The dynamic structural and optical changes of Tb‐based metal–organic frameworks in the presence of aqueous fluoride solutions are reported in this work. The structural transformation of the MOF in the presence of fluorides was scrutinized by XRD, XAFS, and dynamic measurements of the Tb emission, and all the information was summarized in the development of a tech‐demo. The cover shows “The Great Wave off Kanagawa” hinting at the flow between the different but connected states of the MOF when the fluoride concentration increases, first increasing the emission by replacement of Tb−OH groups in the MOF by Tb−F and later quenching the emission by the formation of TbF3. The cover image was designed by ScienceBrush Design. More information can be found in the Full Paper by E. H. Otal, M. Kimura, et al. (DOI: 10.1002/chem.202005222).