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另一种报法：
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还有其他报法，这里条件限制暂时无法一一列出

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目前来看这个issue实际是两个问题，一是/acs/journal/:id被错误解析为/journal/:id，二是正确解析的结果无法在规定时间内返回有效数据

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```rss https://pubs.acs.org/toc/accacs/0/0 RSSHub i@diygod.me (DIYgod) zh-cn Sun, 27 Aug 2023 15:04:39 GMT 5

Catalysis enables many aspects of modern life, including fuels, products, plastics, and medicines. Recent advances in catalysis have enabled us to realize higher efficiencies and new processes. Ideally, we seek to achieve high rates of selective conversions using catalysts derived from abundantly available elements and operating under mild conditions, specifically lower reaction temperatures and pressures. Such catalysts could enable decentralized, on-demand synthesis of chemicals and energy carriers. Nature has demonstrated the feasibility of this approach with enzymes, which showcase catalytic processes at low temperatures and pressures with nonprecious metals. Current thinking holds that in addition to the active site, the complexity of the enzyme structure, specifically the protein scaffold, is also critical to achieving this performance. Recreating this environment has been a long-standing scientific goal. However, we still understand the functions of enzymes better than we understand the de novo design of catalysts that mimic enzymes features, while also retaining their activity and selectivity under more demanding conditions. In this Perspective, we will critically examine four key areas of catalyst design that incorporate the chemical and structural properties of enzymes into synthetic catalysts: (i) the use of confinement to enhance catalytic activity, (ii) tailoring the environment around the active site, (iii) proton transport, and (iv) bifunctionality and cooperativity.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c00320 https://pubs.acs.org/doi/10.1021/acscatal.3c00320

Hydrogenation of CO2 into value-added light olefins is a promising route to achieve carbon recycling. Regulation of light olefins distribution and promotion of target olefins formation are highly important to improve carbon utilization efficiency, but rather challenging. Herein, we designed a series of GaZrOx/H-SAPO-17 composite catalysts, which show the C2=–C4= selectivity of 82.5% (CO free), with those of CH4 and C20–C40 of only 2.5 and 10.2% in hydrocarbons, respectively, at a CO2 conversion of 9.0% at 375 °C and 1.5 MPa. In particular, ethene and propene accounted for >84% of C2=–C5= alkenes. Such a performance was well-maintained for at least 100 h. Temperature-/time-dependent in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), isotope labeling in situ DRIFTS, and 13C magic angle spinning NMR indicated that formate and methoxy are the dominant intermediate species for the production of methanol on GaZrOx oxide. Upon coupling with acidic zeolite, the formed methanol intermediates were rapidly converted to light olefins. The distribution of olefins in subsequent methanol conversion was strongly related to the pore structure of H-SAPO-17 zeolite. In situ UV–vis spectroscopy, in situ DRIFTS, temperature-programed surface reaction, 12C/13C methanol switching experiments, and density functional theory computations confirmed that the small supercage structure of H-SAPO-17 has a stronger steric restriction effect on the formation of bulky aromatic species with large alkyl side chains, which, hence, significantly inhibits the generation of C4+ long-chain olefins through the aromatic-based cycle.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c01785 https://pubs.acs.org/doi/10.1021/acscatal.3c01785

Electrocarboxylation of organic bromide with CO2 toward value-added carboxylic acid, which can be powered by renewable energy, provides one promising solution to facilitate the carbon balance. However, it is still a challenge to achieve high reactivity and selectivity without a sacrificial anode due to difficulties of activating CO2 and aryl bromide simultaneously and competitive reactions. Herein, we report an example of highly efficient electrocarboxylation of aryl bromides at the cathode along with oxygen evolution at the anode. Copper–silver nanowires as the cathodic catalysts demonstrate a Faraday efficiency of 98% for carboxylic acid production. Mechanism studies reveal that CO2 may be activated by Cu, and Ag species are responsible for the activation of aryl bromide and radical coupling process. This bifunctional activation model suppresses competitive hydrogenolysis and reductive coupling reactions of aryl bromide, thus achieving the high efficiency of electrocarboxylation.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02791 https://pubs.acs.org/doi/10.1021/acscatal.3c02791

Dual nickel photoredox catalysis conditions have been developed for the decarboxylative cross-coupling of aryl halides and carboxylic acids containing fully substituted α-carbons, a valuable but challenging substrate class for C(sp2)–C(sp3) bond-forming reactions. High-throughput experimentation identified Ni(TMHD)2 as the optimal precatalyst for this reaction in contrast to the nickel-bipyridyl complexes typically employed in decarboxylative couplings, which predominantly furnished undesired C–O products. Computational work provides insight into the potential mechanistic underpinnings for the C–C vs C–O selectivity for the nickel-diketonate complex.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03353 https://pubs.acs.org/doi/10.1021/acscatal.3c03353

The crystal phase of a catalyst support, such as TiO2, significantly contributes to the activity and stability of metal-loaded catalysts by modifying the metal–support interactions. However, the effect of the crystal phase on hydrogen spillover-induced hydrodeoxygenation (HDO) is relatively less understood, although the spillover of hydrogen on the reducible oxide support could play a crucial role in HDO by providing additional active sites. The HDO of guaiacol by hydrogen spillover was investigated by confirming the synergetic effect when pristine rutile and anatase TiO2 were added to Ru-loaded TiO2, while hydrogen spillover-induced promotion of guaiacol HDO performance was more pronounced for rutile TiO2 than for anatase TiO2. Facilitated hydrogen spillover on rutile TiO2 was confirmed by combined hydrogen temperature-programed reduction, hydrogen chemisorption, and hydrogen diffuse reflectance infrared Fourier transform analysis. The distinctive adsorption behaviors of the reactants on rutile and anatase TiO2 were evaluated by using attenuated total reflectance infrared spectroscopy, which demonstrated that the adsorption behavior was also responsible for the spillover-induced promotion of the HDO performance. This study facilitates the understanding of the distinctive features of spillover hydrogen affecting HDO according to the phase of TiO2, which can provide guidelines for designing catalysts with enhanced HDO performance.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03230 https://pubs.acs.org/doi/10.1021/acscatal.3c03230

Proton exchange membrane fuel cells (PEMFCs) are a promising zero-emission power source for heavy-duty vehicles (HDVs). However, long-term durability of up to 25,000 h is challenging because current carbon support, catalyst, membrane, and ionomer developed for traditional light-duty vehicles cannot meet the stringent requirement. Therefore, understanding catalyst degradation mechanisms under the HDV condition is crucial for rationally designing highly active and durable platinum group metal (PGM) catalysts for high-performance membrane electrode assemblies (MEAs). Herein, we report a PGM catalyst consisting of platinum nanoparticles with a high content (40 wt %) on atomic-metal-site (e.g., MnN4)-rich carbon support. MEAs with the Pt (40 wt %)/Mn–N–C cathode catalyst achieved significantly enhanced performance and durability, generating 1.41 A cm–2 at 0.7 V under HDV conditions (0.25 mgPt cm–2 and 250 kPaabs pressure) and retaining 1.20 A cm–2 after an extended and accelerated stress test up to 150,000 voltage cycles. Electron microscopy studies indicate that most fine Pt nanoparticles are retained on or/and in the carbon support covered with the ionomer throughout the catalyst layer at the end of life. During the long-term stability test, the observed electrochemical active surface area reduction and performance loss primarily result from Pt depletion in the catalyst layer due to Pt dissolution and redeposition at the interface of the cathode and membrane. The first-principle density functional theory calculations further reveal a support entrapment effect of the Mn–N–C, in which the MnN4 site can specifically adsorb the Pt atom and further retard the Pt dissolution and migration, therefore enhancing long-term MEA durability.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03270 https://pubs.acs.org/doi/10.1021/acscatal.3c03270

Structure sensitivity is the phenomenon where the activity of each available active site of a catalyst varies depending on its specific structure and coordination environment. Understanding structure sensitivity can assist in the rational design of catalysts, allowing for control over activity and selectivity. Here, we demonstrate that the activity and selectivity of acetone coupling to 2,5-hexanedione (2,5-HDN), an important raw material, via a photocatalytic dehydrogenative route are highly structure sensitive and prove how the size of the supported Pt influences the catalytic performance. Under optimized conditions, the formation rate of 2,5-HDN on subnanometer Pt cluster modified anatase–TiO2 (PtCL/TiO2) reaches 45.3 μmol/h, 1.5–9.0 times higher than the Pt NPs and Pt single-atom doped TiO2 photocatalysts. Mechanism studies reveal that water, which is oxidized by the excited hole of the anatase semiconductor, acts as a co-catalyst in the reaction and generates hydroxyl radicals. The formed hydroxyl radicals subsequently assist the cleavage of the sp3 C–H bond of acetone. The dimerization of the •CH2COCH3 radicals delivers 2,5-HDN. The remarkable •OH radical formation capability and relatively high H-abstraction activity of the PtCL/TiO2 photocatalyst account for its excellent activity and selectivity over other Pt/TiO2 catalysts.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c01930 https://pubs.acs.org/doi/10.1021/acscatal.3c01930

The synthesis of dialkyl-substituted cyclopropanes is an important challenge in synthesis with applications in drug discovery and agrochemistry. Herein, we report on the synthesis of gem-dialkyl cyclopropanes with in situ-generated dialkyl diazo compounds under Bamford–Stevens conditions. A simple cobalt catalyst was identified to be optimal to achieve high yields. Experimental and computational studies suggest the participation of a metalloradical reaction mechanism that facilitates the carbene transfer reactions and provides access to dialkyl-substituted cyclopropanes in a single step.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02468 https://pubs.acs.org/doi/10.1021/acscatal.3c02468

Developing effective photocatalysts for CO2 reduction to high value-added chemicals or fuels is a promising strategy for alleviating serious environmental problems and energy crisis. Currently, the photocatalytic efficiency is still too slow to arouse industrial interest for most semiconductor photocatalysts due to their low CO2 uptake, limited visible light capture capacity, and serious recombination of electron–hole. Herein, we successfully synthesized a high-density ultrafine Au cluster (∼0.7 nm)-doped cobalt-layered double hydroxide nanocage (Au/Co-LDH) photocatalyst through an in situ redox strategy to explore the structure–activity relationship in the CO2 reduction system. A series of experimental characterizations showed that CO2 adsorption, visible light capture capacity, and charge transfer rate are significantly enhanced due to the highly dispersed and ultrafine Au cluster doping. Density functional theory calculations indicate that Au doping also promoted charge redistribution at the active site, increased the density of states near the Fermi energy level, stabilized the *COOH intermediate, and reduced the energy barrier of the rate-determining step. As a result, Au/Co-LDH delivers a CO evolution rate of 5610 μmol g–1 h–1 toward CO2 reduction under visible light (λ > 420 nm), which is 4 times and 22 times more active than the undoped one and Au nanoparticles, respectively. We believe that this work will provide an important implication for the development and optimization of photocatalysts for CO2 reduction.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02486 https://pubs.acs.org/doi/10.1021/acscatal.3c02486

Ruthenium-promoted ring-opening metathesis polymerization (ROMP) offers potentially powerful routes to amine-functionalized polymers with antimicrobial, adhesive, and self-healing properties. However, amines readily degrade the methylidene and unsubstituted ruthenacyclobutane intermediates formed in metathesis of terminal olefins. Examined herein is the relevance of these decomposition pathways to ROMP (i.e., metathesis of internal olefins) by the third-generation Grubbs catalyst. Primary alkylamines rapidly quench polymerization via fast adduct formation, followed by nucleophilic abstraction of the propagating alkylidene. Bulkier, Brønsted-basic amines are less aggressive: attack competes only for slow polymerization or strong bases (e.g., DBU). Added HCl limits degradation, as demonstrated by the successful ROMP of an otherwise intractable methylamine monomer.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02729 https://pubs.acs.org/doi/10.1021/acscatal.3c02729

We report a detailed study into the method of precatalyst activation during alkyne cyclotrimerization. During these studies we have prepared a homologous series of Fe(III)-μ-oxo(salen) complexes and use a range of techniques including UV–vis, reaction monitoring studies, single crystal X-ray diffraction, NMR spectroscopy, and LIFDI mass spectrometry to provide experimental evidence for the nature of the on-cycle iron catalyst. These data infer the likelihood of ligand reduction, generating an iron(salan)-boryl complex as a key on-cycle intermediate. We use DFT studies to interrogate spin states, connecting this to experimentally identified diamagnetic and paramagnetic species. The extreme conformational flexibility of the salan system appears connected to challenges associated with crystallization of likely on-cycle species.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02898 https://pubs.acs.org/doi/10.1021/acscatal.3c02898

Despite the increasing use of biocatalysis for organic synthesis, there are currently no databases that adequately capture synthetic biotransformations. The lack of a biocatalysis database prevents accelerating biocatalyst characterization efforts from being leveraged to quickly identify candidate enzymes for reactions or cascades, slowing their development. The RetroBioCat Database (available at retrobiocat.com) addresses this gap by capturing information on synthetic biotransformations and providing an analysis platform that allows biocatalysis data to be searched and explored through a range of highly interactive data visualization tools. This database makes it simple to explore available enzymes, their substrate scopes, and how characterized enzymes are related to each other and the wider sequence space. Data entry is facilitated through an openly accessible curation platform, featuring automated tools to accelerate the process. The RetroBioCat Database democratizes biocatalysis knowledge and has the potential to accelerate biocatalytic reaction development, making it a valuable resource for the community.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c01418 https://pubs.acs.org/doi/10.1021/acscatal.3c01418

Redox cofactor utilization is one of the major barriers to the realization of efficient and cost-competitive cell-free biocatalysis, especially where multiple redox steps are concerned. The design of versatile, cofactor balanced modules for canonical metabolic pathways, such as glycolysis, is one route to overcoming such barriers. Here, we set up a computer-aided design framework to engineer the non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (GapN) from Streptococcus mutans for enabling an NADH linked efficient cell-free glycolytic pathway with a net zero ATP usage. This rational design approach combines molecular dynamics simulations with a multistate computational design method that allowed us to consider different conformational states encountered along the GapN enzyme catalytic cycle. In particular, the cofactor flip, characteristic of this enzyme family and occurring before product hydrolysis, was taken into account to redesign the cofactor binding pocket for NAD+ utilization. While GapN exhibits only trace activity with NAD+, a ∼10,000-fold enhancement of this activity was achieved, corresponding to a recovery of ∼72% of the catalytic efficiency of the wild-type enzyme on NADP+, with a GapN enzyme harboring only 5 mutations.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c01452 https://pubs.acs.org/doi/10.1021/acscatal.3c01452

The catalytic activity of actinide-based catalysts is presented herein for the hydroboration and deoxygenation of isocyanates with pinacolborane (HBpin). A modified class of ligand systems possessing a five-membered ring core constructing the N-heterocyclic iminato moiety is introduced. All actinide complexes showed very good catalytic activities under mild conditions, with low catalyst loadings achieving almost quantitative yields. A wide number of isocyanates were studied including aliphatic isocyanates, aromatic isocyanates, and diisocyanates yielding to the corresponding borylated N-methyl amines and the borylated formamides, which are easily hydrolyzed toward the free amines and formamides. These organoactinide catalysts exhibited a great functional group tolerance toward methoxy, amido, and halides. The reaction selectivity was thoroughly investigated and exhibited a very good selectivity toward the isocyanate functionality having double or triple unsaturated C–C bonds. Kinetic studies were performed in order to establish the rate order dependency on the concentrations of the organoactinide complex, HBpin, and isocyanate. A proposed mechanism is presented based on experiments affording a more comprehensive understanding of the experimental activity trends and reinforced by the stoichiometric reaction studies, thermodynamic measurements, deuterium-labeling experiments, and theoretical DFT calculations.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02241 https://pubs.acs.org/doi/10.1021/acscatal.3c02241

Photoelectrochemical (PEC) water electrolysis is an important energy conversion (power-to-chemical) method, providing a solution to the intermittent nature of solar energy. However, as PEC systems usually suffer from low operational stability, they are seriously lagging in up-scaled demonstrations and viability. PEC systems are based on semiconductor/liquid interfaces, which have been extensively studied by experiments and theory, but there is a significant knowledge gap in the energetics of such interfaces during operation. In this work, operando ambient pressure X-ray photoelectron spectroscopy (AP-XPS) has been used to characterize the electrical and spectroscopic properties of a pristine Ta3N5 photoelectrode and a Ta3N5/NiOx protection/passivation layer system, which stabilizes an otherwise quickly corroding pristine photoelectrode. We directly observed Fermi-level pinning of Ta3N5 within the applied potential window under both dark and illumination conditions, detrimental to the performance and stability of the photoelectrode. Interestingly, in the Ta3N5/NiOx protection/passivation layer system, the Fermi level gets unpinned under illumination, allowing quasi-Fermi-level splitting and sustaining a significant PEC performance as well as high stability.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02423 https://pubs.acs.org/doi/10.1021/acscatal.3c02423

