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1.
Nanomedicine (Lond) ; 14(23): 3075-3088, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31797726

RESUMO

Aim: The field of nanotechnology promotes the development of innovative and more effective cancer therapies. This work is aimed to develop a hybrid system that combines the capacity of boron nitride nanotubes (BNNTs) to be internalized by tumor cells and the ability of nickel ferrite nanoparticles to efficiently release heat by induced AC magnetic heating. Materials & methods: The systems studied were characterized by using x-ray diffractometry, transmission electron microscopy, vibrating sample magnetometry and Mössbauer spectroscopy. Results: The ferrite nanoparticles attached to BNNT were able to achieve the required temperatures for magnetohyperthermia therapies. After cellular internalization, AC induced magnetic heating of BNNT@NiFe2O4 can kill almost 80% of Hela cells lineage in a single cycle. Conclusion: This system can be a highly efficient magnetohyperthermia agent in cancer therapy.

2.
Materials (Basel) ; 12(5)2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30871072

RESUMO

The synthesis of mixed-metal spinels based on substituted γ-Ga2O3 is reported using metal acetylacetonate precursors in solvothermal reactions with alcohols as solvents at 240 °C. New oxides of Cr, Mn and Fe have been produced, all of which are formed as nanocrystalline powders, as seen by high-resolution transmission electron microscopy (HR-TEM). The first chromium-gallium mixed oxide is thus formed, with composition 0.33Ga1.87Cr0.8O4 ( = vacant site). X-ray absorption near-edge spectroscopy (XANES) at the chromium K-edge shows the presence of solely octahedral Cr3+, which in turn implies a mixture of tetrahedral and octahedral Ga3+, and the material is stable on annealing to at least 850 °C. An analogous manganese material with average chemical composition close to MnGa2O4 is shown to contain octahedral Mn2+, along with some Mn3+, but a different inversion factor to materials reported by conventional solid-state synthesis in the literature, which are known to have a significant proportion of tetrahedral Mn2+. In the case of iron, higher amounts of the transition metal can be included to give an Fe:Ga ratio of 1:1. Elemental mapping using energy dispersive X-ray spectroscopy on the TEM, however, reveals inhomogeneity in the distribution of the two metals. This is consistent with variable temperature 57Fe Mössbauer spectroscopy that shows the presence of Fe2+ and Fe3+ in more than one phase in the sample. Variable temperature magnetisation and electron paramagnetic resonance (EPR) indicate the presence of superparamagnetism at room temperature in the iron-gallium oxides.

3.
Environ Sci Pollut Res Int ; 25(7): 6762-6771, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29264851

RESUMO

In this work, iron oxide in the red mud (RM) waste was restructured to produce mesopores with surface [FeO x (OH) y ] sites for the efficient complexation/adsorption of ß-lactam antibiotics. Red mud composed mainly by hematite was restructured by an acid/base process followed by a thermal treatment at 150-450 °C (MRM150, MRM200, MRM300, and MRM450) and fully characterized by Mössbauer, XRD, FTIR, BET, SEM, CHN, and thermogravimetric analyses. The characterization data showed a highly dispersed Fe3+ oxyhydroxy phase, which was thermally dehydrated to a mesoporous α-Fe2O3 with surface areas in the range of 141-206 m2 g-1. These materials showed high efficiencies (21-29 mg g-1) for the adsorption of ß-lactam antibiotics, amoxicillin, cephalexin, and ceftriaxone, and the data was better fitted by the Langmuir model isotherm (R 2 = 0.9993) with monolayer adsorption capacity of ca. 39 mg g-1 for amoxicillin. Experiments such as competitive adsorption in the presence of phosphate and H2O2 decomposition suggested that the ß-lactamic antibiotics might be interacting with surface [FeO x (OH) y ] species by a complexation process. Moreover, the OH/Fe ratio, BET surface area and porosity indicated that this complexation is occurring especially on [FeO x (OH) y ]surf sites contained in the mesopore space.


