Navegando por Autor "Mancini, Daiana Teixeira"
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Item 99Tc NMR as a promising technique for structural investigation of biomolecules : theoretical studies on the solvent and thermal effects of phenylbenzothiazole complex.(2014) Mancini, Daiana Teixeira; Souza, Eugenio F.; Caetano, Melissa Soares; Ramalho, Teodorico de CastroThe phenylbenzothiazole compounds show antitumor properties and are highly selective. In this paper, the 99Tc chemical shifts based on the (99mTc)(CO)3(NNO) complex conjugated to the antitumor agent 2-(4′-aminophenyl)benzothiazole are reported. Thermal and solvent effects were studied computationally by quantum-chemical methods, using the density functional theory (DFT) (DFT level BPW91/aug-cc-pVTZ for the Tc and BPW91/IGLO-II for the other atoms) to compute the NMR parameters for the complex. We have calculated the 99Tc NMR chemical shifts of the complex in gas phase and solution using different solvation models (polarizable continuum model and explicit solvation). To evaluate the thermal effect, molecular dynamics simulations were carried, using the atom-centered density matrix propagation method at the DFT level (BP86/ LanL2dz). The results highlight that the 99Tc NMR spectroscopy can be a promising technique for structural investigation of biomolecules, at the molecular level, in different environments.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 Xylose dehydration to furfural using niobium doped δ-FeOOH as catalyst.(2022) Campos, Paulo Tadashi Bannai; Bonesio, Mariana de Rezende; Lima, André Luiz Dias; Silva, Adilson Cândido da; Mancini, Daiana Teixeira; Ramalho, Teodorico de CastroThe effect of modification of δ-FeOOH with niobium, applied to dehydration reaction of xylose, was evaluated by experimental and theoretical methods. The experimental data confirmed, namely the characteristic peaks in the X-ray diffractometer analysis, that the materials were obtained. Inductively coupled plasma mass spectrometry analysis defined the percentage of Nb as 0 for pure δ-FeOOH and 9.5 wt. % (δ-FeOOH/Nb) for doped. In relation to obtaining furfural, the doped material presents a conversion improvement of 290 % when compared to pure catalyst. Theoretical calculations were useful in understanding the preferential route of the mechanisms proposed by the obtained potential energy values. To understand the preferred routes, the most favorable position of xylose in relation to δ-FeOOH was initially calculated. From this, the conditions favoring furfural formation were calculated based on the routes of the proposed mechanisms and the energy values indicated that the furfural formation is more likely to happen on the doped material.