Metal-organic framework (MOF) nanoparticles, also called porous coordination polymers, are a major part of nanomaterials science, and their role in catalysis is becoming central. The extraordinary variability and richness of their structures afford engineering synergies between the metal nodes, functional linkers, encapsulated substrates, or nanoparticles for multiple and selective heterogeneous interactions and activations in these MOF-based nanocatalysts. Pyrolysis of MOF-nanoparticle composites forms highly porous N- or P-doped graphitized MOF-derived nanomaterials that are increasingly used as efficient catalysts especially in electro- and photocatalysis. This review first briefly summarizes this background of MOF nanoparticle catalysis and then comprehensively reviews the fast-growing literature reported during the last years. The major parts are catalysis of organic and molecular reactions, electrocatalysis, photocatalysis, and views of prospects. Major challenges of our society are addressed using these well-defined heterogeneous catalysts in the fields of synthesis, energy, and environment. In spite of the many achievements, enormous progress is still necessary to improve our understanding of the processes involved beyond the proof-of-concept, particularly for selective methane oxidation, hydrogen production, water splitting, CO2 reduction to methanol, nitrogen fixation, and water depollution.

State of the Art and Prospects in Metal-Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis.

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Visible-light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross-coupling reactions, α-amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible-light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible-light-absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo- or metal catalysis.

Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

More than 95% (in volume) of all of today’s chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic rese...

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

The present review offers an overview of the current approaches for the photochemical and photocatalytic generation of reactive intermediates and their application in the formation of carbon–carbon bonds. Valuable synthetic targets are accessible, including arylation processes, formation of both carbo- and heterocycles, alpha- and beta-functionalization of carbonyls, and addition reactions onto double and triple bonds. According to the recent advancements in the field of visible/solar light catalysis, a significant part of the literature reported herein involves radical ions and radicals as key intermediates, with particular attention to the most recent examples. Synthetic application of carbenes, biradicals/radical pairs and carbocations have been also reported.

Carbon-Carbon Bond Forming Reactions via Photogenerated Intermediates.

A nickel-catalyzed product-controllable imidation and amidation of sp3 C–H bonds in substituted toluenes with sulfonamides were developed. Based on the change of the reaction time and atmosphere from N2 to O2, this reaction proceeded in high yields and excellent selectivity under different conditions. Mechanistic details were also described.

Nickel-catalyzed product-controllable amidation and imidation of sp3 C–H bonds in substituted toluenes with sulfonamides

β-O-4 and α-O-4 linkages can be selectively cleaved by Pd–Ni bimetallic nanoparticles in ionic liquids using hydrogen gas as the hydrogen donor under ambient pressure and neutral conditions. No hydrogenation of the benzene ring takes place in the catalytic system. An obvious improvement in activity is found compared with single nickel and palladium catalysts based on the results of experiments and characterization. After the reaction, the catalytic system still remains in the reactor by simple extraction, which can be reused without further treatment.

The selective hydrogenolysis of C-O bonds in lignin model compounds by Pd-Ni bimetallic nanoparticles in ionic liquids.

