Bistable linear electro-optical switching in the B7′ phase of novel bent-core molecules

Abstract

Three novel symmetrical bent-core compounds were synthesized where the terminal alkoxy linkages of the original bent-core mesogen forming a B₂ phase was converted to n-alkyl carboxylates. It is found that instead of the B₂ phase, all three compounds exhibit a transition between B₇′ and B₂ mesophases. The physical and electro-optical properties have been investigated by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and electric field experiments. The higher temperature B₇′ phase has been shown to exhibit bistable but analogous linear electro-optical switching without any observable polarization peak. We analyze two theoretical models and find that a local triclinic symmetry may be responsible for the unusual electro-optical switching.