Tuning the helical twisting power of nematic liquid crystals induced by chiral 1,2-propanediol derivatives using varied substituents

In this study, a novel series of chiral 1,2-propanediol derivatives with different electron-donating and electron-withdrawing groups were synthesized and characterized by FT-IR and 1H NMR. The helical twisting properties of all the chiral dopants were investigated by doping the chiral dopants into a nematic liquid crystal host (SLC-1717). The results indicate that the donor-acceptor electron effect have a prominent influence on helical twisting property of the chiral nematic phase induced by the chiral dopants. Introducing electron-withdrawing groups into the terminal ends of chiral 1,2-propanediol can decrease the absolute values of the helical twisting power. In addition, the helix inversion temperatures of the induced chiral nematic phase are variational with the change of terminal groups.