tellurium and carboxyl-radical

A novel nanohybrid ratiometric fluorescence probe comprised of fluorescent graphene oxide and quantum dots (QDs) has been prepared by bringing CdTe QDs of red fluorescence and fluorescent graphene oxide (FGO) of blue fluorescence together through electrostatic attraction and hydrogen bonding interaction between their surface functional groups including carboxyl and amine groups. The nanohybrid ratiometric fluorescence probe exhibits dual emissions at 450 and 650 nm under a single excitation wavelength and shows high sensitivity for the detection of ferrous ions in the presence of H₂O₂. Ferrous ions reacts with H₂O₂ to generate very reactive hydroxyl radicals which possess a strong oxidizing nature and easily capture the electrons from the surfaces of the CdTe QDs, leading to fluorescence quenching of the QDs and no effect on the fluorescence of the graphene oxide, which hence results in a great change of the fluorescence ratio. Moreover, the ratiometric fluorescence probe is not only extremely sensitive to ferrous ions, but is also selective over other biologically relevant metal cations. The changes of fluorescence colour ratios can be used for visual sensing applications for ferrous ions in the presence of hydrogen peroxide, and can also be used for the indication of the existence of hydrogen peroxide.

Topics: Amines; Cadmium; Carbon Dioxide; Ferrous Compounds; Fluorescent Dyes; Graphite; Hydrogen Peroxide; Quantum Dots; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium

Lanthanum salicylate and Tb3+ -doped lanthanum salicylate were synthesized with the rheological phase reaction method. Elemental analysis, IR, TG, DTA and powder X-ray diffraction were investigated to determine the composition, crystal structure and coordination manner between the COO- and ion La3+ of lanthanum salicylate. The emission and excitation spectra of Tb3+ -doped lanthanum salicylate were also discussed. Powder X-ray diffraction suggests that the compound has a layered monoclinic structure, and the lattice parameters are a = 21.6010 A, b = 13.8015 A , c = 3.8103 A, beta = 97.11 degrees, V = 1127.2 A3, Z = 2, rhocal = 1.621 g x cm(-3) and rhoexp = 1.653 g x cm(-3). The Tb3+ -doped lanthanum salicylate exhibits very strong green luminescence of Tb3+ under the excitation of UV light. And the transition from 5D4 to 7F5 is the strongest one.

Topics: Carbon Dioxide; Lanthanum; Light; Luminescence; Luminescent Measurements; Nanotechnology; Particle Size; Photochemistry; Salicylic Acid; Tellurium; Terbium; Ytterbium; Zinc Oxide