The invention relates to cinnamic acid derivatives of formula S wherein the radicals have the meaning indicated in claim 1, to a process for their preparation and their use as self assembling photoalignment agent in liquid crystal mixtures. The invention further relates to a process for the fabrication of a liquid crystal (LC) display device with homogeneous alignment by photoaligning a liquid crystal mixture with positive or negative dielectric anisotropy comprising one or more compounds of formula S and optionally a polymerizable compound, to the liquid crystal mixture comprising the self assembling photoaligning agent and optionally the polymerizable compound and to the LC display produced by said process.