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Herein we demonstrate an effective and facile end‐capping technique for ring‐opening metathesis polymerization (ROMP) using readily available allyl compounds as a new type of terminating agents. This new type of end‐capping reactions, which are based on the base‐promoted decomposition of ruthenocyclobutane intermediates, introduce diene moiety onto the chain end of ROMP polymers while simultaneously deactivating the ruthenium complex. These termination reactions are highly efficient, typically completing within 1 minute at 0 °C with >95 % end‐capping fidelity. [ABSTRACT FROM AUTHOR]

The late‐stage functionalization of active pharmaceutical ingredients is a key challenge in medicinal chemistry. Furthermore, N‐aryl triazoles and tetrazoles are important structural motifs with the potential to boost the activity of diverse drug molecules. Using easily accessible dibenzothiophenium salts for the ruthenium‐catalyzed C−H arylation, these scaffolds were introduced into a variety of bioactive compounds. Our methodology uses cost‐efficient ruthenium, KOAc as a mild base and gives access to a plethora of highly decorated triazole and tetrazole containing drug derivatives. [ABSTRACT FROM AUTHOR]

The vast bulk of polystyrene (PS), a major type of plastic polymers, ends up in landfills, which takes up to thousands of years to decompose in nature. Chemical recycling promises to enable lower‐energy pathways and minimal environmental impacts compared with traditional incineration and mechanical recycling. Herein, we demonstrated that methanol as a hydrogen supplier assisted the depolymerization of PS (denoted as PS‐MAD) into alkylbenzenes over a heterogeneous catalyst composed of Ru nanoparticles on SiO2. PS‐MAD achieved a high yield of liquid products which accounted for 93.2 wt % of virgin PS at 280 °C for 6 h with the production rate of 118.1 mmolcarbon gcatal.−1 h−1. The major components were valuable alkylbenzenes (monocyclic aromatics and diphenyl alkanes), the sum of which occupied 84.3 wt % of liquid products. According to mechanistic studies, methanol decomposition dominates the hydrogen supply during PS‐MAD, thereby restraining PS aromatization which generates by‐products of fused polycyclic arenes and polyphenylenes. [ABSTRACT FROM AUTHOR]

Singlet oxygen (1O2) is an exceptional reactive oxygen species in advanced oxidation processes for environmental remediation. Despite single‐atom catalysts (SACs) representing the promising candidate for the selective generation of 1O2 from peroxymonosulfate (PMS), the necessity to meticulously regulate the coordination environment of metal centers poses a significant challenge in the precisely‐controlled synthetic method. Another dilemma to SACs is their high surface free energy, which results in an inherent tendency for the surface migration and aggregation of metal atoms. We here for the first time reported that Ru nanoparticles (NPs) synthesized by the facile pyrolysis method behave as robust Fenton‐like catalysts, outperforming Ru SACs, towards efficient activation of PMS to produce 1O2 with nearly 100 % selectivity, remarkably improving the degradation efficiency for target pollutants. Density functional theory calculations have unveiled that the boosted PMS activation can be attributed to two aspects: (i) enhanced adsorption of PMS molecules onto Ru NPs, and (ii) decreased energy barriers by offering adjacent sites for promoted dimerization of *O intermediates into adsorbed 1O2. This study deepens the current understanding of PMS chemistry, and sheds light on the design and optimization of Fenton‐like catalysts. [ABSTRACT FROM AUTHOR]

Searching for highly efficient and economical electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is crucial for the development of alkaline polymer membrane fuel cells. Here, we report a valid strategy to active pyrite‐type RuS2 for alkaline HOR electrocatalysis by introducing sulfur vacancies. The obtained S‐vacancies modified RuS2−x exhibits outperformed HOR activity with a current density of 0.676 mA cm−2 and mass activity of 1.43 mA μg−1, which are 15‐fold and 40‐fold improvement than those of Ru catalyst. In situ Raman spectra demonstrate the formation of S−H bond during the HOR process, identifying the S atom of RuS2−x is the real active site for HOR catalysis. Density functional theory calculations and experimental results including in situ surface‐enhanced infrared absorption spectroscopy suggest the introduction of S vacancies can rationally modify the p orbital of S atoms, leading to enhanced binding strength between the S sites and H atoms on the surface of RuS2−x, together with the promoted connectivity of hydrogen‐bonding network and lowered water formation energy, contributes to the enhanced HOR performance. [ABSTRACT FROM AUTHOR]

Novel concepts to utilize carbon dioxide are required to reach a circular carbon economy and minimize environmental issues. To achieve these goals, photo‐, electro‐, thermal‐, and biocatalysis are key tools to realize this, preferentially in aqueous solutions. Nevertheless, catalytic systems that operate efficiently in water are scarce. Here, we present a general strategy for the identification of enzymes suitable for CO2 reduction based on structural analysis for potential carbon dioxide binding sites and subsequent mutations. We discovered that the phenolic acid decarboxylase from Bacillus subtilis (BsPAD) promotes the aqueous photocatalytic CO2 reduction selectively to carbon monoxide in the presence of a ruthenium photosensitizer and sodium ascorbate. With engineered variants of BsPAD, TONs of up to 978 and selectivities of up to 93 % (favoring the desired CO over H2 generation) were achieved. Mutating the active site region of BsPAD further improved turnover numbers for CO generation. This also revealed that electron transfer is rate‐limiting and occurs via multistep tunneling. The generality of this approach was proven by using eight other enzymes, all showing the desired activity underlining that a range of proteins is capable of photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

