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.