No abstract

The mixed‐metal and mixed‐valance carboxylates of MFe2O(O2CCF3)6(C4H8O)2(H2O) (M = Zn, Mn, Cu) and MFe2O(O2CCCl3)6(C4H8O)2(H2O) (M = Zn, Fe) were utilized as potential precursors for the preparation of spinel. In the pyrolysis of ZnFe2O(O2CCF3)6(C4H8O)2(H2O) in air at 400 °C pure ZnFe2O4 is formed, in contrast to pyrolysis of the trichloro derivative, which resulted in the formation of ZnO and Fe2O3. In the pyrolysis of MnFe2O(O2CCF3)6(C4H8O)2(H2O) in nitrogen, MnFe2O4 was the main phase and single oxides were the minor phases. Copyright © 2005 John Wiley & Sons, Ltd.

Fluorene-functionalised nanoporous silica (FL-NH2-SBA-15) was prepared using the post-synthesis grafting method of SBA-15. The material thus obtained was characterised by means of small- and wide-angle X-ray diffraction, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, and elemental analysis. The results showed that the organised structure is preserved after the post-grafting procedure. Surface area and pore-size decreased by attaching functional groups to the pore surface. In addition, the pore volume was reduced with functionalisation. The amount of fluorene grafted onto the surface of SBA-15 was 0.55 mmol with a yield of approximately 46 %. The emission spectra of FL-NH2-SBA-15 in acidic media were studied and are discussed in detail. The structural change between FL-NH2-SBA-15 and the protonated form might be an effective candidate for acid-dependent molecular-sensor models for advanced application in molecular sensors in the future.

An bis(2-aminoethyl)-2-(9-fluorenyl)malonamide as fluorophore ligand was immobilized onto mesoporous silica type SBA-15 via post synthesis grafting. The obtained material was characterized by small and wide angle X-ray diffraction, N2 adsorption-desorption, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis that indicate the successful immobilization of the ligand on the surface of mesoporous silica. The sensing ability of the obtained material was studied by addition of the cations Fe(3+), Mg(2+), Cr(3+), Co(2+), Ni(2+), Cu(2+), Hg(2+) and Zn(2+) to water suspensions of the assayed solid. Of all the cations tested addition of Fe(3+) ion to a suspension of this material resulted in the largest decrease in the fluorescence intensity. Turn-off photoluminescence of this material was remarkably observed for iron ions in comparing of the other cations. A good linearity between the fluorescence intensity of this material and the concentration of Fe(3+) ion is constructed, which enables it as a fluorescence chemosensor for detecting the Fe(3+) ion with a suitable detection limit of 1.35 × 10(-5). It can be introduced as a novel fluorescent sensor in aqueous solution for a lot of practical applications in chemical, environmental and biological systems.

In this study, fluorene 3-[2-(2-aminoethylamino)ethylamino]propyl trimethoxy silane functionalized nanoporous SBA-15 was incorporated into carbon paste electrode for the potentiometric detection of Cu 2? ions in aqueous medium. With 15.5 wt% FT-SBA-15 proportion, the developed electrode exhibited wide dynamic range of 1.0 9 10 -6 -1.0 9 10 -2 mol L -1 toward Cu 2? with a detection limit of 5.0 9 10 -7 mol L -1 and a Nernstian slope of 29.6 ± 1.0 mV decade -1 . The electrode displayed rapid response (*44 s), long-term stability (more than 6 months) and high sensitivity. Moreover, the potentiometric responses could be carried out with a wide pH range of 3.9-6.6. Finally, the proposed electrode was successfully used as an indicator electrode in potentiometric titration of copper ions with EDTA and to determine the concentration of copper ions in seawater, tap water and black tea samples. The results showed a good correlation with the data obtained by graphite furnace atomic absorption spectrometry method.