Consuming one of the largest amount of electricity, the chlor‐alkali industry supplies basic chemicals for society, which mainly consists of two reactions, hydrogen evolution (HER) and chlorine evolution reaction (CER). Till now, the state‐of‐the‐art catalyst applied in this field is still the dimensional stable anode (DSA), which consumes a large amount of noble metal of Ru and Ir. It is thus necessary to develop new types of catalysts. In this study, an organocatalyst anchored on the single‐atom support (SAS) is put forward. It exhibits high catalytic efficiency towards both HER and CER with an overpotential of 21 mV and 20 mV at 10 mA cm−2. With this catalyst on both electrodes, the energy consumption is cut down by 1.2 % compared with the commercial system under industrial conditions. Based on this novel catalyst and the high activity, the mechanism of modifying non‐covalent interaction is demonstrated to be reliable for the catalyst's design. This work not only provides efficient catalysts for the chlor‐alkali industry but also points out that the SACs can also act as support, providing new twists for the development of SACs and organic molecules in the next step. [ABSTRACT FROM AUTHOR]

Modulating the microenvironment of single‐atom catalysts (SACs) is critical to optimizing catalytic activity. Herein, we innovatively propose a strategy to improve the local reaction environment of Ru single atoms by precisely switching the crystallinity of the support from high crystalline and low crystalline, which significantly improves the hydrogen evolution reaction (HER) activity. The Ru single‐atom catalyst anchored on low‐crystalline nickel hydroxide (Ru−LC−Ni(OH)2) reconstructs the distribution balance of the interfacial ions due to the activation effect of metal dangling bonds on the support. Single‐site Ru with a low oxidation state induces the aggregation of hydronium ions (H3O+), leading to the formation of a local acidic microenvironment in alkaline media, breaking the pH‐dependent HER activity. As a comparison, the Ru single‐atom catalyst anchored on high‐crystalline nickel hydroxide (Ru−HC−Ni(OH)2) exhibits a sluggish Volmer step and a conventional local reaction environment. As expected, Ru−LC−Ni(OH)2 requires low overpotentials of 9 and 136 mV at 10 and 1000 mA cm−2 in alkaline conditions and operates stably at 500 mA cm−2 for 500 h in an alkaline seawater anion exchange membrane (AEM) electrolyzer. This study provides a new perspective for constructing highly active single‐atom electrocatalysts. [ABSTRACT FROM AUTHOR]

An atom‐ and step‐economical and redox‐neutral cascade reaction enabled by asymmetric bimetallic relay catalysis by merging a ruthenium‐catalyzed asymmetric borrowing‐hydrogen reaction with copper‐catalyzed asymmetric Michael addition has been realized. A variety of highly functionalized 2‐amino‐5‐hydroxyvaleric acid esters or peptides bearing 1,4‐non‐adjacent stereogenic centers have been prepared in high yields with excellent enantio‐ and diastereoselectivity. Judicious selection and rational modification of the Ru catalysts with careful tuning of the reaction conditions played a pivotal role in stereoselectivity control as well as attenuating undesired α‐epimerization, thus enabling a full complement of all four stereoisomers that were otherwise inaccessible in previous work. Concise asymmetric stereodivergent synthesis of the key intermediates for biologically important chiral molecules further showcases the synthetic utility of this methodology. [ABSTRACT FROM AUTHOR]

Atomically precise Au nanoclusters (NCs) with discrete energy levels can be used as photosensitizers for CO2 reduction. However, tight ligand capping of Au NCs hinders CO2 adsorption on its active sites. Here, a new hybrid material is obtained by anchoring of thiol functionalized terpyridine metal complexes (metal=Ru, Ni, Fe, Co) on Au NCs by ligand exchange reactions (LERs). The anchoring of Ru and Ni complexes on Au25 NC (Au25−Ru and Au25−Ni) leads to adequate CO2 to CO conversion for photocoupled electrocatalytic CO2 reduction (PECR) in terms of high selectivity, with Faradaic efficiency of CO (FECO) exceeding 90 % in a wide potential range, remarkable activity (CO production rate up to two times higher than that for pristine Au25PET18) and extremely large turnover frequencies (TOFs, 63012 h−1 at −0.97 V for Au25−Ru and 69989 h−1 at −1.07 V vs. RHE for Au25−Ni). Moreover, PECR stability test indicates the excellent long‐term stability of the modified NCs in contrast with pristine Au NCs. The present approach offers a novel strategy to enhance PECR activity and selectivity, as well as to improve the stability of Au NCs under light illumination, which paves the way for highly active and stable Au NCs catalysts. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticles (NPs) immobilized on an amine‐functionalized polymer‐grafted silica support act as adaptive catalysts for the hydrogenation of bicyclic heteroaromatics. Whereas full hydrogenation of benzofuran and quinoline derivatives is achieved under pure H2, introducing CO2 into the H2 gas phase leads to an effective shutdown of the arene hydrogenation while preserving the activity for the hydrogenation of the heteroaromatic part. The selectivity switch originates from the generation of ammonium formate species on the surface of the materials by catalytic hydrogenation of CO2. The CO2 hydrogenation is fully reversible, resulting in a robust and rapid switch between the two states of the catalyst adapting its performance in response to the feed gas composition. A variety of benzofuran and quinoline derivatives were hydrogenated to fully or partially saturated products in high selectivity and yields simply by altering the composition of the feed gas from H2 to H2/CO2. The adaptive catalytic system thus provides controlled access to valuable products using a single catalyst rather than two specific and distinct catalysts with static reactivity. [ABSTRACT FROM AUTHOR]

