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Immobilization of β halogenated ironporphyrin in the silica matrix by the sol–gel process

We present the synthesis and characterization of a hybrid organic–inorganic material using robust metalloporphyrins halogenated in both meso and β-position: the iron complex (5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin and (2,3,7,8,12,13,17,18-octa-β-bromo-5,10,15,20-tetrakis-(pentafluoropheny...

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Bibliographic Details
Published in:Journal of non-crystalline solids 2002-06, Vol.304 (1), p.151-159
Main Authors: Aparecida Vidoto, Ednalva, Silvia Monsalves Moreira, Maria, da Silva Vinhado, Fábio, Jorge Ciuffi, Katia, Rangel Nascimento, Otaciro, Iamamoto, Yassuko
Format: Article
Language:English
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Summary:We present the synthesis and characterization of a hybrid organic–inorganic material using robust metalloporphyrins halogenated in both meso and β-position: the iron complex (5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin and (2,3,7,8,12,13,17,18-octa-β-bromo-5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin, which stabilize the porphyrins against oxidative degradation. The immobilization was developed by the sol–gel process using pyridine and imidazole as template. Electron paramagnetic resonance (EPR) spectra of (2,3,7,8,12,13,17,18-octa-β-bromo-5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin show that the entrapment of ironporphyrin is in a higher symmetry compared to the systems in solution. A reduction of iron was observed in the presence of imidazole, determined by the absence of an EPR spectrum. The addition of chloridric acid vapor induced an oxidation of iron and a small quantity of iron in a high spin state was detected by a component with axial symmetry. The ironporphyrins were active as catalysts for cyclooctene using iodozylbenzene and hydrogen peroxide as oxygen donors. The perhalogenated porphyrins immobilized had a smaller activity due to their iron oxidation and spin states.
ISSN:0022-3093
1873-4812
DOI:10.1016/S0022-3093(02)01019-0