Assuntos
Amoxicilina/química , Antibacterianos/química , Ceftriaxona/química , Cefalexina/química , Compostos Ferrosos/química , Adsorção , Óxido de Alumínio , Resíduos Industriais , Metalurgia
4.
Carbohydr Polym ; 163: 1-9, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28267484

RESUMO

In the present work, we study the role of different components in the formation of more stable iron oxide magnetic nanoparticles (MNPs): ß-cyclodextrin (BCD), 2-hydroxypropyl-ß-cyclodextrin (HP) and citrate anion. MNPs formulations were characterized by FTIR, particles size measurements, zeta potential based on dynamic light scattering principle technique, X-ray powder pattern diffraction, XPS spectroscopy, transmission electron microscopy and thermogravimetric analysis. The results showed that cyclodextrins and citrate plays a key role in order to obtain a lower size of coated MNPs and proved to be an efficient strategy to obtain a more stable colloidal dispersion, avoiding the nanoparticles oxidation, enhancing the irinotecan incorporation and release. Furthermore, citrate-coated BCD-MNPs showed the same cytotoxicity of the free IRI.

5.
Environ Sci Pollut Res Int ; 24(7): 6114-6125, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27040545

RESUMO

Fe2O3-SiO2 composites were prepared by impregnation (sample FeIMP) or doping (sample FeDOP) in the structure of porous silica. The dye removal capacity of the materials was investigated through adsorption and oxidation studies of methylene blue and rhodamine B. N2 adsorption/desorption measurements on FeIMP and FeDOP resulted in specific areas of 27 and 235 m2 g-1, respectively. Mössbauer spectroscopy and XRD data detected hematite and maghemite as the iron phases in the samples FeIMP and FeDOP, respectively. Adsorption isotherms and kinetic studies of the dyes were better fitted in DKR model for FeDOP, where the process follows a pseudo-second order with the interparticle diffusion step being the rate-limiting step. On the other hand, FeIMP has better fit in the Langmuir model. Photocatalytic activity was observed in FeDOP under UV irradiation by the presence of reaction-hydroxylated intermediates for MB (m/z = 301) and RhB (m/z = 459). However, the photocatalytic activity was strongly influenced by the adsorption affinity between dye/catalyst. Photogenerated holes are the species responsible for the dye degradation when the adsorption is too strong, while hydroxyl radical action will be favored when the adsorption is not vigorous as detected by ESI-MS. Graphical Abstract Action of photogenerated holes and free electrons into the photocatalytically mechanism of methylene blue degradation over a semiconductor.


Assuntos
Compostos Férricos/química , Imãs/química , Dióxido de Silício/química , Poluentes Químicos da Água , Purificação da Água/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
6.
Chemosphere ; 159: 602-609, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27343867

RESUMO

Amphiphilic magnetic composites were produced based on chrysotile mineral and carbon structures by chemical vapor deposition at different temperatures (600-900 °C) and cobalt as catalyst. The materials were characterized by elemental analysis, X-ray diffraction, vibrating sample magnetometry, adsorption and desorption of N2, Raman spectroscopy, scanning electronic microscopy, and thermal analysis showed an effective growth of carbon structures in all temperatures. It was observed that at 800 and 900 °C, a large amount of carbon structures are formed with fewer defects than at 600 and 700 °C, what contributes to their stability. In addition, the materials present magnetic phases that are important for their application as catalysts and adsorbents. The materials have shown to be very active to remove the oil dispersed in a real sample of emulsified wastewater from biodiesel production and to remove methylene blue by adsorption and oxidation via heterogeneous Fenton mechanism.


