Novel examples of achiral bent-core azo compounds exhibiting B1 and anticlinic-antiferroelectric B2 mesophases

The first examples of achiral bent-core molecules consisting of an azo linkage and five aromatic rings exhibiting bent-core mesophases are reported. They exhibit B-1 and B-2 phases as identified by optical microscopy, differential scanning calorimetry, X-ray diffraction, and electro-optical techniques. The B-2 phase of these materials is identified to be the anticlinic-antiferroelectric, SmCAPA phase. The mesophases of these compounds have relatively low transition temperatures and wide temperature ranges. The observation of bent-core phases in azo compounds assumes significance from the fact that the introduction of the -N=N-linkage adds a new dimension, namely photochromism, to this field.