Development of a potentiometric sensor for the determination of saccharin in instant tea powders, diet soft drinks and strawberry dietetic jam

The construction and the analytical evaluation of a potentiometric sensor, namely, Pt vertical bar Hg vertical bar Hg-2(Sac)2 vertical bar Graphite, where Sac stands for saccharinate ion, are described. This electrode has a wide linear dynamic range between 5.0 x 10(-7) and 1.0 X 10(-2) mol L-1 with a near-Nernstian slope of -58.1 +/- 1.1 mV decade(-1) and a detection limit of 3.9 x 10(-7) mol L-1. The potentiometric response is independent of the pH of the solution in the pH range 3.0-9.0. The electrode is easily constructed at a relatively low-cost with fast response time (within 10-30 s) and can be used for a period of 10 months without significant change in its performance characteristics. The proposed sensor displayed good selectivities over a variety of other anions (carboxylates and inorganic anions). The potentiometric sensor was successfully applied to the determination of saccharin in real food samples, that is, in instant tea powders, diet soft drinks and strawberry dietetic jam. (c) 2008 Elsevier B.V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Self-assembly of cyclometallated Pd(II) compounds directed by C-H center dot center dot center dot pi interactions: A structural evidence for metalloaromaticity in a cyclopalladated ring

Structural studies on the two binuclear cyclometallated compounds [Pd(C-2,N-bzan)(mu-N-3)](2) (1) and [Pd(C-2,N-bzan)(mu-Pz)](2) (2) (bzan = N-benzylideneaniline) have been carried out in this work. In both compounds, C-H center dot center dot center dot pi interactions play an important role in the molecular self-assembly. In complex 1, ortho-CH bonds from bzan moiety interact with the cyclopalladated ring at a distance of C-bzan center dot center dot center dot C-g 3.448(6) angstrom, providing a new structural evidence for the metalloaromaticity of the cyclometallated ring. (C) 2010 Elsevier B.V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

SÍNTESE, CARACTERIZAÇÃO E AVALIAÇÃO DA ATIVIDADE CITOTÓXICA DE COMPOSTOS CICLOPALADADOS CONTENDO COMO LIGANTES BENZALDEIDOXIMA ORTOMETALADA E ETILENOTIOURÉIA

The halide-bridge cleavage reaction of the [Pd(C2 ,N-bzox)(µ-Cl)]2 compound (bzox = benzaldehydeoxime) with ethylenethiourea (L) in the 1:2 molar ratio at room temperature yielded the cyclopalladated compound [Pd(C2 ,N-bzox)(Cl)(L)] (1) whose replacement of the halide group by the addition of suitable salts afforded compounds of general formulae [Pd(C2 ,N-bzox)(X)(L)] {X = Br- (2), I- (3)}. All compounds were characterized by melting point, elemental analyses, infrared and 1H- and 13C{1H}-NMR spectroscopies revealing the complexes formation with the oxime coordinated to Pd(II) as C,N-chelating and the ethylenethiourea as a monodentate ligand via the sulfur atom. The cytotoxicity of cyclopalladated compounds has been evaluated in vitro against murine mammary tumor cell (LM3) showing cytotoxic activity similar to cisplatin

Synthesis, characterization, thermal studies, and DFT calculations on Pd(II) complexes containing N-methylbenzylamine

This work describes the synthesis, characterization, and the thermal behavior investigation of four palladium(II) complexes with general formulae [PdX(2)(mba)(2)], in which mba = N-methylbenzylamine and X = OAc(-) (1), Cl(-) (2), Br(-) (3) or I(-) (4). The complexes were characterized by elemental analysis, infrared vibrational spectroscopy, and (1)H nuclear magnetic resonance. The stoichiometry of the complexes was established by means of elemental analysis and thermogravimetry (TG). TG/DTA curves showed that the thermodecomposition of the four complexes occurred in 3-4 steps, leading to metallic palladium as final residue. The palladium content found in all curves was in agreement with the mass percentages calculated for the complexes. The following thermal stability sequence was found: 3 > 2 > 4 > 1. The geometry optimization of 1, 2, 3, and 4, calculated using the DFT/B3LYP method, yielded a slightly distorted square planar environment around the Pd(II) ion made by two anionic groups and two nitrogen atoms from the mba ligand (N1 and N2), in a trans-relationship