Assuntos
Asbestos Serpentinas/química , Carbono/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Catálise , Azul de Metileno/química , Oxirredução , Análise Espectral Raman , Propriedades de Superfície , Difração de Raios X
7.
J Hazard Mater ; 317: 327-334, 2016 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-27318729

RESUMO

In this work, [FeOx(OH)y]/Al2O3 composites with different Fe oxyhydroxy contents, i.e. 10, 20 and 50wt% treated at 150, 200, 300 and 450°C were investigated as adsorbents of ß-lactamic antibiotics, i.e. cephalexin, ceftriaxone and especially amoxicillin, from aqueous solutions. The obtained results showed that the nature of the surface Fe(3+) species play a fundamental role on the adsorption process. The most efficient adsorption was obtained for the sample 150Fe50A (50% [FeOx(OH)y] supported in Al2O3 treated at 150°C) whereas the thermal treatment at higher temperatures caused a strong decrease on the adsorption capacity. Mössbauer, XRD, FTIR, Raman, TG-MS, SEM, CHN and BET of the composite 150Fe50A suggested an approximate composition of FeO0.65(OH)1.7 whereas at 450°C strong dehydroxylation process takes place to form FeO1.4(OH)0.21. These results combined with competitive adsorption using amoxicillin mixed with phosphate or H2O2 suggest that the antibiotic molecules adsorb by complexation on surface sites likely based on FeOx(OH)y by the replacement of the labile OH ligands.


Assuntos
Óxido de Alumínio/química , Antibacterianos/análise , Compostos Férricos/química , Águas Residuárias/química , Purificação da Água , beta-Lactamas/análise , Adsorção , Propriedades de Superfície
8.
Nanoscale ; 7(7): 3002-15, 2015 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-25600147

RESUMO

The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.

9.
Environ Sci Pollut Res Int ; 22(2): 882-93, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25196961

RESUMO

Recent research on novel cost-effective adsorbent materials suggests potential use of industrial wastes for effluent treatment, with the added benefit of reuse of the wastes. Waste steel materials, including blast oxygen furnace sludge (BOFS), blast furnace sludge (BFS), and blast furnace dust (BFD), were investigated as low-cost adsorbents for removal of an oil emulsion and RR195 dye. The residues were characterized by X-ray diffraction, Brunauer-Emmett-Teller area, volume and distribution of pore diameters, Mössbauer spectroscopy, X-ray fluorescence, granulometry, scanning electron microscopy/energy dispersive spectroscopy, and pHpzc. Adsorption kinetics data were obtained by UV-vis spectrophotometry at the maximum absorption wavelength of the dye solution and crude oil emulsion. The use of waste as an adsorbent was more efficient for treatment of the oil emulsion than the dye solution. BOFS had higher total organic carbon (TOC) removal efficiency than the other waste materials. For the RR195 dye, good color removal was observed for all adsorbents, >90 % within 24 h. TOC removal was poor, <10 % for BFD and BFS and a maximum of 37 % for BOFS. For the oil emulsion, 97 % TOC removal was obtained by adsorption onto BOFS and 87 % onto BFS.


Assuntos
Resíduos Industriais/análise , Aço/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Adsorção , Corantes/química , Emulsões , Reciclagem
10.
J Hazard Mater ; 248-249: 295-302, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23399907

RESUMO

In this work, chrysotile was used as support to grow carbon nanotubes and nanofibers to produce fibrous amphiphilic magnetic nanostructured composites. Iron impregnated on the chrysotile surface at 1, 5 and 15 wt% was used as catalyst to grow carbon nanostructures by CVD (chemical vapor deposition) with ethanol at 800°C. Raman, TG/DTA, Mössbauer, XRD, BET, SEM, TEM, elemental analyses and contact angle measurements suggested the formation of a complex amphiphilic material containing up to 21% of nanostructured hydrophobic carbon supported on hydrophilic Mg silicate fibers with magnetic Fe cores protected by carbon coating. Adsorption tests for the hormone ethynilestradiol (EE), a hazardous water contaminant, showed remarkable adsorption capacities even compared to high surface area activated carbon and multiwall carbon nanotubes. These results are discussed in terms of the hydrophobic surface of the carbon nanotubes and nanofibers completely exposed and accessible for the adsorption of the EE molecules combined with the hydrophilic Mg silicate surface which allows good dispersion in water. The composites are magnetic and after adsorption the dispersed particles can be removed by a simple magnetic process. Moreover, the fibrous composites can be conformed as threads, screens and pellets to produce different filtering media.


