Selective dual detection of H₂S and Cu²⁺ by a post-modified MOF sensor following a tandem process

Fabrication of metal-organic frameworks (MOFs) based multifunctional sensors for various environmental pollutants represents a promising solution to the development of novel monitoring technologies. In this work, a dual responsive sensor of UiO-66-MA has been efficiently fabricated via post-modification of the UiO-66-MOF with maleic anhydride (MA), and dual detection of H₂S and Cu²⁺ in aquatic environments has been achieved tandemly. UiO-66-MA could selectively undergo Michael addition with H₂S accompanying a linear fluorescence turn-on behavior. The sensing is highly sensitive and selective, and the detection limit value of 3.3 nM represents the lowest record among all MOF-based H₂S sensing researches. Moreover, an alternative sensor for Cu²⁺ could be further tandemly afforded after the H₂S sensing. The H₂S added product of UiO-66-MA/H₂S exhibits selective fluorescence quenching towards Cu²⁺ with a detection limit as low as 2.6 nM. UiO-66-MA exhibits dual sensing functions for H₂S and Cu²⁺ following a tandem process based on combinatorial principles of Michael addition and S-Cu coordination. Evaluation studies suggest the promising potentials of UiO-66-MA in determining the level of H₂S and Cu²⁺ in aquatic environment, and the tandemly derived dual sensing functions demonstrate the advantages of developing multifunctional MOF sensors based on combinatorial principles.