Catalytic behavior of 1-(2-pyridylazo)-2-naphthol transition metal complexes encapsulated in Y zeolite

Applications of Cu(0) encapsulated nanocatalysts as superior catalytic systems in Cu-catalyzed organic transformations

Recently, Cu nanoparticles (NPs) encapsulated into various materials as supports (e.g., zeolite, silica) have attracted much devotion due to their unique catalytic properties such as high catalytic activity, intensive reactivity and selectivity through highly protective properties. Nowadays, the superior catalytic activity of Cu-NPs, encapsulated onto zeolite, silica and different porous systems, is extensively investigated and now well-established. As a matter of fact, Cu-NPs are protected from deactivation by this kind of encapsulation. Thus, their exclusion proceeds smoothly, and their recyclability is significantly increased. Cu-NPs have been used as potential heterogeneous catalysts in different chemical transformations. In this review, we try to show the preparation and applications of Cu(0) encapsulated nanocatalysts in zeolite and silica as superior catalytic systems in Cu-catalyzed organic transformations. In addition, the catalytic activity of these encapsulated Cu-NPs in different important organic transformations (such as hydrogenation, oxidation and carbon-carbon bond formations) are compared with those of a variety of organic, inorganic and hybrid porous bearing a traded metal ion. Moreover, the results from the TGA/DTA analysis and optical properties of Cu-complexes are demonstrated. The inherited characteristic merits of the encapsulated Cu-NPs onto zeolite and silica, such as their low leaching, catalytic activity, reusability economic feasibility and originality are critically considered.

Recent advances in zeolite-encapsulated metal catalysts: A suitable catalyst design for catalytic biomass conversion

Metal clusters and nanoparticles, which have been used to tune the acidity of zeolite support, are beneficial for promoting the catalytic performance of various reaction processes, including biomass conversion. However, catalytic instabilities resulting from metal coalescence, sintering and leaching are major problems that need to be resolved. Therefore, metal encapsulation within the zeolite structure has been proposed as a feasible solution for this issue, particularly for biomass conversions that require high temperatures. In this current review, recent developments in metal confinement techniques are described along with experimental examples of biomass upgrading reactions. The present and future perspectives of zeolite-encapsulated metal catalysts in biomass conversions are also given.

Zeolite encapsulated Ni(ii) Schiff-base complexes: improved catalysis and site isolation

Site isolation and distorted geometry of the zeolite encapsulated complex govern the improved catalysis for phenol hydroxylation reaction.

A selective colorimetric sensing strategy for cysteine based on an indicator-displacement mechanism

Rapid determination of cysteine in aqueous solution is important for the diagnosis and treatment of some diseases.

Tuning of Catalytic Property Controlled by the Molecular Dimension of Palladium-Schiff Base Complexes Encapsulated in Zeolite Y

Planar palladium-Schiff base complexes are synthesized, maintaining the order of their molecular dimensions as PdL1 < PdL2 < PdL3 < PdL4 < PdL5 in free state, as well as encapsulated in zeolite Y, where L1: N,N'-bis(salicylidene)ethylenediamine and L2, L3, L4, and L5 are derivatives of L1. All encapsulated complexes have shown better catalytic activity for the sulfoxidation of methyl phenyl sulfide in comparison to their homogeneous counter parts. These hybrid systems are characterized with the help of different characterization techniques such as X-ray diffraction analysis, scanning electron microscopy-energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, Fourier transform infrared, and UV-visible spectroscopy; all of these studies have suggested that the largest complex deviates by the maximum from its free-state properties, and a radical change in the reactivity of the complex is observed.

Reduction of nitrate by NaY zeolite supported Fe, Cu/Fe and Mn/Fe nanoparticles

Nano particles Fe, Cu/Fe and Mn/Fe supported on NaY zeolite (F@Y, CF@Y, and MF@Y) were prepared by two-step processes consisting of ion exchange and liquid-phase reduction. The characterization by XRD, SEM-EDX and BET-N₂ adsorption demonstrated that Fe, Cu/Fe and Mn/Fe nano particles were successfully loaded onto NaY zeolite and exhibited larger BET surface area compared to nano-Fe⁰ (nZVI). Laboratory experiments showed that nitrate removal by metals@Y in unbuffered conditions reached nearly 100% at a dosage of 4g/L after 6h of reaction. Moreover, the nitrate removal was not sensitive to the initial solution pH. Even at a high pH of 9.0, metals@Y exhibited nitrate reduction above 94%. CF@Y demonstrated high N₂ selectivity, due to the high content of Cu (20wt%) and Fe (41wt%) in CF@Y and the highly active metallic sites on its surface with positive charge. Kinetic data showed a good fit to a first-order kinetic model during early reaction times. A close fit to both a second-order and an nth-order kinetic model was shown for the whole of the reaction period. The data suggest that both liquid phase mass transfer and the intrinsic reaction rate control the process of nitrate reduction by metals@Y.

Tri- and tetradentate copper complexes: a comparative study on homogeneous and heterogeneous catalysis over oxidation reactions

A comparative catalytic study between heterogeneous (zeolite-encapsulated Cu complexes) and homogeneous analogues over oxidation reactions was undertaken in detail.

In vitro and in vivo studies of temozolomide loading in zeolite structures as drug delivery systems for glioblastoma

Y and MOR zeolites were used as a host for the temozolomide (TMZ). Y presented toxicity to glioblastoma cancer cells in contrast to MOR. Higher potentiation of TMZ was obtained with MOR in comparison to free TMZ bothin vitroandin vivo.

Preparation and assessment of antimicrobial properties of bimetallic materials based on NaY zeolite

ZnAg–Y was the most active material tested against the bacteria Escherichia coli and the yeast Saccharomyces cerevisiae as indicator strains.

Potentiation of 5-fluorouracil encapsulated in zeolites as drug delivery systems for in vitro models of colorectal carcinoma

The studies of potentiation of 5-fluorouracil (5-FU), a traditional drug used in the treatment of several cancers, including colorectal (CRC), were carried out with zeolites Faujasite in the sodium form, with different particle sizes (NaY, 700nm and nanoNaY, 150nm) and Linde type L in the potassium form (LTL) with a particle size of 80nm. 5-FU was loaded into zeolites by liquid-phase adsorption. Characterization by spectroscopic techniques (FTIR, (1)H NMR and (13)C and (27)Al solid-state MAS NMR), chemical analysis, thermal analysis (TGA), nitrogen adsorption isotherms and scanning electron microscopy (SEM), demonstrated the successful loading of 5-FU into the zeolite hosts. In vitro drug release studies (PBS buffer pH 7.4, 37°C) revealed the release of 80-90% of 5-FU in the first 10min. To ascertain the drug release kinetics, the release profiles were fitted to zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas and Weibull kinetic models. The in vitro dissolution from the drug delivery systems (DDS) was explained by the Weibull model. The DDS efficacy was evaluated using two human colorectal carcinoma cell lines, HCT-15 and RKO. Unloaded zeolites presented no toxicity to both cancer cells, while all DDS allowed an important potentiation of the 5-FU effect on the cell viability. Immunofluorescence studies provided evidence for zeolite-cell internalization.