Dft
Mostrando 37-48 de 442 artigos, teses e dissertações.
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37. Experimental and Theoretical Study of LiMn2O4 Synthesized by the Solution Combustion Method Using Corn Starch as Fuel
Lithium manganese oxide, LiMn2O4, was synthesized in two temperature stages, where the first consisted by an ecofriendly solution combustion method at 300 °C. Finally, the as-burned powders were thermal treated at 500 and 700 °C. The structural and morphological changes were evaluated by the Rietveld method and density functional theory (DFT) calculations.
J. Braz. Chem. Soc.. Publicado em: 2020-02
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38. Acid-Catalyzed Z-E Isomerization of γ-Alkylidenebutenolides: An Experimental and DFT Study
The Z-E isomerization of γ-alkylidenebutenolide analogues to natural nostoclides and other natural butenolides was investigated using 1H nuclear magnetic resonance (NMR) and high performance liquid chromatography (HPLC) data as well as density functional theory (DFT) calculations at the wB97x-D/6-31G(d,p) level, including solvent effects with the polarizabl
J. Braz. Chem. Soc.. Publicado em: 2020-01
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39. Investigating Surface Properties and Lithium Diffusion in Brookite-TiO2
Surfaces properties of TiO2 in the brookite phase and the lithium diffusion are studied using density functional theory (DFT) and interatomic potential simulations. Simulations predict that the brookite surfaces have a higher intrinsic Lewis acidity compared to the other polymorphs due to the presence of four coordinated Ti atoms on the surface in contrast t
J. Braz. Chem. Soc.. Publicado em: 2020-01
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40. Microstructural Evolution and Phase Transformation of a Ti-5Nb-5Al Alloy During Annealing Treatment
The microstructural evolution and phase transformation of a Ti-5Nb-5Al alloy during isothermal annealing treatment were studied in this paper. The microstructural evolution was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with X-ray energy dispersive spectroscopy (EDS) and electron backscattering diffraction (EBSD). The fi
Mat. Res.. Publicado em: 05/12/2019
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41. Structure and Absolute Configuration of Secondary Metabolites from Two Strains of Streptomyces chartreusis Associated with Attine Ants
The antibiotic streptazolin (1), its E-isomer (2), along with the stereoisomers strepchazolin A (3) and strepchazolin B (4) and the inorganic compound cyclooctasulfur (5) were produced in solid culture by Streptomyces chartreusis ICBG377, which was isolated from the fungal garden of the leaf-cutter ant Acromyrmex subterraneus brunneus. This is the first time
J. Braz. Chem. Soc.. Publicado em: 24/10/2019
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42. ESTUDO ELETRÔNICO DA REATIVIDADE DA 8-HIDROXIQUINOLINA SUBSTITUÍDA FRENTE AO SÍTIO DE LIGAÇÃO DO PEPTÍDEO β-AMILOIDE AO ÍON ZINCO
In this work, density functional theory (DFT) was used to study the caused effect on reactivity of 8-hydroxyquinoline (8-HQ) by substituent groups (-H, -CH3, -OCH3, -Cl and -NO2) on different positions of the 8-HQ structure. DFT was also used to obtain the electronic profile of β-amyloid peptide (Aβ) bind site to Zinc. The energies and absolute hardness (�
Quím. Nova. Publicado em: 21/10/2019
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43. THEORETICAL STUDIES ON THE NEW HIGH-NITROGEN EXPLOSIVES N14 AND N18
The power of a compound is enhanced by the direct connection of nitrogen atoms, and its stability can be improved through conjugated structure. So novel high energy density materials N14 (1,6-dihydro-1,2,3,3a,4,5,5a,6,7,8,8a,9,10,10a-tetradecazapyrene) and N18 (1,2,2a,3,4,4a,5,6,6a,7,8,8a,9,10,10a,11,12a-octadecazacoronene) were designed, and their structure
Quím. Nova. Publicado em: 21/10/2019
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44. Chemosensor Development of Cu2+ Recognition Using 1,5-Diphenylthiocarbazone: Optimization, COSMO-RS and DFT Studies
The sensitive and selective chemosensor for copper(II) ions (Cu2+) was successfully optimized using the 1,5-diphenylthiocarbazone (DPT) compound. The result showed that dimethyl sulfoxide (DMSO) in a 9:1 (DMSO:water) ratio at a pH of 3 was the optimum medium for DPT to act as chemosensor of Cu2+ recognition. The DPT chemosensor did not encounter any interfer
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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45. Benzodioxol Group Driving Supramolecular Arrangement of Two Tri-Methoxy Chalcones onto Β-Secretase 1 Enzyme Active Site
Chalcones are compounds with wide interesting biological activities including Alzheimer’s disease. A comparative study was performed between the chalcones (E)-1-(2-aminophenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one and 1-(6-amino-1,3-benzodioxol-5-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one regarding the influence of benzodioxol group on their molecu
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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46. Alternative Non-Ionic Pathway for Uncatalyzed Prins Cyclization: DFT Approach
Density functional theory calculations (ωB97X-D/6-311++G(d,p)) are employed to investigate an alternative pathway for Prins-like cyclization. Although strong acids usually catalyze this reaction, 4-amino-1,3-dioxanes are rapidly obtained in high yields without catalyst when benzenamines and acetaldehyde react at low temperatures, in aqueous medium. Consider
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
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47. RING OPENING POLYMERIZATION OF L-LACTIDE WITH TWO DIFFERENT ZINC(II) PHENOXY-IMINE COMPLEXES AS INITIATORS
This article reports the synthesis of two zinc(II) complexes containing phenoxy-imine ligands and their application as initiators of bulk ring opening polymerization (ROP) of L-lactide (LLA). The phenoxy-imine ligands (L1 and L2) were obtained by condensation reactions of salicylaldehyde derivatives with 2,6-diisopropylaniline. The reactions of L1 and L2 wit
Quím. Nova. Publicado em: 18/07/2019
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48. Ligand and Solvent Effects on the Structural and Optical Properties of Au13L83+ Clusters: a Density Functional Theory Study
Density functional theory (DFT) calculations have been performed to develop a systematic structural analysis of Au13L83+, where L = SCH3, SeCH3, SCH2OCH3 and S(CH2)2NH2, in order to examine the influence of different ligands. Binding energy calculations indicate that the gold core is more stabilized by the ligand in the following sequence S(CH2)2NH2 > SCH2OC
J. Braz. Chem. Soc.. Publicado em: 04/07/2019