The strong electron-donating ability in the photoactivated state and the structural flexibility of organic anions have led to a growing interest in utilizing photoexcited organic anions as reductive photocatalysts to activate inert chemical bonds. Phenolate and thiolate have been extensively studied and utilized as catalysts in a wide range of photocatalytic transformations. In contrast, catalysts employing nitrogen anions for radical generation have received less attention despite the vast chemical possibilities for designing and adjusting catalyst properties. In this work, we reported that diaryl amides possessing ortho-diphenylphosphaneyl substituents function as visible-light photoredox catalysts for the activation of inert aryl halides (chloride and bromide) and aryl ammonium salts to generate aryl radicals for phosphorylation, borylation, arylation, and alkylation with corresponding radical interceptors. The o-phosphinodiarylamide catalysts also activate trifluoromethyl groups in trifluoromethylarene, trifluoroacetate, and trifluoroacetamide for defluoroalkylation with alkenes. Notably, the methods using o-phosphinodiarylamides as catalysts are very efficient for radical generation from large π-extended aryl halides, spiro-conjugated aryl halides, and poly halides, indicating the advantages of the organic anion-based photocatalytic approach for application in synthesizing conjugated molecules as electronic materials and interface modification materials without recourse to transition-metal catalysis.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03569 https://pubs.acs.org/doi/10.1021/acscatal.3c03569

Ammonia (NH3) splitting to hydrogen (H2) is a promising route for on-site production of green hydrogen energy; however, the application is limited due to high-cost noble-metal-based catalysts and high operating temperature of the endothermic nature. Herein, we develop a series of macroporous carbon nitride-supported single-atom transition metal (TMs-MCN, TMs: Co, Mn, Fe, Ni, Cu) catalyst panels for solar light-driven photocatalytic gaseous NH3 splitting. Under ambient reaction conditions, the optimized Ni-MCN shows an H2 production rate of 35.6 μmol g–1 h–1, much superior to that of MCN and other TMs-MCN. Such enhanced photoactivity is attributed to the presence of Ni–N4 sites, which improve the optical properties, accelerate charge carrier separation/transfer, and boost NH3 splitting kinetics of the catalysts. Density functional theory calculations further reveal that the Ni–N4 sites can effectively modify the electronic structure of the carbon nitride. Compared with other metal sites, the Ni–N4 site possesses moderate NH3 binding strength and the lowest energy barrier to facilitate the formation of key intermediates *NH + *H. These findings provide valuable guidelines for the rational design of single-atom catalysts toward energy- and cost-effective photocatalytic NH3 splitting for H2 production.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02076 https://pubs.acs.org/doi/10.1021/acscatal.3c02076

Nonoxidative conversion of methane (NOCM) under mild conditions is a highly desirable technology for the low-carbon and atom-economical production of H2 and value-added chemicals. Here, we report the fabrication of CeO2 nanoisland patterns on the surface of Ce–Zr solid solutions. These ultrasmall CeO2 nanoislands with abundant step-edge structures provide unprecedented methane adsorption and activation, achieving the highest methane conversion rate of 1517 μmol g–1 h–1 for photocatalytic NOCM to date. Density functional theory calculations revealed that the low-coordinated Ce–O units at the stepped CeO2(111) surface possess more open planar configurations, which facilitate the cleavage of methane C–H bonds via a distinct metal–CH4 σ-complex mechanism that is energetically more favorable than the radical-like mechanism on the flat CeO2(111) surface. Moreover, the photocatalyst demonstrated a reversible and cooperative photoactivation process that enables the transition from the “resting state” to the “active state”, thereby enhancing the photoexcited charge separation efficiency and photocatalytic NOCM activities.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02192 https://pubs.acs.org/doi/10.1021/acscatal.3c02192

Nanoporous gold (Au) films are self-supported structures that possess a large surface area and extraordinary catalytic activity. Generally, nanoporous gold is obtained by solution-based dealloying where the less noble metal, often silver (Ag), is etched out. However, the residual amounts of the sacrificial metal are not well controlled, the impure samples show restructuring, and the residual metal prevents the study of the catalytic role of Au alone. Here, we fabricate impurity-free nanoporous gold films by a plasma-enabled dry synthetic route. The scheme does not include sacrificial metals or solution processing and is much more general. It is used to obtain self-supported ultra-pure nanoporous gold films with controllable pore sizes. The impurity-free nanoporous gold films possess highly curved ligaments, are remarkably robust, and stable over hundreds of electrochemical cycles. Furthermore, they contain many catalytically active sites, which is highly promising for electrocatalytic applications.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02225 https://pubs.acs.org/doi/10.1021/acscatal.3c02225

Hydrogen sulfide (H2S) is a notorious and lethal gas widely generated in human economic activities and natural occurrences. The growing demand for pollution control makes it vital for the development of efficient processes to remove and convert H2S into high-valued products. As such, diversified technologies have been extensively explored, including H2S splitting, selective oxidation of H2S, and simultaneous conversion of H2S and CO2. In this review, the state-of-the-art processes for H2S conversion and utilization are reviewed. The potentials of various value-added products from H2S utilization, such as H2, syngas, COS, CH3SH, and other sulfur-containing fine chemicals are elucidated in detail. Notably, the traditional and emerging materials for H2S removal, mainly including metal oxide catalysts and carbon-based materials are also overviewed in this review. In addition, the catalytic mechanisms for these desulfurization reactions are also briefly discussed. Lastly, perspectives are given on the viability and technological gaps for each technology and corresponding catalysts.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02294 https://pubs.acs.org/doi/10.1021/acscatal.3c02294

The selective semihydrogenation of alkynes to alkenes is of great importance in the chemical industry. However, it remains a big challenge to achieve high catalytic activity and selectivity simultaneously, which calls for developing efficient and selective catalysts. In this work, we develop a spatially confined Ni catalyst with Ni nanoparticles (NPs) as the core and N-doped carbon layers as the shell. The core–shell structure not only effectively protects Ni NPs from aggregation to substantially boost the stability but also creates the steric and electronic effects for Ni NP surface via an intimate interfacial interaction with N-doped carbon layers. As a result, the resultant catalyst exhibited both high activity and selectivity for semihydrogenation of alkynes to alkenes. A broad set of terminal and internal alkynes were efficiently reduced to their respective alkenes in a highly selective manner, and various functional groups were well tolerated. Remarkably, these spatially confined Ni NPs are applicable for scale-up synthesis, demonstrate high stability, and could be readily separated for successive reuses without obvious decay in either activity or selectivity. Comprehensive characterizations and control experiments jointly demonstrate the key role of N-doped carbon layers around Ni NPs for improving the catalytic activity, selectivity, and stability.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02450 https://pubs.acs.org/doi/10.1021/acscatal.3c02450

Pyridoxal phosphate (PLP)-dependent enzymes afford access to a variety of non-canonical amino acids (ncAAs), which are premier building blocks for the construction of complex bioactive molecules. The vinylglycine ketimine (VGK) subfamily of PLP-dependent enzymes plays a critical role in sulfur metabolism and is home to a growing set of secondary metabolic enzymes that synthesize γ-substituted ncAAs. Identification of VGK enzymes for biocatalysis faces a distinct challenge because the subfamily contains both desirable synthases and lyases that break down ncAAs. Some enzymes have both activities, which may contribute to pervasive mis-annotation. To navigate this complex functional landscape, we used a substrate multiplexed screening approach to rapidly measure the substrate promiscuity of 40 homologs in the VGK subfamily. We found that enzymes involved in transsulfuration are less likely to have promiscuous activities and often possess undesirable lyase activity. Enzymes from direct sulfuration and secondary metabolism generally had a high degree of substrate promiscuity. From this cohort, we identified an exemplary γ-synthase from Caldicellulosiruptor hydrothermalis (CahyGS). This enzyme is thermostable and has high expression (∼400 mg protein per L culture), enabling preparative-scale synthesis of thioether containing ncAAs. When assayed with l-allylglycine, CahyGS catalyzes a stereoselective γ-addition reaction to afford access to a unique set of γ-methyl-branched ncAAs. We determined high-resolution crystal structures of this enzyme that define an open-close transition associated with ligand binding and set the stage for future engineering within this enzyme subfamily.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02498 https://pubs.acs.org/doi/10.1021/acscatal.3c02498

It is desirable to regulate charge migration synergistically via atomic level decoration because it can construct active sites with both thermodynamic and kinetic advantages in photocatalytic hydrogen (H2) evolution. Here, a mild cation exchange-mediated strategy was applied to anchor palladium (Pd) cations in the ZnIn2S4 nanostructure, achieving an outstanding H2 evolution rate of 1236.4 μmol h–1 (λ ≥ 420 nm) accompanied by an apparent quantum efficiency of 60.06% (λ = 420 nm). Pd dopants act as both active sites and surface chemical state modulators, which help to balance *H adsorption thermodynamically. More importantly, in situ electron spin resonance and in situ XPS analysis reveal that the synergistic electron interaction brought by the Pd–S structure constructs an efficient transfer channel, leading to more delocalized photocarriers to the active sites for H2 evolution reaction. A feasible strategy is proposed in this study to improve the performance of photocatalysts from the viewpoint of Pd cation exchange. Simultaneously, synergistic electron interaction is verified to modulate charge accumulation at Pd substitution sites, providing substantiation and unique insights into the electronic structure modification of photocatalysts.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02563 https://pubs.acs.org/doi/10.1021/acscatal.3c02563

The electrochemical reduction of CO2 (CO2ER) holds great promise as a method to achieve carbon neutrality and revolutionize the utilization of fossil fuels. Advanced catalysts used in CO2ER have demonstrated the ability to generate valuable multi-carbon products through the formation of carbon–carbon (C–C) bonds. Previous research has predominantly focused on C–C formation by dimerizing *CO or coupling *CO with other *C1 intermediates. However, the potential coupling of CO2 with *C1 intermediates has not been explored experimentally or theoretically despite CO2 being the exclusive reactant in CO2ER and having a high concentration. This study employed DFT calculations and a constant electrode potential model to investigate the possibility of CO2 + *C1 couplings on Cu(100) surfaces. Surprisingly, the results indicate that CO2 can serve as a favorable reagent for C–C bond formation, surpassing the reactivity of *CO under alkaline conditions. The enhanced reactivity of CO2 compared to that of *CO was elucidated based on a barrier decomposition analysis. Experimental validation was conducted to confirm these theoretical results.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02607 https://pubs.acs.org/doi/10.1021/acscatal.3c02607

Replacing the oxidation of water with the electrocatalytic oxidation of methanol is an attractive route to level the cost of H2 production with value-added chemicals; however, this reaction has been notoriously known for quickly poisoning electrocatalysts and/or sliding into complete oxidation, thereby producing CO2. Here, we report an acid-stable Ru metal atom array that is supported by MnO2 nanofibers (Ru-MAC/MnO2) for the electrocatalytic valorization of methanol to methyl formate (MF). The productivity of MF is 10 to 100 times higher than those reported in thermal- and photocatalytic processes at commercially viable current densities. Our experimental and simulation results demonstrate that the atom array possesses long-term electrochemical stability and prefers the MF pathway without generating *CO intermediates. The synergistic intersite metal–metal and metal–support electronic interactions endow Ru-MAC/MnO2 with outstanding structural stability toward large-current-density methanol electrolysis.

]]> Mon, 21 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02644 https://pubs.acs.org/doi/10.1021/acscatal.3c02644

Regulating the electronic properties or morphology feature of CO2 electroreduction catalysts can maintain selectivity toward certain reduction products. Here we report a nitrogen doped carbon (NxC) modification strategy that can switch CH4 and CH2CH2 product selectivity during CO2 electrolysis over the Cu catalyst. The fabricated core–shell Cu@NxC catalyst exhibited good performance in suppressing HER and promoting CO2RR. About 90% FEs was achieved over the Cu@NxC-350 °C (10:4) catalyst, of which the CH2CH2 FEs was 54% at −1.4 V vs RHE. However, the C1 product was the majority over the Cu@NxC-400 °C (10:4) catalyst, and 63% FEs of CH4 was achieved at the same applied potential. The in-depth characterization revealed that the remarkable selectivity switching of CH4 and CH2CH2 products originated from the NxC shell, rather than the change in the electronic feature of the Cu core. The more pyrrolic N contained in the Cu@NxC catalyst tended to form bridge-bonded *CO, leading to a dominant CH4 product, while the more pyridinic N contained in the Cu@NxC catalyst tended to form linearly bonded *CO, which was favorable for C–C coupling to form the CH2CH2 product. Our results provided insights into the role of the chemical environment on CO2 electroreduction processes.

]]> Sat, 19 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02451 https://pubs.acs.org/doi/10.1021/acscatal.3c02451

Defects that commonly exist on the surface of zeolites pose notable mass transport constraints and influence the catalytic performance. The mechanism underlying the surface defects inducing molecular transport limitations, however, is not fully understood. Herein, we use versatile spectroscopy, imaging techniques, and multiscale simulations to investigate the effect of surface defects on the molecular surface transport in zeolites, intending to establish the terminal structure–mass transport–performance relationship. Isolated silanol, which represents the foremost and eventual chemical defective accessible site at zeolite termination for guest molecules from the bulk fluid phase into zeolites or vice versa, is taken as a showcase. We demonstrate that isolated silanol at H-SAPO-34 zeolite termination not only enhances the adsorptive interaction between the polar molecules/alkenes and interface but also narrows the local 8-membered-ring pore at the external surface. The exterior surface with more isolated silanol could cause a higher diffusion barrier and hamper the accessibility of intracrystalline active sites. This work is expected to shed light on the mechanism underlying the zeolite catalyst upgrading via terminal surface modifications at zeolites.

]]> Fri, 18 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c01932 https://pubs.acs.org/doi/10.1021/acscatal.3c01932

We report the solution structure of an authentic sortase A thioester intermediate, including the bound substrate. The structure was determined by a combination of site-specific tagging, selective isotope labeling, and paramagnetic nuclear magnetic resonance spectroscopy. Pseudocontact shifts generated with different lanthanide tags delivered the conformation of the isotope-labeled bound substrate at atomic resolution, enabling the determination of the complete 3D structure of the short-lived and lowly populated enzymatic reaction intermediate in solution. The formation of the unstable thioester complex is accompanied by an increase in calcium binding affinity. Furthermore, the intermediate is significantly stabilized by calcium and decays quickly upon removal of calcium. Cooperativity between calcium binding and substrate recognition thus plays an important role in the function of sortase A.

]]> Fri, 18 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02214 https://pubs.acs.org/doi/10.1021/acscatal.3c02214

Water electrolysis using anion exchange membranes is promising for hydrogen production, and Ni–Mo catalysts have shown high activity for alkaline hydrogen evolution reaction (HER). However, their performance has been mostly tested in a half-cell setup and rarely studied in a single-cell setup with a membrane electrode assembly (MEA) structure, which is used for practical applications. With Ni3Mo as the cathode, a single cell was fabricated using non-noble metal catalysts exclusively. Interestingly, the activation procedure significantly affected the cell performance. The single cell performed better than that with the Pt/C catalyst when the Ni3Mo catalyst was mildly activated. The distribution of Mo in electrodes, membrane, and electrolytes was estimated, confirming Mo dissolution from the cathode. Once the cell was activated, the cell performance was stable without degradation in long-term chronopotentiometry operation, but the performance was degraded by sudden voltage change such as imposing open circuit voltage (OCV). The surface structure and reaction mechanism were studied with density functional theory: the Mo-dissolved Ni3Mo(101) surface could promote H2O dissociation, while MoO3 stably adsorbed on the surface weakened H* adsorption, promoting HER. This study provides important insights into the development of efficient catalysts for large-scale hydrogen production.

]]> Fri, 18 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02406 https://pubs.acs.org/doi/10.1021/acscatal.3c02406

Despite the frequent occurrence of sulfonamides in contemporary pharmaceuticals and agrochemicals, the synthesis of these compounds is limited by the availability of preexisting sulfur functionality, amine nucleophilicity, and functional group compatibility. Herein, we report the use of synergetic photoredox and copper catalysis to synthesize sulfonamides from a variety of aryl radical precursors, readily available amines, and a sulfur dioxide source in air at room temperature. The reactions proceeded smoothly with various electron-rich and electron-deficient amines to generate sulfonamides in a single-step process. Oxygen in air was deemed to be essential for both catalytic cycles, acting as a catalyst. Experimental studies, including electron paramagnetic resonance spectroscopy, provided insights into the possible mechanism.

