New (-)-menthol-based blue phase liquid crystals with different polar substituents in the terminal group: Synthesis, mesophase behaviors, and DFT calculations

•Eight novel CLCs MtLC-X were synthesized by varying the electron-donating/withdrawing substituents X in terminal groups.•The effect of polar group X on mesomorphic behaviros of chiral (-)-menthanol based CLCs was disscussed.•By DFT calculations the relationship between mesomorphic behaviros and polarizability anisotropy (Δα) was investigated.•The effect of polar group X on the formation of blue phase of CLCs MtLC-X were studied. Eight novel Schiff base ester chiral liquid crystals, MtLC-X (X: -OCH3, -CH3, -F, -H, -CF3, -OCF3, -NO2, -CN), were successfully synthesized and analyzed for their mesophase formation and stability. Each of them was attached to the end of (-)-menthol as a chiral group, and the other end of these molecules was connected with different polar substituent X. The chemical structures of the prepared compounds were characterized via FT-IR, 1H NMR and 13C NMR. The combination differential scanning calorimeter (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD) measurements were carried out to systematically study the characterization of mesomorphic properties. The photophysical property was studied by UV–vis spectroscopy. All the prepared CLCs, besides the H derivative, MtLCH, are mesomorphic exhibiting N* and/or SA* mesophase. The results revealed that the mesomorphic behavior and the clearing point of mesophase (Tc) correlate well with polarizability anisotropy (Δα). [Display omitted]