Synthesis of fluorinated metalloporphyrinosilica imprinted with templates through sol-gel process

We present the synthesis of a hybrid material containing fluorinated iron porphyrins through hydrolysis and polycondensation of iron porphyrin bearing a trifluorosilyl Function with tetraethoxysilane in the presence of nitrogen bases acting as template molecules. The presence of metalloporphyrin Soret band is detected in the ultraviolet-visible absorption spectra of all metalloporphyrinosilica-templates. Thermogravimetric analysis and electron paramagnetic resonance of the materials also confirm the presence of metalloporphyrin in a silica network. Electron spectroscopy imaging was that of a non-crystalline microstructure. The iron and silicon distribution are homogeneous for the elements in all particle sites. The iron porphyrinosilicas-template were active as catalysts for cyclooctene epoxidation using iodozylbenzene as oxygen donor. In general, the epoxidation yield is larger for iron porphyrinosilicas-template than for manganese porphyrinosilicas-template. The manganese porphyrinosilicas-template had a smaller activity due to their manganese oxidation state. The largest catalytic yield were obtained with the iron porphyrinosilica-pyridine (85%). (C) 2000 Elsevier Science B.V. All rights reserved.