]]> Fri, 18 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03096 https://pubs.acs.org/doi/10.1021/acscatal.3c03096

Ruthenium-based supported catalysts are of great potential for CO2 methanation, while the catalytic mechanisms remain elusive owing to the conjunction of the metal size and support effect, as well as the possible strong metal/support interactions (SMSI) in a practical catalyst. Herein, with the deposition of alumina over the Ru/SiC model nanocatalysts by the method of the atomic layer deposition (ALD) technique, the corrugated (1011) surface of Ru nanoparticles can be selectively insulated due to its preference for alumina deposition, and the intrinsic activity of CO2 conversion was confirmed to depend crucially on the residual planar (0001) surface. Characterizations including in situ infrared spectroscopy (IR) combined with density functional theory (DFT) calculation and the microkinetic modeling revealed that the competitive kinetics of H2 and CO2 activation on the Ru surface governs the activity and selectivity of methanation. The terrace sites of Ru nanocatalysts serve as the genuine active site through the HCOO* intermediate with the surface occupied by the H* species for further methanation. The (1011) surface suffers from a lower capability for hydrogenation due to its preference toward CO2 adsorption and results in the surface poisoning by the *C and *CH species, which thus makes it a negligible contribution toward methanation over Ru nanocatalysts. However, the presence of the alumina overlayer on the corrugated surface also improves the stability of the Ru nanocatalyst, to keep its activity even at a high temperature pretreatment. Our results demonstrate the terrace sites as the intrinsic active sites for CO2 methanation and also deepen insights on the catalytic mechanism of CO2 transformation over Ru-based nanocatalysts.