Assuntos
Asbestos Serpentinas/química , Carbono/química , Etinilestradiol/química , Nanofibras/química , Nanotubos/química , Poluentes Químicos da Água/química , Adsorção , Estrogênios/química , Ferro/química , Silicatos de Magnésio/química , Fenômenos Magnéticos , Eliminação de Resíduos Líquidos/métodos
11.
Eur J Med Chem ; 58: 493-503, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23159807

RESUMO

The reaction of 2,2-dimethoxy-N-methylethyllamine or 2-methyl-1,3-dioxolane with CS(2) in alkaline media produced two novel dithiocarbamate salts. Subsequent reactions with organotin halides yielded six new complexes: [SnMe(2){S(2)CNR(R(1))(2)}(2)] (1), [Sn(n-Bu)(2){S(2)CNR(R(1))(2)}(2)] (2), [SnPh(2){S(2)CNR(R(1))(2)}(2)] (3), [SnMe(2){S(2)CNR(R(2))(2)}(2)] (4), [Sn(n-Bu)(2){S(2)CNR(R(2))(2)}(2)] (5), [SnPh(2){S(2)CNR(R(2))(2)}(2)] (6), where R = methyl, R(1) = CH(2)CH(OMe)(2), and R(2) = 2-methyl-1,3-dioxolane. All compounds were identified in terms of infrared, (1)H and (13)C NMR, and the complexes were also characterized using (119)Sn NMR, (119)Sn Mössbauer and X-ray crystallography. The biological activity of all derivatives has been screened in terms of IC(90) and IC(50) against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Penicillium citrinum, Curvularia senegalensis, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Streptococcus sanguinis, Escherichia coli, Citrobacter freundii, Salmonella typhimurium, and Pseudomonas aeruginosa and the results correlated well with a performed study of structure-activity relationship (SAR). Complexes (3), (5) and (6) displayed the best IC(90) and IC(50) in the presence of the fungi, greater than that of miconazole, used as control drug.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Desenho de Fármacos , Fungos/efeitos dos fármacos , Compostos Orgânicos de Estanho/farmacologia , Tiocarbamatos/farmacologia , Anti-Infecciosos/síntese química , Anti-Infecciosos/química , Bactérias/crescimento & desenvolvimento , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Fungos/crescimento & desenvolvimento , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Compostos Orgânicos de Estanho/síntese química , Compostos Orgânicos de Estanho/química , Relação Estrutura-Atividade , Tiocarbamatos/síntese química , Tiocarbamatos/química
12.
J Nanosci Nanotechnol ; 12(3): 2661-7, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22755105

RESUMO

In this work, it is demonstrated how a novel technique based on temperature-programmed chemical vapor deposition (TPCVD) can be used to investigate the synthesis of carbon nanotubes (CNTs) from methane on a classic catalyst FeMo(x)/MgO (x = 0.07, 0.35 and 1.00). TPCVD monitors carbon deposition by measuring H2 formed during CH4 decomposition and affords information on the different catalytic species, deactivation process, reaction kinetics and carbon yields. The obtained results showed for FeMgO catalyst a simple TPCVD peak related to the production of carbon beginning at 760 degrees C with maximum at 800 degrees C followed by a rapid deactivation resulting in a low carbon yield. The addition of Mo to Fe/MgO catalyst completely changes the TPCVD profile with the formation of a new catalytic species active at temperatures higher than 900 degrees C, which is stable and continuously decomposes CH4 to produce high carbon yields. Raman, TG/DTG, Mössbauer, SEM, TEM, XRD and TPR analyses suggested that this active catalytic phase is likely related to Fe-Mo and Fe-Mo-C phases active to produce single wall and mainly multiwall carbon nanotubes.

