A mesoporous silica functionalized by a covalently bound calixarene-based fluoroionophore for selective optical sensing of mercury(II) in water

With the aim of optical sensing of Hg2+ in water, a calixarene bearing two dansyl fluorophores was grafted on a large pore mesoporous silica material (SBA-15) via two long alkyl chains containing triethoxysilane groups. The characterization of the obtained material 2-SBA-15 shows that the organized structure is preserved after the post-grafting procedure. A detailed study of the complexing and fluorescence properties of 2-SBA-15 is reported. The functionalized material is able to reversibly detect Hg2+ with a response time of a few seconds and a detection limit of 3.3 x 10(-7) mol L-1 in water. Furthermore, this system offers a high selectivity over several interfering cations (Na+, K+, Ca2+, Cu2+, Cd2+, Pb2+).