Chemical upcycling that catalyzes waste plastics back to high‐purity chemicals holds great promise in end‐of‐life plastics valorization. One of the main challenges in this process is the thermodynamic limitations imposed by the high intrinsic entropy of polymer chains, which makes their adsorption on catalysts unfavorable and the transition state unstable. Here, we overcome this challenge by inducing the catalytic reaction inside mesoporous channels, which possess a strong confined ability to polymer chains, allowing for stabilization of the transition state. This approach involves the synthesis of p‐Ru/SBA catalysts, in which Ru nanoparticles are uniformly distributed within the channels of an SBA‐15 support, using a precise impregnation method. The unique design of the p‐Ru/SBA catalyst has demonstrated significant improvements in catalytic performance for the conversion of polyethylene into high‐value liquid fuels, particularly diesel. The catalyst achieved a high solid conversion rate of 1106 g ⋅ gRu−1 ⋅ h−1 at 230 °C. Comparatively, this catalytic activity is 4.9 times higher than that of a control catalyst, Ru/SiO2, and 14.0 times higher than that of a commercial catalyst, Ru/C, at 240 °C. This remarkable catalytic activity opens up immense opportunities for the chemical upcycling of waste plastics. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have emerged as crucial players in catalysis research, prompting extensive investigation and application. The precise control of metal atom nucleation and growth has garnered significant attention. In this study, we present a straightforward approach for preparing SACs utilizing a photocatalytic radical control strategy. Notably, we demonstrate for the first time that radicals generated during the photochemical process effectively hinder the aggregation of individual atoms. By leveraging the cooperative anchoring of nitrogen atoms and crystal lattice oxygen on the support, we successfully stabilize the single atom. Our Pd1/TiO2 catalysts exhibit remarkable catalytic activity and stability in the Suzuki–Miyaura cross‐coupling reaction, which was 43 times higher than Pd/C. Furthermore, we successfully depose Pd atoms onto various substrates, including TiO2, CeO2, and WO3. The photocatalytic radical control strategy can be extended to other single‐atom catalysts, such as Ir, Pt, Rh, and Ru, underscoring its broad applicability. [ABSTRACT FROM AUTHOR]

To date, only a few noble metal oxides exhibit the required efficiency and stability as oxygen evolution reaction (OER) catalysts under the acidic, high‐voltage conditions that exist during proton exchange membrane water electrolysis (PEMWE). The high cost and scarcity of these catalysts hinder the large‐scale application of PEMWE. Here, we report a novel OER electrocatalyst for OER comprised of uniformly dispersed Ru clusters confined on boron carbon nitride (BCN) support. Compared to RuO2, our BCN‐supported catalyst shows enhanced charge transfer. It displays a low overpotential of 164 mV at a current density of 10 mA cm−2, suggesting its excellent OER catalytic activity. This catalyst was able to operate continuously for over 12 h under acidic conditions, whereas RuO2 without any support fails in 1 h. Density functional theory (DFT) calculations confirm that the interaction between the N on BCN support and Ru clusters changes the adsorption capacity and reduces the OER energy barrier, which increases the electrocatalytic activity of Ru. [ABSTRACT FROM AUTHOR]

Developing efficient nanozymes to mimic natural enzymes for scavenging reactive radicals remains a significant challenge owing to the insufficient activity of conventional nanozymes. Herein, we report a novel Ru single‐atom nanozyme (SAE), featuring atomically dispersed Ru atoms on a biocompatible MgAl‐layered double hydroxide (Ru1/LDH). The prepared Ru1/LDH SAE shows high intrinsic peroxidase (POD)‐like catalytic activity, which outperforms the Ru nanoclusters (NCs) nanozyme by a factor of 20 and surpasses most SAEs. The density functional theory calculations reveal that the high intrinsic POD‐like activity of Ru1/LDH can be attributed to a heterolytic path of H2O2 dissociation on the single Ru sites, which requires lower free energy (0.43 eV) compared to the homolytic path dissociation on Ru NC (0.63 eV). In addition, the Ru1/LDH SAE shows excellent multiple free radicals scavenging ability, including superoxide anion radical (O2⋅−), hydroxyl radical (⋅OH), nitric oxide radical (NO⋅) and 2, 2‐diphenyl‐1‐picrylhydrazyl radical (DPPH⋅). Given the advantages of Ru1/LDH with high enzymatic activities, biosafety, and ease to scale up, it paves the way for exploring SAEs in the practical biological immunity system. [ABSTRACT FROM AUTHOR]

Heterogeneous single‐metal‐site catalysts usually suffer from poor stability, thereby limiting industrial applications. Dual Pd1−Ru1 single‐atom‐sites supported on porous ionic polymers (Pd1−Ru1/PIPs) were constructed using a wetness impregnation method. The two isolated metal species in the form of a binuclear complex were immobilized on the cationic framework of PIPs through ionic bonds. Compared to the single Pd‐ or Ru‐site catalyst, the dual single‐atom system exhibits higher activity with 98 % acetylene conversion and near 100 % selectivity to dialkoxycarbonylation products, as well as better cycling stability for ten cycles without obvious decay. Based on DFT calculations, it was found that the single‐Ru site exhibited a strong CO adsorption energy of −1.6 eV, leading to an increase in the local CO concentration of the catalyst. Notably, the Pd1−Ru1/PIPs catalyst had a much lower energy barrier of 2.49 eV compared to 3.87 eV of Pd1/PIPs for the rate‐determining step. The synergetic effect between neighboring single sites Pd1 and Ru1 not only enhanced the overall activity, but also stabilized PdII active sites. The discovery of synergetic effects between single sites can deepen our understanding of single‐site catalysts at the molecular level. [ABSTRACT FROM AUTHOR]

