We report here, for the first time, synthesis of anchored Pd complexes in mesoporous supports such as MCM-41 and MCM-48 as true heterogeneous catalysts for hydrocarboxylation of aryl olefins and alcohols to give excellent conversion ( approximately 100%) and regioselectivity ( approximately 99%) for 2-arylpropionic acids. The catalysts were characterized by powder-XRD, 31P CP-MAS NMR, FT-IR, TEM, XPS and ICP-AES. Recycle studies with these anchored Pd mesoporous catalysts were performed to confirm true heterogeneity.

Novel heterogeneous catalysts for hydroformylation of olefins to aldehydes using encapsulation and anchoring methodologies for HRh(CO)(PPh 3 ) 3 in zeolite Na-Y and MCM-41 and MCM-48 mesoporous materials have been reported. The heterogeneous catalysts were characterized and used for hydroformylation of linear and branched olefins to show high activity and recyclability without leaching of the Rh metal during the course of reactions. Using CP-MAS NMR, FT-IR, TEM, XPS, and powder XRD studies, characterization of the Rh complex inside the porous structures of the heterogeneous catalysts has been investigated. 31P CP-MAS NMR spectra of the encapsulated Rh complex catalyst inside zeolite Na-Y and mesoporous MCM-41 and MCM-48 supports showed a possible encapsulation of the Rh complex in the pores. TEM images and the diffraction patterns of the heterogenized Rh complex in mesoporous and zeolitic supports further supported a possible entrapment of the complex inside the porous frameworks. Rhodium is present as Rh(I) in the encapsulated catalysts before and after the experiments, as envisaged by XPS spectra. In contrast to other heterogeneous catalytic systems for hydroformylation, the catalysts reported here are highly stable, easily separable, and recyclable. The TON/TOF values of these catalysts were also found to be significantly higher than those of the previously reported heterogeneous catalysts.

Development of simple and reliable protocols for the immobilization of enzymes is an important aspect of biotechnology. Gold nanoparticles are known to bind enzymes, but reuse characteristics of the gold nano−enzyme bioconjugates has hitherto been poor. In this paper, we demonstrate that gold nanoparticles bound at high surface coverage on 3-aminopropyltrimethoxysilane (APTS)-functionalized Na−Y zeolites are excellent candidates for the immobilization of pepsin. The assembly of gold nanoparticles on the zeolite surface occurs through the amine groups present in APTS. Pepsin was then bound to the Na−Y zeolite (core)−Au nano (shell) structures via interaction with the gold nanoparticles leading to a new class of biocatalyst. A highlight of the new biocatalyst wherein the enzyme is supported by a more massive biocompatible surface is the ease with which separation from the reaction medium may be achieved by simple sedimentation. The catalytic activity of pepsin in the bioconjugate was comparable to that of the free enzyme in solution. The pepsin−gold nano−zeolite bioconjugate material exhibited excellent activity over seven successive reuse cycles as well as enhanced pH and temperature stability.

Gold nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. However, separation of the gold nanoparticle-enzyme bioconjugate material from the reaction medium is often difficult. In this study, we investigate the assembly of the gold nanoparticles on the surface of the amine-functionalized zeolite microspheres in the formation of zeolite-gold nanoparticle "core-shell" structures and, thereafter, the use of this structure in immobilization of fungal protease. The assembly of gold nanoparticles on the zeolite surface occurs through the amine groups present in 3-aminopropyltrimethoxysilane (3-APTS). The fungal proteases bound to the massive "core-shell" structures were easily separated from the reaction medium by mild centrifugation and exhibited excellent reuse characteristics. The biocatalytic activity of fungal protease in the bioconjugate was marginally enhanced relative to the free enzyme in solution. The bioconjugate material also showed significantly enhanced pH and temperature stability and a shift in the optimum temperature of operation.

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