Mesomorphic, dielectric, and optical properties of fluorosubstituted biphenyls, terphenyls, and quaterphenyls

Abstract

Compounds with moderate and large negative dielectric anisotropy (Δɛ) are very attractive liquid crystal (LC) for vertical alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic molecule. We synthesized some new LC materials with a negative value of Δɛ, a moderately high birefringence (Δn), and a low viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δɛ∼−3.25 will be presented.

66.2: Effects of Diluters on High Δn and Low Viscosity Negative Δε Liquid Crystals

“…Laterally fluorinated terphenyl compounds exhibit a high birefringence and relatively low rotational viscosity [11,12]. Therefore, they may be a good candidate for improving the LC response time thru cell gap reduction while no penalty will be paid in rotational viscosity.…”

Characterization of Some Fluorinated Mesogens for Application in Liquid Crystal Displays

“…Usually the decrease of the melting point and reduction of viscosity is observed. The fluoro-substituted liquid crystals are characterized by good optical and chemical stability, extended mesophase range, low viscosity, high specific resistance, low threshold voltage [1][2][3]. Due to their unique physical and material properties they are of great interest as components of mixtures for twisted nematic (TN) or supertwisted nematic (STN) liquid crystal displays, especially with the use of thin film transistor (TFT) technology [4,5].…”

Liquid Crystals and their Applications in the THz Frequency Range

“…In negative dielectric anisotropic (NDA) LCs, the different dielectric anisotropic behavior is, for example, caused by the laterally substituted cyanide (CN) or fluorine (F) groups [57][58][59]. As a result, a strong permanent dipole moment is formed in the direction perpendicular to the molecular long axis.…”

“…Like its PDA counterpart (BL037), 1808 is designed to have a high optical birefringence. The mixture consists of difluoroalkylterphenyls and alkyl-alkoxytolanes [59,62,85] (Roman Dabrowski, Military Technical Academy of Warsaw). Its THz properties are presented in Fig.…”