Amino-Functionalized Metal-Organic Frameworks Nanoplates-Based Energy Transfer Probe for Highly Selective Fluorescence Detection of Free Chlorine

Novel highly fluorescent NH2-MIL-53(Al) was controllably synthesized by a facile one-step hydrothermal treatment of AlCl3 center dot 6H(2)O and NH2-H2BDC in water with urea as a modulator. The as-synthesized NH2-MIL-53(Al) nano-plates exhibited excellent water :solubility and stability. In the present work, it can be found that strong fluorescence of NH2-MIL-53(Al) nanoplates was significantly suppressed after the addition of free chlorine, and a simple sensing system for fast, highly selective direct detection of free chlorine in water was established. Compared with other, fluorescent sensors for free chlorine, the present methodology has a comparable detection limit of 0.04 mu M (S/N = 3) and a wide detection range of 0.05 to 15 mu M. On the other hand, the traditional redox-based fluorescent probes sharply suffered from the interference of MnO4-, Cr2O72-, and other oxidants with stronger oxidation capability than free chlorine while ours overcame this disadvantage. Further research suggests that it is more likely the energy transfer through. N-H center dot center dot center dot O-Cl hydrogen bonding interaction between amino group and ClO- ions plays the key role in our system, providing a new and promising platform for free chlorine determination in water quality monitoring.