Luminophore-immobilized mesoporous silica for selective Hg2+ sensing

Novel mesoporous silica-immobilized rhodamine (MSIR) and silica particle-immobilized rhodamine (SPIR) anchored by a tren (N(CH2CH2NH2)3) were synthesized. The binding and adsorption abilities of both MSIR and SPIR for metal cations were investigated with fluorophotometry and ion chromatography, respectively. Both MSIR and SPIR show selectivity for Hg2+ ion over other metal cations because the Hg2+ ion selectively induces a ring opening of the rhodamine fluorophores. The sensitivity of the MSIR for Hg2+ ion is greater than that of the SPIR and the MSIR adsorbs 70% of Hg2+ ion while the SPIR does only 40%. The MSIR can be also easily recovered by treatment of a solution of TBA+OH−. For the application of Hg2+ detection in the environmental field, the MSIR-coated glass plate is also developed and exhibits an excellent function in visual and fluorescence changes with Hg2+ ion.