SmCP phases chiral structure

FIGURE 6.9 (a) AF and FE switching in SmCP phases formed by bent-core molecules (b) two basic switching mechanisms switching around the molecular long axes (A) reverses layer chirality, and switching on a smectic cone (B) retains layer chirality. The polar direction is not illustrated in (b) since it can be either parallel or antiparallel to the bend direction depending on the molecular structures. 

Since most of bent-core mesophases (e.g., Bl, B2, B5, B7, B7-like, and B8) possess intrinsic polar order, they are responsive upon applying an external stimulus such as an E-field, exhibiting either AF or EE switching or both. In this section, the author will focus on polar SmCP phases including B2 and DC, SmAP, and polar Col phases and review their field-induced switching, chirality transformation, and structural transformation. 

Textures in the SmCP phase, (a) 4-Chloro-l,3-phenylene bis[4-4(4-octyloxy phenyliminomethyl) benzoates in the chiral state (b) the same material in the racemic state (both at 125°C) (c) a sulphur-containing material B-IO(S) at 120°C and at 130°C (d). The domains with red color comespond to anticlinic structure, whereas those with green color have syncHnic structure. Bar 100 im. 

Sketch of the racemic and chiral structures of the SmCP phase of achiral banana-shape molecules in antiferroelectric (at E = 0) and ferroelectric (at E > Etj, 5 V/ om) states. Left column Racemic structure, in which the chirality alternates in the adjacent layers. The APE domains are synclinic with coexisting opposite tilt directions. Right column chiral structure, in which the adjacent layers have the same handedness, but domains of different chirality coexist. The shading illustrates the bent or tilted shape of the molecules (brighter parts are closer to the reader). R (L) is the chirality descriptor corresponding to right (left(-handed layer conformations. 

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