Absorption Uv Vis Spectroscopy
Mostrando 1-12 de 58 artigos, teses e dissertações.
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1. Atomic Absorption Spectrometry as an Alternative to Determine the Presence of Gold Nanoparticles on or in Silica Matrix
Two different gold-silica-based nanomaterials were prepared: (i) silica-supported gold nanoparticles (AuNP/SiO2); and (ii) gold-silica core-shell nanoparticles (AuNP@SiO2). Three strategies for sample treatment (S), consisting in acid treatments, were employed: (S1) HNO3; (S2) HNO3 + HCl; and (S3) HF + HNO3 + HCl, applying microwave oven digestion for S2 and
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. Gold Nanorods Capped with Different Ammonium Bromide Salts on the Catalytic Chemical Reduction of p-Nitrophenol
It is known that the reactivity of the nanocatalytic systems is related to the particle size and shape and also to the features of the capping agents on the nanostructures. In this study, gold nanorods (AuNRs) were synthesized by the seed-mediated method using different tetra-alkylammonium bromide salts as capping agents, that are, cetyltrimethylammonium (CT
J. Braz. Chem. Soc.. Publicado em: 2021-06
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3. Study of structural, optical, and morphological characteristics of manganese titanate (MnTiO3) obtained by combustion reaction using microwave energy
Abstract MnTiO3 is a semiconductor that has relevant dielectric and optical properties. For the synthesis of manganese titanate (MnTiO3) powders, the combustion method via microwave and subsequent calcination at 500, 700, and 900 °C were used. The structural, morphological, and optical properties of the samples were investigated. X-ray diffraction analyzes
Cerâmica. Publicado em: 2021-03
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4. Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent
Five new π-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the ta
J. Braz. Chem. Soc.. Publicado em: 2021-01
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5. Gold Nanoparticle/Tetrapyridylporphyrin Hybrid Material: Spectroscopic and Electrocatalytic Properties and Sensor Application
An electrocatalytic active hybrid material prepared by successive stepwise coordinative deposition of 20 nm diameter gold nanoparticles (AuNP) with 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) on fluorine-doped tin oxide (FTO) substrates previously modified with 3-mercaptopropylsilane is described. Their interaction and assembly were studied by UV-Vis
J. Braz. Chem. Soc.. Publicado em: 2020-11
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6. Ações contra a Covid-19 na População com Síndrome de Down
An electrocatalytic active hybrid material prepared by successive stepwise coordinative deposition of 20 nm diameter gold nanoparticles (AuNP) with 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) on fluorine-doped tin oxide (FTO) substrates previously modified with 3-mercaptopropylsilane is described. Their interaction and assembly were studied by UV-Vis
Arq. Bras. Cardiol.. Publicado em: 2020-11
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7. Kaolinite/TiO2/cobalt(II) Tetracarboxymetallophthalocyanine Nanocomposites as Heterogeneous Photocatalysts for Decomposition of Organic Pollutants Trimethoprim, Caffeine and Prometryn
São Simão’s Brazilian kaolinite has been treated with titanium(IV) isopropoxide and cobalt(II) tetracarboxymetallophthalocyanine under different conditions (acidic or basic), leading, after drying at 100 ºC, to new titania-doped cobalt(II)-metallophthalocyanine/kaolinite solids. These solids were characterized by chemical analysis, powder X-ray diffract
J. Braz. Chem. Soc.. Publicado em: 24/10/2019
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8. Photochemical Synthesis of Ag and Au Nanoparticles Using a Thioxanthone Substituted Chitosan as Simultaneous Photoinitiator and Stabilizer
Silver (AgNPs) and gold (AuNPs) nanoparticles in aqueous solution were generated and stabilized using the 10-oxo-10H-dibenzene thiopyran-3-4-dicarboximide chitosan (TXICh) macrophotoinitiator. The photoinitiator and the nanoparticles in aqueous solution were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). Pure TXICh in aqueou
J. Braz. Chem. Soc.. Publicado em: 24/10/2019
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9. Synthesis and Characterization of Fluorescent PVA/PVAc-Rodhamine Microspheres
Fluorescent polymeric microspheres are used in a wide range of biomedical and technological applications, including blood flow determination, screening, flow visualization, flow tracing, medical imaging, fluorescence microscopy and flow cytometry among others. Rhodamine 6G (R6G) is a lipophilic cationic dye, which is among the most stable organic fluorophore
Mat. Res.. Publicado em: 02/09/2019
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10. Tuning Emitting Color of Electroluminescent Devices Containing Tris(2-acyl-1,3-indandionate)aluminum(III) Complexes as Emitting Layers
In this study, a novel type of tris(2-acyl-1,3-indandione)-aluminum(III) coordination compounds of the general formula [Al(acind)3]H2O, where 2-acyl-1,3-indandione (acind), 2-acetyl-1,3-indandione (aind), 2-benzoyl-1,3-indandione (bind), and 4-methyl-2-benzoyl-1,3-indandione (mbind), were synthesized and characterized by elemental analysis (CHN), Fourier tra
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
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11. Cr3+ Doped Al2O3 Obtained by Non-Hydrolytic Sol-Gel Methodology
This paper reports the synthesis and characterization of Cr3+-doped alumina by the sol-gel non-hydrolytic methodology. The resulting sample was treated at different temperatures. X-ray diffraction revealed that the ruby phase emerged in the sample treated at 1100 ºC, which was later confirmed by absorption bands correspondent to Cr3+ ions allowed transition
J. Braz. Chem. Soc.. Publicado em: 2019-04
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12. Síntese da perovskita [KNbO3]0,9[BaNi0,5Nb0,5O3-δ]0,1 por combustão em solução
Resumo O desenvolvimento de perovskitas ferroelétricas capazes de absorver a luz visível, particularmente KBNNO - [KNbO3]0,9[BaNi0,5Nb0,5O3-δ]0,1 (band-gap Eg= 1,39 eV), tem encorajado a aplicação desses materiais na camada ativa de células solares. Em dispositivos fotovoltaicos, esses materiais podem permitir a obtenção de voltagens superiores à ma
Cerâmica. Publicado em: 2019-01