Navegando por Autor "Luz, Sulusmon Cesar"
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Item 1D coordination polymer based on copper(II)-containing tetrameric 1,2,3- triazole ligand from click chemistry : magnetic and catalytic properties.(2019) Teixeira, Leonardo César de Moraes; Souza, Gilmar Pereira de; Fajardo, Humberto Vieira; Luz, Sulusmon Cesar; Álvarez, Eleuterio; Lloret, Francesc; Viana, Renato Márcio Ribeiro; Rojo Marcos, Francisco Javier; Stumpf, Humberto Osório; Figueiredo, Rute Cunha; Correa, Rodrigo de SouzaA novel tetrameric tetra[O-((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)]-pentaerythritol (TBTP) has been synthesized using click chemistry strategy. TBTP was characterized and used as ligand to form new Cu(II) complexes, forming 1-D coordination polymers. Two square planar complexes were characterized by single-crystal X-ray diffraction, presenting formula [Cu(TBTP)][Cu(NO3)4] (1) and [Cu(TBTP)](NO3)2 (2). In both structures, a cationic 1-D coordination polymer (CP) has been formed. The CP contain a 1:1 Cu(II)/TBTP ratio with four neutral triazole groups coordinating the Cu(II) center, forming a CuN bonds ranging 1.988(2)–2.001(2) Å. The study of the magnetic properties of compounds 1 and 2 pointed to an antiferromagnetic behavior for both compounds, defined by inter- and intra-chain dipolar interactions among their metallic centers. In addition, the complex 1 was found to be an efficient catalyst for selective oxidation of aniline to azobenzene under mild reaction conditions.Item Application of Al2O3/AlNbO4 in the oxidation of aniline to azoxybenzene.(2019) Batalha, Daniel Carreira; Luz, Sulusmon Cesar; Taylor, Jason Guy; Fajardo, Humberto Vieira; Noremberg, Bruno S.; Cherubin, Igor José da Silva; Silva, Ricardo Marques e; Gonçalves, Margarete Regina Freitas; Bergmann, Carlos Pérez; Valentini, Antoninho; Carreño, Neftalí Lenin VillarrealAl2O3/AlNbO4 powder was fabricated by a facile high-energy milling process. The precursor materials, Al2O3 and Nb2O5, are readily available and have very attractive properties. Moreover, the catalytic activity of the sample in the liquid phase oxidation of aniline (OA) in the presence of hydrogen peroxide as oxidant was evaluated. The catalyst was found to be highly efficient and selective in the oxidation of aniline to azoxybenzene under mild conditions. When mixed with 28% AlNbO4 the alumina-based catalyst achieved high conversion and selectivity and very similar to the pure Nb2O5.Item Sub-15 nm CeO2 nanowires as an efficient nonnoble metal catalyst in the room-temperature oxidation of aniline.(2018) Silva, Anderson Gabriel Marques da; Batalha, Daniel Carreira; Rodrigues, Thenner Silva; Candido, Eduardo Guimarães; Luz, Sulusmon Cesar; Freitas, Isabel Cristina de; Fonseca, Fabio Coral; Oliveira, Daniela Coelho de; Taylor, Jason Guy; Torresi, Susana Ines Cordoba de; Camargo, Pedro Henrique Cury; Fajardo, Humberto VieiraWe described herein the facile synthesis of sub-15 nm CeO2 nanowires based on a hydrothermal method without the use of any capping/stabilizing agent, in which an oriented attachment mechanism took place during the CeO2 nanowire formation. The synthesis of sub-15 nm CeO2 nanowires could be achieved on relatively large scales (∼2.6 grams of nanowires per batch), in high yields (>94%), and at low cost. To date, there are only a limited number of successful attempts towards the synthesis of CeO2 nanowires with such small diameters, and the reported protocols are typically limited to low amounts. The nanowires displayed uniform shapes and sizes, high surface areas, an increased number of oxygen defects sites, and a high proportion of Ce3+/Ce4+ surface species. These features make them promising candidates for oxidation reactions. To this end, we employed the selective oxidation of aniline as a model transformation. The sub-15 nm CeO2 nanowires catalyzed the selective synthesis of nitrosobenzene (up to 98% selectivity) from aniline at room temperature using H2O2 as the oxidant. The effect of solvent and temperature during the catalytic reaction was investigated. We found that such parameters played an important role in the control of the selectivity. The improved catalytic activities observed for the sub-15 nm nanowires could be explained by: i) the uniform morphology with a typical dimension of 11 ± 2 nm in width, which provides higher specific surface areas relative to those of conventional catalysts; ii) the significant concentration of oxygen vacancies and high proportion of Ce3+/Ce4+ species at the surface that represent highly active sites towards oxidation reactions; iii) the crystal growth along the (110) highly catalytically active crystallographic directions, and iv) the mesoporous surface which is easily accessible by liquid substrates. The results reported herein demonstrated high activities under ambient conditions, provided novel insights into selectivities, and may inspire novel metal oxide-based catalysts with desired performances