A REVIEW OF OPTICALLY PUMPED FAR-INFRARED LASER LINES FROM METHANOL ISOTOPES

The technique of optical pumping in polar molecules is the most efficient for Far-Infrared (FIR) laser generation, providing also a versatile and powerful tool for molecular spectroscopy in this spectral region. Methanol (CH3OH) and its isotopic varieties are the best media for optically pumped FIR laser, with over thousand lines observed, and the most widely used for investigations and applications. In this sense, it is important organize and make available catalogues of FIR laser lines as complete as possible. Since the last critical reviews of 1984 [1] on methanol and its isotopic varieties [2,3,4], over hundred papers have been published dealing with hundreds of new FIR laser lines. In 1992 a review of FIR laser lines from CH3OH was presented [5]. In this communication we extend this work to the other methanol isotopes, namely CH3OD, CD3OH, CD3OD, (CH3OH)-C-13, (CD3OH)-C-13, (CD3OD)-C-13, (CH3OH)-O-18, CH2DOH, CHD2OH and CH2DOD.

Anxiolytic effects of erythrinian alkaloids from Erythrina mulungu

One new erythrinian alkaloid derivative, (+)-11 alpha-hydroxyerythravine (1), and the known (+)-erythravine (2) and (+)-alpha-hydroxyerysotrine (3) were isolated from the flowers of Erythrina mulungu. Their structures were determined by spectroscopic/spectrometric data interpretation of H-1, C-13, and 2D NMR and MS experiments. The relative configuration was established by NOESY analysis, while the conformation adopted by these molecules was evaluated through molecular modeling studies and coupling constants obtained by NMR analysis. Furthermore, the anxiolytic effects of the E. mulungu aqueous alcoholic crude extract and of the purified alkaloids were evaluated using the elevated T-maze test.

APPLICATIONS OF ARTIFICIAL-INTELLIGENCE IN ORGANIC-CHEMISTRY .17. NEW PROGRAMS IN THE SISTEMAT PROJECT

This work describes the new improvements of the SISTEMAT project, one system for structural elucidation mainly in the field of Natural Products Chemistry. Some examples of the resolution of problems using C-13 Nuclear Magnetic Resonance and Mass Spectroscopy are given. Programs to discover new heuristic rules for structure generation are discussed. The data base contains about 10000 C-13 NMR spectra.

Studies on the constituents of a Brazilian folk infusion. Isolation and structure elucidation of new triterpene saponins from Ilex amara leaves

The isolation of three new triterpene saponins 3beta-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-2-O-acetylara-binopyranosylolean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl ester (2), 3beta-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-O-arabinopyranosylurs-12-en-28-oic acid (3), and 3beta-O-beta-D-glucopyranosyl-(1-->2)-beta-D-O-galactopyranosylurs-12-en-28-oic acid (4) together with five known saponins and one flavonoid glycoside from the aqueous infusion of flex amara (Vellozo) Loes. leaves is reported. All structures were elucidated by spectroscopic methods, including the concerted application of one-dimensional (H-1, TOCSY, C-13, and C-13 DEPT NMR) and two-dimensional NMR techniques (DQF-COSY, HSQC, and HMBC).

Limonoids showing selective toxicity to DNA repair-deficient yeast and other constituents of Trichilia emetica

Bioactivity-directed fractionation of the MeCOEt extract of Trichilia emetica (Meliaceae) resulted in the isolation of the limonoids nymania 1 (1), drageana 4 (3), trichilin A (4), rohituka 3 (5),and Tr-B (7) and the novel seco-A protolimonoid 8. of these, nymania 1 and Tr-B showed selective inhibitory activity toward DNA repair-deficient yeast mutants. The isolation, structure elucidation, C-13 NMR spectral assignments, and biological activities of:these compounds are reported.

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.

X-ray powder diffraction analysis of methionine sulfoxide

Powder X-ray diffraction data for methionine sulfoxide, C5H11NO3S, obtained from the commercial amino acid, are presented in this work. Monoclinic cell parameters are: a = 15.500 Angstrom; b = 3.820 Angstrom; c = 13.490 Angstrom; 8=97.300 degrees. (C) 2001 International Centre for Diffraction Data.

X-ray powder data and bond valence of La0.65Sr0.35MnO3 after Rietveld refinement

Powder X-ray diffraction (XRD) data were collected for La0.65Sr0.35MnO3 prepared through an alternative method from a stoichiometric mixture of Mn2O3, La2O3, and SrO2, fired at 1300 degreesC for 16 h. XRD analysis using the Rietveld method was carried out and it was found that manganite has rhombohedral symmetry (space group R(3) over bar c). The lattice parameters are found to be a=5.5032 Angstrom and c=13.3674 Angstrom. The bond valence computation indicates that the initial inclusion of Sr occurs at higher temperature. (C) 2002 International Centre for Diffraction Data.

