First insight into catalytic activity of anionic iron porphyrins immobilized on exfoliated layered double hydroxides

Mg–Al layered double hydroxide (LDH) intercalated with glycinate anions was synthesized through co-precipitation and exfoliated in formamide and the single-layer suspension was reacted with aqueous iron porphyrin solutions (Fe(TDFSPP) and Fe(TCFSPP)). The obtained materials were characterized by X-r...

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Bibliographic Details
Published in:Journal of colloid and interface science 2005-01, Vol.281 (2), p.417-423
Main Authors: Nakagaki, Shirley, Halma, Matilte, Bail, Alesandro, Arízaga, Gregório Guadalupe Carbajal, Wypych, Fernando
Format: Article
Language:English
Subjects:
Aluminum Hydroxide - chemistry
Catalysis
Chemistry
Electron Spin Resonance Spectroscopy
Exact sciences and technology
Exfoliation
Ferric Compounds - chemistry
General and physical chemistry
Iron porphyrin
Layered double hydroxide (LDH)
Magnesium Hydroxide - chemistry
Oxidation
Oxidation-Reduction
Porphyrins - chemistry
Porphyrins - metabolism
Supported catalysts
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
X-Ray Diffraction
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Summary:Mg–Al layered double hydroxide (LDH) intercalated with glycinate anions was synthesized through co-precipitation and exfoliated in formamide and the single-layer suspension was reacted with aqueous iron porphyrin solutions (Fe(TDFSPP) and Fe(TCFSPP)). The obtained materials were characterized by X-ray powder diffraction, UV–vis, and electron paramagnetic resonance and investigated in the oxidation reaction of cyclooctene and cyclohexane using iodosylbenzene as oxidant. The iron porphyrin seems to be immobilized at the surface of the glycinate intercalated LDH. The catalytic activities obtained in heterogeneous media for iron porphyrin, Fe(TDFSPP), was superior to the results obtained under homogeneous conditions, but the opposite effect was observed on the Fe(TCFSPP), indicating that, instead of the structural similarity of both iron porphyrins (second-generation porphyrins), the immobilization of each one produced different catalysts. The best catalytic activity of the Fe(TDFSPP)/Gly-LDH, compared to Fe(TCFSPP)/Gly-LDH, can be explained by the easy access of the oxidant and the substrate to the catalytic sites in the former, probably located at the surface of the layered double hydroxide pillared with glycinate anions. A model for the immobilization and a mechanism for the oxidation reaction will be discussed.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2004.08.098