and polarized optical microscopy measurements confirmed that both compounds exhibit enantiotropic mesophases with remarkable thermal stability. The introduction of difluoro groups had a marked effect compared with their laterally unsubstituted analogues. In addition, we investigated the optical absorption thin films of a representative compound (DFPIMB- 12) as a function of thermal annealing at different temperatures. The data exhibited temperature-dependent differences in absorption intensity and a clear blue shift of the absorption band.