13.
J Colloid Interface Sci ; 379(1): 84-8, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22608147

RESUMO

In this work, hybrid magnetic amphiphilic composites were prepared by the catalytic growth of carbon nanotubes (CNTs) and nanofibers CNF on layered silicates fragments. SEM, TEM, Raman, XRD, Mössbauer, TG/DTA showed that CVD with CH(4) at 800°C produced CNF and magnetic Fe cores fixed on the surface of microfragments of silicates layers. Due to the amphiphilic character, the composites can be easily dispersed in water and efficiently adsorb hydrophobic contaminant molecules. For example, the composites showed remarkable adsorption capacities for the hormone ethinylestradiol, e.g. 2-4 mg m(-2), compared to ca. 0.1 mg m(-2) obtained for high surface area activated carbon and multiwall CNT. These results are discussed in terms of a high hydrophobic exposed surface area of the CNT and CNF fixed on the layered silicates fragments surface. Moreover, the composites can be easily removed from water by a simple magnetic separation process.


Assuntos
Etinilestradiol/química , Magnetismo , Nanofibras/química , Nanotubos de Carbono/química , Silicatos/química , Tensoativos/química , Adsorção , Tamanho da Partícula , Propriedades de Superfície
14.
J Hazard Mater ; 194: 393-8, 2011 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-21890267

RESUMO

A magnetic fraction (15%) from a waste of foundry sand (WFS), composed of sand, carbon, bentonite clay and iron (10%) was modified by thermal treatment at 400, 600 and 800°C under inert atmosphere. Mössbauer analyses showed that the thermal treatment increased the amount of Fe(3)O(4) from 25 to 55% by reduction of Fe(2)O(3) and highly dispersed Fe(3+) by the carbon present in the waste. The Fe(3)O(4) caused a significant increase on the activity of two important reactions with application in environmental remediation: the Fenton oxidation of indigo carmine dye with H(2)O(2) and the reduction of Cr(VI) to Cr(III). The magnetic fraction of WFS was also mixed with hematite (Fe(2)O(3)) and thermally treated at 400, 600 and 800°C. This treatment produced large amounts of surface Fe(3)O(4) and increased substantially the rate of Fenton reaction as well as Cr(VI) reduction. This reactivity combined with the presence of carbon (an adsorbent for organic contaminants), bentonite clay (an adsorbent for metallic contaminants) and the granulometry/packing/hydrodynamic features make WFS a promising material for use in reactive permeable barriers.


Assuntos
Cromo/química , Ferro/química , Temperatura Alta , Magnetismo , Microscopia Eletrônica de Varredura , Oxirredução
15.
Chemosphere ; 78(9): 1116-20, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20060564

RESUMO

In this work, controlled reduction of red mud with H(2) was used to produce active systems for two different environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Mössbauer, powder X-ray diffraction, thermal analyses and scanning electron microscopy analyses showed that at different temperatures, i.e. 300, 400, 500 and 600 degrees C, H(2) reduces red mud to different phases, mainly Fe(3)O(4), Fe(0)/Fe(3)O(4) and Fe(0). These Fe phases are dispersed on Al, Si and Ti oxides present in the red mud and show high reactivity towards two environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Reduction with H(2) at 400 degrees C showed the best results for the oxidation of the model dye methylene blue with H(2)O(2) at neutral pH due to the presence of the composite Fe(0)/Fe(3)O(4). The reduced red mud at 500-600 degrees C produced Fe(0) highly active for the reduction of Cr(VI) in aqueous medium. Another feature of these red mud based system is that after deactivation due to extensive use they can be completely regenerated by simple treatment with H(2).