In this article, we report a novel targeting strategy involving the combination of an enzyme‐instructed self‐assembly (EISA) moiety and a strained cycloalkyne to generate large accumulation of bioorthogonal sites in cancer cells. These bioorthogonal sites can serve as activation triggers in different regions for transition metal‐based probes, which are new ruthenium(II) complexes carrying a tetrazine unit for controllable phosphorescence and singlet oxygen generation. Importantly, the environment‐sensitive emission of the complexes can be further enhanced in the hydrophobic regions offered by the large supramolecular assemblies, which is highly advantageous to biological imaging. Additionally, the (photo)cytotoxicity of the large supramolecular assemblies containing the complexes was investigated, and the results illustrate that cellular localization (extracellular and intracellular) imposes a profound impact on the efficiencies of photosensitizers. [ABSTRACT FROM AUTHOR]

High‐entropy alloy (HEA) catalysts have been widely studied in electrocatalysis. However, identifying atomic structure of HEA with complex atomic arrangement is challenging, which seriously hinders the fundamental understanding of catalytic mechanism. Here, we report a HEA‐PdNiRuIrRh catalyst with remarkable mass activity of 3.25 mA μg−1 for alkaline hydrogen oxidation reaction (HOR), which is 8‐fold enhancement compared to that of commercial Pt/C. Through machine learning potential‐based Monte Carlo simulation, we reveal that the dominant Pd−Pd−Ni/Pd−Pd−Pd bonding environments and Ni/Ru oxophilic sites on HEA surface are beneficial to the optimized adsorption/desorption of *H and enhanced *OH adsorption, contributing to the excellent HOR activity and stability. This work provides significant insights into atomic structure and catalytic mechanism for HEA and offers novel prospects for developing advanced HOR electrocatalysts. [ABSTRACT FROM AUTHOR]

The ambient ammonia synthesis coupled with distributed green hydrogen production technology can provide promising solutions for low‐carbon NH3 production and H2 storage. Herein, we reported Ru‐loaded defective pyrochlore K2Ta2O6−x with remarkable visible‐light absorption and a very low work function, enabling effective visible‐light‐driven ammonia synthesis from N2 and H2 at low pressure down to 0.2 atm. The photocatalytic rate was 2.8 times higher than that of the best previously reported photocatalyst and the photo‐thermal rate at 425 K was similar to that of Ru‐loaded black TiO2 at 633 K. Compared to perovskite‐type KTaO3−x with the same composition, the pyrochlore exhibited a 3.7‐fold increase in intrinsic activity due to a higher photoexcited charge separation efficiency and a higher conduction band position. The interfacial Schottky barrier and spontaneous electron transfer between K2Ta2O6−x and Ru further improve photoexcited charge separation and accumulate energetic electrons to facilitate N2 activation. [ABSTRACT FROM AUTHOR]

Photothermal catalysis is one of the most promising green catalytic technologies, while distinguishing the effects of hot electrons and local heating remains challenging. Herein, we reported that the actual reaction temperature of photothermal ammonia synthesis over carbon‐supported Ru catalyst can be measured based on Le Chatelier′s principle, enabling the hot‐electron contribution to be quantified. By excluding local heating effects, we established that the activation energy via photothermal catalysis was much lower than that of thermocatalysis (54.9 vs. 126.0 kJ mol−1), stemming from hot‐electron injection lowering the energy barriers for both N2 dissociation and intermediates hydrogenation. Furthermore, hot‐electron injection acted to suppress carbon support methanation, giving the catalyst outstanding operational stability over 1000 h. This work provides new insights into the hot‐electron effects in ammonia synthesis, guiding the design of high‐performance photothermal catalysts. [ABSTRACT FROM AUTHOR]

Increasing selectivity without the expense of activity is desired but challenging in heterogeneous catalysis. By revealing the molecule saturation and adsorption sensitivity on overlayer thickness, strain, and coordination of Pd‐based catalysts from first‐principles calculations, we designed a stable Pd monolayer (ML) catalyst on a Ru terrace to boost both activity and selectivity of acetylene semihydrogenation. The least saturated molecule is most sensitive to the change in catalyst electronic and geometric properties. By simultaneously compressing the Pd ML and exposing the high coordination sites, the adsorption of more saturated ethylene is considerably weakened to facilitate the desorption for high selectivity. The even stronger weakening to the least saturated acetylene drives its hydrogenation such that it is more exothermic, thereby boosting the activity. Tailoring the molecule saturation and its sensitivity to structure and composition provides a tool for rational design of efficient catalysts. [ABSTRACT FROM AUTHOR]

Glycosyl anomeric radical addition reactions have been well‐explored and proved efficient for the C‐alkyl glycosides synthesis, but multicomponent Domino transformations for the rapid and controllable construction of structurally diversified C‐alkyl glycosides in a single step are still rare. In contrast, we, herein, report a ruthenium(II)‐catalyzed Domino meta‐C−H ethyl glycosylation, enabling the construction of challenging meta‐C‐alkyl glycosides. Our ruthenium(II) catalysis was reflected by the mild reaction condition, exclusive meta‐site selectivity and high levels of anomeric selectivity. In addition, the ruthenium(II)‐catalyzed Domino meta‐C−H glycosylation allowed for the synthesis of versatile 1,2‐trans‐C‐alkyl glycosides with commercially available vinyl arenes, acrylates and easily accessible glycosyl bromides. [ABSTRACT FROM AUTHOR]

