Some of 3, 5, 8-tri (donor) substituted-1, 4-naphthoquinonoid dyes show the novel dichroic properties which is applicable for color-switching liquid crystal display. These dyes have two independent benzenoid and quinoid absorption bands in visible region, and each of the band show the order parameter of positive and negative value, respectively. The transition moments calculated by means of the PPPMO method disclose that the polarization directions of the benzenoid band is x-axis, and that of the quinoid band is y-axis, respectively. The relationship between the dichroism and the absorption spectra of these dyes are discussed from the results of excitation wavelength, order parameter and polarized angle θ.
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