Assuntos
Cromo/química , Peróxido de Hidrogênio/química , Ferro/química , Corantes/química , Recuperação e Remediação Ambiental , Compostos Férricos/química , Temperatura Alta , Hidrogênio/química , Azul de Metileno/química , Oxirredução
16.
Eur J Med Chem ; 45(3): 883-9, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19959261

RESUMO

The reaction of 1,3-cyclohexadione with 2-aminobenzoic acid has produced the 2-(3-oxocyclohex-1-enyl)benzoic acid (HOBz). Subsequent reactions of the ligand with organotin chlorides led to [Me(2)Sn(OBz)O](2) (1), [Bu(2)Sn(OBz)O](2) (2), [Ph(2)Sn(OBz)O](2) (3), [Me(3)Sn(OBz)] (4), [Bu(3)Sn(OBz)] (5) and [Ph(3)Sn(OBz)] (6). All complexes have been fully characterized. In addition the structure of complexes (2) and (4) have been authenticated by X-ray crystallography. The biological activity of all derivatives has been screened against Cryptococcus neoformans and Candida albicans. In addition we have performed toxicological testes employing human kidney cell. The complexes (3), (5) and (6) displayed the best values of inhibition of the fungus growing, superior to ketoconazole. Compound (5) presented promising results in view of the antifungal and cytotoxicity assays.


Assuntos
Ácido Benzoico/química , Candida albicans/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Ácidos Cicloexanocarboxílicos/química , Desinfetantes/síntese química , Desinfetantes/farmacologia , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Linhagem Celular , Cristalografia por Raios X , Desinfetantes/química , Humanos , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Compostos Orgânicos de Estanho/síntese química , Compostos Orgânicos de Estanho/química , Compostos Orgânicos de Estanho/farmacologia
17.
Eur J Med Chem ; 43(7): 1454-61, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17983689

RESUMO

Reaction of n-butyltin trichloride [(n-Bu)SnCl(3)] with 2-pyridineformamide thiosemicarbazone (H2Am4DH) and its N(4)-methyl (H2Am4Me) and N(4)-ethyl (H2Am4Et) derivatives gave [(n-Bu)Sn(2Am4DH)Cl(2)] (1), [(n-Bu)Sn(2Am4Me)Cl(2)] (2), and [(n-Bu)Sn(2Am4Et)Cl(2)] (3). Thiosemicarbazones as well as their tin complexes are active as antimicrobials against the growth of Candida albicans and Salmonella typhimurium and were highly active against malignant glioblastoma. The cytotoxic activity of complexes 1-3 is similar. Among the studied compounds [(n-Bu)Sn(2Am4DH)Cl(2)] (1) was the most active as antiproliferative (cytostatic) agent. Thiosemicarbazones and their tin(IV) complexes proved to be more potent as cytotoxic agents than cisplatin. All the compounds were able to induce apoptosis.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Formamidas/química , Compostos Orgânicos de Estanho/química , Piridinas/química , Tiossemicarbazonas/química , Tiossemicarbazonas/farmacologia , Linhagem Celular Tumoral , Cristalografia por Raios X , Humanos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Difração de Raios X
18.
Inorg Chem ; 45(26): 10642-50, 2006 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-17173419

RESUMO

This work reports the incorporation of ferrocene into a porous silica glass under ambient temperature and atmosphere. After or during the ferrocene incorporation, the spontaneous formation of ferricinium ions was observed by electron paramagnetic resonance (EPR), UV-visible, X-ray absorption near-edge structure (XANES), and 57Fe Mössbauer measurements. It was shown that the oxidation of ferrocene molecules to ferricinium ions was promoted by air and that the Si-O- groups on the surface of the pores act as counteranions. Pyrolysis of the porous glass/ferricinium material under argon atmosphere and variable temperature yields different glass/carbon nanocomposites, which were subsequently treated with an HF solution in order to remove the glassy fraction. The resulting insoluble carbon materials were characterized by transmission electron microscopy (TEM), Raman, and EPR spectroscopy and consisted of amorphous carbon when the pyrolysis was carried out at 900 or 1000 degrees C and of a mixture of carbon nanotubes and carbonaceous materials at a pyrolysis temperature of 1100 degrees C. When the pyrolysis was conducted under air, the incorporated ferricinium forms alpha-Fe2O3, and the resulting material is a transparent and highly homogeneous glass/iron oxide nanocomposite.