Structure of a glycoglucuronomannan from the low-viscosity gum of Vochysia lehmannii

The polysaccharide (VSP) from the gum exudate of quaruba (Vochysia lehmannii) had two components of almost identical M. centred at 24,800, as shown by HSPEC-MALLS. The presence of aggregates was shown since carboxy-reduction gave VSP-RED, which contained low molecular weight components with M-w 19,000 > 5800 and polydispersity ratios dn/dc 0.160 and 0.149, respectively. VSP formed low viscosity aqueous solutions and acid hydrolysis gave Man (30%), Ara (16%), Gal (10%), and Glc (14%). The latter arose partly from GlcA (30%). Methylation analysis revealed mainly neutral units of 2-O- (60%) and 2,3-di-O-substituted Manp (5%), and those of nomeducing ends (8%), 2-O- (3%), and 4-O-substituted Arap and/or 5-O-substituted Araf units (6%). VSP-RED contained Glc (45%), Man (35%), and Ara (13%) and methylation analysis indicated mainly 4-O-substituted Glcp (31%) and 2-O- (51%) and 2,3-di-O-substituted Manp units (5%). A predominant alternating structure for VSP was shown by its C-13 NMR spectrum, which contained 10 main signals and a small one of C-6 of GlcpA. This was confirmed by formation, on partial hydrolysis of VSP, of a tetrasaccharide, which was characterised by NMR spectroscopy and ESI-MS as beta-GlcpA-(1 --> 2)-alpha-Manp-(1 --> 4)-beta-GlcpA-(1 --> 2)-Man, which arose from the main chain, thus confirming VSP to be a glycoglucuronomannan. (C) 2004 Elsevier Ltd. All rights reserved.

Solid-state and solution structural study of acetylacetone-modified tin(IV) chloride used as a precursor of SnO2 nanoparticles prepared by a sol-gel route

The effect of addition of different amounts of acetylacetone (acacH) on the species formed at room temperature and after thermohydrolysis at 70 degreesC for 30 and 120 min of ethanolic SnCl4.5H(2)O solutions is followed by EXAFS spectroscopy at the Sn K-edge. We show that thermohydrolyzed solutions are a mixture of SnO2 nanoparticles and soluble tin polynuclear species. The complexation of the tin molecular precursors by acetylacetonate ligands is evidenced by H-1, C-13, and Sn-119 NMR spectroscopy and EXAFS for a acacH/Sn ratio higher than 2. Single crystals are isolated from solution and the structure, determined by X-ray diffraction, is built up from monomeric Cl-3(H2O)Sn(acac)-H2O units bridged together by hydrogen bonding. The acacH/Sn ratio in solution controls the polycondensation of the hydrolyzed species but not the crystallite size of the SnO2 nanoparticles (similar to2 nm). Because of the major presence of chelated tin mono- and dimeric complexes in solution for acacH/Sn > 2, the condensation is almost inhibited, meanwhile the decrease of amount of chelated complexes for the acacH/Sn < 2 gives rise to an increase of the number of nanoparticles.

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.

A laser-induced fluorescence spectroscopic study of organic matter in a Brazilian Oxisol under different tillage systems

Laser-induced fluorescence (LIF) spectroscopy has been proposed as new method for determining the degree of humification of organic matter (OM) in whole soils. It can be also used to analyze the OM in whole soils containing large amounts of paramagnetic materials, and which are neither feasible to Electron Paramagnetic Resonance (EPR) nor to C-13 Nuclear Magnetic Resonance (NMR) spectroscopy. In the present study, 3 LIF spectroscopy was used to investigate the OM in a Brazilian Oxisol containing high concentration of Fe+3. Soil samples were collected from two areas under conventional tillage (CT), two areas under no-till management (NT) and from a non-cultivated (NC) area under natural vegetation. The results of LIF spectroscopic analysis of the top layer (0-5 cm) of whole soils showed a less aromatic OM in the non-cultivated than in the cultivated soils. This is consistent with data corresponding to HA samples extracted from the same soils and analyzed by EPR, NMR and conventional fluorescence spectroscopy. The OM of whole soils at 5-10 and 10-20 cm depth was also characterized by LIF spectroscopy.Analysis of samples of NT and NC soils showed a higher OM aromatic content at depth. This is a consequence of the accumulation of plant residues at the soil surface in quantities that are too large for microorganisms to metabolize fully, thus, resulting in less aromatic or less hurnified humic substances. In deeper soil layers, the input of residues was lower and further decomposition of humic substances by microorganisms continued, and the aromaticity and degree of humification increased with soil depth. This data indicates that the gradient of humification of OM in the NT soil was similar to those observed in natural soils. Nevertheless, the degree of humification of the OM in the soils under no-till management varied less than that corresponding to non-cultivated soils. This may be because the former have been managed under these practices for only 5 years, in contrast to the continuous humification process occurring in the natural soils. on the other band, LIF spectroscopic analysis of the CT soils showed less pronounced changes or no change in the degree of humification with depth. This indicates that the ploughing and harrowing involved in CT lead to homogenization of the soil and thereby also of the degree of humification of OM throughout the profile. (c) 2006 Elsevier B.V. All rights reserved.

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.