Stabilization of the blue phases of simple rodlike monoester compounds by addition of their achiral homologues

As novel rodlike liquid crystalline ester compounds exhibiting blue phases (BPs), chiral 4-(4′-alkoxyphenyl)phenyl 4-(4′-alkoxyphenyl)benzoate derivatives (R–C6H4–C6H4–OCO–C6H4–C6H4–R′), 1 (R = R′ = (R)-1-methylheptyloxy, BP range: 1.6 K on heating), 2 (R = (R)-1-methylheptyloxy, R′ = n-octyloxy, BP range: 0.8 K on heating), 4 (R = (R)-1-methylheptyloxy, R′ = H, BP range: 1.0 K on heating), were synthesized and their phase behaviors were investigated. Further, the BP of 1 was stabilized by addition of its achiral homologue ester compound 3 (R = R′ = n-octyloxy). In the range of the composite ratio of 1 : 3 from 10 : 0 to 0 : 10, the BP temperature range became wider with increase of the content of 3 in the mixture. At the ratio of 6 : 4, the BP indicated the widest temperature range in the mixing experiment (5.0 K on heating and 6.0 K on cooling).