Periodic mesoporous organosilica based sensor for broad range mercury detection by simultaneous downshifting/upconversion luminescence

Recent research in lanthanide materials has strongly contributed to the development of high-performance chemical sensors. However, the current reported high-responsive chemical sensors still have a limited detection range, restraining their further application. We developed lanthanide-based periodic mesoporous organosilica (LnPMO) hollow spheres with interior lanthanide-doped fluorides for luminescence turn-off sensing of Hg2+ with a low detection limit and wide detection range. This yolk-shell structure was built of Tb3+ grafted diureido-benzoicacid PMO (shell) and lanthanide-doped fluoride NaYF4:Yb,Er (yolk), exhibiting both downshifting (DS) and upconversion (UC) luminescence. Visible photoluminescence properties of the developed hybrid material were studied using UV and near-infrared (NIR) excitation. In DS mode, benzoic acid-functionalized PMO acts as an organic co-sensitizer for Tb3+ beta-diketonate complexes, which can significantly enhance the ion sensing and detection range. In UC mode, Hg2+-responsive rhodamine B thiolactone (RBT) was used as an antenna species for the lanthanide-doped fluorides to sense Hg2+ with high sensitivity.