Síntese e caracterização de complexos de base de schiff com níquel (ii) ancorados no material mesoporoso SBA-15
SBA-15 are mesoporous materials, having a network of channels and well defined pore size in the nanometer range, as well as, other features such as high thermal stability and surface area. This particular pore architecture makes these promising materials in the anchoring area of a variety of comp...
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| Formato: | doctoralThesis |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/20556 |
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| Resumo: | SBA-15 are mesoporous materials, having a network of channels and well defined
pore size in the nanometer range, as well as, other features such as high thermal stability and
surface area. This particular pore architecture makes these promising materials in the anchoring
area of a variety of compounds in the silica matrix resulting in applications in various
fields, among them, in catalysis. In this work, complexes were synthesized Schiff base with
nickel (II) to be anchored in the functionalized SBA-15 3 – chloropropyltrimethoxysilane and
a study of the thermal stability of these compounds. After synthesis of the complexes, they
were characterized by elemental analysis (CHN), melting point, conductivity, magnetic susceptibility,
absorption spectroscopy in the UV-visible region absorption, spectroscopy in the
infrared region and thermal analysis (TG/DTG). Elemental analysis suggests that the complexes
have the general formula chemical: [Ni(C18H19N3O2)].2CH3COO.H2O,
[Ni(C20H23N3O2)(2Cl)].2H2O, [Ni(C19H20N3O2)(2Cl)].3H2O, and L1= C18H19N3O2, L2=
C20H23N3O2, L3 = C19H20N3O2. In absorption spectroscopy in UV - visible and infrared complexes
was evidenced the coordination metal - ligand. After characterization of the complexes,
confirming the metal - ligand coordination, they have been anchored in the mesoporous
material. The characterization of these materials were made by x- ray diffraction, x- ray fluorescence,
N2 adsorption and desorption spectroscopy, the infrared spectroscopy and thermal
analysis (TG/DTG). XRD analysis revealed three main diffraction peaks, whose Miller indices
are (100), (110) and (200), showing that even after the anchoring, the mesoporous materials
do not lose their structural characteristics. The percentages of the elements (nickel chloride
and silica) found in the anchored materials through the x-ray fluorescence analysis showed
that the complexes were anchored in the pores of the silica. Through adsorption and desorption
of N2, we observed that the materials presented isotherm type IV and type H1 hysteresis
characteristic of mesoporous materials. In the infrared spectroscopy, the materials showed
characteristic bands of ligands (Schiff base) and silica demonstrating the success of the anchor.
In the thermal analysis (TG/DTG), there were observed the decomposition of adsorbed
water, coordinated water, amines, aromatics, ligands, chloropropyltrimethoxysilane and an
increase in thermal stability (removal of ligand) of silicas anchored [Ni(L1)]SBA-15,
[Ni(L2)SBA-15 and [Ni(L3)SBA-15 compared of free complexes, showing successful anchoring
of complex molecular sieve. |
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