Colored and Black Liquid Crystalline Mixtures with New Antraquinone Dyes

Various yellow, red, and blue anthraquinone dyes have been synthesized. The structures of the dyes are presented and their properties are discussed with respect to the dichroic ratios, the color gamut, and the obtainable contrast in black colored liquid crystalline dye mixtures. Dichroic ratios of up to N = 10.2 in NP 1132 and ň = 12.3 in RO-TN 404 are calculated. The influence of the positions of the absorption bands on the perceived contrast is studied. It is shown that by shifting the absorption bands of the dyes, the effective dichoric ratio can be increased to N eff = 9.1 in NP 1132 and N eff = 11.4 in RO-TN 404