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http://localhost:1200/acs/journal/jacsat - Success ✔️

```rss https://pubs.acs.org/toc/jacsat/0/0 RSSHub i@diygod.me (DIYgod) zh-cn Sun, 27 Aug 2023 15:04:42 GMT 5

Site-specific protein decaging by light has become an effective approach for in situ manipulation of protein activities in a gain-of-function fashion. Although successful decaging of amino acid side chains of Lys, Tyr, Cys, and Glu has been demonstrated, this strategy has not been extended to aspartic acid (Asp), an essential amino acid residue with a range of protein functions and protein–protein interactions. We herein reported a genetically encoded photocaged Asp and applied it to the photocontrolled manipulation of a panel of proteins including firefly luciferase, kinases (e.g., BRAF), and GTPase (e.g., KRAS) as well as mimicking the in situ phosphorylation event on kinases. As a new member of the increasingly expanded amino acid-decaging toolbox, photocaged Asp may find broad applications for gain-of-function study of diverse proteins as well as biological processes in living cells.

]]> Sat, 26 Aug 2023 00:00:00 GMT 10.1021/jacs.3c03701 https://pubs.acs.org/doi/10.1021/jacs.3c03701

We report the first one-pot formal alkene carboradiofluorination reaction employing easily accessible alkenes as both prosthetic group precursors and coupling partners. The methodology features rapid sequential Markovnikov-selective iodofluorination and photoinduced Pd(0/I/II)-catalyzed alkyl Heck reaction as a mild and robust fluorine-18 (18F) radiochemical approach for positron emission tomography (PET) imaging probe development. A new class of prosthetic groups for PET imaging probe synthesis was isolated as iodofluorinated intermediates in moderate to excellent yields. The one-pot formal alkenylfluorination reaction was carried out to produce over 30 analogues of a wide range of bioactive molecules. Further application of the Pd(0/I/II) manifold in PET probe development was illustrated by the direct carbo(radio)fluorination of electron-rich alkenes. The methods were successfully translated to radiolabel a broad scope of medicinally relevant small molecules in generally good radiochemical conversion. The protocol was further optimized to accommodate no-carrier-added conditions with similar efficiency for future (pre)clinical translation. Moreover, the radiosynthesis of prosthetic groups was automated in a radiochemistry module to facilitate its practical use in multistep radiochemical reactions.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04548 https://pubs.acs.org/doi/10.1021/jacs.3c04548

Coupled photocatalysis without cocatalysts can maximize the utilization of photons and atoms, which puts forward higher demands on photocatalysts. Polymeric carbon nitride (CN) has become the most promising photocatalyst, but still suffers from major drawbacks of insufficient catalytic sites and low quantum efficiency. Herein, we report a fluid shear stress-assisted molecular assembly to prepare ultrathin-nanosheet-assembled acanthosphere-like CN (ASCN) with nitrogen vacancy (Nv) and carbonyl modification. Shear stress breaks the stacking interactions between layers and cuts the stacked structure into ultrathin layers, which are further reassembled into acanthosphere bundles driven by “centrifugal force”. Benefitted greatly from the ultrathin nature that provides more exposed active sites and improves charge carrier separation, ASCN-3 exhibits a 20-fold higher activity than the bulk counterpart toward oxygen reduction to H2O2 coupled with 4-methoxybenzyl alcohol (4-MBA) oxidation to anisaldehyde (AA), with significantly increased turnover frequency (TOF) values (TOF: 1.69 h–1 for H2O2 and 1.02 h–1 for AA). Significantly, ASCN-3 exhibits 95.8% conversion for 4-MBA oxidation with nearly 100% selectivity. High apparent quantum yields of 11.7% and 9.3% at 420 nm are achieved for H2O2 photosynthesis and 4-MBA oxidation. Mechanism studies suggest that carbonyl induces holes concentrated at the neighboring melem unit to directly oxidize the Cα–H bond of 4-MBA to produce carbon radicals, and Nv as oxygen adsorption active site traps electrons to form a superoxide radical that further combines with the shed protons into H2O2. This work presents a simple physical method to break the layered stack of CN for creating hierarchical assembly for coupled photocatalysis.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05234 https://pubs.acs.org/doi/10.1021/jacs.3c05234

In order to use holes as catalysts, the oxidized product should be able to transfer the hole to a fresh reactant. For that, the hole-catalyzed reaction must increase the oxidation potential along the reaction path, i.e., lead to “hole upconversion.” If this thermodynamic requirement is satisfied, a hole injected via one-electron oxidation can persist through multiple propagation cycles and serve as a true catalyst. This work provides guidelines for the rational design of hole-catalyzed Diels–Alder (DA) reactions, the prototypical cycloaddition. After revealing the crucial role of hyperconjugation in the absence of hole upconversion in the parent DA reaction, we show how upconversion can be reactivated by proper substitution. For this purpose, we computationally evaluate the contrasting effects of substituents at the three possible positions in the two reactants. The occurrence and magnitude of hole upconversion depend strongly on the placement and nature of substituents. For example, donors at C1 in 1,3-butadiene shift the reaction to the hole-upconverted regime with an increased oxidation potential of up to 1.0 V. In contrast, hole upconversion in C2-substituted 1,3-butadienes is activated by acceptors with the oxidation potential increase up to 0.54 V. Dienophile substitution results in complex trends because the radical cation can be formed at either the dienophile or the diene. Hole upconversion is always present in the former scenario (up to 0.65 V). Finally, we report interesting stereoelectronic effects that can activate or deactivate upconversion via a conformational change.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06106 https://pubs.acs.org/doi/10.1021/jacs.3c06106

The chemical industry and the chemical processes underscoring it are under intense scrutiny as the demands for the transition to more sustainable and environmentally friendly practices are increasing. Traditional industrial separation systems, such as thermally driven distillation for hydrocarbon purification, are energy intensive. The development of more energy efficient separation technologies is thus emerging as a critical need, as is the creation of new materials that may permit a transition away from classic distillation-based separations. In this Perspective, we focus on porous organic cages and macrocycles that can adsorb guest molecules selectively through various host–guest interactions and permit molecular sieving behavior at the molecular level. Specifically, we summarize the recent advances where receptor-based adsorbent materials have been shown to be effective for industrially relevant hydrocarbon separations, highlighting the underlying host–guest interactions that impart selectivity and permit the observed separations. This approach to sustainable separations is currently in its infancy. Nevertheless, several receptor-based adsorbent materials with extrinsic/intrinsic voids or special functional groups have been reported in recent years that can selectively capture various targeted guest molecules. We believe that the understanding of the interactions that drive selectivity at a molecular level accruing from these initial systems will permit an ever-more-effective “bottom-up” design of tailored molecular sieves that, in due course, will allow adsorbent material-based approaches to separations to transition from the laboratory into an industrial setting.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06175 https://pubs.acs.org/doi/10.1021/jacs.3c06175

Multiple proton transfer (PT) controllable by external stimuli plays a crucial role in fundamental chemistry, biological activity, and material science. However, in crystalline systems, controlling multiple PT, which results in a distinct protonation state, remains challenging. In this study, we developed a novel tridentate ligand and iron(II) complex with a short hydrogen bond (HB) that exhibits a PT-coupled spin transition (PCST). Single-crystal X-ray and neutron diffraction measurements revealed that the positions of the two protons in the complex can be controlled by temperature and photoirradiation based on the thermal- and photoinduced PCST. The obtained results suggest that designing molecules that form short HBs is a promising approach for developing multiple PT systems in crystals.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06323 https://pubs.acs.org/doi/10.1021/jacs.3c06323

Verruculogens are rare fumitremorgin alkaloids that contain a highly unusual eight-membered endoperoxide. In this paper, we report a concise chemoenzymatic synthesis of 13-oxoverruculogen using enzymatic C–H peroxidation and rhodium-catalyzed C–C bond activation reactions to install the eight-membered endoperoxide and the pentacyclic core of the natural product, respectively. Our strategy involves the use of 13-epi-fumitremorgin B as a substrate analog for endoperoxidation by verruculogen synthase, FtmOx1. The resulting product, 13-epi-verruculogen, is the first unnatural endoperoxide generated by FtmOx1 and is used in the first synthesis of 13-oxoverruculogen. This strategy enables a 10-step synthesis of this natural product from commercially available starting materials and illustrates a hybrid approach utilizing biocatalytic and transition-metal-catalyzed reactions to access challenging alkaloid architectures. Moreover, this work demonstrates the use of native enzyme promiscuity as a viable strategy for the chemoenzymatic synthesis of natural products.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c07078 https://pubs.acs.org/doi/10.1021/jacs.3c07078

Alkene ozonolysis generates short-lived Criegee intermediates that are a significant source of hydroxyl (OH) radicals. This study demonstrates that roaming of the separating OH radicals can yield alternate hydroxycarbonyl products, thereby reducing the OH yield. Specifically, hydroxybutanone has been detected as a stable product arising from roaming in the unimolecular decay of the methyl-ethyl-substituted Criegee intermediate (MECI) under thermal flow cell conditions. The dynamical features of this novel multistage dissociation plus a roaming unimolecular decay process have also been examined with ab initio kinetics calculations. Experimentally, hydroxybutanone isomers are distinguished from the isomeric MECI by their higher ionization threshold and distinctive photoionization spectra. Moreover, the exponential rise of the hydroxybutanone kinetic time profile matches that for the unimolecular decay of MECI. A weaker methyl vinyl ketone (MVK) photoionization signal is also attributed to OH roaming. Complementary multireference electronic structure calculations have been utilized to map the unimolecular decay pathways for MECI, starting with 1,4 H atom transfer from a methyl or methylene group to the terminal oxygen, followed by roaming of the separating OH and butanonyl radicals in the long-range region of the potential. Roaming via reorientation and the addition of OH to the vinyl group of butanonyl is shown to yield hydroxybutanone, and subsequent C–O elongation and H-transfer can lead to MVK. A comprehensive theoretical kinetic analysis has been conducted to evaluate rate constants and branching yields (ca. 10–11%) for thermal unimolecular decay of MECI to conventional and roaming products under laboratory and atmospheric conditions, consistent with the estimated experimental yield (ca. 7%).

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c07126 https://pubs.acs.org/doi/10.1021/jacs.3c07126

Benzoic acid dissolved in water is electrosprayed (−4 kV) by using nitrogen gas at a pressure of 120 psi to form ∼10 μm diameter microdroplets. Analysis with mass spectrometry (MS) and tandem mass spectrometry (MS2) of the resulting microdroplets shows the direct formation of phenol via decarboxylation without any catalyst or added reagents. This process represents an ecofriendly, environmentally benign method for producing phenol and related aromatic alcohols from their corresponding aromatic acids. The mechanism of this transformation was unambiguously characterized using mass spectrometry, radical trapping, and 18O labeling.

]]> Fri, 25 Aug 2023 00:00:00 GMT 10.1021/jacs.3c08638 https://pubs.acs.org/doi/10.1021/jacs.3c08638

Nanoscale heterostructures of covalent intermetallics should give birth to a wide range of interface-driven physical and chemical properties. Such a level of design however remains unattainable for most of these compounds, due to the difficulty to reach a crystalline order of covalent bonds at the moderate temperatures required for colloidal chemistry. Herein, we design heterostructured cobalt silicide nanoparticles to trigger magnetic and catalytic properties in silicon-based materials. Our strategy consists in controlling the diffusion of cobalt atoms into silicon nanoparticles, by reacting these particles in molten salts. By adjusting the temperature, we tune the conversion of the initial silicon particles toward homogeneous CoSi nanoparticles and core–shell nanoparticles made of a CoSi shell and a silicon-rich core. The increased interface-to-volume ratio of the CoSi component in the core–shell particles yields distinct properties compared to the bulk and homogeneous nanoparticles. First, the core–shell particles exhibit increased ferromagnetism, despite the bulk diamagnetic properties of cobalt monosilicide. Second, the core–shell nanoparticles act as efficient precatalysts for alkaline water oxidation, where the nanostructure is converted in situ into a layered cobalt silicon oxide/(oxy)hydroxide with high and stable oxygen evolution reaction (OER) electrocatalytic activity. This work demonstrates a route to design heterostructured nanocrystals of covalent intermetallic compounds and shows that these new structures exhibit very rich, yet poorly explored, interface-based physical properties and reactivity.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c01110 https://pubs.acs.org/doi/10.1021/jacs.3c01110

Lipid nanoreactors are biomimetic reaction vessels (nanoreactors) that can host aqueous or membrane-associated chemical and enzymatic reactions. Nanoreactors provide ultra-miniaturization from atto- to zeptoliter volumes per reaction vessel with the major challenge of encoding and spatio-temporal control over reactions at the individual nanoreactor or population level, thereby controlling volumes several orders of magnitude below advanced microfluidic devices. We present DNA-programmed lipid nanoreactors (PLNs) functionalized with lipidated oligonucleotides (LiNAs) that allow programming and encoding of nanoreactor interactions by controlled membrane fusion, exemplified for a set of carbohydrate mimetics with mono- to hexasaccharide azide building blocks connected by click-chemistry. Programmed reactions are initiated by fusion of distinct populations of nanoreactors with individually encapsulated building blocks. A focused library of triazole-linked carbohydrate-Cy5 conjugates formed by strain-promoted azide-alkyne cycloadditions demonstrated LiNA-programmed chemistry, including two-step reaction schemes. The PLN method is developed toward a robust platform for synthesis in confined space employing fully programmable nanoreactors, applicable to multistep synthesis for the generation of combinatorial libraries with subsequent analysis of the molecules formed, based on the addressability of the lipid nanoreactors.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04093 https://pubs.acs.org/doi/10.1021/jacs.3c04093

Metal–organic frameworks (MOFs) featuring redox activity are highly appealing for electrocatalytic or charge accumulation applications. An important aspect in this field is the ability to address as many redox centers as possible in the material by an efficient diffusion of charges. Herein, we investigate for the first time the charge diffusion processes occurring upon two sequential one-electron reductions in an MOF thin film. Two pyrazolate-zinc(II)-based MOFs including highly electro-deficient perylene diimide (PDI) ligands were grown on conducting substrates, affording thin films with double n-type electrochromic properties as characterized by spectroelectrochemical analysis. In depth electrochemical and chronoabsorptiometric investigations were carried out to probe the charge diffusion in the MOF layers and highlighted significant differences in terms of diffusion kinetics and material stability between the first and second successive reduction of the redox-active PDI linkers. Our results show that MOFs based on multiredox centers are more sensitive to encumbrance-related issues than their monoredox analogues in the context of electrochemical applications, an observation that further underlines the fundamental aspect of careful pore dimensions toward efficient and fast ion diffusion.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04114 https://pubs.acs.org/doi/10.1021/jacs.3c04114

Herein, we present a new series of CuI-based hybrid materials with tunable structures and semiconducting properties. The CuI inorganic modules can be tailored into a one-dimensional (1D) chain and two-dimensional (2D) layer and confined/stabilized in coordination frameworks of potassium isonicotinic acid (HINA) and its derivatives (HINA-R, R = OH, NO2, and COOH). The resulting CuI-based hybrid materials exhibit interesting semiconducting behaviors associated with the dimensionality of the inorganic module; for instance, the structures containing the 2D-CuI module demonstrate significantly enhanced photoconductivity with a maximum increase of five orders of magnitude compared to that of the structures containing the 1D-CuI module. They also represent the first CuI-bearing hybrid chemiresistive gas sensors for NO2 with boosted sensing performance and sensitivity at multiple orders of magnitude over that of the pristine CuI. Particularly, the sensing ability of CuI-K-INA containing both 1D- and 2D-CuI modules is comparable to those of the best NO2 chemiresistors reported thus far.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05095 https://pubs.acs.org/doi/10.1021/jacs.3c05095

Symmetry-breaking charge separation in molecular materials has attracted increasing attention for optoelectronics based on single-material active layers. To this end, Fe(III) complexes with particularly electron-donating N-heterocyclic carbene ligands offer interesting properties with a 2LMCT excited state capable of oxidizing or reducing the complex in its ground state. In this Communication, we show that the corresponding symmetry-breaking charge separation occurs in amorphous films of pristine [Fe(III)L2]PF6 (L = [phenyl(tris(3-methylimidazol-2-ylidene))borate]−). Excitation of the solid material with visible light leads to ultrafast electron transfer quenching of the 2LMCT excited state, generating Fe(II) and Fe(IV) products with high efficiency. Sub-picosecond charge separation followed by recombination in about 1 ns could be monitored by transient absorption spectroscopy. Photoconductivity measurements of films deposited on microelectrode arrays demonstrated that photogenerated charge carriers can be collected at external contacts.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05404 https://pubs.acs.org/doi/10.1021/jacs.3c05404

We present the first enantioselective nickel-catalyzed borylative coupling of 1,3-dienes with aldehydes, providing an efficient route to highly valuable homoallylic alcohols in a single step. The reaction involves the 1,4-carboboration of dienes, leading to the formation of C–C and C–B bonds accompanied by the construction of two continuous stereogenic centers. Enabled by a chiral spiro phosphine-oxazoline nickel complex, this transformation yields products with exceptional diastereoselectivity, E-selectivity, and enantioselectivity. The diastereoselectivity of the reaction can be controlled by employing either (Z)-1,3-dienes or (E)-1,3-dienes.

]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c07697 https://pubs.acs.org/doi/10.1021/jacs.3c07697 null]]> Thu, 24 Aug 2023 00:00:00 GMT 10.1021/jacs.3c09176 https://pubs.acs.org/doi/10.1021/jacs.3c09176

A ZnII8L6 pseudocube containing anthracene-centered ligands, a ZnII4L′4 tetrahedron with a similar side length as the cube, and a trigonal prism ZnII6L3L′2 were formed in equilibrium from a common set of subcomponents. Hetero-Diels–Alder reaction with photogenerated singlet oxygen transformed the anthracene-containing “L” ligands into endoperoxide “LO” ones and ultimately drove the integrative self-sorting to form the trigonal prismatic cage ZnII6LO3L′2 exclusively. This ZnII6LO3L′2 structure lost dioxygen in a retro-Diels–Alder reaction after heating, which resulted in reversion to the initial ZnII8L6 + ZnII4L′4 ⇌ 2 × ZnII6L3L′2 equilibrating system. Whereas the ZnII8L6 pseudocube had a cavity too small for guest encapsulation, the ZnII6L3L′2 and ZnII6LO3L′2 trigonal prisms possessed peanut-shaped internal cavities with two isolated compartments divided by bulky anthracene panels. Guest binding was also observed to drive the equilibrating system toward exclusive formation of the ZnII6L3L′2 structure, even in the absence of reaction with singlet oxygen.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04228 https://pubs.acs.org/doi/10.1021/jacs.3c04228

Photolytic delivery of nitric oxide and nitroxide has substantial biomedical and phototherapeutic applications. Here, we utilized hard X-ray spectroscopic methods to identify key geometric and electronic structural features of two photolabile {FeNO}6 complexes where the compounds differ in the presence of a pendant thiol in [Fe(NO)(TMSPS2)(TMSPS2H)] and thioether in [Fe(NO)(TMSPS2)(TMSPS2CH3)] with the former complex being the only transition metal system to photolytically generate HNO. Fe Kβ XES identifies the photoreactant systems as essentially Fe(II)–NO+, while valence-to-core XES extracts a NO oxidation state of +0.5. Finally, the pre-edge of the Fe high-energy-resolution fluorescence detected (HERFD) XAS spectra is shown to be acutely sensitive to perturbation of the Fe–NO covalency enhanced by the 3d–4p orbital mixing dipole intensity contribution. Collectively, this X-ray spectroscopic approach enables future time-resolved insights in these systems and extensions to other challenging redox noninnocent {FeNO}x systems.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04479 https://pubs.acs.org/doi/10.1021/jacs.3c04479

