Different morphological organic-inorganic hybrid nanomaterials as fluorescent chemosensors and adsorbents for CuII ions

Functionalized silica nanotubes (FSNT), functionalized mesoporous silica (FMS), and functionalized silica nanoparticles (FSNP-15) with an immobilized phenanthroline moiety as a fluorescent receptor were fabricated by a sol-gel reaction, and their binding abilities with metal ions were evaluated by fluorophotometry in water/acetonitrile (8:2, v/v) at pH 7. They selectively recognized Cu2+ ions among other metal cations such as Co2+, Cd2+, Hg2+ Ni2+, Fe3+, Ag+, Ph2+, and Zn2+, because the Cu2+ ion selectively binds to the nitrogen atoms of the phenanthroline moiety. Among the three silica nanomaterials with the immobilized receptor 1, the sensitivity of FSNT for Cu2+ ions is better than those of EMS and FSNP-15, indicating that the adsorption capacity for metal ions is dependent on the shape and surface area of the supporting nanomaterials. FSNT (10 mg) adsorb 75 % of the Cu2+ ions (2.0 x 10(-4) mm) while FSNP-15 (10 mg) adsorb only 36%. The detection limit of FSNT for Cu2+ ions was ca. 3.0 x 10(-8) m. FSNT and EMS can be easily renewed by treatment with a solution of HCl and tetrabutylammonium hydroxide. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).