A Flexible Fluorescent Zr Carboxylate Metal-Organic Framework for the Detection of Electron-Rich Molecules in Solution

A novel Zr(IV) dicarboxylate metal organic framework (MOP) built up from an s-tetrazine derived ligand was prepared. This solid, which exhibits a diamond type network, combines a good stability in water, a structural flexibility, and fluorescence properties thanks to, the organic ligand. It is noteworthy that this fluorescence is quenched when exposed to electron-rich molecules in solution, such as amines or phenol, this phenomenon being associated with the adsorption of the quencher, as unambiguously proven by X-ray diffraction (XRD) analysis. Finally, the quenching efficiency is shown to be governed not only by electronic and steric factors but also by the relative polarity of the solvent, the MOF, and the quencher. This work thus suggests that it is possible to develop new MOF-based sensors presenting in a given medium (such as water) highly selective responses.