Oxymethylene-bridged negative liquid crystal has been widely used in VA-TFT mixtures owing to its relatively large negative dielectric anisotropy, low viscosity and good phase solubility with other liquid crystals. However, the long synthetic route and difficulty in purification have been obstacles in application. In this paper, three oxymethylene-bridged negative liquid crystal compounds were synthesized via the etherification reaction of 4-ethoxy-2, 3-difluorophenol with different alkylbenzene sulfonate. The method effectively avoids impurity resulting from the introduction of halogen ions in conventional method. All key compounds were characterized by 1 H NMR spectroscopy. The liquid crystal properties, such as phase transition temperature, optical anisotropy and dielectric anisotropy were measured by DSC, TPOM and LCR testing analyzer.
As established previously [ 12 ], the hydrolases do not recognize dinucleoside triphosphates as substrates. Thus, it was to be expected that the oxymethylene analogs of Ap 3 A – compounds 1 and 2 – would not be degraded. The absence of any detectable hydrolysis of compounds 4 and 6 suggests that the enzymes tolerate neither a -CH 2 -P α - sequence, which occurs in 4 , nor a -CH 2 -P γ -CH 2 - sequence, as in 6 . Apparently, ‘the frameshift’ is unable to accommodate two oxymethylene inserts, as occurs in 6 .