Synthesis and characterization of a new platinum(II) complex with L-mimosine

Synthesis and characterization of a new Pt(II)-mimosine complex are described. Elemental, mass spectrometry and thermal analyses for the complex are consistent with the formula [PtCl2(C8H10N2O4)]center dot 1.5H(2)O. C-13 NMR, N-15 NMR and infrared spectroscopy indicate coordination of the ligand to Pt(II) through the N and O atoms in a square-planar geometry. The final residue after thermal treatment was identified as metallic Pt. The complex is soluble in dimethylsulfoxide.

New layered double hydroxides intercalated with substituted pyrroles. 2. 3-(Pyrrol-1-yl)-propanoate and 7-(pyrrol-1-yl)-heptanoate LDHs

We report the synthesis and characterization of organic-inorganic hybrid materials: Zn-2-Al-LDHs (layered double hydroxides) containing 3-(1H-pyrrol-1-yl)-propanoate and 7-(1H-pyrrol-l-yl)-heptanoate as the interlayer anions. The LDHs were synthesized by the co-precipitation method at constant pH followed by hydrothermal treatment for 72 h. The materials were characterized by PXRD, C-13 CP-MAS NMR, TGA, and ESR. The basal spacing found by PXRD technique is coincident with the formation of bilayers of the intercalated anions. The solid state C-13 NMR showed that the interlayered anions remain identical after intercalation. ESR data suggest that the monomers connect each other in a limited number of guests when a thermal treatment is applied. The inorganic LDH sheets delay the temperature of degradation of the monomers. (c) 2006 Elsevier Ltd. All rights reserved.

Isolation and structure elucidation of two new flavonoid glycosides from the infusion of Maytenus aquifolium leaves. Evaluation of the antiulcer activity of the infusion

Droplet countercurrent chromatography and high-performance liquid chromatography fractionation of the aqueous infusion from Maytenus aquifolium Martius leaves afforded two flavonoid tetrasaccharides: quercetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-O-[beta-D-glucopyranosyl(1-->3)-O-alpha-L-rhamnopranosyl( 1-->2)-O-beta-D-galactopyranoside and kaempferol 3-O-alpha-L-rhamnopyranosyl(1-->6)-O-[beta-D-glucopyranosyl( 1-->3)-O-alpha-L-rhamnopyranosy(1-->2-2)-O-beta-D-galactopyranoside. All structures were elucidated by spectroscopic methods. Pharmacological essays of the infusion showed antiulcer activity in rats.

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.

Thermal and photochemical stability of poly(vinyl alcohol)/modified lignin blends

A kraft lignin derivative (KLD) obtained by reaction with p-aminobenzoic acid/phthalic anhydride was blended with poly(vinyl alcohol) (PVA) by solution casting from DMSO. PVA and PVA/KLD films were exposed to ultraviolet radiation (24, 48, and 96 h) and analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (H-1 NMR) spectroscopy, and scanning electron microscopy (SEM). PVA films show a loss of thermal stability due to irradiation. PVA/KLD reveals greater thermal stability than PVA and an increase in thermal stability after irradiation. These results suggest that the incorporation of KLD into PVA provides a gain in thermal and photochemical stability. FTIR, H-1 NMR, DSC, and TG results obtained for the blends suggest that intermolecular interactions between PVA and KLD chains are present. SEM micrographs revealed blend miscibility for a KLD blend content of up to 15 wt%, as observed at magnification of 1000 times. (c) 2005 Elsevier Ltd. All rights reserved.

