Hybrid organic-inorganic catalyst

A new family of hybrid organic-inorganic catalysts with dispersed active sites inside ordered mesoporous materials has been prepared by anchorage of transition-metal ligands of Schiff base-type and chiral amino alcohols like (li ,2S)-ephedrine on micelle-templated silicas [180]. Metalation of the grafted ligands with manganese was followed by UV-VIS spectroscopy. 

Metalloporphyrinosilicas as a new class of hybrid organic-inorganic materials were prepared by polymerization of 3- er -butyl-5-vinylsalicylaldehyde with styrene and divinylbenzene and used as selective biomimetic oxidation catalyst.27 Synthesis and structural characterization of rare-earth bisfdimethyl-silyl)amides and their surface organometallic chemistry on mesoporous silicate MCM-41 have been reported.28... 

As shown, for instance, by the lack of any sol-gel catalyst cited in a recent, thorough review covering tens of industrial applications of sol-gel hybrid materials C. Sanchez, B. Julian, P. Belleville and M. Popall, Applications of hybrid organic-inorganic nanocomposites, J. Mater. Chem., 2005, 15, 3559. 

As expected, this functionalization causes a decrease of the average pore diameter suggesting that the environment for organic reactions is spatially more constrained after surface modification. The so obtained hybrid organic-inorganic material MC M-4I TBD was used as catalyst in the Michael reaction between 2-cyclopentcn-1-one 64 and ethylcyanoacctatc 10 (Scheme 17). 

Numerous other examples of supported catalyst systems have since been described in the literature from Shi [29], Grubbs [30], Thieuleux and Coperet [31, 32], and Pleixats and Wong Chi Man [33, 34]. All of these examples describe some form of a silica-supported analog, either from grafting onto commercial silica, or through the preparation of a hybrid organic-inorganic material prepared by sol-gel chemistry, with the functionality incorporated into the silica matrix. 

These cage structures can be derivatized with heteroatoms (539) to form catalysts or organic ligands that can act as precursors to hybrid organic/inorganic materials (540) or ligands (536). 

Application in catalyst and inorganic membranes preparation. J. Mater. Chem. 1999 9 55-65 Guizard C., Julbe A. Nanophase ceramic ion transport membranes for oxygen separation and gas stream enrichment. In Recent Advances in Gas Separation by Microporous Ceramic Membranes, Kanellopoulos N.K., ed., Amsterdam Elsevier, 2000, pp. 435-471 Guizard C., Barboiu M., Bac A., Hovnanian N. Hybrid organic-inorganic membranes with specific transport properties. Applications in separation and sensors technology. Separ. Purif. Technol. 2001 25 167-180... 

Therefore, numerous siloxane-based hybrid organic-inorganic materials have been developed in the past few years. This development yields many interesting new materials, with improved mechanical properties timable between those of glasses and those of polymers. Sol-gel processed hybrid materials such as, optical devices, new sensors and biosensors, new catalysts or membranes have been reported to have high efficiencly, good selectivity and stability (Lebeau, 1999). 

Battioni P., Cardin E., Louloudi M., Schollhom B., Spyroulias G.A., Mansuy D., Traylor T.G. Metalloporphyrinosilicas A new class of hybrid organic-inorganic materials acting as selective biomimetic oxidation catalysts. Chem. Commun. 1996 2037-2038 Benson B.C., Jackson R., Joshi K.K., Thompson D.T. A new method for preparation of mixed metal complexes. Chem. Commim. 1968 1506-1508... 

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