Synthesis and thermal study of the prodrug of oxamniquine

Oxamniquine polymeric prodrug with potential antischistosomal activity was prepared using dextran T-70 as a carrier, which was analysed by (HNMR)-H-1, C-13 NMR and IR spectroscopy. The formation of the oxamniquine salt was confirmed by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) which showed a different thermal behaviour when compared to the physical mixture.

Acylated flavonol glycosides and terpenoids from the leaves of Alibertia sessilis

Two novel acylated flavonol glycosides, along with iridoids, triterpenes, steroids and alpha-tocopherolquinone, were isolated from the leaves of Alibertia sessilis (Rubiaceae). The determination of the structures of the new compounds was based mainly on H-1- and C-13-NMR.

Synthesis, characterization and initial biological studies of a new platinum(II) complex with deoxyalliin

A new platinum(II) complex with deoxyalliin was synthesized and characterized by chemical and spectroscopic techniques. Elemental and mass spectrometry analyses of the solid complex fit to the composition [Pt(C6H11NO2S)Cl-2] center dot H2O. C-13 NMR, N-15 NMR and infrared spectra of the complex are consistent with coordination of deoxyalliin to Pt( II) through the nitrogen and sulfur atoms forming a square-planar geometry. The complex is soluble in dimethylsulfoxide. Biological analysis for evaluation of a potential cytotoxic effect of the complex was performed using HeLa cells, a human cervix adenocarcinoma-derived cell line. The results were compared with those of a palladium( II) complex previously described.

NMR study of ion-conducting organic-inorganic nanocomposites poly(ethylene glycol) - Silica - LiClO4

Hybrid organic-inorganic ionic conductors, also called ormolytes, were obtained by dissolution of LiClO4 into silica/poly(ethylene glycol) matrices. Solid-state nuclear magnetic resonance (NMR) was used to probe the inorganic phase structure (Si-29) and the effects of the temperature and composition on the dynamic behavior of the ionic species (Li-7) and the polymer chains (H-1 and C-13). The NMR results between -100 and +90 degrees C show a strong correlation with ionic conductivity and differential scanning calorimetry experiments. The results also demonstrate that the cation mobility is assisted by segmental motion of the polymer, which is in agreement with the results previously reported for pure poly(ethylene oxide), PEG, electrolytes.

Synthesis and structural characterization of dichlorobis (1-phenyl-3-methylpyrazole) palladium(II) and diazidobis (1-phenyl-3-methylpyrazole) palladiium(II)

Mononuclear pyrazolyl Pd(II) complexes of the type [PdX2(phmPz)(2)] (X = Cl-, N-3(-)) have been prepared. The 1-phenyl-3-methylpyrazole displaces acetonitrile from [PdCl2(CH3CN)(2)] to form [PdCl2(PhMPz)(2)] (phmPz = 1-phenyl-3-methylpyrazole) (1). [Pd(N-3)(2)(PhmPz)(2)] (2) could be obtained by metathesis from [PdCl2(CH3CN)(2)] or by substitution of the chloride in (1) by the azide ion. Both complexes were characterized by elemental analysis, infrared spectroscopy, H-1 and C-13 NMR and by single crystal X-ray diffraction. The coordination geometry around Pd(II) in these complexes is nearly square-planar, with the ligands in a trans configuration.

Tetrahydroisoquinoline alkaloids and 2-deoxyribonolactones from Aristolochia arcuata

2-Deoxyribonolactones and four tetrahydroisoquinoline alkaloids were isolated from the acetone extract of the leaves of Aristolochia arcuata Mast., together with pinitol, sequoyitol, glycerol, fructose, sucrose, eupomatenoid-7, salsolinol, and 6,7-dihydroxyl,1-dimethyl-1,2,3,4-tetrahydroisoquinoline. Their structures were determined on the basis of spectroscopic methods, mainly using H-1, C-13, N-15, and P-31 NMR. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

A DNA-damaging sesquiterpene and other constituents from Frullania nisquallensis

Bioassay-guided fractionation of an MeCOEt extract of Frullania nisquallensis Sull. has furnished a DNA-damaging sesquiterpene, costunolide (1), and two inactive compounds, a sesquiterpene (-)-frullanolide (2) and a tridepside tenuiorin (3). C-13-NMR data of 3 are reported.

