Crystal structure of di-mu(N,S)-thiocyanato-bis[(N-benzylideneaniline-C-2,N)palladium(II)], [Pd(C6H4CH=NC6H5)(mu-SCN)](2)

C28H20N4Pd2S2, monoclinic, P12(1)/c1 (No. 14), a = 11.325(1) Angstrom, b = 13.530(1) Angstrom, c = 17.925(1) Angstrom, beta = 106.23(1)degrees, V = 2637.1 Angstrom(3), Z = 4, R-gt(F) = 0.052, wR(ref)(F-2) = 0.129, T = 293 K.

Enhanced Eu3+ Emission in Aqueous Phosphotungstate Colloidal Systems: Stabilization of Polyoxometalate Nanostructures

Luminescent Eu3+-containing polyphosphate tungstate aqueous colloidal systems were prgared and studied as a function of the relative polyphosphate tungstate content. In polyphosphate-rich solutions, Eu-H- ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu3+ ion and the 500 emission quantum efficiency is 0.22. Tungstatc addition leads to important modifications in neighboring Eu3+ leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show \V-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstatc relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu34- in polyoxometalate (P0M)-like sites by comparison with the well-known decatungstoeuropate [EuW10O36](9-) structure. These new aqueous colloids display surprisingly high 5llo emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu3+ first coordination shell.

Synthesis, X-ray Crystal Structure and Theoretical Calculations of Antileishmanial Neolignan Analogues

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A Dielectric Model of Self-Assembled Monolayer Interfaces by Capacitive Spectroscopy

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

Controlling the growth of zirconia needles precursor from a liquid crystal template

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Stable colloidal suspensions of nanostructured zirconium oxide synthesized by hydrothermal process

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

Crystal structure refinement of Co-doped lanthanum chromites

Results of crystal structure refinements and phase quantification for samples of Co-doped lanthanum chromites with nominal composition LaCr(1-x)Co(x)O(3), for x=0.00, 0.10, 0.20, and 0.30, prepared by combustion synthesis are presented. The resulting powders were characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD patterns were obtained with Cu K alpha radiation for non-doped lanthanum chromite sample and additionally with Cr K alpha radiation for Co-doped lanthanum chromites samples, in order to enhance the signal from scattering. Rietveld analysis of XRD data showed that the studied samples presented the lanthanum chromite with an orthorhombic structure (Pnma), except for the composition with x=0.30, in which the space group was found to be R (3) over barc. (C) 2008 International Centre for Diffraction Data.

Pt(II) and Ag(I) complexes with acesulfame: Crystal structure and a study of their antitumoral, antimicrobial and antiviral activities

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

Terbium(III) and dysprosium(III) 8-connected 3D networks containing 2,5-thiophenedicarboxylate anion: Crystal structures and photoluminescence studies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Synthesis and electrochemical behavior of single-crystal magnetite nanoparticles

Water-dispersed magnetite nanoparticle synthesis from iron(II) chloride in dimethyl sulfoxide (DMSO)-water solution at different DMSO-water ratios in alkaline medium was reported. TEM and XRD results suggest a single-crystal formation with mean particle size in the range 4-27 nm. Magnetic nanoparticles are formed by the oxidative hydrolysis reaction from green rust species that leads to FeOOH formation, followed by autocatalysis of the adsorbed available Fe(II) on the FeOOH surfaces. The available hydroxyl groups seem to be dependent on the DMSO-water ratio due to strong molecular interactions presented by the solvent mixture. Goethite phase on the magnetite surface was observed by XRD data only for sample synthesized in the absence of DMSO. In addition, cyclic voltammetry with carbon paste electroactive electrode (CV-CPEE) results reveal two reduction peaks near 0 and +400 mV associated with the presence of iron(III) in different chemical environments related to the surface composition of magnetite nanoparticles. The peak near +400 mV is related to a passivate thin layer surface such as goethite on the magnetite nanoparticle, assigned to the intensive hydrolysis reaction due to strong interactions between DMSO-water molecules in the initial solvent mixture that result in a hydroxyl group excess in the medium. Pure magnetite phase was only observed in the samples prepared at 30% (30W) and 80% (80W) water in DMSO in agreement with the structured molecular solvent cluster formation. The goethite phase present on the, magnetite nanoparticle surface like a thin passivate layer only was detectable using CV-CPEE, which is a very efficient, cheap, and powerful tool for surface characterization, and it is able to determine the passivate oxyhydroxide or oxide thin layer presence on the nanoparticle surface.

DNA hybridization mechanism in an interfacial environment: What hides beneath first order k (s(-1)) kinetic constant?

The scientific question addressed in this work is: what hides beneath first order kinetic constant k (s(-1)) measured for hybridization of a DNA target on a biosensor surface. Kinetics hybridization curves were established with a 27 MHz quartz microbalance (9 MHz, third harmonic) biosensor, constituted of a 20-base probe monolayer deposited on a gold covered quartz surface. Kinetics analysis, by a known two-step adsorption-hybridization mechanism, is well appropriate to fit properly hybridization kinetics curves, for complementary 20-base to 40-base targets over two concentration decades. It was found that the K-1 (M-1) adsorption constant, relevant to the first step, concerns an equilibrium between non hybridized targets and hybridized pre-complex and increases with DNA target length. It was established that k(2) (s(-1)), relevant to irreversible formation of a stable duplex, varies in an opposite way to K-1 with DNA target length. (C) 2012 Published by Elsevier B.V.

Nanocomposites of Styrene-Butadiene Rubber and Synthetic Anatase Obtained by a Colloidal Route and Their Photooxidation

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

Synthesis, characterization, crystal structure, and biological studies of vanadium complexes with glycolic acid

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Crystal structure of a novel myotoxic Arg49 phospholipase A(2) homolog (zhaoermiatoxin) from Zhaoermia mangshanensis snake venom: Insights into Arg49 coordination and the role of Lys122 in the polarization of the C-terminus

The venom of Zhaoermia mangshanensis, encountered solely in Mt Mang in China's Hunan Province, exhibits coagulant, phosphodiesterase, L-amino acid oxidase, kallikrein, phospholipase A(2) and myotoxic activities. The catalytically inactive PLA(2) homolog referred to as zhaoermiatoxin is highly myotoxic and displays high myonecrotic and edema activities. Zhaoermiatoxin possesses a molecular weight of 13,972 Da, consists of 121 amino-acid residues crosslinked by seven disulfide bridges and shares high sequence homology with Lys49-PLA(2)s from the distantly related Asian pitvipers. However, zhaoermiatoxin possesses an arginine residue at position 49 instead of a lysine, thereby suggesting a secondary Lys49 -> Arg substitution which results in a catalytically inactive protein. We have determined the first crystal structure of zhaoermiatoxin, an Arg49-PLA(2), from Zhaoermia mangshanensis venom at 2.05 A resolution, which represents a novel member of phospholipase A(2) family. In this structure, unlike the Lys49 PLA(2)s, the C-terminus is well ordered and an unexpected non-polarized state of the putative calcium-binding loop due to the flip of Lys122 towards the bulk solvent is observed. The orientation of the Arg-49 side chain results in a similar binding mode to that observed in the Lys49 PLA(2)s; however, the guadinidium group is tri-coordinated by carbonyl oxygen atoms of the putative calcium-binding loop, whereas the N zeta atom of lysine is tetra-coordinated as a result of the different conformation adopted by the putative calcium-binding loop. (c) 2008 Elsevier Ltd. All rights reserved.