The cytochrome P450 (CYP) AspB is involved in the biosynthesis of the diketopiperazine (DKP) aspergilazine A. Tryptophan-linked dimeric DKP alkaloids are a large family of natural products that are found in numerous species and exhibit broad and often potent bioactivity. The proposed mechanisms for C-N bond formation by AspB, and similar C-C bond formations by related CYPs, have invoked the use of a ferryl-intermediate as an oxidant to promote substrate dimerization. Here, the parallel application of steady-state and transient kinetic approaches reveals a very different mechanism that involves a ferric-superoxide species as a primary oxidant to initiate DKP-assembly. Single turnover kinetic isotope effects and a substrate analog suggest the probable nature and site for abstraction. The direct observation of CYP-superoxide reactivity rationalizes the atypical outcome of AspB and reveals a new reaction manifold in heme enzymes.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c04542 https://pubs.acs.org/doi/10.1021/jacs.3c04542

Metal-free magnetism remains an enigmatic field, offering prospects for unconventional magnetic and electronic devices. In the pursuit of such magnetism, triangulenes, endowed with inherent spin polarization, are promising candidates to serve as monomers to construct extended structures. However, controlling and enhancing the magnetic interactions between the monomers persist as a significant challenge in molecular spintronics, as so far only weak antiferromagnetic coupling through the linkage has been realized, hindering their room temperature utilization. Herein, we investigate 24 triangulene dimers using first-principles calculations and demonstrate their tunable magnetic coupling (J), achieving unprecedented strong J values of up to −144 meV in a non-Kekulé dimer. We further establish a positive correlation between bandgap, electronic coupling, and antiferromagnetic interaction, thereby providing molecular-level insights into enhancing magnetic interactions. By twisting the molecular fragments, we demonstrate an effective and feasible approach to control both the sign and strength of J by tuning the balance between potential and kinetic exchanges. We discover that J can be substantially boosted at planar configurations up to −198 meV. We realize ferromagnetic coupling in nitrogen-doped triangulene dimers at both planar and largely twisted configurations, representing the first example of ferromagnetic triangulene dimers that cannot be predicted by the Ovchinnikov rule. This work thus provides a practical strategy for augmenting magnetic coupling and open up new avenues for metal-free ferromagnetism.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05178 https://pubs.acs.org/doi/10.1021/jacs.3c05178

The establishment of active sites as the frustrated Lewis pair (FLP) has recently attracted much attention ranging from homogeneous to heterogeneous systems in the field of catalysis. Their unquenched reactivity of Lewis acid and base pairs in close proximity that are unable to form stable adducts has been shown to activate small molecules such as dihydrogen heterolytically. Herein, we show that grafted Ru metal–organic framework-based catalysts prepared via N-containing linkers are rather catalytically inactive for H2 activation despite the application of elevated temperatures. However, upon light illumination, charge polarization of the anchored Ru bipyridine complex can form a transient Lewis acid–base pair, Ru+–N– via metal-to-ligand charge transfer, as confirmed by time-dependent density functional theory (TDDFT) calculations to carry out effective H2–D2 exchange. FTIR and 2-D NMR endorse the formation of such reactive intermediate(s) upon light irradiation.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05244 https://pubs.acs.org/doi/10.1021/jacs.3c05244

The pH dependence of proton-coupled electron transfer (PCET) reactions, which are critical to many chemical and biological processes, is a powerful probe for elucidating their fundamental mechanisms. Herein, a general, multichannel kinetic model is introduced to describe the pH dependence of both homogeneous and electrochemical PCET reactions. According to this model, a weak pH dependence can arise from the competition among multiple sequential and concerted PCET channels involving different forms of the redox species, such as protonated and deprotonated forms, as well as different proton donors and acceptors. The contribution of each channel is influenced by the relative populations of the reactant species, which often depend strongly on pH, leading to complex pH dependence of PCET apparent rate constants. This model is used to explain the origins of the experimentally observed weak pH dependence of the electrochemical PCET apparent rate constant for a ruthenium-based water oxidation catalyst attached to a tin-doped In2O3 (ITO) surface. The weak pH dependence is found to arise from the intrinsic differences in the rate constants of participating channels and the dependence of their relative contributions on pH. This model predicts that the apparent maximum rate constant will become pH-independent at higher pH, which is confirmed by experimental measurements. Our analysis also suggests that the dominant channels are electron transfer at lower pH and sequential PCET via electron transfer followed by fast proton transfer at higher pH. This work highlights the importance of considering multiple competing channels simultaneously for PCET processes.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05535 https://pubs.acs.org/doi/10.1021/jacs.3c05535

Substitutional heteroatom doping of bottom-up engineered 1D graphene nanoribbons (GNRs) is a versatile tool for realizing low-dimensional functional materials for nanoelectronics and sensing. Previous efforts have largely relied on replacing C–H groups lining the edges of GNRs with trigonal planar N atoms. This type of atomically precise doping, however, only results in a modest realignment of the valence band (VB) and conduction band (CB) energies. Here, we report the design, bottom-up synthesis, and spectroscopic characterization of nitrogen core-doped 5-atom-wide armchair GNRs (N2-5-AGNRs) that yield much greater energy-level shifting of the GNR electronic structure. Here, the substitution of C atoms with N atoms along the backbone of the GNR introduces a single surplus π-electron per dopant that populates the electronic states associated with previously unoccupied bands. First-principles DFT-LDA calculations confirm that a sizable shift in Fermi energy (∼1.0 eV) is accompanied by a broad reconfiguration of the band structure, including the opening of a new band gap and the transition from a direct to an indirect semiconducting band gap. Scanning tunneling spectroscopy (STS) lift-off charge transport experiments corroborate the theoretical results and reveal the relationship among substitutional heteroatom doping, Fermi-level shifting, electronic band structure, and topological engineering for this new N-doped GNR.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05755 https://pubs.acs.org/doi/10.1021/jacs.3c05755

Charge transfer complexes (CTCs) based on self-assembled donor and acceptor molecules allow light absorption of significantly redshifted wavelengths to either the donor or acceptor. In this work, we demonstrate a CTC embedded in a hydrogen-bonded liquid crystal elastomer (LCE), which in itself is fully reformable and reprocessable. The LCE host acts as a gate, directing the self-assembly of the CTC. When hydrogen bonding is present, the CTC behaves as a near-infrared (NIR) dye allowing photothermal actuation of the LCE. The CTC can be disassembled in specific regions of the LCE film by disrupting the hydrogen bond interactions, allowing selective NIR heating and localized actuation of the films. The metastable non-CTC state may persist for weeks or can be recovered on demand by heat treatment. Besides the CTC variability, the capability of completely reforming the shape, color, and actuation mode of the LCE provides an interactive material with unprecedented application versatility.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c05905 https://pubs.acs.org/doi/10.1021/jacs.3c05905

Nickel’s +1 oxidation state has received much interest due to its varied and often enigmatic behavior in increasingly popular catalytic methods. In part, the lack of understanding about NiI results from common synthetic strategies limiting the breadth of complexes that are accessible for mechanistic study and catalyst design. We report an oxidative approach using tribromide salts that allows for the generation of a well-defined precursor, [NiI(COD)Br]2, as well as several new NiI complexes. Included among them are complexes bearing bulky monophosphines, for which structure–speciation relationships are established and catalytic reactivity in a Suzuki–Miyaura coupling (SMC) is investigated. Notably, these routes also allow for the synthesis of well-defined monomeric t-Bubpy-bound NiI complexes, which has not previously been achieved. These complexes, which react with aryl halides, can enable previously challenging mechanistic investigations and present new opportunities for catalysis and synthesis.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06233 https://pubs.acs.org/doi/10.1021/jacs.3c06233

Advances in single-atom (-site) catalysts (SACs) provide a new solution of atomic economy and accuracy for designing efficient electrocatalysts. In addition to a precise local coordination environment, controllable spatial active structure and tolerance under harsh operating conditions remain great challenges in the development of SACs. Here, we show a series of molecule-spaced SACs (msSACs) using different acid anhydrides to regulate the spatial density of discrete metal phthalocyanines with single Co sites, which significantly improve the effective active-site numbers and mass transfer, enabling one of the msSACs connected by pyromellitic dianhydride to exhibit an outstanding mass activity of (1.63 ± 0.01) × 105 A·g–1 and TOFbulk of 27.66 ± 1.59 s–1 at 1.58 V (vs RHE) and long-term durability at an ultrahigh current density of 2.0 A·cm–2 under industrial conditions for oxygen evolution reaction. This study demonstrates that the accessible spatial density of single atom sites can be another important parameter to enhance the overall performance of catalysts.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06665 https://pubs.acs.org/doi/10.1021/jacs.3c06665

Novel axially chiral biphenyl diphosphine ligands Enm-BridgePhos, bearing an ether chain bridge at the 5,5′-position of the biphenyl backbone, have been developed and successfully applied in the Rh-catalyzed enantioselective desymmetric hydrogenation of α-acetamido-1,3-indanediones, providing chiral α-acetamido-β-hydroxybenzocyclic pentones in high yields (up to 97%) and with excellent enantioselectivities (up to 99% ee). The reaction could be carried out on a gram scale, and the corresponding products were used as vital intermediates for the synthesis of analogues of chiral spirobenzylisoquinoline alkaloids. Both the crystal structure analysis and the DFT calculations revealed that the large dihedral angle of the Enm-BridgePhos-Rh complexes is highly related to the excellent enantioselectivities.

]]> Wed, 23 Aug 2023 00:00:00 GMT 10.1021/jacs.3c07509 https://pubs.acs.org/doi/10.1021/jacs.3c07509

Proton-exchange membrane fuel cells enable the portable utilization of hydrogen (H2) as an energy resource. Current electrolytic materials have limitation, and there is an urgent need to develop new materials showing especially high proton conductivity. Here, we report the ultra-fast proton conduction in a novel metal–organic framework, MFM-808, which adopts an unprecedented topology and a unique structure consisting of two-dimensional layers of {Zr6}-clusters. By replacing the bridging formate with sulfate ligands within {Zr6}-layers, the modified MFM-808-SO4 exhibits an exceptional proton conductivity of 0.21 S·cm–1 at 85 °C and 99% relative humidity. Modeling by molecular dynamics confirms that proton transfer is promoted by an efficient two-dimensional conducting network assembled by sulfate–{Zr6}-layers. MFM-808-SO4 also possesses excellent photocatalytic activity for water splitting to produce H2, paving a new pathway to achieve a renewable hydrogen-energy cycle.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/jacs.3c03943 https://pubs.acs.org/doi/10.1021/jacs.3c03943

We demonstrate that ATP synthase-reconstituted proteoliposome coatings on the surface of microcapsules can realize photozyme-catalyzed oxidative phosphorylation. The microcapsules were assembled through layer-by-layer deposition of semiconducting graphitic carbon nitride (g-C3N4) nanosheets and polyelectrolytes. It is found that electrons from polyelectrolytes are transferred to g-C3N4 nanosheets, which enhances the separation of photogenerated electron–hole pairs. Thus, the encapsulated g-C3N4 nanosheets as the photozyme accelerate oxidation of glucose into gluconic acid to yield protons under light illumination. The outward transmembrane proton gradient is established to drive ATP synthase to synthesize adenosine triphosphate. With such an assembled system, light-driven oxidative phosphorylation is achieved. This indicates that an assembled photozyme can be used for oxidative phosphorylation, which creates an unusual way for chemical-to-biological energy conversion. Compared to conventional oxidative phosphorylation systems, such an artificial design enables higher energy conversion efficiency.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06090 https://pubs.acs.org/doi/10.1021/jacs.3c06090

Advances in controlled radical polymerizations by cobalt complexes have primarily taken advantage of the reactivity of cobalt as a persistent radical to reversibly deactivate propagating chains by forming a carbon–cobalt bond. However, cobalt-mediated radical polymerizations require stoichiometric ratios of a cobalt complex, deterring its utility in synthesizing well-defined polymers. Here, we developed a strategy to use cobalt as a catalyst to control radical polymerizations via halogen atom transfer with alkyl halide initiators. Using a modified, hydrophobic analogue of vitamin B12 (heptamethyl ester cobyrinate) as a cobalt precatalyst, we controlled the polymerization of acrylate monomers. The polymerization efficiency of the cobalt catalyst was significantly improved by additional bromide anions, which enhanced the deactivation of propagating radicals yielding polymers with dispersity values <1.2 using catalyst concentrations as low as 5 mol %. We anticipate that the development of cobalt catalysis in atom transfer radical polymerization will enable new opportunities in designing catalytic systems for the controlled synthesis of polymers.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06783 https://pubs.acs.org/doi/10.1021/jacs.3c06783

In this study, single Ni2 clusters (two Ni atoms bridged by a lattice oxygen) are successfully synthesized on monolayered CuO. They exhibit a remarkable activity toward low-temperature CO2 thermal dissociation, in contrast to cationic Ni atoms that nondissociatively adsorb CO2 and metallic Ni ones that are chemically inert for CO2 adsorption. Density functional theory calculations reveal that the Ni2 clusters can significantly alter the spatial symmetry of their unoccupied frontier orbitals to match the occupied counterpart of the CO2 molecule and enable its low-temperature dissociation. This study may help advance single-cluster catalysis and exploit the unexcavated mechanism for low-temperature CO2 activation.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06845 https://pubs.acs.org/doi/10.1021/jacs.3c06845

Designing Pb-free relaxors with both a high capacitive energy density (Wrec) and high storage efficiency (η) remains a remarkable challenge for cutting-edge pulsed power technologies. Local compositional heterogeneity is crucial for achieving complex polar structure in solid solution relaxors, but its role in optimizing energy storage properties is often overlooked. Here, we report that an exceptionally high Wrec of 15.2 J cm–3 along with an ultrahigh η of 91% can be achieved through designing local chemical clustering in Bi0.5Na0.5TiO3–BaTiO3-based relaxors. A three-dimensional atomistic model derived from neutron/X-ray total scattering combined with reverse Monte Carlo method reveals the presence of subnanometer scale clustering of Bi, Na, and Ba, which host differentiated polar displacements, and confirming the prediction by density functional theory calculations. This leads to a polar state with small polar clusters and strong length and direction fluctuations in unit-cell polar vectors, thus manifesting improved high-field polarizability, steadily reduced hysteresis, and high breakdown strength macroscopically. The favorable polar structure features also result in a unique field-increased η, excellent stability, and superior discharge capacity. Our work demonstrates that the hidden local chemical order exerts a significant impact on the polarization characteristic of relaxors, and can be exploited for accessing superior energy storage performance.

]]> Tue, 22 Aug 2023 00:00:00 GMT 10.1021/jacs.3c06912 https://pubs.acs.org/doi/10.1021/jacs.3c06912

Efficient C–C bond cleavage and oxidation of alcohols to CO2 is the key to developing highly efficient alcohol fuel cells for renewable energy applications. In this work, we report the synthesis of core/shell Au/Pt nanowires (NWs) with stepped Pt clusters deposited along the ultrathin (2.3 nm) stepped Au NWs as an active catalyst to effectively oxidize alcohols to CO2. Th ```

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```rss https://pubs.acs.org/toc/accacs/0/0 RSSHub i@diygod.me (DIYgod) zh-cn Thu, 07 Sep 2023 14:25:11 GMT 5

Selective hydrodehalogenation and hydrodearomatization of toxic chlorophenols into value-added chemicals represents a grand challenge for their efficient reutilization. For this purpose, single-atom catalysts (SACs) could be a strategy with relatively high catalytic selectivity and atom utilization but suffer from the catalytic limitation caused by low metal loading densities. Graphdiyne and γ-graphyne are considered promising substrates of SACs with excellent catalytic properties. Additionally, their quantum dots with nanometer size are expected to supply numerous surface anchoring sites and large atom spacing to confine metal cations to synthesize high-loading SACs. Here we report a synthesis approach for high-loading Ru SACs anchored on graphdiyne/γ-graphyne quantum dots (GDQD-Ru/GNQD-Ru), which exhibit remarkably higher turnover frequency (TOF) and selectivity (>99%) of hydrodehalogenation and hydrodearomatization of chlorophenols than graphdiyne/γ-graphyne nanosheet-based Ru SACs and nanoparticles. There is no significant selectivity decrease in chlorophenol transformation by GDQD-Ru/GNQD-Ru observed in 5 catalyst reuse cycles. GDQD-Ru/GNQD-Ru contribute to nearly exclusive hydrodehalogenation and hydrodearomatization without altering any other bonds in chlorophenols. Experimental results and theoretical calculations reveal that GDQD-Ru is more prone to lower energies of rate-limiting steps in H2-driven chlorophenol transformation than GNQD-Ru. The results confirm that graphdiyne/γ-graphyne quantum dots play crucial roles in facilitating the metal atom loading of SACs. Ru loadings are 27.6 and 16.0 wt % in GDQD-Ru/GNQD-Ru, approximately 7-fold and 4-fold higher than reported Ru SACs, respectively. This study provides mechanistic insights toward the roles of high-loading Ru SACs on sp- and sp2-hybridized carbonaceous substrates in selective hydrodehalogenation and hydrodearomatization.

]]> Thu, 07 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c01390 https://pubs.acs.org/doi/10.1021/acscatal.3c01390

Determining precise locations of hydrogen atoms in enzyme active sites, especially those in the reaction intermediates, provides important information for understanding the structure–function relationships, such as a correlation between pH-dependency and protonation/deprotonation states of dissociable groups. To experimentally determine the coordinates of hydrogen atoms, we solved the neutron crystallographic structure of a catalytic intermediate of copper amine oxidase, containing a peptidyl quinone cofactor, topa quinone (TPQ), which is converted to a semiquinone radical form by anaerobic reaction with an amine substrate. Neutron diffraction data at 1.67 Å resolution revealed the protonation/deprotonation state of the active-site residues, including TPQ. The semiquinone form was doubly deprotonated at the 2-OH and 4-OH positions. The surrounding hydrogen-bond network and the CH···π and NH···π-like interactions with both sides of the TPQ ring were identified, affording a stabilization mechanism for the semiquinone radical structure. The pH-dependent conformational change of TPQ from an ‘off-copper’ aminoresorcinol to an ‘on-copper’ semiquinone was accompanied by protein/solvent proton exchange in the main-chain peptide bond of TPQ. Moreover, the neutron diffraction data disclosed the number of deuterium/hydrogen atoms covalently attached to the terminal heavy atom of the ligand bound in a hydrophobic pocket adjacent to TPQ, which led to the conclusion that the product aldehyde was replaced by an amine substrate in the pocket. The amino group of the bound substrate interacted with the deprotonated side chain of a conserved aspartic acid residue that acts as a catalytic base. These findings demonstrate that the additional substrate binding triggers the conformational change of TPQ in the reductive half-reaction and makes the enzyme catalysis proceed into the subsequent oxidative half-reaction.

]]> Thu, 07 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02629 https://pubs.acs.org/doi/10.1021/acscatal.3c02629

Generating singlet oxygen (1O2) on single atom catalysts (SACs) in peroxymonosulfate (PMS)-based Fenton-like reactions exhibits great potential for selective degradation of contaminants in complex wastewater. Clarifying the structure–activity relationship between the electronic structure of SACs and the 1O2 generation selectivity is crucial for the precise design of efficient Fenton-like catalysts, but it is challenging. Herein, the generation selectivity of 1O2 on Cu SACs with different electronic structures (namely, Cu–O2X, where X = N, S, B, P, and O) is investigated by density functional theory calculations using the adsorption selectivity of terminal oxygen atoms in PMS as an activity descriptor. Significantly, the selectivity of 1O2 generation is affected by the electronic structure of the Cu center in which the electron-depleted Cu-O2B site exhibits a higher selectivity for the adsorption of terminal oxygen atoms. Experimentally, the Cu-O2B moiety exhibits superior catalytic activity for PMS activation, showing nearly 100% selectivity for 1O2 generation and a ciprofloxacin degradation rate of 0.2250 min–1, outperforming those of the other counterparts. The high catalytic activity is attributed to the asymmetric Cu-O2B site accelerating faster electron transfer and O–O bond stretching, lowering the energy barrier of key intermediates toward 1O2 generation. This work provides a broader perspective for regulating the electronic structure of single Cu sites at the atomic level and for the precise design of efficient Fenton-like catalysts.

