Highly selective fluorescent chemosensor for detecting Hg(II) in water based on pyrene functionalized core–shell structured mesoporous silica

Novel pyrene functionalized mesoporous core–shell structured silica (denoted as SiO2@mSiO2/Py-Si) was designed and synthesized as a highly selective fluorescent chemosensor for detecting Hg2+ in water. The core–shell structured silica was prepared by a simple sol–gel process through coating SiO2 nanospheres with a layer of ordered mesoporous silica. The surface of outer mesoporous silica shell was then further functionalized by the fluorescent chromophore alkoxysilane modified pyrene (Py-Si). XRD data confirmed that the hexagonal ordered mesoporous structure was preserved after functionalization. The chemosensing material successfully exhibited a remarkable “turn on” response toward Hg2+ over miscellaneous metal ions. A good linear response towards Hg2+ in the concentration range of 10−8–10−4 M was constructed with R2=0.9913. Most importantly, a satisfactory detection limit of 3.4×10−9 g mL−1 (down to ppb level) was obtained, which is 100 times lower than our previous report of covalently grafted Py-OH to the bulk mesoporous silica SBA-15. These results indicated that SiO2@mSiO2/Py-Si can be used as a highly selective and sensitive fluorescence sensor for Hg2+.