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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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Published in: | Journal of non-crystalline solids 2002-06, Vol.304 (1), p.151-159 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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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. |
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ISSN: | 0022-3093 1873-4812 |
DOI: | 10.1016/S0022-3093(02)01019-0 |