MS32-P11 Altering the solid-state photochromic behavior of N-salicylideneanilines molecular switches by co-crystallizationN-salicylideneaniline derivatives are among the most studied man-made thermo- and photo-switchable systems. These systems can switch between three different colored forms: an enol colorless form, a yellow cis-keto form and a red trans-keto form. A thermal tautomeric equilibrium between the enol and cis-keto form accounts for their thermochromism, whereas a cis-trans photoisomerization between the cis-keto form and the trans-keto form is the mechanism behind their photochromism. Photochromism can lead to a broad range of applications, i.e. in information storage and electronic display systems or in optical switching devices like ophthalmic glasses. However, due to the volume requirements of the cis-trans photoisomerization, photochromism is not easily encountered in the solid state. For this reason, we have used co-crystallization with the aim to induce photochromism in a non-photochromic N-salicylideneaniline chromophore. Our results (single-crystal structures and UV-vis diffusion reflectance) reveal how co-crystallization can be successfully employed for this purpose due to the fact that it changes both the free available volume of each molecule in the crystal and the intermolecular interactions.[1,2]
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 Carletta, A, et al. (2016) J. Phys. Chem. C, 120, 10001–10008.
Keywords: Co-crystals, photochromism, N-salicylideneanilines