Porphyrinic Metal-Organic Framework Catalyzed Heck-Reaction: Fluorescence Turn-On Sensing of Cu(II) Ion

It is of great importance for the highly selective, rapid, and sensitive detection of Cu(II) ion, as copper is an essential element in the environment and the human body, and exposure to high concentrations of Cu(II) will potentially cause health issues. In this work, we have developed a novel catalytic Heck reaction system based on Pd(II)-porphyrinic metal-organic framework (MOF), PCN-222-Pd(II), to generate highly fluorescent product in the presence of Cu(II). In this system, the achieved signal enlargement toward Cu(II) with high sensitivity not only takes advantage of a stronger binding affinity of Cu(II) over Pd(II) to the nitrogen atoms in the porphyrin, but also a rapid Pd(0)-catalyzed Heck-reaction triggered by the addition of Cu(II) ion. Compared with the previous detection methods, the current fluorescence turn-on approach not only realizes highly selective and sensitive detection of Cu(II) in aqueous solution, but also is able to separate the Cu(II) from the system. This work would open up a new door for MOF applications in the detection of metal ions in complex environments.