Water-Stable Eu-Cluster-Based fcu-MOF with Exposed Vinyl Groups for Ratiometric and Fluorescent Visual Sensing of Hydrogen Sulfide.

Detection of HS in the biological system has attracted enormous attention in recent years. In this work, a new vinyl-functionalized metal-organic framework (MOF), [(MeNH)] [Eu(μ-OH)(BDC-CH═CH)(HO)] (Eu-BDC-CH═CH, BDC-CH═CH = 2-vinylterephthalic acid), was synthesized under solvothermal conditions. The vinyl groups in the ligands can not only modulate the "antenna effect" of the ligand on Eu ions but also serve as an exposed reactive site to allow for the quantitative detection of HS by Eu-BDC-CH═CH. The ratiometric fluorescent probe has the advantages of water stability, acid-base stability (pH = 2-11), fast response (<2 min), high selectivity, and sensitivity (LOD = 38.4 μM). We also used Eu-BDC-CH═CH to detect and analyze HS in tap and lake waters, demonstrating the potential of the probe for biological and environmental applications. In addition, the MOF-based agarose hydrogel film allows for the visual detection of HS via a smartphone by identifying the RGB values. The vinyl-functionalized MOF can thus be a powerful sensing platform for HS.