Molecular electrocatalysts for CO2‐to‐CO conversion often operate at large overpotentials, due to the large barrier for C−O bond cleavage. Illustrated with ruthenium polypyridyl catalysts, we herein propose a mechanistic route that involves one metal center that acts as both Lewis base and Lewis acid at different stages of the catalytic cycle, by density functional theory in corroboration with experimental FTIR. The nucleophilic character of the Ru center manifests itself in the initial attack on CO2 to form [Ru‐CO2]0, while its electrophilic character allows for the formation of a 5‐membered metallacyclic intermediate, [Ru‐CO2CO2]0,c, by addition of a second CO2 molecule and intramolecular cyclization. The calculated activation barrier for C−O bond cleavage via the metallacycle is decreased by 34.9 kcal mol−1 as compared to the non‐cyclic adduct in the two electron reduced state of complex 1. Such metallacyclic intermediates in electrocatalytic CO2 reduction offer a new design feature that can be implemented consciously in future catalyst designs. [ABSTRACT FROM AUTHOR]

Nano and single‐atom catalysis open new possibilities of producing green hydrogen (H2) by water electrolysis. However, for the hydrogen evolution reaction (HER) which occurs at a characteristic reaction rate proportional to the potential, the fast generation of H2 nanobubbles at atomic‐scale interfaces often leads to the blockage of active sites. Herein, a nanoscale grade‐separation strategy is proposed to tackle mass‐transport problem by utilizing ordered three‐dimensional (3d) interconnected sub‐5 nm pores. The results reveal that 3d criss‐crossing mesopores with grade separation allow efficient diffusion of H2 bubbles along the interconnected channels. After the support of ultrafine ruthenium (Ru), the 3d mesopores are on a superior level to two‐dimensional system at maximizing the catalyst performance and the obtained Ru catalyst outperforms most of the other HER catalysts. This work provides a potential route to fine‐tuning few‐nanometer mass transport during water electrolysis. [ABSTRACT FROM AUTHOR]

Easily accessible via a simple esterification of alcohols with formic acid, alkyl formates are used as a novel class of transfer hydroalkylation reagents, CO2 acting as a traceless linker. As a proof‐of‐concept, their reactivity in the transfer hydroalkylation of imines is investigated, using a ruthenium‐based catalyst and LiI as promoter to cleave the C−O σ‐bond of the formate scaffold. Providing tertiary amines, the reaction displays a divergent regioselectivity compared to previously reported transfer hydroalkylation strategies. [ABSTRACT FROM AUTHOR]

Water‐soluble multinuclear complexes based on ruthenium 2,2′‐bipyridine‐6,6′‐dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three‐component visible light‐driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co‐solvents and with increasing oligomer length. In‐depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self‐assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s−1) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)‐based photocatalytic water oxidation systems. [ABSTRACT FROM AUTHOR]

Alkene metathesis catalyzed by enantiopure metal alkylidene complexes enables exceptionally versatile strategies to products with configurationally‐defined stereocenters. Desymmetrization processes thereby provide reliable stereoselective routes to aliphatic structures, while the differentiation of aromatic stereogenic units remained an outstanding challenge. Herein, we describe the feasibility of alkene metathesis to catalytically control stereogenic axes by traceless arene formation. Stereodynamic trienes are selectively converted into corresponding binaphthalene atropisomers upon exposure to a chiral molybdenum catalyst. Remarkably, stereoselective arene‐forming metathesis allows enantioselectivities of up to 98 : 2 e.r. and excellent yields. As the disconnection of each bond of an aromatic target is retrosynthetically conceivable, it is anticipated that forging arenes by means of stereoselective metathesis will enable versatile approaches for the synthesis of a broad range of molecular topologies with precisely defined configuration. [ABSTRACT FROM AUTHOR]

The potential for ultrahigh‐throughput compartmentalization renders droplet microfluidics an attractive tool for the directed evolution of enzymes. Importantly, it ensures maintenance of the phenotype‐genotype linkage, enabling reliable identification of improved mutants. Herein, we report an approach for ultrahigh‐throughput screening of an artificial metalloenzyme in double emulsion droplets (DEs) using commercially available fluorescence‐activated cell sorters (FACS). This protocol was validated by screening a 400 double‐mutant streptavidin library for ruthenium‐catalyzed deallylation of an alloc‐protected aminocoumarin. The most active variants, identified by next‐generation sequencing, were in good agreement with hits obtained using a 96‐well plate procedure. These findings pave the way for the systematic implementation of FACS for the directed evolution of (artificial) enzymes and will significantly expand the accessibility of ultrahigh‐throughput DE screening protocols. [ABSTRACT FROM AUTHOR]

Sustainable sources are key to future chemicals production. Microalgae are promising resources as they fixate carbon dioxide to organic molecules by photosynthesis. Thereby they produce unsaturated fatty acids as established raw materials for the industrial production of chemical building blocks. Although these renewable feedstocks are generated inside cells, their catalytic upgrading to useful products requires in vitro transformations. A synthetic catalysis inside photoautotrophic cells has remained elusive. Here we show that a catalytic conversion of renewable substrates can be realized directly inside living microalgae. Organometallic catalysts remain active inside the cells, enabling in vivo catalytic olefin metathesis as new‐to‐nature transformation. Stored lipids are converted to long‐chain dicarboxylates as valuable building blocks for polymers. This is a key step towards the long‐term goal of producing desired renewable chemicals in microalgae as living "cellular factories". [ABSTRACT FROM AUTHOR]

Electrochemical reduction of biomass‐derived 5‐hydroxymethylfurfural (HMF) represents an elegant route toward sustainable value‐added chemicals production that circumvents the use of fossil fuel and hydrogen. However, the reaction efficiency is hampered by the high voltage and low activity of electrodes (Cu, Bi, Pb). Herein, we report a Ru1Cu single‐atom alloy (SAA) catalyst with isolated Ru atoms on Cu nanowires that exhibits an electrochemical reduction of HMF to 2,5‐dihydroxymethylfuran (DHMF) with promoted productivity (0.47 vs. 0.08 mmol cm−2 h−1) and faradic efficiency (FE) (85.6 vs. 71.3 %) at −0.3 V (vs. RHE) compared with Cu counterpart. More importantly, the FE (87.5 %) is largely retained at high HMF concentration (100 mM). Kinetic studies by using combined electrochemical techniques suggest disparate mechanisms over Ru1Cu and Cu, revealing that single‐atom Ru promotes the dissociation of water to produce H* species that effectively react with HMF via an electrocatalytic hydrogenation (ECH) mechanism. [ABSTRACT FROM AUTHOR]

