Polymeric hybrid mesoporous silica hollow nanospheres as a support for palladium and application of the PdNPs@PANI/HNS nanocomposite for aerobic benzyl alcohol oxidation

Rotenone nanoparticles based on mesoporous silica to improve the stability, translocation and insecticidal activity of rotenone

Nanotechnology has been widely applied for pesticide carriers, which is an important way to improve the utilization, stability, and sustained release of pesticides. Mesoporous silica nanoparticles (MSNs) are a nanomaterial with adjustable particle and pore sizes, with a high specific surface area and good biocompatibility. Rotenone is a non-systemic botanical insecticide that is easily degraded in the environment. We used a modified soft-template method to prepare MSNs, in which rotenone was loaded using the solvent evaporation method. The prepared rotenone nanopesticide based on mesoporous silica showed considerable drug loading rates of 33.2%. Moreover, the prepared rotenone nanoparticles showed improved photostability and sustained release behavior, which improved the translocation of rotenone in tomato plants. Finally, the rotenone nanoparticles displayed superior insecticidal activity compared to traditional preparations. In summary, the rotenone nanopesticide improved the persistence and utilization rates of rotenone. These findings are of significance in reducing pesticide usage, mitigating environmental pollution, and ensuring food safety.

Single-pot tandem oxidative/C-H modification amidation process using ultrasmall PdNP-encapsulated porous organosilica nanotubes

Herein, we studied a single-pot method with a dual catalysis process towards the conversion of primary aromatic alcohols to amides using ultrasmall PdNPs of controlled uniform size (1.8 nm) inside hybrid mesoporous organosilica nanotubes (MO-NTs). The catalyst exhibited excellent performance in water under mild conditions and showed high stability. The catalytic activity towards the tandem oxidation of alcohols in the presence of amine salts and H2O2 to their corresponding amides without producing byproducts was evaluated, and high yields were obtained for all products. The structure of the organosilica nanotubes containing palladium nanoparticles was investigated using various characterization techniques such as XRD, TEM, BET, solid-state 29Si NMR and solid-state 13C CP MAS NMR. Catalyst recycling tests showed that the catalytic power of PdNPs@B-SNTs was preserved after 8 cycles and a slight decrease in catalyst activity was observed.

N,P co-doped microporous carbon as a metal-free catalyst for the selective oxidation of alcohols by air in water

NPMCs are fabricated from one-step pyrolysis of an aerogel precursor derived from direct polymerization of p-phenylenediamine with phytic acid, which can be used as metal-free catalysts for highly selective oxidation of alcohols by air in water.

Functionalized Silicas for Metal-Free and Metal-Based Catalytic Applications: A Review in Perspective of Green Chemistry

Heterogeneous catalysis plays a key role in promoting green chemistry through many routes. The functionalizable reactive silanols highlight silica as a beguiling support for the preparation of heterogeneous catalysts. Metal active sites anchored on functionalized silica (FS) usually demonstrate the better dispersion and stability due to their firm chemical interaction with FSs. Having certain functional groups in structure, FSs can act as the useful catalysts for few organic reactions even without the need of metal active sites which are termed as the covetous reusable organocatalysts. Magnetic FSs have laid the platform where the effortless recovery of catalysts is realized just using an external magnet, resulting in the simplified reaction procedure. Using FSs of multiple functional groups, we can envisage the shortened reaction pathway and, reduced chemical uses and chemical wastes. Unstable bio-molecules like enzymes have been stabilized when they get chemically anchored on FSs. The resultant solid bio-catalysts exhibited very good reusability in many catalytic reactions. Getting provoked from the green chemistry aspects and benefits of FS-based catalysts, we confer the recent literature and progress focusing on the significance of FSs in heterogeneous catalysis. This review covers the preparative methods, types and catalytic applications of FSs. A special emphasis is given to the metal-free FS catalysts, multiple FS-based catalysts and magnetic FSs. Through this review, we presume that the contribution of FSs to green chemistry can be well understood. The future perspective of FSs and the improvements still required for implementing FS-based catalysts in practical applications have been narrated at the end of this review.