| 摘要 |
<p>New liquid crystals of the diester type are of formula (I) (in which R1 is CnH2n+1 or CnH2n+1O when n is 1-10; R2 is CmH2m+1 where m = 1-10; the combination X/Y denotes H/Br, H/CN, Br/Cl, CN/Cl or Br/CN respectively. R1 is pref. C8H17O, C7H15O, C6H13, or C817; R2 is pref. C5H11. A pref. compsn. contains a mixt. of cpds. in which X is H, Y is Br, R2 is C5H11, and R1 is C8H17 (28 mol.%), C6H13 (36 mol.%) and C7H15 (36 mol.%) USE/ADVANTAGE : Cpds. are used in electro-optical display panels employing dynamic light feathering, or field effect with information storage, or double frequency action. These cpds. have dielectric isotropy at very low frequencies. The anisotropy may be positive at low frequencies and, at higher frequencies, a negative dielectric anisotropy, which can be very high. These cpds. contain in most cases >=1 nematic mesomorphic phase and, usually >=1 smectic mesomorphic phases.</p> |
