Complexos de rutênio(III) com bases de Schiff tridentadas e tetradentadas do tipo Salophen : potenciais catalisadores na oxidação de catecol
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2015-09-09Autor
Katayama, Juliana Midori Toia
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Ruthenium complexes are known as versatile electron-transfer and energy-transfer
compounds. Due to these unique characteristics, ruthenium complexes exhibit a wide
range of applications in various research areas such as artificial photosynthesis,
photomolecular devices, biological probes, oxidation catalysts and organic synthesis.
In the last two decades, salophen ligands and their complexes have received much
attention, mainly because of their extensive applications in the fields of synthesis and
catalysis. Thus, ruthenium(III) complexes with Schiff bases have several potential
applications in the catalytic reactions such as cyclopropanation, epoxidation,
aziridination, sulfimidation, catechols oxidation and Diels-Alder reactions. In this work
were synthesized ligands and ruthenium complexes containing tridentate and
tetradentate Schiff bases, which have substituted aromatic diimines, with satisfactory
yields. The compounds synthesized in this work were characterized by melting point
measurements, solubility tests, conductivity measurements, vibrational spectroscopy
in the IR region, absorption spectra in the UV-vis, and cyclic voltammetry. The
ligands were also characterized by nuclear magnetic resonance. The synthesized
complex catalyzed oxidation of the substrate, 3,5-di-tert-butylcatechol, in their
respective quinone; and these transformations were accompanied by absorption
spectroscopy in the UV-vis region in 24 hours of reaction. The complexes’ structures
have allowed structural and electronic effects to be evaluated and correlated with
their catalytic activities. Although slow and low substrate conversion, less than 30%,
trends were observed for correlations between structure and catalytic activity. The
percentages of 3,5-di-tert-butilquinone obtained for the best catalysts among these
complexes suggests that there is a step of forming a catalytically active species
during the reaction time.