the invention relates to chiral photoisomerizable compounds of formula wherein x 1 , x 2 , x 3 , x 4 , x 5 and x 6 have the meanings given in claim 1 , to liquid crystalline mixtures and polymers containing them , and to the use of chiral photoisomerizable compounds , liquid crystalline mixtures and polymers containing them in optical and electrooptical devices like liquid crystal displays or projection systems , in optical elements like polarizers , retardation films , compensators , color filters or holographic elements , in liquid crystal pigments and colored films or coatings for decorative or security applications , cosmetic and pharmaceutical compositions , in nonlinear optics and optical information storage .