Synthesis and structural characterization of a new polymeric zinc(II) complex with thiophene-2-carboxylic acid

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

Palladium(II) Complexes with Thiosemicarbazones. Syntheses, Characterization and Cytotoxicity against Breast Cancer Cells and Anti-Mycobacterium tuberculosis Activity

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

Synthesis and characterization of a platinum(II) complex with N-acetyl-L-cysteine

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

Mercury(II) and thallium(III) organometallic derivatives of 2-Mercaptobenzoxazole

Some derivatives of 2-mercaptobenzoxazole (HL) of the type MRnL [M = Hg or Tl, R = Me or Ph and n = 1 (Hg) or 2 (Tl)] have been prepared. The structure of HgMeL has been determined by an X-ray diffraction study; in the crystal there are two independent planar molecules in each asymmetric unit, with the ligand in its thiolic form and an almost linear CHgS linkage. Weak intramolecular and intermolecular secondary interactions complement the mercurysulphur bond. The spectroscopic (IR, Raman, mass, 13C-NMR), conductimetric, and dipolar properties of this and the other compounds are discussed. © 1991.

Lead-cadmium fluorogermanate glasses and transparent glassceramics. Spectroscopy and structure

In Lead-cadmium fluorogermanate glasses (PbF2-CdF 2-PbGeO3) the addition of metal fluorides to the base PbGeO3 glass leads to a decrease of the glass transition temperature (Tg) and to an enhancement of the ionic conductivity properties. Based on different spectroscopic techniques (19F NMR, Ge K-edge X-ryas absorption and Raman scattering) an heterogeneous glass structure is proposed at the molecular scale, which can be described by fluoride rich regions permeating the metagermanate chains. The temperature dependence of the 19F NMR lineshapes and relaxation times exhibits the qualitative and quantitative features associated with the high fluoride mobility in these systems. Eu 3+ emission and vibronic spectra are used to follow the crystallization process leading to transparent glass ceramics.

Study of adsorption and preconcentration by using a new silica organomodified with [3-(2,2′-dipyridylamine)propyl] groups

In this work, a silica surface chemically modified with [3-(2,2′-dipyridylamine)propyl] groups, named [3-(2,2′- dipyridylamine)propyl]silica (Si-Pr-DPA) was prepared, characterized, and evaluated for its heavy metal adsorption characteristics from aqueous solution. To our knowledge, we are the first authors who have reported the present modification. The material was characterized using infrared spectroscopy, SEM, and NMR 29Si and 13C solid state. Batch and column experiments were conducted to investigate for heavy metal removal from dilute aqueous solution by sorption onto Si-Pr-DPA. From a number of studies the affinity of various metal ions for the Si-Pr-DPA sorbent was determined to follow the order Fe(III) > Cr(III) >> Cu(II) > Cd(II) > Pb(II) > Ni(II). Two standard reference materials were used for checking the accuracy and precision of the method. The proposed method was successfully applied to the analysis of environmental samples. This ligand material has great advantage for adsorption of transition-metal ions from aqueous medium due to its high degree of organofunctionalization associated with the large adsorption capacity, reutilization possibility, and rapidity in reaching the equilibrium. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of heavy metal ions and epoxidation catalysis using a new polyhedral oligomeric silsesquioxane

The objective of this research was the preparation of a silsesquioxane functionalized with eight chloropropyl chains (T8-PrCl) and of a new derivative functionalized with a pendant linear chain (2-amino-1,3,4-thiadiazole - ATD; T8-Pr-ATD). The two nanostructured materials were characterized by 13C and 29Si NMR, FTIR and elemental analysis. The new nanostructured material, octakis[3-(2-amino-1,3,4-thiadiazole)propyl] octasilsesquioxane (T8-Pr-ATD), was tested as a ligand for transition-metal ions with a special attention to adsorption isotherms. The adsorption was performed using a batchwise process and the organofunctionalized surface showed the ability to adsorb the metal ions Cu (II), Co (II), and Ni (II) from water and ethanol. The adsorption isotherms were fitted by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) model. The kinetics of adsorption of metals were performed using three models such as pseudo-first order, pseudo-second order and Elovich. The Langmuir and Elovich models were the most appropriate to describe the adsorption and kinetic data, respectively. Furthermore, the T8-Pr-ATD was successfully applied to the analysis of environmental samples (river and sea water). Subsequently, a new nanomaterial was prepared by functionalization of the T8-Pr-ATD with a Mo (II) organometallic complex (T8-Pr-ATD-Mo). Only a few works in the literature have reported this type of substitution, and none dealt with ATD and Mo (II) complexes. The new Mo-silsesquioxane organometallic nanomaterial was tested as precursor in the epoxidation of cyclooctene and styrene. © 2012 Elsevier B.V.

