Fluorinated xanthenes and use thereof in liquid-crystal mixtures

摘要

Concerning the compound of the formula (I) R¹, R³ are each independently, for example, H R², R⁴ are each independently, for example, H X¹, X² are each independently H or F M¹ is -CO-O-, -O-CO-, -CH₂-O-, -O-CH₂-, -CF₂-O-, -O-CF₂-, -CH-CH-, -CF-CF-, -C≡C-, -CH₂-CH₂-CO-O-, -O-CO-CH₂-CH₂-, -CH₂-CH₂-, -CF₂-CF₂-, -(CH₂)₄-, -OC(-O)CF-CF- or a single bond A¹ is, for example, 1,4-phenylene, and R⁵ has the same possible definitions as specified for R² and R⁴, with the exception of -M¹-A¹-R⁵, but independently of the particular definitions of R² and R⁴ with the following provisos: 1) at least one of X¹, X² has to be F 2) R¹, R², R³ and R⁴ must not at the same time be H 3) at most two of R¹, R², R³ and R⁴ may be c).