A highly selective regenerable optical sensor for detection of mercury(II) ion in water using organic-inorganic hybrid nanomaterials containing pyrene

A novel fluorescent chemosensing hybrid material (Py-SBA-15) for detecting Hg2+ ions in water was prepared through the functionalization of mesoporous silica (SBA-15) with a modified fluorescent chromophore, 1-(4'-hydroxyphenyl)-4-pyrenyl-2,3-diaza-1,3-butadiene (Py-OH). Py-OH covalently grafted to the coupling agent 3-(triethoxysilyl)propylisocyanate (TESPIC) was used as the precursor for the preparation of mesoporous hybrid material. The XRD data and TEM images of Py-SBA-15 confirm that the hexagonal ordered mesoporous structure is preserved after functionalization. Py-SBA-15 demonstrates a high selectivity for Hg2+ ions in the presence of other metal ions, which results from a dramatic fluorescence enhancement by the addition of Hg2+ ions upon the suspensions of Py-SBA-15. A good linearity (R-2 = 0.9989) between the fluorescence intensity of Py-SBA-15 and the concentration of Hg2+ ions is constructed, and a satisfactory detection limit of 1.7 x 10(-7) g mL(-1) is obtained. More importantly, Py-SBA-15 shows good regenerative ability due to the greatly minimized leaching effect of the sensing molecules by covalent grafting strategy. These results presented in this paper indicate that this hybrid material could be a promising fluorescence chemosensor for detecting Hg2+ ions.