Post-synthetic modification of a metal-organic framework with a chemodosimeter for the rapid detection of lethal cyanide via dual emission

A new Hf(iv) based metal-organic framework with the UiO-66 (UiO = University of Oslo) topology was preparedviaa standard modulated solvothermal reaction. The weakly emissive MOF material was well characterizedviavarious analytical techniques. The parent MOF was then post-synthetically modified with a highly emissive pyrene based chemodosimeter probe without altering the parent framework structure. The incorporation of the chemodosimeter in the modified MOF material was successfully confirmed by using FT-IR and(1)H NMR spectroscopy. The emission behaviour of the parent MOF was changed drastically with a noticeable colour change after post-synthetic modification. After modification, the MOF material showed a very selective colorimetric and fluorometric dual-emissive response towards lethal cyanide ions. A large blue shift (Delta lambda= 127 nm) was observed in the emission spectra which can be also visualized with the naked eye under a hand held UV lamp. The presence of a vinyl functional group in the chemodosimeter can serve as a potential nucleophilic reaction centre, which was also confirmed by the DFT calculations. The reaction based sensing mechanism of the MOF material was successfully confirmed by(1)H NMR spectroscopy. Furthermore, to apply the modified MOF material in real life, the test strip based sensing of cyanide in drinking water was demonstrated.