New banana-shaped mesogens with bromine-substituted central core

Banana-shaped five-ring mesogens derived from either isophthalic acid or 4-bromoisophthalic acid have been synthesized. It is shown that the melting and clearing points of the bromine-substituted compounds are markedly decreased in comparison with the analogous unsubstituted compounds. On the basis of X-ray diffraction studies and NMR measurements, as well as dielectric and electro-optical investigations, the mesophase of these compounds could be identified as a B-2 phase.