Porphyrins entrapped in an alumina matrix

Novel hybrid organic-inorganic catalysts constituted by iron( III) or manga nese( III) 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin entrapped in an alumina amorphous matrix have been prepared. The hybrid materials were obt ained by a non-hydrolytic sol-gel route, through the condensation of alumin ium chloride with diisopropyl ether in the presence of metalloporphyrin. Th e presence of the metalloporphyrin entrapped in the alumina matrix is confi rmed by ultraviolet-visible spectroscopy and electron spectroscopic imaging . The material was also analysed by infrared spectroscopy, selected area di ffraction, scanning electron microscopy, thermogravimetric analysis and dif ferential thermal analysis, and its surface area was determined. Comparison between the leaching of metalloporphyrin from non-hydrolytic materials and adsorbed metalloporphyrin on commercial neutral alumina confirms that in t he non-hydrolytic materials the metalloporphyrin is entrapped and not just adsorbed on the alumina surface. The use of a conventional hydrolytic sol-g el process leads to the complete leaching of the metalloporphyrin from the matrix, underlining the importance of the non-hydrolytic alumina gel proces s in the matrix preparation. The prepared alumina matrix materials are amor phous, even after heat treatment up 270 degreesC. The new catalysts prepared were tested for their ability to catalyse the ep oxidation of (Z)-cyclooctene using iodosylbenzene as oxygen donor, giving h igh yields in the epoxidation, similar to those obtained using the metallop orphyrin in solution or supported on a silica matrix.