2,5-Diaryl-1,3,2-dioxaborinane derivatives having various terminal groups were synthesized and found to form mesomorphic phases in a wide temperature range. They provide a new series of liquid-crystalline compounds containing a boron atom in the principal structure.
Two homologous series of carborane-containing dioxanes 1[n] and 2[n] (n = 1–10) were prepared and their mesogenic properties investigated. All compounds exhibit nematic behavior and three members of series 2[n] show an E phase. Numerical analysis of the clearing temperatures gave a limiting value TNI(∞) of 89 °C for series 2[n] and indicated conformational flexibility of the dioxane ring. Investigations of three-ring derivative 1[4] gave Δn = 0.17, S = 0.53, and Δε = +0.4 ± 0.1 at 85 °C. Extrapolation of dielectric data for dilute solutions of 1[4] in 6-CHBT gave Δε = +0.4 ± 0.25 at 24 °C. Modelling of dielectric results with the Maier–Meier equation demonstrated that conformers with a higher β angle are preferred, which is consistent with conformational selection for the most elongated conformers.
A new series of liquid crystalline materials containing boron atoms
作者:Koji Seto、Shigetoshi Takahashi、Tadasu Tahara
DOI:10.1039/c39850000122
日期:——
The dioxaborinane derivatives, which were synthesized by a method including a new Pd-catalysed coupling reaction, form mesomorphic phases in a wide temperature range, and provide a new series of liquidcrystalline compounds containing a boronatom in the principal structure.