]]> Thu, 07 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c03303 https://pubs.acs.org/doi/10.1021/acscatal.3c03303

Formation of amides, acids, and thioesters are readily fashioned from precursor aryl/heteroaryl halides under micellar catalysis conditions using W(CO)6 as a source of carbon monoxide. Loadings of ligated palladium catalysts are usually in the 0.5 mol % range. Yields with iodides tended to be higher than those using bromides. Applications to targets in the pharmaceutical industry are demonstrated, as are cases from the Merck Informer Library. Both E Factor calculations and options for recycling the aqueous reaction medium are presented.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c01757 https://pubs.acs.org/doi/10.1021/acscatal.3c01757

Artificial photosynthesis is a viable approach for transforming carbon dioxide (CO2) into value-added chemicals driven by renewable solar energy. Studies on photocatalytic CO2 reduction (CO2R) have thus been expedited in recent years. Cadmium sulfide quantum dots (CdS QDs) have been regarded as one of the most promising photocatalysts, offering a myriad of advantages for CO2R, such as a narrow band gap, quantum confinement effect, and tunable redox potential. However, CdS QDs usually suffer from photo, thermal, and oxidative instability. In this work, we demonstrate an effective method to endow CdS QDs by assembling them with amphiphilic metallopolymers to enhance their stability and synergistically increase their catalytic activity. The metallopolymers were synthesized via precise radical polymerization between 1-ethyl-3-vinylimidazolium bromide and rhenium(I)-N-(3-((4′-methoxy-[2,2′-bipyridin]-4-yl)oxy)propyl)acrylamide compounds. The resultant positively charged rhenium complex-containing metallopolymer (P(Re-IL)) underwent spontaneous assembly with the negatively charged thioglycolate-capped CdS QDs via electrostatic interaction, forming highly active and stable CdS/P(Re-IL) hybrids. The ultimate interfacial interaction between the two components in CdS/P(Re-IL) facilitated photoinduced electron transfer (PET) from CdS to the vicinal bipyridyl ReI(CO)3Cl derivatives, promoting the photocatalytic CO2 reduction to CO with a high production rate and selectivity in a 25 mL-DMF/water (4:1 v/v) solution under LED 370 nm irradiation. For example, CdS/P(5% Re-IL) was the optimum catalyst in our system, showing the highest CO production rate of 38.3 mmol g–1 h–1 and selectivity of 93.8% within 2 h with no induction period, which is ranked among the top state-of-the-art CO2R photocatalysts in mixed organic-water media.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c01979 https://pubs.acs.org/doi/10.1021/acscatal.3c01979

Using solar energy to fix N2 and produce NH3 is a promising route. For nitrogen photofixation, the transition-metal active site in the low oxidation state is conducive to the adsorption of N2, but it is often difficult to further dissociate N2, restricting the reaction. Therefore, it is necessary to precisely modulate the electron energy level of the active site to couple with the molecular orbitals of N2, thus reducing the energy barrier of N2 dissociation. Here, the perovskite-type LaTiO3–x with an ultralow oxidation state Ti2+ site is achieved via in situ modulation of phase transition and defect engineering. The obtained Ti2+ sites could inject more d-orbital electrons into the N2 π* antibonding orbitals to achieve N2 activation and dissociation. Therefore, compared with pristine La2Ti2O7 and La2Ti2O7–x samples without ammonia production activity, LaTiO3–x samples showed a remarkable performance for photocatalytic N2 fixation. The NH3 generation rate reached up to 107 μmol gcat–1 h–1 after the 1st hour, and the average NH3 generation rate after 4 h was approximately 51.5 μmol gcat–1 h–1. Furthermore, in situ characterization and density functional theory (DFT) calculations revealed the role of Ti sites with different oxidation states (Ti4+, Ti3+, Ti2+) in N2 activation, which would provide a unique perspective for designing efficient N2 fixation catalysts.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02198 https://pubs.acs.org/doi/10.1021/acscatal.3c02198

The direct alkylation of benzenes with simple alkanes is one of the ideal processes for the production of alkylbenzenes. We demonstrated that Pd nanoparticles on the outer surface of H-ZSM-5 are efficient catalysts for direct alkylation. The reaction proceeds through the activation of an alkane on the acid sites present inside the zeolite pores. This process is followed by the nucleophilic addition of an arene to activate the activated alkane. The spillover of the abstracted hydrogen atoms from the acid sites to the Pd nanoparticles on the outer surface accelerates recombination to H2. A maximum toluene conversion of 58.5% and a selectivity of 95.6% for the alkylated products are achieved when toluene is reacted with n-heptane. para-selective alkylation is achieved due to the effect of the pore size of H-ZSM-5. The μ+SR study of muonium, a pseudoisotope of hydrogen, in aluminosilicates suggested that the formation of atomic hydrogen is possible and its lifetime is in the submicrosecond range or longer, which is long enough for chemical reactions.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02309 https://pubs.acs.org/doi/10.1021/acscatal.3c02309

The deactivation of catalysts by metal poisons is a pressing and ongoing concern in heterogeneous catalysis. The design of catalysts with good resistance to metal poisons under harsh reaction conditions is a formidable challenge. Herein, we report on the delicate engineering of a catalyst comprising α-Fe2O3 crystals embedded in amorphous FeVO4, which exhibits remarkable resistance to metal poisons during the catalytic elimination of nitric oxide. X-ray atomic pair distribution function analysis, confocal and in situ Raman spectra, and vertex component analysis were used to show that amorphous FeVO4 provides the “ion channel”, enabling the migration of poisons away from the surface-active sites and into an inner sacrifice zone. Crystal-in-amorphous catalysts are universally resistant to metal poisons due to the migration of these poisons caused by differences in chemical potential and low diffusion energy barriers. The embedded α-Fe2O3 crystals act as a stabilizing skeleton for the amorphous FeVO4, conferring good robustness to the catalyst, even after an aging process. Our work represents a rational design of crystal-in-amorphous structure catalysts, providing an alternative approach to fabricating excellent poison-resistant catalysts for other heterogeneous catalysis processes.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02571 https://pubs.acs.org/doi/10.1021/acscatal.3c02571

Hydrogen-dependent CO2 reductase (HDCR) is the key enzyme in CO2 fixation and acetogenesis in some anaerobic, acetogenic bacteria. The enzyme has four subunits, a hydrogenase module HydA2 and a formate dehydrogenase module FdhF that are connected by two small iron–sulfur proteins, HycB3 and HycB4. The enzyme catalyzes the conversion of H2 + CO2 to formate and vice versa with the highest rates ever reported. HDCR from Acetobacterium woodii was shown in vitro to also use ferredoxin (Fd) as the electron carrier, a central electron carrier in anaerobes. The same was observed here for the enzyme purified from the thermophile Thermoanaerobacter kivui: the HDCR catalyzed formate production from reduced ferredoxin and CO2 and vice versa. The enzyme also catalyzed Fd-dependent proton reduction with the production of molecular hydrogen. After deletion of HydA2 and its corresponding subunit HycB4, the purified deletion variants still catalyzed formate-dependent Fd reduction with activities even higher than the wild type enzyme, and likewise, Fd2–-dependent CO2 reduction was also stimulated. To determine whether ferredoxin can be utilized by HDCR also in vivo, growth studies were performed with strains producing the different HDCR variants. When HydA2 or HydA2 plus HycB4 were deleted, cells still grew on glucose and still fixed CO2, although the growth rate and the yield were reduced. Cells did not grow on H2 + CO2 but on formate or carbon monoxide. Resting cells without HydA2 did not convert H2 + CO2 to acetate. Formate was oxidized by wild type cells mainly to H2 + CO2 with little acetate formed, but the deletion variants did not produce H2 anymore but acetate instead. CO conversion to acetate was similar in the wild type and the deletion strains. These experiments demonstrate that hydrogen is not essential as an electron donor for HDCR in vivo.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02753 https://pubs.acs.org/doi/10.1021/acscatal.3c02753

Photocatalysis offers promising technology for converting plastic waste into valuable chemicals. However, fully digging out the embedded value to incentivize the valorization of plastic waste is still a challenge. Herein, we first design an intramolecular donor–acceptor (D–A) structure by introducing the terephthalic acid (PTA) derived from polyethylene terephthalate (PET) waste into P-doped g-C3N4 (CN-P). Impressively, CN-P-PTA exhibits higher activity in the photocatalysis of PET to H2O2 compared with CN-P. The superior performance is attributed to the prolonged photogenerated carrier lifetime and the enhanced delocalization of π electrons. Moreover, single-particle PL quenching and DFT calculations reveal that PTA and CN-P can form an intimate interface via π–π conjugation, which facilitates the flow of photoexcited electrons from PTA to CN-P.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c03509 https://pubs.acs.org/doi/10.1021/acscatal.3c03509

Proton exchange membrane water electrolysis (PEMWE) is being actively developed as a promising technology to produce high-purity hydrogen. While PEMWE has been commercialized, a serious roadblock for wider deployment is the high cost associated with the use of high loadings of the noble metal Ir-based anode catalysts for the oxygen evolution reaction (OER). To lower the Ir loading amount, it is critically important to develop efficient catalysts with increased Ir utilization and higher OER activity. Herein, we report the preparation of one-dimensional Ir oxide nanorod catalysts supported on Sb-doped SnO2 and demonstrate their extremely high activity in the OER catalysis, with the Ir mass-specific activity being 10 times higher than that of commercial IrOx catalyst at 1.5 V vs reversible hydrogen electrode (RHE), showing great promise in dramatically reducing the Ir loading in PEMWE cells. The experiment also found that the OER activation energy was greatly reduced for the Ir oxide nanorod/Sb-SnO2 catalyst. It was proposed, based on experimental results and density functional theory (DFT) calculations, that the nanorod geometry and the interaction with SnO2 support rendered a surface with a lower degree of Ir oxidation, which allows the surface terminal oxygens to be closer together while allowing facile desorption of oxygenated species, which could play an important role in facilitating the crucial step of the OER, thereby enhancing the OER activity.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c01647 https://pubs.acs.org/doi/10.1021/acscatal.3c01647

Biocatalysis is important in the discovery, development, and manufacture of pharmaceuticals. However, the identification of enzymes for target transformations of interest requires major screening efforts. Here, we report a structure-based computational workflow to prioritize protein sequences by a score based on predicted activities on substrates, thereby reducing a resource-intensive laboratory-based biocatalyst screening. We selected imine reductases (IREDs) as a class of biocatalysts to illustrate the application of the computational workflow termed IREDFisher. Validation by using published data showed that IREDFisher can retrieve the best enzymes and increase the hit rate by identifying the top 20 ranked sequences. The power of IREDFisher is confirmed by computationally screening 1400 sequences for chosen reductive amination reactions with different levels of complexity. Highly active IREDs were identified by only testing 20 samples in vitro. Our speed test shows that it only takes 90 min to rank 85 sequences from user input and 30 min for the established IREDFisher database containing 591 IRED sequences. IREDFisher is available as a user-friendly web interface (https://enzymeevolver.com/IREDFisher). IREDFisher enables the rapid discovery of IREDs for applications in synthesis and directed evolution studies, with minimal time and resource expenditure. Future use of the workflow with other enzyme families could be implemented following the modification of the workflow scoring function.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02278 https://pubs.acs.org/doi/10.1021/acscatal.3c02278

Electrochemical reactive capture of CO2, which integrates CO2 capture with its conversion directly from amine and other capture solutions, is of growing interest to enable net zero and eventually negative greenhouse gas emissions. While integration has been proposed to mitigate certain energy penalties and inefficiencies that accrue when capture and conversion are decoupled, integration introduces considerable complexity to the electrochemical process due to the number of possible reactant participants, especially in an aqueous-based capture solution. Moreover, the influence of amine-based sorbents on CO2 reduction (CO2R) mechanisms is not well-understood, making rational design elusive at present. In this work, we reveal the governing parameters and active species in amine-mediated CO2 conversion as an essential initial step toward improving these processes. We first demonstrate the critical influence of CO2 partial pressure of the capture stream on the resulting solution pH, which directly affects amine speciation and the Faradaic efficiency of CO production on Ag. Moreover, by considering amines of different pKa and with different propensities to form the amine-CO2 adduct carbamate, we show that dissolved CO2 is the active species for CO2R in amine-containing solutions, enabling some capture solutions to have comparable CO2R selectivity and kinetics to amine-free bicarbonate solutions. As a result, amines can serve as a reservoir of dissolved inorganic carbon that can replenish dissolved CO2 as it is consumed during CO2R, alleviating mass transfer/transport limitations without directly participating electrochemically.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02500 https://pubs.acs.org/doi/10.1021/acscatal.3c02500

Carbon corrosion is a common problem during the oxygen evolution reaction (OER) in water electrolysis which occurs at high anodic potentials. Metal oxides can be used to improve overall durability and activity via catalyst/support interactions in the OER, but many of these oxides suffer from low electrical conductivity. Recently, antimony-doped tin oxide (ATO) has been shown to offer sufficient conductivity and low dissolution in acidic environments. Here, PtNiIr nanoframes (NFs) were successfully loaded onto ATO using a n-butylamine treatment and tested under OER conditions. These PtNiIr NFs form a rhombic dodecahedral shape with Pt and Ir forming a homogeneous alloy at the edges and vertices. The PtNiIr NF/ATO electrocatalyst shows comparable results to PtNiIr NF/C with current densities of 0.57 and 0.62 mA/cm2 at 1.53 VRHE. The Faradaic efficiency for the OER of NF/ATO was found to be 92% which was close to NF/C at 94%. Furthermore, PtNiIr NF/ATO shows a lower dissolution during accelerated durability testing which was further shown during online electrochemical mass spectrometry measurements. PtNiIr NF/ATO showed only a minor decrease in mass activity (0.57–0.54 A/mg based on the platinum group metal content) at 1.53 VRHE after 10,000 potential cycles and no signs of dissolution or catalyst migration when compared to PtNiIr NF/C.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02541 https://pubs.acs.org/doi/10.1021/acscatal.3c02541

Reactive intermediates are essential for determining the reaction mechanism of biomass pyrolysis. However, these short-life compounds are rarely reported because they are difficult to probe and identify. Here, the catalytic pyrolysis of furanic compounds over HZSM-5 was investigated by combining a low-pressure reactor and an in situ synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometer (SVUV-PI-MBMS). Important reactive intermediates (m/z < 200) can be detected and characterized by this in situ analysis method, which also allows studying the dynamics of volatile formation as a function of catalyst deactivation. Strikingly, formaldehyde and acetaldehyde as reactive intermediates in the upgrading of 5-methylfurfural (5-MFF) are mainly produced from its side-chain cracking on the external surface of the zeolite, while their conversion is highly related to the contribution of the Brønsted acid site inside the zeolite. It is also evidenced that reactive methylcyclopenadienes (MCPDs) are formed from various compounds (alkynes, furans and olefins) and can be further converted to methylbenzenes (MBs) via ring-expansion. Finally, more complete conversion pathways that contain reactive intermediates for zeolite-catalyzed pyrolysis of furanic compounds are proposed. The key roles of some reactive intermediates in promoting the deoxidation and aromatization of furans are also illustrated.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c01948 https://pubs.acs.org/doi/10.1021/acscatal.3c01948

Here, we report a unique porous FeCoAl Prussian blue analogue (PBA)-based core–shell catalyst (Na/Fe@FeCoAl-P) with a well-defined spatial arrangement of double-active interfaces for superior CO2 conversion to C2–C4 hydrocarbons. Compared to the traditional Na/Fe catalyst, which has a selectivity of 32.0% to C2–C4 hydrocarbons at a CO2 conversion of 38.1%, the resulting Na/Fe@FeCoAl-P0.1 catalyst exhibits significantly improved selectivity (40.8%) to C2–C4 hydrocarbons with a high olefin/paraffin (O/P) ratio of 8.7 at a largely improved CO2 conversion of 54% at 330 °C, while the CO selectivity decreases from 7.3 to 3.5%. Furthermore, the selectivity of C2–C4 hydrocarbons can reach 45.7% containing 38.7% of C2=–C4= products at 280 °C. In addition, the in-depth characterization results have indicated that the presence of FeCoAl PBA not only inhibits the generation of heavy hydrocarbons by the unique porous structure space but also considerably facilitates the formation of an abundant Fe5C2 phase for boosting Fischer–Tropsch synthesis (FTS) activity. Also, a distinctive reaction scheme of CO2 hydrogenation to hydrocarbons over the Na/Fe@FeCoAl-P0.1 catalyst is proposed on the basis of extensive characterizations. Moreover, we also demonstrate that porous-structured PBA is a highly promising material for use in CO2 hydrogenation, although its application has been rarely reported in CO2 Fischer–Tropsch synthesis.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02034 https://pubs.acs.org/doi/10.1021/acscatal.3c02034

The synthesis of stereoregular polymers through ionic mechanisms using asymmetric ion-pairing (AIP) catalysis is emerging as an effective strategy to achieve differentiated material properties from readily available building blocks. Stereoselective cationic polymerization in particular is primed for advancement using AIP by leveraging the breadth of Brønsted and Lewis acid small-molecule catalysis literature; however, mechanistic studies that address polymer-specific phenomena are scarce and, as a result, the lack of mechanistic understanding has limited catalyst design. In a recent study, we demonstrated the only example of a stereoselective and helix-sense-selective cationic vinyl polymerization of N-vinylcarbazole using chiral scandium-bis(oxazoline) Lewis acids. To better understand the mechanism of this highly stereoselective polymerization and elicit design principles for future advances, we present a combined experimental and computational study into the relevant factors that determine tacticity and helicity control. Key mechanistic experiments suggest two competing elementary steps─chain-end conformation equilibration and propagation─whose relative rates can be influenced by monomer concentration, isotope effects, and catalyst design to tune tacticity. In contrast, helicity is influenced by complex relationships between the stereoselectivity of the first monomer propagation and a time-dependent initiator-catalyst mixing time. The more complete understanding of stereoselective cationic polymerization through AIP developed herein provides insights into polymer-specific mechanisms for stereocontrol, which we believe will motivate continued catalyst discovery and development for stereoselective vinyl polymerization.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02165 https://pubs.acs.org/doi/10.1021/acscatal.3c02165

Zeolites are a family of nanoporous crystalline materials with ordered channel systems, flexibly adjustable activity, and high hydrothermal stability and have been widely used as adsorbents and catalysts. The micropores of zeolites are comparable to the size of single molecules, which can function as “molecular sieves” by selectively adsorbing or transforming targeted guest molecules. Therefore, a slight mismatch in the dimensions of the pore architecture and guest molecules sometimes will cause thousands of times of changes in the physicochemical processes inside zeolite channels. Adjusting the pore structures to match targeted molecules to precisely regulate the host–guest interactions between them and thereby control the diffusion or reaction pathways has always been one of the most essential principles for designing novel zeolite materials and applications. Thus, it is highly desirable to understand the moving and transforming behaviors of different small molecules in zeolitic nanopores and probe the intricate interactions between them in such delicate situations. The recently emerged integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) holds great potential for imaging zeolite materials at an atomic resolution, since it can greatly improve electron utilization efficiency to reduce the required electron dose and is conducive to light element imaging. This Perspective focuses on the in situ observation of single-molecule adsorption–desorption behaviors in zeolites using the in situ iDPC-STEM imaging technique. We demonstrated that iDPC-STEM is an effective method for probing atomic structures of beam-sensitive zeolite materials and exhibits a remarkable ability in imaging light elements under low-dose conditions. Subsequently, we introduce a general “confined freezing” strategy to immobilize small molecules in size-matchable nanopores, which are stable enough for atomically resolved single-molecule imaging. Finally, three industrially important aromatic molecules with slight differences, including benzene, p-xylene, and pyridine, were selected to demonstrate the different adsorption/desorption behaviors and corresponding host–guest interactions at the subnanometer scale. In this way, we provide a real-space methodology to actually “see” the movement and transformation of individual molecules at the atomic scale and pave the way for clarifying the key role of host–guest interactions in molecular adsorption, diffusion, and reaction processes.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02270 https://pubs.acs.org/doi/10.1021/acscatal.3c02270

