PHYSICAL-PROPERTIES OF NEMATIC SCHIFFS BASES

The anisotropy of the diamagnetic susceptibility, the density and the entropy change at the nematic-isotropic transition of a number of structurally related Schiff's bases are reported. Order parameters have been calculated from the anisotropies of the susceptibility. The results indicate that there is a close correspondence between the order parameter and the relative volume charge at the nematic-isotropic transition. The experimental data suggest that there exists considerable flexibility of the alkylene chains both in the nematic and isotropic phases. The experimentally observed trends can be understood within the framework of theoretical models, which take account of molecular flexibility.