Photo and electrically switchable B7 mesophase exhibiting asymmetric bent-core liquid crystals

Abstract

The first bent-core liquid crystal materials with a photo-active azo linkage exhibiting the B₇ mesophase are reported. The lower homologues of the bent-core compounds display the B₁ phase and higher homologues show the B₇ mesophase. The mesomorphic properties were characterized using polarized optical microscopy, differential scanning calorimetry and X-ray diffraction. The B₇ phase of these materials establishes ferroelectric switching characteristics with anticlinic organization (SmC_AP_F) of the molecules in the layers. The bent-core molecules with an azo linkage are important for photoisomerization studies, which indicate trans to cis isomerization at 30 s, whereas the reverse processes take place over 40 s in chloroform.