Steady-state (SS) and time-resolved (TR) fluorescence spectroscopy were applied in the characterization of catalytically active metallocene (MCN) species, both in solution and on silica support. The spectral study of the solution activation of model MCN rac-C2H4(indenyl)2ZrMe2 by methylalumoxane (MAO) revealed that the hetero-binuclear Zr cation [(L)2Zr(μ-Me)2AlMe2]+ (a catalytically active species) is a lumophore, emitting phosphorescence light with a long Stokes shift. A lumophore with the same spectroscopic fingerprint but reduced mobility was detected in supported catalysts prepared with the model MCN, supporting the presence of surface-anchored ion pair consisting of the [(L)2Zr(μ-Me)2AlMe2]+ cation and the [Me–MAO–O–SiO⋮]− anion. Guided by the cation’s spectroscopic fingerprint, its spatial distribution on support was mapped with laser confocal fluorescence microscopy via two orthogonal approaches (SS and TR fluorescence). Besides the model MCN, the MAO activation of four other MCNs was examined in a comparative study, which revealed that the ion pair containing the [(L)2M(μ-Me)2AlMe2]+ (M = Zr or Hf) cation generally emits phosphorescence light. The cation’s molar absorption coefficient, quantum yield, excitation and emission peak positions, and lifetime strongly depend on its structure.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02903 https://pubs.acs.org/doi/10.1021/acscatal.3c02903

Organofluorine compounds have attracted extensive attention in various industrial fields due to their unique chemical and physical properties. Despite increasing demand in a wide range of scientific fields, the synthesis of organofluorine compounds still faces several problems, such as difficulties in the handling of fluorinating reagents and the control of chemoselectivity. Compared with the formation of C–F bonds, the activation and functionalization of carbon–fluorine bonds is a very important but challenging topic in synthetic chemistry. Due to the unique properties of nickel, Ni-catalyzed defluorinative cross-couplings have been greatly developed in the past few decades as powerful strategies for the construction of fluorinated organic compounds. This Review summarizes important advances in the Ni-catalyzed defluorinative cross-coupling of aryl fluorides, gem-difluorovinyl and trifluoromethyl compounds.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c02993 https://pubs.acs.org/doi/10.1021/acscatal.3c02993

Developing strategies to accelerate the electron–hole pair separation and understanding the mechanism are important for improving the activity of photocatalysts. Herein, constructing a weak interaction between nickel thiolate cluster (i.e., Ni12(SPhCH3)24) and graphitic carbon nitride (g-C3N4) is revealed as an effective strategy to regulate electron–hole pair separation. The π–π interaction between the triazine rings in g-C3N4 and the phenyl rings in Ni12(SPhCH3)24 offers a primary pathway for photogenerated electrons transfer from nickel cluster to g-C3N4. The photocatalytic hydrogen evolution rate of Ni12(SPhCH3)24/C3N4 achieves ∼3000 μmol g–1 h–1, which is about 230 times higher than that of pure g-C3N4. Theoretical analysis and femtosecond transient absorption spectroscopy show that the photogenerated electrons on the phenyl groups contribute to the unoccupied molecular orbitals (i.e., LUMOs+1) of Ni12(SPhCH3)24 and then transfer to the conduction band of g-C3N4 via the π–π interaction, which eventually results in the spatial electron–hole pair separation and improves the hydrogen evolution activity of the catalyst.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c03063 https://pubs.acs.org/doi/10.1021/acscatal.3c03063

Polymeric carbon nitride (CN)-based materials enable the visible-light-induced photocatalytic oxidation (PCO) mainly through the reductive pathway (O2 → H2O2 → •OH) to generate reactive oxygen species (ROS) because the CN valence band edge position is not sufficiently positive to oxidize water directly to generate •OH. Consequently, the hole-mediated process in the CN-PCO system has been largely overlooked. In this study, we conducted a comprehensive investigation of the PCO behavior of pristine and modified CN materials to assess the role of direct hole transfer in oxidizing aromatic compounds as a model substrate. The direct hole-mediated oxidation path was investigated in the anoxic aqueous suspension containing Cu2+ or BrO3– as an alternative electron acceptor while inhibiting the ROS formation via the O2 reduction pathway. The observed rate constant exhibited a logarithmic correlation with both the Hammett constant (σ) and the half-wave-oxidation potential (E1/2) for 12 phenols and 6 anilines. The analysis using (i) Fukui function, (ii) the energy of the highest occupied molecular orbital (HOMO), and (iii) the acid dissociation constant (pKa) provided insights into the role of the hydroxyl and amine substituents as a reactive site for the hole transfer reaction. These findings propose that the hole-driven extraction of an electron from substituted aromatic compounds is a rate-determining step in the overall PCO process. The study identified the key descriptors that exhibit pronounced correlation with the PCO kinetics, which should be useful in understanding and developing the CN-based photocatalytic systems.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c03342 https://pubs.acs.org/doi/10.1021/acscatal.3c03342 Fri, 01 Sep 2023 00:00:00 GMT 10.1021/acscatal.3c03925 https://pubs.acs.org/doi/10.1021/acscatal.3c03925

Fully exposed cluster catalysts (FECCs) can not only provide the catalytic sites with multiple metal atoms as in nanoparticles (NPs) but also maintain a full atomic utilization efficiency as in single-atom catalysts (SACs), making them a bridge linking metal SACs and NPs. Due to these particular characteristics, FECCs have been widely studied and have exhibited enhanced catalytic performance in dehydrogenation and oxidation reactions. However, their application in hydrogenation was rarely reported, and the reaction mechanism has yet to be understood. Herein, we report that fully exposed Ir clusters anchored on the sulfur-doped carbon support (Irn/SC) are an efficient catalyst for hydrogenation of N-heteroarenes and exhibit much higher activity and stability compared to the counterpart Ir SAC (Ir1/SC) and Ir NPs catalysts. Especially, we elucidate the hydrogenation reaction mechanism on Irn/SC and disclose how it differs from that on Ir1/SC. Both experimental studies and density functional theory calculations reveal that the distinct geometric and electronic structures of Irn/SC enable the preferable dissociation of H2 molecules and improve the hydrogenation of quinoline via the classic Horiuti–Polanyi mechanism. In contrast, the absence of metal–metal bonds and the oxidized state of Ir atoms in Ir1/SC result in the difficulty in hydrogen activation and the hydrogenation of quinoline into dihydroquinoline via the Langmuir–Hinshelwood mechanism. This work demonstrates the particular usefulness of fully exposed metal clusters in hydrogenation and provides an insightful understanding of the reaction mechanism.

]]> Thu, 31 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c03148 https://pubs.acs.org/doi/10.1021/acscatal.3c03148

Sulfur poisoning remains a severe problem in industrial applications for CH4 dry reforming, and developing a highly active and durable catalyst is of great environmental importance. Meanwhile, designing a Lewis acid catalyst of CeO2 to replace traditional metal Ni for the challenging activation of CH4 is interesting. Herein, valuable insights into the role of H2S in promoting the catalytic activity of ceria catalysts for the dry reforming of methane are presented. Moreover, the special role of redox functions over the sulfur-accelerated CeO2 catalyst and its reaction mechanism are unraveled by using quasi in situ XPS, in situ CH4/CO2-TPSR, and in situ DRIFTS and DFT calculations. This work gives a distinctive example of a sulfur-accelerated ceria catalyst for efficient CH4/CO2 reforming.

]]> Wed, 30 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c00752 https://pubs.acs.org/doi/10.1021/acscatal.3c00752

Oxidative desulfurization (ODS) using H2O2 oxidant has emerged as a viable carbon-neutral way to produce premium-grade sulfur-free fuels, yet it currently suffers from overconsumption of oxidants and low efficiency for the immiscibility and high interfacial tension of water and oil. Here, we report efficient ODS using minimal H2O2 oxidant without phase transfer agents. This is achieved by introducing organic modifiers (for example, etidronic acid (EA)) on molybdenum oxides anchored carbon nanotubes to dynamically activate Mo active sites and capture H2O2 molecules. Such in situ generated local hydrophilicity depends on the electron-donating and hydrophilic −OH functional groups in EA, which can not only endow Mo active sites with high electron density for chemisorption of H2O2 but also ensure the sufficient supply of H2O2. Combined with the substrate enrichment effect of hydrophobic porous carbon to sulfur contaminants, the efficient ODS reaction occurs at the solid–water–oil three-phase interface. The complete desulfurization was achieved within 10 min at 40 °C with an O/S ratio of 1, surpassing the optimum in the literature. This work unveils an avenue to improve ODS activity by harnessing the local reaction environment.

]]> Wed, 30 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02509 https://pubs.acs.org/doi/10.1021/acscatal.3c02509

In traditional electrochemical CO2 reduction (ECR), pressurized pure CO2 gas is typically employed as the feedstock, which consumes large amounts of energy to capture and separate. Herein, we present a method for the direct bicarbonate reduction to formate on a cost-effective Sn foil electrode by integrating the thermochemical and electrochemical methods. Through the simultaneous thermal and electrochemical reactions on the Sn surface, a continuous Snδ+/Sn redox loop was formed. This dynamic Snδ+/Sn interface significantly boosts the direct reduction of bicarbonate to formate, resulting in an optimal partial current density of 121 mA cm–2 for formate with an 83% Faradaic efficiency obtained in 3 mol L–1 KHCO3 at 100 °C. A detailed study revealed that the formate was produced from the bicarbonate directly rather than from the CO2 generated from the dissociation of bicarbonate at elevated temperatures. Compared to the traditional ECR, which involves the complicated processes of CO2 separation, compression, and recirculation, this research presents a straightforward and efficient way for direct bicarbonate reduction, holding promise for practical applications.

]]> Wed, 30 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02630 https://pubs.acs.org/doi/10.1021/acscatal.3c02630

Unraveling metal nuclearity effects is central for active site identification and the development of high-performance heterogeneous catalysts. Herein, a platform of nanostructured palladium (Pd) in gold (Au) dilute alloy nanoparticles supported on raspberry-colloid-templated (RCT) silica was employed to systematically assess the impact of the Pd ensemble size for the low-nuclearity regime in the Au surface layer, from single atoms to clusters, on the catalytic performance in the liquid-phase hydrogenation of benzaldehyde to benzyl alcohol. Combining catalyst evaluation, detailed characterization, and mechanistic studies based on density functional theory, we show that Pd single atoms in the Au surface plane (corresponding to samples with 4 atom % Pd in Au) are virtually inactive in this reaction and benzyl alcohol production is optimal over small Pd clusters (corresponding to samples with 10–12 atom % Pd in Au) due to superior benzaldehyde adsorption and transition state stabilization for the C–H bond formation step. For larger Pd ensembles (samples with ≥10 atom % Pd in Au), C–O bond hydrogenolysis occurs, promoting toluene formation and decreasing the selectivity toward benzyl alcohol, in line with a relatively lowered C–O bond cleavage barrier. Nevertheless, the nanostructured bimetallic Pd13Au87/SiO2-RCT catalyst still outperforms monometallic Pd counterparts in terms of selectivity for benzyl alcohol over toluene at comparable conversion and rate. Furthermore, the stability is improved compared to pure Pd nanoparticles due to inhibited particle agglomeration in the RCT silica matrix.

]]> Wed, 30 Aug 2023 00:00:00 GMT 10.1021/acscatal.3c02671 https://pubs.acs.org/doi/10.1021/acscatal.3c02671

Photocatalytic CO2 reduction into CH4 is an appealing approach to alleviate the current energy and environmental crisis; however, achieving high selectivity and conversion efficiency still remains challenging. The rational design of photocatalysts for CO2 adsorption and activation is thus crucial. Here, we designed and synthesized two redox-active truxene-based conjugated microporous polymers linked by thiazolo[5,4-d]thiazole for metal-free photocatalytic reduction of CO2 to CH4. Significantly, the optimized polymer with the extended π-conjugated system, denoted Tx-TzTz-CMP-2, presented a higher CH4 production rate of 300.6 μmol g–1 h–1 with a selectivity of 71.2% without any metal cocatalyst and photosensitizer, which outperformed most of the previously reported photocatalysts. Experimental and theoretical investigations revealed that introducing phenyl as a ```

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```rss https://pubs.acs.org/toc/jacsat/0/0 RSSHub i@diygod.me (DIYgod) zh-cn Thu, 07 Sep 2023 14:25:15 GMT 5

In this work, a comprehensive investigation of the photoinduced processes and mechanisms linked to the luminescence of a novel nonperchlorinated Thiele hydrocarbon (TTH) is presented. Despite the comparable diradical character of TTH (y0 = 0.32–0.44) and the unsubstituted Thiele hydrocarbon (TH) (y0 = 0.30), the polyhalogenated species is inert and photostable, showing an intense deep-red/near-infrared (NIR) fluorescence (photoluminescence quantum yield (PLQY) = 0.84 in toluene) even at room temperature and in the solid state (PLQY = 0.19). TTH displays a large Stokes shift (307 nm in benzonitrile) and solvatochromic behavior, which is unusual for a centrosymmetric, nonpolar, and low-conjugated species. These outstanding emission features are interpreted through quantum-chemical calculations, indicating that its fluorescence arises from the low-lying dark doubly excited zwitterionic state, typically found at low excitation energies in diradicaloids, acquiring dipole moment and intensity by state mixing via twisting around the strongly elongated exocyclic CC bonds of the excited p-quinodimethane (pQDM) core, with a mechanism similar to sudden polarization occurring in olefins. Such a mechanism is derived from ns and fs transient absorption measurements.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05251 https://pubs.acs.org/doi/10.1021/jacs.3c05251

Here we report the controlled self-assembly of vanadium-seamed metal–organic nanocapsules with specific metal oxidation state distributions. Three supramolecular assemblies composed of the same numbers of components including 24 metal centers and six pyrogallol[4]arene ligands were constructed: a VIII24L6 capsule, a mixed-valence VIII18VIV6L6 capsule, and a VIV24L6 capsule. Crystallographic studies of the new capsules reveal their remarkable structural complexity and geometries, while marked differences in metal oxidation state distribution greatly affect the photoelectric conversion properties of these assemblies. This work therefore represents a significant step forward in the construction of intricate metal–organic architectures with tailored structure and functionality.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05448 https://pubs.acs.org/doi/10.1021/jacs.3c05448

Plastic upcycling through catalytic transformations is an attractive concept to valorize waste, but the clean and energy-efficient production of high-value products from plastics remains challenging. Here, we introduce chemoenzymatic photoreforming as a process coupling enzymatic pretreatment and solar-driven reforming of polyester plastics under mild temperatures and pH to produce clean H2 and value-added chemicals. Chemoenzymatic photoreforming demonstrates versatility in upcycling polyester films and nanoplastics to produce H2 at high yields reaching ∼103–104 μmol gsub–1 and activities at >500 μmol gcat–1 h–1. Enzyme-treated plastics were also used as electron donors for photocatalytic CO2-to-syngas conversion with a phosphonated cobalt bis(terpyridine) catalyst immobilized on TiO2 nanoparticles (TiO2|CotpyP). Finally, techno-economic analyses reveal that the chemoenzymatic photoreforming approach has the potential to drastically reduce H2 production costs to levels comparable to market prices of H2 produced from fossil fuels while maintaining low CO2-equivalent emissions.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05486 https://pubs.acs.org/doi/10.1021/jacs.3c05486

This study reports the successful development of a sustainable synthesis protocol for a phase-pure metal azolate framework (MAF-6) and its application in enzyme immobilization. An esterase@MAF-6 biocomposite was synthesized, and its catalytic performance was compared with that of esterase@ZIF-8 and esterase@ZIF-90 in transesterification reactions. Esterase@MAF-6, with its large pore aperture, showed superior enzymatic performance compared to esterase@ZIF-8 and esterase@ZIF-90 in catalyzing transesterification reactions using both n-propanol and benzyl alcohol as reactants. The hydrophobic nature of the MAF-6 platform was shown to activate the immobilized esterase into its open-lid conformation, which exhibited a 1.5- and 4-times enzymatic activity as compared to free esterase in catalyzing transesterification reaction using n-propanol and benzyl alcohol, respectively. The present work offers insights into the potential of MAF-6 as a promising matrix for enzyme immobilization and highlights the need to explore MOF matrices with expanded pore apertures to broaden their practical applications in biocatalysis.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05488 https://pubs.acs.org/doi/10.1021/jacs.3c05488

The glucagon-like peptide-1 receptor (GLP-1R) is a key regulator of blood glucose and a prime target for the treatment of type II diabetes and obesity with multiple public drugs. Here we present a comprehensive computational analysis of the interactions of the activated GLP-1R–Gs signaling complex with a G protein biased agonist, Exendin P5 (ExP5), which possesses a unique N-terminal sequence responsible for the signal bias. Using a refined all-atom model of the ExP5–GLP-1R–Gs complex in molecular dynamics (MD) simulations, we propose a novel mechanism of conformation transduction in which the unique interaction network of ExP5 N-terminus propagates the binding signal across an array of conserved residues at the transmembrane domain to enhance Gs protein coupling at the cytoplasmic end of the receptor. Our simulations reveal previously unobserved interactions important for activation by ExP5 toward GDP-GTP signaling, providing new insights into the mechanism of class B G protein-coupled receptor (GPCR) signaling. These findings offer a framework for the structure-based design of more effective therapeutics.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05996 https://pubs.acs.org/doi/10.1021/jacs.3c05996

The dehydration of aqueous calcium and magnesium cations is the most fundamental process controlling their reactivity in chemical and biological phenomena, such as the formation of ionic solids or passing through ion channels. It holds particular relevance in light of recent advancements in the development of carbon capture techniques that rely on mineralization for long-term carbon storage. Specifically, dehydration of Ca2+ and Mg2+ is a key step in proposed carbon capture processes aiming to exploit the relatively high concentration of dissolved carbon dioxide in seawater via the formation of carbonate minerals from solvated Ca2+ and Mg2+ cations for sequestration and storage. Nevertheless, atomic-scale understanding of the dehydration of aqueous Ca2+ and Mg2+ cations remains limited. Here, we utilize rare event sampling via density functional theory molecular dynamics and embedded wavefunction theory calculations to elucidate the dehydration dynamics of aqueous Ca2+ and Mg2+. Emphasis is placed on the investigation of the effect pH has on the stability of the different coordination environments. Our results reveal significant differences in the dehydration dynamics of the two cations and provide insight into how they may be modulated by pH changes.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06182 https://pubs.acs.org/doi/10.1021/jacs.3c06182

Self-assembly of colloidal particles into ordered superstructures is an important strategy to discover new materials, such as catalysts, plasmonic sensing materials, storage systems, and photonic crystals (PhCs). Here we show that porous covalent organic frameworks (COFs) can be used as colloidal building particles to fabricate porous PhCs with an underlying face-centered cubic (fcc) arrangement. We demonstrate that the Bragg reflection of these can be tuned by controlling the size of the COF particles and that species can be adsorbed within the pores of the COF particles, which in turn alters the Bragg reflection. Given the vast number of existing COFs, with their rich properties and broad modularity, we expect that our discovery will enable the development of colloidal PhCs with unprecedented functionality.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06265 https://pubs.acs.org/doi/10.1021/jacs.3c06265

Metal–organic frameworks (MOFs) that contain open metal sites have the potential for storing hydrogen (H2) at ambient temperatures. In particular, Cu(I)-based MOFs demonstrate very high isosteric heats of adsorption for hydrogen relative to other reported MOFs with open metal sites. However, most of these Cu(I)-based MOFs are not stable in ambient conditions since the Cu(I) species display sensitivity toward moisture and can rapidly oxidize in air. As a result, researchers have focused on the synthesis of new air-stable Cu(I)-based materials for H2 storage. Here, we have developed a de novo synthetic strategy to generate a robust Cu(I)-based MOF, denoted as NU-2100, using a mixture of Cu/Zn precursors in which zinc acts as a catalyst to transform an intermediate MOF into NU-2100 without getting incorporated into the final MOF structure. NU-2100 is air-stable and displays one of the initial highest isosteric heats of adsorption (32 kJ/mol) with good hydrogen storage capability under ambient conditions (10.4 g/L, 233 K/100 bar to 296 K/5 bar). We further elucidated the H2 storage performance of NU-2100 using a combination of spectroscopic analysis and computational modeling studies. Overall, this new synthetic route may enable the design of additional stable Cu(I)-MOFs for next-generation hydrogen storage adsorbents at ambient temperatures.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06393 https://pubs.acs.org/doi/10.1021/jacs.3c06393