Distal C(sp2)−H and C(sp3)−H functionalizations have recently emerged as step‐economical tools for molecular synthesis. However, while the C(sp2)−C(sp3) construction is of fundamental importance, its formation through double remote C(sp2)−H/C(sp3)−H activation has proven elusive. By merging the ruthenium‐catalyzed meta‐C(sp2)−H functionalization with an aliphatic hydrogen atom transfer (HAT) process, we, herein, describe the catalyzed twofold remote C(sp2)−H/C(sp3)−H functionalizations via photo‐induced ruthenium‐mediated radical relay. Thus, meta‐C(sp2)−H arene bonds and remote C(sp3)−H alkane bonds were activated by a single catalyst in a single operation. This process was accomplished at room temperature by visible light—notably without exogenous photocatalysts. Experimental and computational theory studies uncovered a manifold comprising ortho‐C−H activation, single‐electron‐transfer (SET), 1,n‐HAT (n=5–7) and σ‐activation by means of a single ruthenium(II) catalyst. [ABSTRACT FROM AUTHOR]

Disclosed here is the first geminal (gem‐) hydroborative cyclization of enynes. Different from known hydroborative cyclizations, this process adds hydrogen and boron to the same position, leading to a new reaction mode. With [Cp*RuCl]4 as catalyst, a range of gem‐hydroborated bicyclic products bearing a cyclopropane unit could be rapidly assembled from simple enyne substrates. Control experiments and density functional theory (DFT) calculations provided important insights into the reaction mechanism. Notably, two major competing pathways may operate with substrate‐dependence. 1,6‐Enynes favor initial oxidative cyclometalation to form a ruthenacyclopentene intermediate prior to engaging hydroborane, while other enynes (e.g. 1,7‐enynes) that lack strong propensity toward cyclization prefer initial alkyne gem‐(H,B)‐addition to form an α‐boryl ruthenium carbene followed by intramolecular olefin cyclopropanation. This process also represents the first ruthenium‐catalyzed enyne hydroborative cyclization. [ABSTRACT FROM AUTHOR]

Ruthenium‐mediated olefin metathesis has been widely applied for the synthesis of various organic molecules and polymers. Inspired by the cocatalyst strategy for olefin polymerization, here we demonstrate that the abstraction of a chloride ion from various commercially available ruthenium catalysts significantly enhances their reactivity towards electron‐deficient internal olefins. This cocatalyst strategy can be implemented in ethenolysis and cross‐metathesis reactions of FG‐CH=CH‐FG type substrates bearing electron‐withdrawing groups and the synthesis of telechelic polymers that can be converted to polyethylene‐like materials with closed‐loop recycling properties. The copolymerization of cyclic substrate with cycloolefins followed by hydrogenation afforded polyolefin materials with in‐chain break points. Interestingly, switchable catalysis was achieved in the absence and presence of a cocatalyst, which allowed the polymer microstructure and material properties to be fine‐tuned. [ABSTRACT FROM AUTHOR]

Development of chiral ligands is the most fundamental task in metal‐catalyzed asymmetric synthesis. In the last 60 years, various kinds of ligands have been sophisticatedly developed. However, it remains a long‐standing challenge to develop practically useful chiral η6‐arene ligands, thereby seriously hampering the asymmetric synthesis promoted by arene‐metal catalysts. Herein, we report the design and synthesis of a class of readily tunable, C2‐symmetric chiral arene ligands derived from [2.2]paracyclophane. Its ruthenium(II) complexes have been prepared and successfully applied in the enantioselective C−H activation to afford a series of axially chiral isoquinolones (up to 99 % yield and 96 % ee). This study not only lays chemists' longstanding doubts about whether it is possible to use chiral arene ligands to stereocontrol ruthenium(II)‐catalyzed asymmetric C−H activation, but also opens up a new avenue to achieve asymmetric C−H activation. [ABSTRACT FROM AUTHOR]

Transition‐metal catalysts exhibit great potential as therapeutic agents to inhibit tumor growth. However, the precise delivery and in situ catalysis are challenging in catalytic medicine. Herein, we report an anti‐HER2 affibody‐ruthenium catalyst hybrid, named Ru‐HER2 for selective and effective killing of cancer cells. Ru‐HER2 binds to the HER2 receptor on a tumor cell and in situ catalyzes the activation of gemcitabine prodrug, resulting in enhanced selectivity in suppression of tumor growth and reduction of side effects. Immunoblotting reveals that Ru‐HER2 in combination with gemcitabine prodrug can not only induce DNA damage, but also effectively block the HER2 signaling pathway in cancer cells. Therefore, the HER2‐targeted chemotherapy exhibits substantially high anticancer activity toward HER2‐positive cancer cells in vitro and in vivo. In a word, we report the first affibody‐ruthenium catalyst hybrid and reveal its potential for effective HER2‐targeted cancer chemotherapy. [ABSTRACT FROM AUTHOR]