Sulfonation and anticoagulant activity of fungal exocellular β-(1→6)-d-glucan (lasiodiplodan)

An exocellular β-(1→6)-d-glucan (lasiodiplodan) produced by a strain of Lasiodiplodia theobromae (MMLR) grown on sucrose was derivatized by sulfonation to promote anticoagulant activity. The structural features of the sulfonated β-(1→6)-d-glucan were investigated by UV-vis, FT-IR and 13C NMR spectroscopy, and the anticoagulant activity was investigated by the classical coagulation assays APTT, PT and TT using heparin as standard. The content of sulfur and degree of substitution of the sulfonated glucan was 11.73% and 0.95, respectively. UV spectroscopy showed a band at 261 nm due to the unsaturated bond formed in the sulfonation reaction. Results of FT-IR and 13C NMR indicated that sulfonyl groups were inserted on the polysaccharide. The sulfonated β-(1→6)-d-glucan presented anticoagulant activity as demonstrated by the increase in dose dependence of APTT and TT, and these actions most likely occurred because of the inserted sulfonate groups on the polysaccharide. The lasiodiplodan did not inhibit the coagulation tests. © 2012 Elsevier Ltd.

A theoretical and experimental study to unequivocal structural assignment of tetrahydroquinoline derivatives

The tetrahydroquinoline derivatives can be easily synthesized through Povarov reaction and have several important biological activities. This work describes a comparative study for the unequivocal assignment of molecular structure of different tetrahydroquinoline derivatives, through a complete analysis of NMR 1D and 2D NMR spectra (1H, 13C, COSY, HSQC, and HMBC), and the correlation this data with theoretical calculations of energy-minimization and chemical shift (δ), employing the theory level of DFT/B3LYP with set of the cc-pVDZ basis. For these derivatives the experimental analyses and the theoretical model adopted were sufficient to obtain a good description of its structures, and these results can be used to assign the structure of various others tetrahydroquinoline derivatives. © 2013 Springer Science+Business Media New York.

Synthesis, characterization, x-ray structure, DNA cleavage, and cytotoxic activities of palladium(ii) complexes of 4-phenyl-3-thiosemicarbazide and triphenylphosphane

Complexes of the type [PdX(PPh3)(1)]X [1 = 4-phenyl-3- thiosemicarbazide; X = Cl- (2), Br- (3), I- (4), and SCN- (5)] have been synthesized and characterized by elemental analyses and IR, UV/Vis, and 1H and 13C NMR spectroscopy. The molecular structure of complex 4 was determined by single-crystal X-ray diffraction. The binding of the complexes with a purine base (guanosine) was investigated by 1H NMR spectroscopy and mass spectrometry, which showed the complexes to coordinate to guanosine through N7. A gel electrophoresis assay demonstrated the ability of 2-5 to cleave DNA plasmid. All the complexes were tested in vitro by means of the MTT assay for their cytotoxicity against two murine cell lines, LM3 (mammary adenocarcinoma) and LP07 (lung adenocarcinoma), and compared with cisplatin. Complexes 2-5 exhibited good cytotoxicity that surpasses that of cisplatin in the case of LM3. A series of thiosemicarbazide/phosphane palladium(II) complexes have been synthesized and fully characterized. These complexes are able to cleave DNA plasmid and show cytotoxicity against adenocarcinoma (mammary LM3 and lung LP07), surpassing the cytotoxicity of cisplatin in the case of LM3. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.