Ester-Substituted Anthraquinone Dyes Soluble in Nematic Liquid Crystal Mixtures

In liquid crystal mixtures of positive dielectric anisotropy, phenyl-substituted anthraquinones dyes have the properties required for Guest-Host applications. To display dark figures on a clear background (positive contrast), it is necessary to use mixtures of negative dielectric anisotropy. In these, the order parameters of the above mentioned dyes drop so much that they are not useful for practical applications. Ester derivatives have been synthesized in order to overcome this drawback. 3-Benzoyloxy-phenyl-and derivatives of 2-carboxy-substituted anthraquinones form a class of useful dyes for display applications.