Eu3+/TFA Functionalized MOF as Luminescent Enhancement Platform: A Ratiometric Luminescent Sensor for Hydrogen Sulfide in Aqueous Solution

In this work, a facile and fast luminescence sensing platform for the ratiometric detection of hydrogen sulfide (H 2 S/HS − ) has been constructed by encapsulating the Eu 3+ /β-diketone chromophore into the host framework of MIL-140 (Eu 3+ /TFA@MIL-140C, TFA = 1,1,1-Trifluoro-2,4-pentanedione). It is well known that the energy transfer from the host framework or/and TFA to the Eu 3+ ions can be disturbed easily by some metal ions, such as Cu 2+ ions. Therefore, the ratiometric sensor was constituted with the Eu 3+ /β-diketone moiety as the response signal and the host framework moiety as the reference signal. Furthermore, on the basis of the hard–soft acid–base theory, the Cu 2+ ions could be rapidly caught by HS − , profiting from the low solubility of CuS, realizing the real-time detection by luminescence color change. This sensor shows remarkable property on the detection of H 2 S (HS − in water solution) with low limit of detection (LOD = 7.43 μM) and short response time (< 0.5 min). The good linearity between luminescent intensity and concentration makes the luminescent ratio meter feasible.