Metal Nanoparticles Confined within an Inorganic–Organic Framework Enable Superior Substrate-Selective Catalysis

Abstract

The search for catalysts with a perfect substrate selectivity toward the hydrogenation of nitroarenes is a goal of high importance, which still remains a significant challenge. Here, we designed a new type of catalyst with superior substrate selectivity by combining a space-confined effect and a hydrogen-bonding network, in which metal nanoparticles (MNPs) were confined in hierarchical hollow silica (HHS) with a poly(N-isopropylacrylamide) (PNIPA) coating. Given the strong induced properties of hydrogen-bond donors and acceptors in the HHS support and PNIPA coating, the as-synthesized catalyst would achieve perfect substrate selectivity for the hydrogenation of various nitroarenes and their mixture by thoroughly impeding the reduction of nitroarenes with any hydroxyl or carboxyl groups, which is typically very difficult to be realized over almost all of the reported supported-metal catalysts. Notably, the hydrogenation of nitroarenes can produce almost quantitative yields of anilines over the as-synthesized catalyst. Furthermore, density functional theory and experimental evidence are also provided for the hierarchical structure of HHS and PNIPA coating associated with substrates to demonstrate how a substrate could have access or be blocked into the confined active centers (MNPs). Therefore, this work would open a new window to design efficient catalysts for a wide variety of substrate-selective catalyses.

High photocatalytic activity of Cu2O embedded in hierarchically hollow SiO2 for efficient chemoselective hydrogenation of nitroarenes

“…The hydrogenation of o-chloronitrobenzene (o-NCB) over two photocatalysts was investigated at a variety of temperatures for different times to understand the influence of temperature on the apparent rate constant (kapp) based on Eq. (1) [27,41]:…”

Enhancing Targeted Therapy in Hepatocellular Carcinoma through a pH-Responsive Delivery System: Folic Acid-Modified Polydopamine-Paclitaxel-Loaded Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Nanoparticles

“…To date, materials utilized as NP carriers can be broadly categorized into two main groups: inorganic NPs and organic NPs. , The use of effective drug delivery systems based on biodegradable and biocompatible polymers, such as NPs, can significantly enhance the efficiency of insoluble or highly toxic compounds, thereby reducing their side effects and providing protection through encapsulation . Carbohydrate polymers have been recognized for their favorable characteristics, including good biocompatibility, inherent nontoxicity, and biodegradability. , Among these polymers, poly­(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) stands out as a biodegradable biopolymer derived from starch through fermentation engineering technology .…”

Stimuli-Responsive Polymer Stabilized Iron Oxide Nanoparticle as Green Catalyst for Styrene Oxidation Reaction

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“…In catalysis, use of polymers as a capping agent for metal nanoparticles is gaining enormous interest since the polymers help by transforming the reaction system into a homogeneous one by dispersing the nanoparticles in the reaction media. Accordingly, these polymer-coated metal nanoparticles are known as ’quasi-homogeneous’ catalysts. − Due to better dispersion in the reaction medium and easier access to the catalytic surface, the quasi-homogeneous catalysts are catalytically more efficient. , Among the various capping molecules, polymers have several benefits like robust steric stabilization, the ability to alter nanoparticle morphology, and flexibility. , Polypyrrole, − chitosan, − polyaniline, , poly­( N -isopropylacrylamide), , polyphenylquinoxalines are some polymers that are used to coat nanoparticles used as a catalyst in several organic reactions. , Presently, there is a need for “green catalysts” that will be effective at room temperature, in an aqueous medium, and easily recoverable and recyclable.…”