Ln Based Meta-organic Framework for Fluorescence "Turn Off-On" Sensing of Hg2+

A highly luminescent Ln-MOF [La-3(NDC)(4)(DMF)(3)(H2O)(4)](n), (NDC = 2, 6 naphthalen dicarboxylic acid) was designed and synthesized. The structure was characterized by x-ray single structure determination, TGA, IR spectra and PXRD and fluorescence spectroscopy. The structure shows high fluorescence intensity based on the presence of lanthanide metal and ligand. In the presence of I-, the emission can be effectively quenched introducing turn off system. Furthermore, the synthesized Ln-MOF can recognize Hg (II) by showing fluorescence turn-on signal because of the high affinity between Hg (II) and I-. Moreover, the high selectivity and sensitivity of the synthesized Ln-MOF makes it quit qualified for determination of the low concentration of mercury (2.00 nM).