In Situ Surface Engineering of Mesoporous Silica Generates Interfacial Activity and Catalytic Acceleration Effect

Abstract

Mesoporous structured catalysts featuring interfacial activity are the most promising candidates for biphasic interface catalysis because their nanopores can concurrently accommodate catalytic active components and provide countless permeable channels for mass transfer between the interior and the exterior of Pickering droplets. However, to date, a convenient and effective strategy for the preparation of an anchor site-containing interfacial active mesoporous catalyst is still lacking. In the present work, we report a novel and efficient interfacial active mesoporous silica (MS) catalyst, which is prepared by a facile cocondensation of two types of organosilanes and subsequent anchoring of Pd NPs onto its surface through the confinement and coordination interactions. The as-prepared catalyst is then applied as emulsifier to stabilize the water-in-oil (W/O) Pickering emulsion and investigated as an interfacial catalyst for the hydrogenation of nitroarenes. An obviously enhanced rate toward the nitrobenzene hydrogenation is observed for the 0.8 mol% Pd/PAP-functionalized mesoporous silica-20 catalyst in the emulsion system (both conversion and selectivity are >99% within 30 min) in comparison to a single aqueous solution. Moreover, the emulsion catalytic system can be easily recycled six times without the separation of the catalyst from the water phase during the recycling process. This finding demonstrates that the incorporation of phenylaminopropyl trimethoxysilane amphiphilic groups during the hydrolysis of tetramethyl orthosilicate not only endows MS with interfacial activity but also improves the catalytic activity and stability.

Porous Polymer Bearing Polyphenolic Organic Building Units as a Chemotherapeutic Agent for Cancer Treatment

“…Moreover, the nanoscale porosity, flexible synthesis strategy, diversity in the framework building units as well as the framework stability have made them a promising candidate for biomedical applications. 25 Although for catalysis, drug delivery, and biomoleculesensing applications, the porous nanomaterials such as functionalized mesoporous materials, 26,27 covalent organic framework, 28 and graphene-based composites 29 have been utilized, the anticancer activity of the porous polymers bearing organic functionalities is largely unexplored till date. It is noteworthy to mention that curcumin bearing multiple phenolic-OH groups with extended π-conjugation has displayed a remarkable anticancer activity for pancreatic cancer.…”

Spatial Isolation of Carbon and Silica in a Single Janus Mesoporous Nanoparticle with Tunable Amphiphilicity

“…5−8 They can also serve as carriers of catalysts, which is very promising for enhancing the catalytic ability of biphasic reactions. 9,10 Similar to traditional organic amphiphilic surfactants with hydrophilic/hydrophobic ends for stabilizing emulsions, asymmetric nanoparticles are much preferred for the stabilization of Pickering emulsions compared to normal homogeneous particles 11−13 because the two sides of the Janus particles can be positioned in their respective affinitive phase (oil or water) to lower the thermo-dynamical energy. The emulsion stabilizing ability of molecular amphiphilic surfactants changes with different hydrophobic carbon chains and hydrophilic ionic heads.…”

“…Oil–aqueous biphasic reactions, despite being important for organic synthesis, petroleum processing, biorefineries, and enzymatic reactions, suffer from limited efficiencies due to the low reaction interface area caused by immiscibility between water and oil. − Thus, formation of stabilized emulsions for a maximum interaction area is essential for improving their practicability. Solid nanoparticles, while stabilizing the biphasic system to form a Pickering emulsion like organic amphiphilic surfactants, have superior functionalities and recycling abilities. − They can also serve as carriers of catalysts, which is very promising for enhancing the catalytic ability of biphasic reactions. , …”

Poly(tetrafluoroethylene)-Stabilized Metal Nanoparticles: Preparation and Evaluation of Catalytic Activity for Suzuki, Heck, and Arene Hydrogenation in Water

“…For this reason, a number of different solid support materials for metal nanoparticles have been investigated, including natural polymers, 6−12 synthetic polymers, 13−18 surfactants, 19,20 inorganic supports, 21,22 metal–organic frameworks, 23,24 covalent organic frameworks, 25,26 and mesoporous supports. 27−29…”