19.
Inorg Chem ; 45(11): 4518-25, 2006 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-16711702

RESUMO

The synthesis and the IR, NMR (1H, 13C, and 119Sn), and Mössbauer spectroscopies and single-crystal X-ray diffraction studies of seven-coordinated diorganotin(IV) complexes, namely, [Ph2Sn(Hdapsc)]Cl.H2O.DMF [7; H(2)dapsc = 2,6-diacetylpyridine bis(semicarbazone)], [Me(2)Sn(H2,6Achexim)]Br.H2O [8; H(2)2,6Achexim = 2,6-diacetylpyridine bis(3-hexamethyleneiminylthiosemicarbazone)], [Me(2)Sn(dapmts)] [9; H(2)dapmts = 2,6-diacetylpyridine bis(4-methythiosemicarbazone)], and [nBu2Sn(dapmdtc)] [10; H(2)dapmdtc = 2,6-diacetylpyridine bis(S-methydithiocarbazate)], were done. The determination of the structures of [Ph(2)Sn(Hdapsc)]+, [Me2Sn(H2,6Achexim)]+ and [Me2Sn(dapmts)], [nBu2Sn(dapmdtc)] revealed the presence of monocationic and neutral complexes, respectively. The structures consist of monomeric units in which the Sn(IV) ions exhibit distorted pentagonal-bipyramidal geometries, with the X,N,N,N,X-donor (X = O, S) systems of the ligands lying in the equatorial plane and the organic groups in the apical positions. The C-Sn-C angle in the seven-coordinated diorganotin(IV) complexes was estimated using a correlation between Mössbauer and X-ray data based on the point-charge model and using new values obtained in this work for [alkyl] = -1.00 mm s(-1) and [aryl] = -0.80 mm s(-1) for complexes containing O,N,N,N,O-pentadentate ligands and new values for [alkyl] = -0.87 mm s(-1) and [aryl] = -0.75 mm s(-1) for complexes containing S,N,N,N,S-pentadentate ligands.

20.
Chemosphere ; 60(8): 1118-23, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15993160

RESUMO

In this work a novel heterogeneous Fenton system based on Fe(0)/Fe3O4 composites is described. The composites with several Fe(0)/Fe3O4 ratios were prepared by two different methods, i.e. mechanical alloying of Fe(0) and Fe3O4 powders and controlled reduction of Fe3O4 with H2. Reaction studies and detailed Conversion Electron Mössbauer surface characterization of the composites Fe(0)/Fe3O4, Fe(0), Fe3O4, alpha-Fe2O3 and gamma-Fe2O3 suggested that Fe2+surf species are essential to produce an active Fenton system. Kinetic studies for the oxidation of the dye methylene blue, used as an organic model molecule, and for the peroxide decomposition suggest that the reactions proceed via HO* radicals generated from Fe2+surf species and H2O2 in a Fenton like mechanism. The increase in activity caused by the addition of Fe(0) is discussed in terms of a creation of Fe2+surf species during the preparation of the composite and by an electron transfer mechanism from Fe(0) to Fe3+surf during the Fenton reaction to regenerate the Fe2+surf active species.


Assuntos
Ferro/química , Corantes/química , Compostos Férricos/química , Peróxido de Hidrogênio/química , Azul de Metileno/química , Oxirredução , Eliminação de Resíduos Líquidos
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