The invention relates to chiral photoisomerizable compounds of formula (I) wherein X?1, X2, X3, X4, X5 and X6¿ 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, inoptical elements like polarizers, retardation films, compensators, colour filters or holographic elements, in liquid crystal pigments and coloured films or coatings for decorative or security applications, cosmetic and pharmaceutical compositions, in nonlinear optics and optical information storage.