Aquatic humus from an unpolluted Brazilian dark-brown stream: general characterization and size fractionation of bound heavy metals

The main pool of dissolved organic carbon in tropical aquatic environments, notably in dark-coloured streams, is concentrated in humic substances (HS). Aquatic HS are large organic molecules formed by micro-biotic degradation of biopolymers and polymerization of smaller organic molecules. From an environmental point of view, the study of metal-humic interactions is often aimed at predicting the effect of aquatic HS on the bioavailability of heavy metal ions in the environment. In the present work the aquatic humic substances (HS) isolated from a dark-brown stream (located in an environmental protection area near Cubatao city in São Paulo-State, Brazil) by means of the collector XAD-8 were investigated. FTIR studies showed that the carboxylic carbons are probably the most important binding sites for Hg(II) ions within humic molecules. C-13-NMR and H-1-NMR studies of aquatic HS showed the presence of constituents with a high degree of aromaticity (40% of carbons) and small substitution. A special five-stage tangential-flow ultrafiltration device (UF) was used for size fractionation of the aquatic HS under study and for their metal species in the molecular size range 1-100 kDa (six fractions). The fractionation patterns showed that metal traces remaining in aquatic HS after their XAD-8 isolation have different distributions. Generally, the major percentage of traces of Mn, Cd and Ni (determined by ICP-AES) was preferably complexed by molecules with relatively high molecular size. Cu was bound by fractions with low molecular size and Co showed no preferential binding site in the various humic fractions. Moreover, the species formed between aquatic HS and Hg(II), prepared by spiking (determined by CVAAS), appeared to be concentrated in the relatively high molecular size fraction F-1 (> 100 kDa).

Synthesis, characterization and electrochemical study of layered double hydroxides intercalated with 2-thiophenecarboxylate anions

The synthesis, characterization, and electrochemical study of the Zn(II)-Al(III) and Zn(II)-Cr(III) Layered Double Hydroxides (LDHs) containing 2-thiopenecarboxylate as the interlayer anions are described. The LDHs were prepared by the constant pH coprecipitation technique followed by hydrothermal treatment for 72 h. The materials were analyzed by PXRD, FT-IR, C-13 CP-MAS, EDX, TEM, and CV. The presence of the organic heterocyclic anions was confirmed by FT-IR and the related solid-state C-13 NMR data strongly suggested that these were dimerised during coprecipitation. Accordingly, the basal spacing found by the X-ray technique was similar to 15.3 Angstrom, a distance coincident with the formation of bilayers of the intercalated anions. The structural organization of all the new materials was greatly enhanced by hydrothermal treatment, as shown by PXRD. The improved organization of the bilayered structures had a strong influence in the electrochemical behaviour of clay-modified electrodes produced with these materials, such as the diminished resistance to the ionic flow through the LDHs films. (C) 2003 Elsevier Ltd. All rights reserved.

Essential oil from leaves of Cryptocarya mandioccana Meisner (Lauraceae): Composition and intraspecific chemical variability

