Enhancing Birefringence by Doping Fluorinated Phenyltolanes

We have designed, synthesized, and evaluated the physical properties of some high birefringence (Delta n) isothiocyanato phenyltolane and quaterphenyl liquid crystals. These compounds exhibit Delta n similar to 0.48-0.52 at room temperature and wavelength lambda = 633 nm. Laterally substituted short alkyl chains and fluorine atom eliminate smectic phase and lower the melting temperature. The moderate melting temperature and very high clearing temperature make those compounds attractive for eutectic mixture formulation. These compounds can be used as dopants for color-sequential liquid crystal displays or eutectic mixtures for laser beam steering.