Metal-Organic-Framework-Based Chemosensor for Ultrafast and Ultrasensitive Detection of Pd Ions in Water, Real Specimens, and Test Strips.

A new ultrasensitive and ultrafast Al(III) metal-organic-framework (MOF)-based probe () was constructed to detect Pd ions. Extremely selective recognition of Pd ion was demonstrated by the guest-free compound (called ) using a fluorescence signal. The quenching in the fluorescence signal was observed due to the weak interaction between the linker alkyne-π bond and Pd. The mechanism of isophthalic alkyne-π and Pd interaction was systematically examined with the help of isothermal titration calorimetry (ITC), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. The response time of the MOF for sensing of Pd was 30 s, which is the lowest response time for MOF-based Pd sensing to date, with an ultralow detection limit (102 nM) and Stern-Volmer constant (4.39 × 10 M), evidencing the outstanding ability to sense Pd ion by this probe. The Pd detection limit falls among the lowest values. Activated MOF () also showed considerable recyclability up to five steps with a constant sensing ability. In different water resources (Milli-Q water, lake water, river water, and tap water), the probe also showed excellent sensing ability. A paper-strip device was developed for the applicability of our material for the real field sensing application of Pd. The relevance of is not only up to Pd, but it could also sense palladium in other possible oxidation states.