Navegando por Autor "Cunha, Elaine Fontes Ferreira da"
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Item Bonding, structure, and stability of [(Na)𝑛(Phe)𝑚]𝑛+ clusters : some surprising results from an experimental and theoretical investigation in gas phase.(2013) Caetano, Melissa Soares; Ramalho, Teodorico de Castro; Vieira, Tales Giuliano; Gonçalves, Arlan da Silva; Mancini, Daiana Teixeira; Cunha, Elaine Fontes Ferreira daStructure and stability of [(Na) 𝑛 (Phe)𝑚]𝑛+ clusters in the ground state were analyzed at the theoretical and experimental levels. Our experimental and theoretical findings showed that the [(Na) 𝑛 (Phe)𝑚]𝑛+ clusters in gas phase tend to form mainly planar rings of four members. The symmetry and the small dipole moment in these specific configurations suggested that their stability could be associated with an alignment of the water molecules, maximizing attractive electrostatic interactions caused by changes in the charge distribution of the clusters.Item Molecular insight into the inhibition mechanism of plant and rat 4-hydroxyphenylpyruvate dioxygenase by molecular docking and DFT calculations.(2015) Silva, Telles Cardoso; Pires, Maíra dos Santos; Castro, Alexandre Alves de; Cunha, Elaine Fontes Ferreira da; Caetano, Melissa Soares; Ramalho, Teodorico de CastroThe 4-hydroxyphenylpyruvate dioxygenase (HPPD) is a relevant target protein for therapeutic and agrochemical research. It is an iron-dependent enzyme, and its inhibition has very different effects on plants and animals. In animals, the enzyme has an important role in the catabolism of tyrosine, and in the plant, it operates in the cascade of photosynthesis. Potent HPPD inhibitors have been described, and all contain the 1,3-diketone group in its shape. In this research, we carried out a study of the interaction modes of HPPD enzymes from plant and rat with selective and non-selective herbicides which already available with their structures to identify the molecule groups which are essential to their activity and those that are likely to changes, mediated by molecular computations. In this theoretical investigation, methods of molecular docking, reaction mechanism (QM/MM) and AIM calculations were employed, aiming the search for new more active and selective herbicides. Modifications were performed for DAS 645 and DAS 869 inhibitors. DAS 645 presented a good selectivity for the inhibition of the plant enzyme, and the modifications to the analogs design done increased its activity. For this compound, p–p* stacking interactions seem to be important, and this fact was proven by using AIM calculations. The other prototype compound, DAS 869, a potent inhibitor for both enzymes, had its increased activity in the plant and rat enzyme after added groups capable of performing p–p* stacking interactions.Item Synthesis, structural characterization, and thermalproperties of the poly (methylmethacrylate) / 𝛿 FeOOH hybrid material : an experimental and theoretical study.(2016) Corrêa, Silviana; Lacerda, Lívia Clara Tavares; Santos, Maíra dos Santos; Rocha, Marcus Vinícius Juliaci; Nogueira, Francisco Guilherme Esteves; Silva, Adilson Cândido da; Pereira, Márcio César; Brito, Angela Dayana Barrera de; Cunha, Elaine Fontes Ferreira da; Ramalho, Teodorico de CastroThe 𝛿-FeOOH/PMMA nanocomposites with 0.5 and 2.5 wt.% of 𝛿-FeOOH were prepared by grafting 3 (trimethoxysilyl)propyl methacrylate on the surface of the iron oxyhydroxide particles.TheFTIR spectra of the 𝛿-FeOOH/PMMA nanocomposites showed that the silanemonomers were covalently attached to the 𝛿 FeOOHparticles. Because of the strong interaction between the PMMA and 𝛿-FeOOH nanoparticles, the thermal stability of the 𝛿-FeOOH/PMMA nanocomposites was improved compared to the pure PMMA.The SEM analysis conferred the size agglomerate of particles regarding the morphology of samples.The theoretical study enabled a better understanding of the interaction of the polymer with the iron oxyhydroxide.The DFT-based calculations reinforce the radical trapping mechanism of stabilization of nanocomposites; that is, Fe3+ species might be able to accept electrons coming from the organic phase that decomposes via radical unzipping.The radical scavenge effect delays the weight loss of polymer.