A new hybrid polyhedral cubic silsesquioxane chemically modified with 4-amino-5-(4-pyridyl)-4H-1,2,4-triazole-3-thiol (APTT) and copper hexacyanoferrate(III) for voltammetric determination of nitrite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synthesis, crystal structure and photoluminescence of a binuclear complex of europium(III) containing 3,5-dicarboxypyrazolate and succinate

The new europium binuclear complex [Eu2(dcpz) 2(suc)(H2O)8]·(H2O) 1.5 (dcpz = 3,5-dicarboxypyrazolate and suc = succinate) has been synthesized and structurally characterized by single crystal X-ray diffraction methods. The binuclear complex crystallizes in the triclinic space group P1̄ and consists of two lanthanide ions linked by two different bridging organic ligands. 3D supramolecular framework is constructed by hydrogen bonds. The compound shows strong red emission under UV excitation at room temperature associated to IL transitions indicating a ligand to metal energy transfer mechanism since the triplet energy level lies higher than that of europium 5D0 level. Magnetic susceptibility studies showed weak temperature dependence characteristic of the Van Vleck paramagnetism. © 2013 Elsevier Ltd. All rights reserved.

CYP-450 isoenzymes catalyze the generation of hazardous aromatic amines after reaction with the azo dye Sudan III

This work describes the mutagenic response of Sudan III, an adulterant food dye, using Salmonella typhimurium assay and the generation of hazardous aromatic amines after different oxidation methods of this azo dye. For that, we used metabolic activation by S9, catalytic oxidation by ironporphyrin and electrochemistry oxidation in order to simulate endogenous oxidation conditions. The oxidation reactions promoted discoloration from 65% to 95% of Sudan III at 1×10-4molL-1 and generation of 7.6×10-7molL-1 to 0.31×10-4molL-1 of aniline, o-anisidine, 2-methoxi-5-methylaniline, 4-aminobiphenyl, 4,4'-oxydianiline; 4,4'-diaminodiphenylmethane and 2,6-dimethylaniline. The results were confirmed by LC-MS-MS experiments. We also correlate the mutagenic effects of Sudan III using S. typhimurium with the strain TA1535 in the presence of exogenous metabolic activation (S9) with the metabolization products of this compound. Our findings clearly indicate that aromatic amines are formed due to oxidative reactions that can be promoted by hepatic cells, after the ingestion of Sudan III. Considering that, the use of azo compounds as food dyestuffs should be carefully controlled. © 2013 Elsevier Ltd.

Spectroscopic study and thermal behavior of trivalent lanthanides and yttrium(III) chelates of EDTA using TG-DSC, FTIR, and TG-DSC coupled to FTIR

Solid-state compounds of yttrium and lanthanide chelates of ethylenediaminetetraacetic acid have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), theoretical and experimental infrared spectroscopy (FTIR), elemental analysis, complexometry and TG-DSC coupled to FTIR were used to characterize and to study the thermal decomposition of these compounds. The results provided information about the composition, dehydration, thermal stability, thermal decomposition and identification of gaseous products evolved during the thermal decomposition of these compounds. The theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the lanthanum and terbium metal ions. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Synthesis, thermal behavior and spectroscopic study of trivalentlanthanide and yttrium(III) α-hydroxyisobutyrates, in solid state

Thermal and spectroscopic studies on solid trivalent lanthanides and yttrium(III) α-hydroxyisobutyrates, Ln(C4H7O 3)3·nH2O were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), elemental analysis, X-ray diffractometry, complexometry, experimental and theoretical infrared spectroscopy and TG-DSC coupled to FTIR. The dehydration of lanthanum to neodymium and terbium to thulium and yttrium compounds occurs in a single step while for samarium, europium and gadolinium ones it occurs in three consecutives steps. Ytterbium and lutetium compounds were obtained in the anhydrous state. The thermal decomposition of the anhydrous compounds occursin two consecutives steps, except lanthanum (five steps) and cerium (single step), with formation of the respective oxides CeO2, Pr6O 11, Tb4O7 and Ln2O3 (Ln = La, Nd to Lu and Y), as final residue. The resultsalso provided information concerning the composition, thermal behavior, crystallinity and gaseous products evolved during the thermal decomposition. The theoretical and experimental spectroscopic data suggested the possible modes of coordination of the ligand with the lanthanides.© 2013 Elsevier B.V.

Synthesis, structural characterization and photophysical properties of highly photoluminescent crystals of Eu(III), Tb(III) and Dy(III) with 2,5-thiophenedicarboxylate

Lanthanide compounds of general formula [Ln2(2,5-tdc) 3(dmf)2(H2O)2] ·2dmf·H2O (Ln = Eu(III) (1), Tb(III) (2), Gd(III) (3) and Dy(III) (4), dmf = N,N′-dimethylformamide and 2,5-tdc2- = 2,5-thiophedicarboxylate anion) were synthesized and characterized by elemental analysis, X-ray powder diffraction patterns, thermogravimetric analysis and infrared spectroscopy. Phosphorescence data of Gd(III) complex showed that the triplet states (T1) of 2,5-tdc2- ligand have higher energy than the main emitting states of Eu(III), Tb(III) and Dy(III), indicating that 2,5-tdc2- ligand can act as intramolecular energy donor for these metal ions. An energy level diagram was used to establish the most relevant channels involved in the ligand-to-metal energy transfer. The high value of experimental intensity parameter Ω2 for the Eu(III) complex indicate that the europium ion is in a highly polarizable chemical environment. The emission quantum efficiency (η) of the 5D0 emitting level of Eu(III) was also determined. The complexes act as possible light conversion molecular devices (LCMDs). © 2013 Elsevier B.V. All rights reserved.

Structure, characterization and near-infrared emission of a novel 6-connected uninodal 3D network of Nd(III) containing 2,5-thiophenedicarboxylate anion

The novel coordination polymer with the formula {[Nd2(2,5-tdc)3(dmf)2(H2O)2].dmf.H2O}n (2,5-tdc2-=2,5-thiophedicarboxylate anion and dmf=dimethylformamide) has been synthesized and characterized by thermal analysis (TG/DTA), vibrational spectroscopy (FTIR) and single crystal X-ray diffraction analysis (XRD). Structure analysis reveals that Nd(III) ions show dicapped trigonal prism coordination geometry. The 2,5-tdc2- ligands connect four Nd(III) centers, adopting (κ1 - κ1) - (κ1 - κ1) - μ4 coordination mode, generating an interesting 6-connected uninodal 3D network. Photophysical properties were studied using diffuse reflectance spectroscopy (DR) and excitation/emission spectra. The photoluminescence data show the near infrared emission (NIR) with the characteristic 4F3/2→4IJ (J=9/2, 11/2 and 13/2) transitions of Nd(III) ion, indicating that 2,5-tdc2- is able to act as a sensitizer for emission in NIR region. © 2013 Elsevier B.V.

Pagos interlatinoamericanos, anexo III: Liberalización = Payments in inter-Latin American trade, annex III: Liberalization

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