Tilt of the π-conjugated rods in square honeycombs leads to a phase transition being related to the SmA–SmC transition and to an inversion of birefringence in the temperature range of the tilted honeycombs.
Abstract The phase diagram and the 35Cl NQR spectrum of (ClH2C)2(CH3)C -COOH have been studied in the temperature range 77 ≤ T/K ≤ melting point (343.8 K). On heating no phase transition appears. The cooling cycle shows strong undercooling of the melt, a phase transition at Tm → I = 319.9 K and a transition from the orientationally disordered phase I to the ordered phase II at TI → II = 297.2 K.The 35Cl NQR spectrum is a doublet with negative temperature coefficients within the temperature range covered, showing no phase transition in the heating cycle. At 77 K (298 K) the frequencies are in MHz: γ1 = 34.830 (34.140); γ2 = 34.018 (33.258).The ordered solid crystallizes in the space group Pbca, Z = 8, a = 1019.7 (3) pm, b = 1146.3 (3) pm, c = 1293.8 (3) pm. Phase I (plastic phase) is cubic face centered, a = 911 pm, Z = 4.
Spontaneous emergence of chirality is a pervasive theme in soft matter. We report a transient twist forming in achiral nematic liquid crystals confined to a capillary tube with square cross...
Emergence and stabilization of transient twisted defect structures in confined achiral liquid crystals at a phase transition.