The asymmetric hydroalkylation of racemic allylic alcohols has been developed for the synthesis of chiral amino acid derivatives with two remote chiral centers by borrowing hydrogen catalysis. The stereoselectivities are controlled by a single chiral Ru catalyst via a dynamic kinetic asymmetric transformation process and an interesting diastereoselectivity amplification process of the product. The method could be used for the synthesis of several types of biologically important molecules, including stereodivergent synthesis of chiral pyrrolidine derivatives. [ABSTRACT FROM AUTHOR]

Formation of sterically hindered C−C double bonds via catalytic olefin metathesis is considered a very challenging task for Ru catalysts. This limitation led to the development of specialised catalysts bearing sterically reduced N‐heterocyclic carbene (NHC) ligands that are very active in such transformations, yet significantly less stable as compared to general purpose catalysts. To decrease the small‐size NHC catalysts susceptibility to decomposition, a new NHC ligand was designed, in which two sterically reduced aryl arms were tied together by a C‐8 alkyl chain. The installation of this macrocyclic ligand on the ruthenium centre led to the formation of an olefin metathesis catalyst (trans‐Ru6). Interestingly, this complex undergoes transformation into an isomer bearing two Cl ligands in the cis‐arrangement (cis‐Ru6). These two isomeric complexes exhibit similarly high thermodynamic stability, yet different application profiles in catalysis. [ABSTRACT FROM AUTHOR]

During an investigation into the fate of ruthenium precatalysts used for light‐driven alkyne gem‐hydrogenation reactions with formation of Grubbs‐type ruthenium catalysts, it was found that the reaction of [(IPr)(η6‐cymene)RuCl2] with H2 under UV‐irradiation affords an anionic dinuclear σ‐dihydrogen complex, which is thermally surprisingly robust. Not only are anionic σ‐complexes in general exceedingly rare, but the newly formed species seems to be the first example lacking any structural attributes able to counterbalance the negative charge and, in so doing, prevent oxidative insertion of the metal centers into the ligated H2 from occurring. [ABSTRACT FROM AUTHOR]

Tetrahydropyran‐containing macrolactones were synthesized by integrating Meyer–Schuster rearrangement, macrocyclic ring‐closing metathesis, and transannular oxa‐Michael addition under gold and ruthenium catalysis. Single‐step access to a variety of 14‐ to 20‐membered macrolactones containing a tetrahydropyran ring was possible from readily available linear precursors in good yields and with moderate to excellent diastereoselectivity. A 13‐step synthesis of (−)‐exiguolide, an anticancer marine macrolide, showcased the feasibility of our tandem reaction sequence for macrolactone synthesis and also demonstrated the power of transannular reactions for rapid assembly of the tetrahydropyran rings of the target natural product. [ABSTRACT FROM AUTHOR]

The asymmetric hydrogenation (AH) of 3H‐indoles represents an ideal approach to the synthesis of useful chiral indoline scaffolds. However, very few catalytic systems based on precious metals have been developed to realize this challenging reaction. Herein, we report a Mn‐catalyzed AH of 3H‐indoles with excellent yields and enantioselectivities. The kinetic resolution of racemic 3H‐indoles by AH was also achieved with high s‐factors to construct quaternary stereocenters. Many acid‐sensitive functional groups, which cannot be tolerated when using a state‐of‐the‐art ruthenium catalyst, were compatible with manganese catalysis. This new process expands the scope of this transformation and highlights the uniqueness of earth‐abundant metal catalysis. The reaction could proceed with catalyst loadings at the parts per million (ppm) level with an exceptional turnover number of 72 350. This is the highest value yet reported for an earth‐abundant metal‐catalyzed AH reaction. [ABSTRACT FROM AUTHOR]

The biomass‐derived alcohol oxidation reaction (BDAOR) holds great promise for sustainable production of chemicals. However, selective electrooxidation of alcohols to value‐added aldehyde compounds is still challenging. Herein, we report the electrocatalytic BDAORs to selectively produce aldehydes using single‐atom ruthenium on nickel oxide (Ru1‐NiO) as a catalyst in the neutral medium. For electrooxidation of 5‐hydroxymethylfurfural (HMF), Ru1‐NiO exhibits a low potential of 1.283 V at 10 mA cm−2, and an optimal 2,5‐diformylfuran (DFF) selectivity of 90 %. Experimental studies reveal that the neutral electrolyte plays a critical role in achieving a high aldehyde selectivity, and the single‐atom Ru boosts HMF oxidation in the neutral medium by promoting water dissociation to afford OH*. Furthermore, Ru1‐NiO can be extended to selective electrooxidation of a series of biomass‐derived alcohols to corresponding aldehydes, which are conventionally difficult to obtain in the alkaline medium. [ABSTRACT FROM AUTHOR]

A tritopic, Ni‐substituted Keggin cluster, {SiW9Ni4}, assembles with rigid dicarboxylate linkers to give rise to a set of discrete, POM2nL3n‐type structures (POM={SiW9Ni4}) with defined interior voids. The outcome of coordination‐driven self‐assemblies of these polyhedral cages—from fused dimers to trigonal prisms—was found to be sensitive to bend angles of the ditopic ligands, which vary from 122° to 180°. These polyoxotungstate‐based metal–organic polyhedra, when coupled with [Ru(bpy)3]Cl2 as a photosensitizer and triethanolamine as the electron donor, serve as highly effective catalysts for CO2 reduction, with turnover numbers up to 328 and CO selectivity as high as 96.2 %. The inner cavities of such cage structures, if functionalized or of sufficient size to encapsulate targeted guest molecules, could present a new strategy towards functional materials for potential applications. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of ammonia (NH3) holds significant potential compared with the Haber–Bosch process. However, the reported photocatalysts suffer from low efficiency owing to localized electron deficiency. Herein, Ru‐SA (single atoms)/HxMoO3−y hybrids with abundant of Mon+ (4

