Bent-shaped mesogens without an azomethine joint

A new series of banana-shaped mesogens with ethylene links in the branches and laterally substituted are presented. They form B-1, B-2, B-6 and B-7-like phases. The B-7-like and B-2 phases are not miscible although identical crystallographic structures are deduced from X-ray studies. The switching in the B-7-like phase is without a threshold and occurs only in a small number of domains. Dielectric measurements do not confirm ferroelectric properties for the B7-like phase, and only a weak non-collective relaxation process was observed. In the B-2 phase a collective and weak dielectric mode was detected. The B1 phase exhibits a columnar structure with a large rectangular cell 111.6 x 51 Angstrom(2).