The composition of the essential oil from leaves of Cryptocarya mandioccana has been determined by chromatographic fractionation and GC-FID, GC-MS and C-13 NMR analyses, yielding the identification of 64 compounds with predominance of isomeric sesquiterpenes with molecular weights of 204. The main components of the oil obtained by hydrodistillation were beta-caryophyllene, spathulenol, caryophyllene oxide, delta-cadinene, germacrene D, benzaldehyde and bicyclogermacrene. However, the oil obtained by steam distillation contained higher levels of sesquiterpene hydrocarbons, with predominance of P-caryophyllene (C), germacrene D (G) and bicyclogermacrene (B), and was considered to be more representative of the composition of the oil in its natural state. The intraspecific chemical variability of the essential oil obtained by steam distillation was evaluated within populations of trees growing at three separate locations in the state of São Paulo, Brazil. Three distinct chemical groups could be characterised due to differences in the relative percentages of the three main sesquiterpenes from essential oil: CGB [relative contents of C (14-34%), G (5-28%), B (8-15%)], BCG [B (17-34%), C (9-24%), G (12-25%)] and GCB [G (22-42%), C (4-17%), B (7-15%)]. Individuals from groups CGB and BCG were found to be more frequent at south locations while group GCB is predominant in north location. (c) 2006 Elsevier Ltd. All rights reserved.

Linear low density polyethylene (LLDPE) from ethylene using Tp(Ms)NiCl (Tp(Ms) = hydridotris(3-mesitylpyrazol-1-yl)) and CP2ZrCl2 as a tandem catalyst system

Linear low density polyethylene (LLDPE) with different branching contents were prepared from ethylene, without the addition of alpha-olefin comonomer, using a combination of catalyst precursors {Tp(Ms)}NiCl (1) (Tp(Ms) = hydridotris(3-mesitylpyrazol-1-yl)) and Cp2ZrCl2 (2) activated with MAO/TMA (1:1) in toluene at 0degreesC and by varying the nickel loading mole fraction (x(Ni)). The polymerization results showed that the turnover frequencies are strongly dependent on the x(Ni) varying from 6.6 x 10(3) to 32.1 x 10(3) mol[C2H4]/mol[Zr] h. The C-13 NMR spectra of the copolymers showed that the branch contents of the polymers increase as the x(Ni) increase in the medium promoting the production of polymers with a wide range of melting point (T-m) (C) 2004 Elsevier B.V. All rights reserved.

NEW FIR LASER LINES AND FREQUENCY MEASUREMENTS FROM OPTICALLY PUMPED CD-13(3)OH-3

We report the discovery of 57 new fir laser lines from (CD3OH)-C-13 molecule optically pumped by a waveguide CO2 laser of 300 MHz tunability. For all lines, precise frequency offset measurements between the CO2 line center and the center of the absorbing (CD3OH)-C-13 line were performed using the transferred Lamb-Dip technique. We have also measured directly the frequency of seven FIR laser lines by heterodyning with already known laser lines.We present a complete list of all known laser lines (134) and frequency measurements (24) for this molecule.

Sterolic and triterpenoidic constituents of stem bark of Drypetes gossweileri

Four compounds have been identified from the stem bark of Drypetes gossweileri by means of H-1- and C-13-NMR spectroscopy, stearic acid, methyl putranjate, and two new compounds: stigmasterol stearate and beta-sitosterol stearate.

Configurational analysis of cubebins and bicubebin from Aristolochia lagesiana and Aristolochia pubescens

(8S,8'R,9S)-, (8R,8'R,9R)-, and (8R,8',R,9S)-cubebins, together with (8R,8'R,8R,8'''R,9R,9S)-bicubebin, were isolated from Aristolochia lagesiana and Aristolochia pubescens. Their structures were determined by spectroscopic methods, including H-1 and C-13 NMR spectroscopy at low temperatures, and by chemical transformations. (c) 2006 Elsevier Ltd. All rights reserved.

H-1-N-15 NMR studies of the complex bis(S-allyl-L-cysteinate)palladium(II)

H-1-N-15 2D NMR data for S-allyl-L-cysteine (deoxyalliin) and for bis(S-allyl-L-cysteinate)palladium(II) complex are presented in this manuscript. Large upfield N-15 NMR shift of the amine nitrogen in the spectrum of the complex when compared to the spectrum of the ligand shows clearly coordination of S-allyl-L-cysteine, in the anion form, to palladium(II) through the NH2 group. (c) 2005 Elsevier B.V. All rights reserved.