Metal-organic framework film for fluorescence turn-on H2S gas sensing and anti-counterfeiting patterns

Hydrogen sulphide (H2S) is a common air pollutant, which is produced in various industry processes. Therefore, it is of crucial importance to detect H2S in real time. Many fluorescent sensors were reported aiming at detecting H2S in solution; however, the fluorescence sensing of gaseous H2S has not yet been reported. In this work, we utilized the post-functionalized fluorescent film, MIL-100(In) @Eu3+/ Cu2+ film, realizing fluorescence turn-on sensing of gaseous H2S at room temperature for the first time with the limit of detection as low as 0.535 ppm, which is comparable to some reported fluorescent probes for S2− ions and semiconductor based gaseous H2S sensors. The sensor was designed due to the strong affinity of H2S with Cu2+. With the formation of CuS, the “antenna effect” between the ligand and Eu3+ recovered, resulting in the fluorescence turn-on of Eu3+ emission. Additionally, we proposed a new method to realize multi-colour anti-counterfeiting patterns with lanthanide ions ink, taking advantage of the extraordinary smooth surface and uncoordinated carboxylate groups within the MIL-100(In) film.