Orientational Order in n-alkyl-p-(4-ethoxy benzylidene amino)-α-methyl cinnamates

Abstract

The paper discusses the results of the calculation of the orientational order parameters and the Lorentz field factors from birefringence data in the case of the homologous series of compounds, n-alkyl-p-(4-ethoxy benzylidene amino)-α-methyl cinnamates. The order parameters are found to exhibit the well known zig-zag alternation with increase in the number of carbon atoms of the alkyl chain. The anisotropy (L_o-L_e ), of the Lorentz field factors also decreases with increasing number of carbon atoms indicating that as a consequence of the numerous conformations possible for the alkyl group, there is a reduction in the anisotropy of the polarization field. The calculated values of the optical anisotropy of the different molecules are approximately equal, indicating that the optical anisotropy arises mainly from the central rigid portion of the molecule and that the contribution of the alkyl chain to the optical anisotropy is not significant.