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

Abstract

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⁺ β-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.