Rewritable optical memory in liquid crystals containing photo-epimerizing Cr(III) complexes.

We describe herein a concept of optical memory using a photosensitive metal complex, [Cr((-)-tfac)3] ((-)-tfac = (-)-3-trifluoroacetylcamphorato), as a dopant to induce chiral nematic phases. The memory was written by the photo-epimerization of the complex and read-out in terms of circular dichroism spectra. The rewritability of the memory was attempted by using the cycles between liquid crystals and isotropic phases.