2,5-substituted 1,3,4-thiadiazoles of the general formula ##STR1## The aforementioned compounds are used in amounts of 0.1 to 80 mole percent in mixtures for electrooptical arrangements for the modulation of transmitted and reflected light, as well as for the colored or black-and-white display of numerals, symbols and moving or still pictures. The compounds endow the liquid-crystalline mixtures with an extended phase field of the smectic C phase, negative dielectric anisotropy and the property of forming optically active C phases upon admixture with optically active compounds.
通式为##STR1##的2,5-取代的1,3,4-
噻二唑化合物,可用于电光装置的混合物中,用于调制透射和反射光的量为0.1至80摩尔百分比,以及用于数字、符号和动态或静态图像的有色或黑白显示。这些化合物赋予液晶混合物具有扩展的SmC相领域、负介电各向异性和与光学活性化合物混合后形成光学活性C相的特性。