The selective oxidation of alcohols to their corresponding carbonyl compounds is one of the most fundamental and challenging processes in organic chemistry. Current methods for alcohol oxidation are based on the use of stoichiometric amounts of toxic or corrosive reagents, mainly heavy metal salts with high oxidation states. Recently, the catalytic oxidation of alcohols using hydrogen peroxide as oxidant has received much attention from the viewpoint of green chemistry, because it leads to water as the sole byproduct. In addition, high content of oxygen and simplicity of handling make it more advantageous than its counterparts. Since the discovery that gold nanoparticles can be very active in oxidation reactions by Haruta and co-workers, selective oxidation of alcohols to the corresponding carbonyl compounds catalyzed by gold nanoparticles has been widely investigated. Of particular interest in this area is the use of supported gold nanoparticles because of their advantages in product isolation, product selectivity, and catalyst recycling. Over the last few years, Cao et al. , Kobayashi et al. , and Corma et al. reported that gold nanoparticles deposited on metal oxides or polymers are highly effective for the oxidation of various alcohols. In general, organic solvents and/or bases are necessary to achieve high yield and selectivity. Just recently, Cao and co-workers reported a fascinating protocol for the efficient oxidation of alcohols by Au/TiO2 in aqueous H2O2 under base-free conditions. 3g] However, selective oxidation of primary alcohols to aldehydes was still a problem. To the best of our knowledge, very few examples reported the selective alcohols to aldehydes using supported gold nanoparticles because the aldehydes are more active than alcohols and it is not easy to control the over oxidation processes. Fluorous silica gel (FSG)-supported catalyst is a new type of heterogeneous catalyst and has shown excellent catalytic efficiency and recyclability in a series of reactions. Such catalysts could also work well in aqueous medium despite the hydrophobicity of the support. Recently, both Vallribera’s group and our group showed that metal nanoparticles could be stabilized by heavily fluorinated compounds (Figure 1) and immobilized on fluorous silica gel by fluorous–fluorous interactions, and the precatalyst could also be applied in a series of C C bond forming and oxidation reactions. Herein, we describe the highly selective oxidation of alcohols in aqueous H2O2 under base-free conditions with an ultra-low amount of FSG-supported gold nanoparticles using compound 1 as ligand. The selective oxidation of primary alcohols to the corresponding aldehydes is also investigated. The FSG-supported gold nanoparticles were prepared according to literature to give the precatalyst as grey-pink powder (Au: 0.31 %, 0.015 mmol g 1 based on inductively coupled plasma (ICP) analysis). The precatalyst was also characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Figure 2 shows the XRD patterns of the support, perfluoro-tagged gold nanoparticles, and the supported gold nanoparticles. Although it has very weak diffraction lines for gold due to the low concentration of gold in the support (Figure 2 b), the characteristic diffraction peaks could

A Green and Highly Selective Oxidation of Alcohols by Fluorous Silica Gel-Supported Gold Nanoparticles in Aqueous H2O2 under Base-Free Conditions

An efficient approach for the synthesis of N-substituted 3-oxoisoindoline-1-difluoroalkyl derivatives via a one-pot cascade reaction has been developed. The reaction proceeded smoothly in the presence of In(OTf)3 and afforded a broad scope of isoindolinones with moderate to good yields. Moreover, the reaction could be run on a gram-scale with comparable yield.

An efficient approach to 3-oxoisoindoline-1-difluoroalkyl derivatives via a metal triflate-catalyzed Mannich/lactamization cascade reaction

An efficient copper-free protocol for the synthesis of 5-methyl-1H-1,2,3-triazole-modified peptidomimetics through the combination of Ugi four-component reaction with a three-component cycloaddition, has been developed. The copper-free straightforward process is suitable for drug discovery. The chemoselective preparation of 1,4-disubstituted, triazole-modified peptidomimetics by using alkynyl substituted amines may have potential biological and synthetic application. At last, a “Lapinski type” analysis of the physical properties was performed, which is expected to help drug discovery.

Chun Cai

Papers

Nickel-catalyzed product-controllable amidation and imidation of sp3 C–H bonds in substituted toluenes with sulfonamides

The selective hydrogenolysis of C-O bonds in lignin model compounds by Pd-Ni bimetallic nanoparticles in ionic liquids.

A Green and Highly Selective Oxidation of Alcohols by Fluorous Silica Gel-Supported Gold Nanoparticles in Aqueous H2O2 under Base-Free Conditions

An efficient approach to 3-oxoisoindoline-1-difluoroalkyl derivatives via a metal triflate-catalyzed Mannich/lactamization cascade reaction

Copper-free route to triazole-modified peptidomimetic by the combination of two multicomponent reactions in one pot.