Synthetic chemists have learned to mimic nature in using hydrogen bonds and other weak interactions to dictate the spatial arrangement of reaction substrates and to stabilize transition states to enable highly efficient and selective reactions. The activation of a catalyst molecule itself by hydrogen‐bonding networks, in order to enhance its catalytic activity to achieve a desired reaction outcome, is less explored in organic synthesis, despite being a commonly found phenomenon in nature. Herein, we show our investigation into this underexplored area by studying the promotion of carbonyl‐olefin metathesis reactions by hydrogen‐bonding‐assisted Brønsted acid catalysis, using hexafluoroisopropanol (HFIP) solvent in combination with para‐toluenesulfonic acid (pTSA). Our experimental and computational mechanistic studies reveal not only an interesting role of HFIP solvent in assisting pTSA Brønsted acid catalyst, but also insightful knowledge about the current limitations of the carbonyl‐olefin metathesis reaction. [ABSTRACT FROM AUTHOR]

We demonstrate catalytic organic synthesis by Resonant Acoustic Mixing (RAM): a mechanochemical methodology that does not require bulk solvent or milling media. Using as model reactions ruthenium‐catalyzed ring‐closing metathesis and copper‐catalyzed sulfonamide‐isocyanate coupling, RAM mechanosynthesis is shown to be faster, operationally simpler than conventional ball‐milling, while also providing the first example of a mechanochemical strategy for ruthenium‐catalyzed ene‐yne metathesis. Reactions by RAM are readily and directly scaled‐up without any significant changes in reaction conditions, as shown by the straightforward 200‐fold scaling‐up of the synthesis of the antidiabetic drug Tolbutamide, from hundreds of milligrams directly to 30 grams. [ABSTRACT FROM AUTHOR]

gem‐Hydrogenation of propargyl alcohol derivatives with [CpXRu(MeCN)3]PF6 (CpX=substituted cyclopentadienyl) as catalysts affords cationic pianostool ruthenium carbene complexes which are so electrophilic that they attack a tethered olefin to furnish cyclopentene products; cyclopropanation or metathesis do not compete with this novel transformation. If the transient carbenes carry appropriate propargylic substituents, however, they engage in ([2,3]‐sigmatropic) rearrangements to give enol esters (carbonates, carbamates, sulfonates) or alkenyl halides. Both pathways are unprecedented in the vast hydrogenation literature. The proposed mechanistic scenarios are in line with labeling experiments and spectroscopic data; most notably, PHIP NMR spectroscopy (PHIP=parahydrogen induced polarization) provides compelling evidence that the reactions are indeed triggered by highly unorthodox gem‐hydrogenation events. [ABSTRACT FROM AUTHOR]

Compartmentalization of chemical reactions inside cells are a fundamental requirement for life. Encapsulins are self‐assembling protein‐based nanocompartments from the prokaryotic repertoire that present a highly attractive platform for intracellular compartmentalization of chemical reactions by design. Using single‐molecule Förster resonance energy transfer and 3D‐MINFLUX analysis, we analyze fluorescently labeled encapsulins on a single‐molecule basis. Furthermore, by equipping these capsules with a synthetic ruthenium catalyst via covalent attachment to a non‐native host protein, we are able to perform in vitro catalysis and go on to show that engineered encapsulins can be used as hosts for transition metal catalysis inside living cells in confined space. [ABSTRACT FROM AUTHOR]

Cyclophane structures can control steric pressure in the otherwise open spaces of square‐planar d8‐metal catalysts. This elegant concept was so far limited to symmetrical coordinated metals. We report how a cyclophane motif can be generated in ligands that chelate via two different donors. An ancillary second imine in the versatile κ2‐N,O‐salicylaldiminato catalyst type enables ring closure via olefin metathesis and selective double bond hydrogenation to yield a 30‐membered ring efficiently. Experimental and theoretical analyses show the ancillary imine is directed away from the active site and inert for catalysis. In ethylene polymerization the cyclophane catalyst is more active and temperature stable vs. an open structure reference, notably also in polar solvents. Increased molecular weights and decreased degrees of branching can be traced to an increased energy of sterically demanding transition states by the encircling cyclophane while chain propagation remains highly efficient. [ABSTRACT FROM AUTHOR]

We present herein an unprecedented diastereoconvergent synthesis of vicinal diamines from diols through an economical, redox‐neutral process. Under cooperative ruthenium and Lewis acid catalysis, readily available anilines and 1,2‐diols (as a mixture of diastereomers) couple to forge two C−N bonds in an efficient and diastereoselective fashion. By identifying an effective chiral iridium/phosphoric acid co‐catalyzed procedure, the first enantioconvergent double amination of racemic 1,2‐diols has also been achieved, resulting in a practical access to highly valuable enantioenriched vicinal diamines. [ABSTRACT FROM AUTHOR]

A strategy to improve homogeneous molecular catalyst stability, efficiency, and selectivity is the immobilization on supporting surfaces or within host matrices. Herein, we examine the co‐immobilization of a CO2 reduction catalyst [ReBr(CO)3(4,4′‐dcbpy)] and a photosensitizer [Ru(bpy)2(5,5′‐dcbpy)]Cl2 using the isoreticular series of metal–organic frameworks (MOFs) UiO‐66, ‐67, and ‐68. Specific host pore size choice enables distinct catalyst and photosensitizer spatial location—either at the outer MOF particle surface or inside the MOF cavities—affecting catalyst stability, electronic communication between reaction center and photosensitizer, and consequently the apparent catalytic rates. These results allow for a rational understanding of an optimized supramolecular layout of catalyst, photosensitizer, and host matrix. [ABSTRACT FROM AUTHOR]