Chalcogens, especially tellurium (Te), as conversion-type cathodes possess promising prospects for zinc batteries (ZBs) with potential rich valence supply and high energy density. However, the conversion reaction of Te is normally restricted to the Te2–/Te0 redox with a low voltage plateau at ∼0.59 V (vs Zn2+/Zn) rather than the expected positive valence conversion of Te0 to Ten+, inhibiting the development of Te-based batteries toward high output voltage and energy density. Herein, the desired reversible Te2–/Te0/Te2+/Te4+ redox behavior with up to six-electron transfer was successfully activated by employing a highly concentrated Cl–-containing electrolyte (Cl– as strong nucleophile) for the first time. Three flat discharge plateaus located at 1.24, 0.77, and 0.51 V, respectively, are attained with a total capacity of 802.7 mAh g–1. Furthermore, to improve the stability of Ten+ products and enhance the cycling stability, a modified ionic liquid (IL)-based electrolyte was fabricated, leading to a high-performance Zn∥Te battery with high areal capacity (7.13 mAh cm–2), high energy density (542 Wh kgTe–1 or 227 Wh Lcathdoe+anode–1), excellent cycling performance, and a low self-discharge rate based on 400 mAh-level pouch cell. The results enhance the understanding of tellurium chemistry in batteries, substantially promising a remarkable route for advanced ZBs.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06488 https://pubs.acs.org/doi/10.1021/jacs.3c06488

Existing methodologies for metal-catalyzed cross-couplings typically rely on preinstallation of reactive functional groups on both reaction partners. In contrast, C–H functionalization approaches offer promise in simplification of the requisite substrates; however, challenges from low reactivity and similar reactivity of various C–H bonds introduce considerable complexity. Herein, the oxidative cross dehydrogenative coupling of α-amino C(sp3)–H bonds and aldehydes to produce ketone derivatives is described using an unusual reaction medium that incorporates the simultaneous use of di-tert-butyl peroxide as an oxidant and zinc metal as a reductant. The method proceeds with a broad substrate scope, representing an attractive approach for accessing α-amino ketones through the formal acylation of C–H bonds α to nitrogen in N-heterocycles. A combination of experimental investigation and computational modeling provides evidence for a mechanistic pathway involving cross-selective nickel-mediated cross-coupling of α-amino radicals and acyl radicals.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06532 https://pubs.acs.org/doi/10.1021/jacs.3c06532

Crystal polymorphism has been a topic of much interest for the past 20 years or so, especially since its scientific (and legal) importance to the pharmaceutical industry was realized. By contrast, the formation of solid solutions in molecular crystals has been overlooked despite its long-standing prevalence in the analogous field of inorganic crystals. Wilfully forgotten, crystalline molecular solid solutions may be very common in our world since molecular compounds are rarely produced with 100% purity, and impurities able to form solid solutions are difficult to reject via recrystallization. Given the importance of both polymorphism and solid solutions in molecular crystals, we share here some tips, tricks, and observations to aid in their understanding. First, we propose a nomenclature system fit for the description of molecular crystalline solid solutions capable of polymorphism (tips). Second, we highlight the challenges associated with their experimental and computational characterization (tricks). Third, we show that our recently reported observation that polymorph stabilities can change by virtue of solid solution formation is a general phenomenon, reporting it on a second system (switches). Our work focuses on the historically important compound benzamide forming solid solutions with nicotinamide and 3-fluorobenzamide.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c07105 https://pubs.acs.org/doi/10.1021/jacs.3c07105

Transition metal nitrides have received considerable attention owing to their crucial roles in nitrogen fixation and nitrogen atom transfer reactions. Compared to the early and middle transition metals, it is much more challenging to access late transition metal nitrides, especially cobalt in group 9. So far, only a handful of cobalt nitrides have been reported; consequently, their hydrogenation reactivity is largely unexplored. Herein, we present a structurally and spectroscopically well-characterized thiolate-bridged dicobalt μ-nitride [Cp*CoIII(μ-SAd)(μ-N)CoIIICp*] (2) featuring a bent {CoIII(μ-N)CoIII} core. Remarkably, complex 2 can realize not only direct hydrogenation of nitride to amide but also stepwise N–H bond formation from nitride to ammonia. Specifically, 2 can facilely activate dihydrogen (H2) at mild conditions to generate a dicobalt μ-amide [Cp*CoII(μ-SAd)(μ-NH2)CoIICp*] (4) via an unusual mechanism of two-electron oxidation of H2 as proposed by computational studies; in the presence of protons (H+) and electrons, nitride 2 can convert to dicobalt μ-imide [Cp*CoIII(μ-SAd)(μ-NH)CoIIICp*][BPh4] (3[BPh4]) and to CoIICoII μ-amide 4, and finally release ammonia. In contrast to 2, the only other structurally characterized dicobalt μ-nitride Na(THF)4{[(ketguan)CoIII(N3)]2(μ-N)} (ketguan = [(tBu2CN)C(NDipp)2]−, Dipp = 2,6-diisopropylphenyl) (e) that possesses a linear {CoIII(μ-N)CoIII} moiety cannot directly react with H2 or H+. Further in-depth electronic structure analyses shed light on how the varying geometries of the {CoIII(μ-N)CoIII} moieties in 2 and e, bent vs linear, impart their disparate reactivities.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c07254 https://pubs.acs.org/doi/10.1021/jacs.3c07254

Hydroxylamine-derived reagents have enabled versatile nitrene transfer reactions for introducing nitrogen-containing functionalities in small-molecule catalysis, as well as biocatalysis. These reagents, however, result in a poor atom economy and stoichiometric organic waste. Activating hydroxylamine (NH2OH) for nitrene transfer offers a low-cost and sustainable route to amine synthesis, since water is the sole byproduct. Despite its presence in nature, hydroxylamine is not known to be used for enzymatic nitrogen incorporation in biosynthesis. Here, we report an engineered heme enzyme that can utilize hydroxylammonium chloride, an inexpensive commodity chemical, for nitrene transfer. Directed evolution of Pyrobaculum arsenaticum protoglobin generated efficient enzymes for benzylic C–H primary amination and styrene aminohydroxylation. Mechanistic studies supported a stepwise radical pathway involving rate-limiting hydrogen atom transfer. This unprecedented activity is a useful addition to the “nitrene transferase” repertoire and hints at possible future discovery of natural enzymes that use hydroxylamine for amination chemistry.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c08053 https://pubs.acs.org/doi/10.1021/jacs.3c08053

Stoichiometric oxidants are always consumed in organic oxidation reactions. For example, olefins react with peroxy acids to be converted to epoxy, while the oxidant, peroxy acid, is downgraded to carboxylic acid. In this paper, we aim to regenerate carboxylic acid into peroxy acid through electric water splitting at the anode, in order to construct an electrochemical catalytic cycle to accomplish the cycloolefin epoxidation reaction. Benzoic acid, which can be strongly adsorbed onto the anode and rapidly converted to peroxy acid, was selected to catalyze the cycloolefin epoxidation. Furthermore, the peroxybenzoic acid will be further activated on the electrode to fulfill the epoxidation and release the benzoic acid to complete the catalytic cycle. In this designed reaction cycle, benzoic acid acts as a molecular catalyst with the assistance of the electrode-generated reactive oxygen species (ROS). This method can successfully reform the consumable oxidants to molecular catalysts, which can be generalized to other green organic syntheses.

]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c08227 https://pubs.acs.org/doi/10.1021/jacs.3c08227 null]]> Wed, 06 Sep 2023 00:00:00 GMT 10.1021/jacs.3c09723 https://pubs.acs.org/doi/10.1021/jacs.3c09723

Installing ketones into a polymer backbone is a known method for introducing photodegradability into polymers; however, most current methods are limited to ethylene–carbon monoxide copolymerization. Here we use isocyanides in place of carbon monoxide in a copolymerization strategy to access degradable nonalternating poly(ketones) that either maintain or enhance the thermal properties. A cobalt-mediated radical polymerization of acrylates and isocyanides synthesizes nonalternating poly(acrylate-co-isocyanide) copolymers with tunable incorporation using monomer feed ratios. The kinetic product of the polymerization is a dynamic β-imine ester that tautomerizes to the β-enamine ester. Hydrolysis of this copolymer affords a third copolymer microstructure─the elusive nonalternating poly(ketone)─from a single copolymerization strategy. Analysis of the copolymer properties demonstrates tunable thermal properties with the degree of incorporation. Finally, we show that poly(acrylate-co-isocyanide) and poly(acrylate-co-ketone) are photodegradable with 390 nm light, enabling chain cleavage.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/jacs.3c04595 https://pubs.acs.org/doi/10.1021/jacs.3c04595

Realizing the dual emission of fluorescence–phosphorescence in a single system is an extremely important topic in the fields of biological imaging, sensing, and information encryption. However, the phosphorescence process is usually in an inherently “dark state” at room temperature due to the involvement of spin-forbidden transition and the rapid non-radiative decay rate of the triplet state. In this work, we achieved luminescent harvesting of the dark phosphorescence processes by coupling singlet-triplet molecular emitters with a rationally designed plasmonic cavity. The achieved Purcell enhancement effect of over 1000-fold allows for overcoming the triplet forbidden transitions, enabling radiation enhancement with selectable emission wavelengths. Spectral results and theoretical simulations indicate that the fluorescence–phosphorescence peak position can be intelligently tailored in a broad range of wavelengths, from visible to near-infrared. Our study sheds new light on plasmonic tailoring of molecular emission behavior, which is crucial for advancing research on plasmon-tailored fluorescence–phosphorescence spectroscopy in optoelectronics and biomedicine.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05496 https://pubs.acs.org/doi/10.1021/jacs.3c05496

Carbon is a primary element to constitute organic molecules, while metal catalysis is a basic tool in organic synthesis. The establishment of a link between the ubiquitous carbon bonding and metal catalysis is thus a fundamentally important problem. However, there is yet no experimental example to introduce the role of carbon bonding in a metal catalysis process. Herein, we merged the topics of carbon bonding and metal catalysis together and demonstrated that a supramolecular carbon-bonding metal complex can not only give rise to catalytic activity but, more remarkably, direct structural-isomer selection events in gold-catalyzed reactions. The experimental results unveil the fact that the imposing of weak carbon-bonding interactions on a gold complex can alter the carbene as well as the Lewis acid property of these catalysts. These results illustrate a non-negligible role of weak carbon-bonding interactions in the modulation of metal catalysis. As such, carbon-bonding metal catalysis is suggested to be used as a routine tool not only in the development of reactions but more frequently in analyzing reaction processes in metal catalysis.

]]> Tue, 05 Sep 2023 00:00:00 GMT 10.1021/jacs.3c07551 https://pubs.acs.org/doi/10.1021/jacs.3c07551

The development of inhibitors that selectively block protein–protein interactions (PPIs) is crucial for chemical biology, medicinal chemistry, and biomedical sciences. Herein, we reported the design, synthesis, and investigation of sulfonyl-γ-AApeptide as an alternative strategy of canonical peptide-based inhibitors to disrupt hypoxia-inducible factor 1α (HIF-1α) and p300 PPI by mimicking the helical domain of HIF-1α involved in the binding to p300. The designed molecules recognized the p300 protein with high affinity and potently inhibited the hypoxia-inducible signaling pathway. Gene expression profiling supported the idea that the lead molecules selectively inhibited hypoxia-inducible genes involved in the signaling cascade. Our studies also demonstrated that both helical faces consisting of either chiral side chains or achiral sulfonyl side chains of sulfonyl-γ-AApeptides could be adopted for mimicry of the α-helix engaging in PPIs. Furthermore, these sulfonyl-γ-AApeptides were cell-permeable and exhibited favorable stability and pharmacokinetic profiles. Our results could inspire the design of helical sulfonyl-γ-AApeptides as a general strategy to mimic the protein helical domain and modulate many other PPIs.

]]> Mon, 04 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06694 https://pubs.acs.org/doi/10.1021/jacs.3c06694

Senolytics, which eliminate senescent cells from tissues, represent an emerging therapeutic strategy for various age-related diseases. Most senolytics target antiapoptotic proteins, which are overexpressed in senescent cells, limiting specificity and inducing severe side effects. To overcome these limitations, we constructed self-assembling senolytics targeting senescent cells with an intracellular oligomerization system. Intracellular aryl-dithiol-containing peptide oligomerization occurred only inside the mitochondria of senescent cells due to selective localization of the peptides by RGD-mediated cellular uptake into integrin αvβ3-overexpressed senescent cells and elevated levels of reactive oxygen species, which can be used as a chemical fuel for disulfide formation. This oligomerization results in an artificial protein-like nanoassembly with a stable α-helix secondary structure, which can disrupt the mitochondrial membrane via multivalent interactions because the mitochondrial membrane of senescent cells has weaker integrity than that of normal cells. These three specificities (integrin αvβ3, high ROS, and weak mitochondrial membrane integrity) of senescent cells work in combination; therefore, this intramitochondrial oligomerization system can selectively induce apoptosis of senescent cells without side effects on normal cells. Significant reductions in key senescence markers and amelioration of retinal degeneration were observed after elimination of the senescent retinal pigment epithelium by this peptide senolytic in an age-related macular degeneration mouse model and in aged mice, and this effect was accompanied by improved visual function. This system provides a strategy for the treatment of age-related diseases using supramolecular senolytics.

]]> Mon, 04 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06898 https://pubs.acs.org/doi/10.1021/jacs.3c06898

Functionalized polymer vesicles have been proven to be highly promising in biomedical applications due to their good biocompatibility, easy processability, and multifunctional responsive capacities. However, photothermal-responsive polymer vesicles triggered by near-infrared (NIR) light have not been widely reported until now. Herein, we propose a new strategy for designing NIR light-mediated photothermal polymer vesicles. A small molecule (PTA) with NIR-triggered photothermal features was synthesized by combining a D-D′-A-D′-D configuration framework with a molecular rotor function (TPE). The feasibility of the design strategy was demonstrated through density functional theory calculations. PTA moieties were introduced in the hydrophobic segment of a poly(ethylene glycol)-poly(trimethylene carbonate) block copolymer, of which the carbonate monomers were modified in the side chain with an active ester group. The amphiphilic block copolymers (PEG44-PTA2) were then used as building blocks for the self-assembly of photothermal-responsive polymer vesicles. The new class of functionalized polymer vesicles inherited the NIR-mediated high photothermal performance of the photothermal agent (PTA). After NIR laser irradiation for 10 min, the temperature of the PTA-Ps aqueous solution was raised to 56 °C. The photothermal properties and bilayer structure of PTA-Ps after laser irradiation were still intact, which demonstrated that they could be applied as a robust platform in photothermal therapy. Besides their photothermal performance, the loading capacity of PTA-Ps was investigated as well. Hydrophobic cargo (Cy7) and hydrophilic cargo (Sulfo-Cy5) were successfully encapsulated in the PTA-Ps. These properties make this new class of functionalized polymer vesicles an interesting platform for synergistic therapy in anticancer treatment.

]]> Mon, 04 Sep 2023 00:00:00 GMT 10.1021/jacs.3c07134 https://pubs.acs.org/doi/10.1021/jacs.3c07134 Mon, 04 Sep 2023 00:00:00 GMT 10.1021/jacs.3c07460 https://pubs.acs.org/doi/10.1021/jacs.3c07460

This paper describes the nature of the hydrogen bond (HB), B:---H–A, using valence bond theory (VBT). Our analysis shows that the most important HB interactions are polarization and charge transfer, and their corresponding sum displays a pattern that is identical for a variety of energy decomposition analysis (EDA) methods. Furthermore, the sum terms obtained with the different EDA methods correlate linearly with the corresponding VB quantities. The VBT analysis demonstrates that the total covalent-ionic resonance energy (RECS) of the HB portion (B---H in B:---H–A) correlates linearly with the dissociation energy of the HB, ΔEdiss. In principle, therefore, RECS(HB) can be determined by experiment. The VBT wavefunction reveals that the contributions of ionic structures to the HB increase the positive charge on the hydrogen of the corresponding external/free O–H bonds in, for example, the water dimer compared with a free water molecule. This increases the electric field of the external O–H bonds of water clusters and contributes to bringing about catalysis of reactions by water droplets and in water-hydrophobic interfaces.

]]> Mon, 04 Sep 2023 00:00:00 GMT 10.1021/jacs.3c08196 https://pubs.acs.org/doi/10.1021/jacs.3c08196

Removal of the CO2 impurities from C2H2/CO2 mixtures is an essential process to produce high-purity C2H2. Fabricating an adsorbent capable of discriminating these species, which have close kinetic diameters, is critical for developing advanced adsorption processes. Herein, we demonstrate a strategy to exploit the tunability of interlayer and intralayer spaces of two-dimensional (2D) layered metal–organic frameworks to achieve high performance for C2H2/CO2 separation. This indicates that interlayer symmetrical control can achieve more efficient packing of C2H2 into Ni(4-DPDS)2CrO4, with a high C2H2 capacity of 45.7 cm3·g–1 at 0.01 bar and a selectivity of 67.7 (298 K, 1 bar), which strikes a good balance between working capacity and separation selectivity compared to other isostructural Ni(4-DPDS)2MO4 (M = Mo, W). Crystallographic studies and DFT-D calculations reveal that such a C2H2-selective adsorbent possesses strong binding interactions due to the tailored pore confinement provided by the angular anions and rich electronic environment. Experimental breakthrough results comprehensively demonstrate the efficient C2H2/CO2 separation performance of this unique material.

]]> Sun, 03 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06138 https://pubs.acs.org/doi/10.1021/jacs.3c06138

Aryl corrins represent a novel class of designed B12 derivatives with biological properties of “antivitamins B12”. In our previous study, we experimentally determined bond strength in a series of aryl-corrins by the threshold collision-induced dissociation experiments (T-CID) and compared the measured bond dissociation energies (BDEs) with those calculated with density functional theory (DFT). We found that the BDEs are modulated by the side chains around the periphery of the corrin unit. Given that aryl cobinamides have many side chains that increase their conformational space and that the question of a specific structure, measured in the gas phase, was important for further evaluation of our T-CID experiment, we proceeded to analyze structural properties of aryl cobinamides using cryogenic ion vibrational predissociation (CIVP) spectroscopy, static DFT, and Born–Oppenheimer molecular dynamic (BOMD) simulations. We found that none of the examined DFT models could reproduce the CIVP spectra convincingly; both “static” DFT calculations and “dynamic” BOMD simulations provide a surprisingly poor representation of the vibrational spectra, specifically of the number, position, and intensity of bands assigned to hydrogen-bonded versus non-hydrogen-bonded NH and OH moieties. We conclude that, for a flexible molecule with ca. 150 atoms, more accurate approaches are needed before definitive conclusions about computed properties, specifically the structure of the ground-state conformer, may be made.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c03001 https://pubs.acs.org/doi/10.1021/jacs.3c03001

Preventing fluorophore photobleaching and unwanted blinking is crucial for single-molecule fluorescence (SMF) studies. Reductants achieve photoprotection via quenching excited triplet states, yet either require counteragents or, for popular alkyl-thiols, are limited to cyanine dye Cy3 protection. Here, we provide mechanistic and imaging results showing that the naturally occurring amino acid ergothioneine and its analogue dramatically enhance photostability for Cy3, Cy5, and their conformationally restrained congeners, providing a biocompatible universal solution for demanding fluorescence imaging.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c03058 https://pubs.acs.org/doi/10.1021/jacs.3c03058

Hepatic ischemia–reperfusion injury (HIRI) is mainly responsible for morbidity or death due to graft rejection after liver transplantation. During HIRI, superoxide anion (O2•–) and adenosine-5′-triphosphate (ATP) have been identified as pivotal biomarkers associated with oxidative stress and energy metabolism, respectively. However, how the temporal and spatial fluctuations of O2•– and ATP coordinate changes in HIRI and particularly how they synergistically regulate each other in the pathological mechanism of HIRI remains unclear. Herein, we rationally designed and successfully synthesized a dual-color and dual-reversible molecular fluorescent probe (UDP) for dynamic and simultaneous visualization of O2•– and ATP in real-time, and uncovered their interrelationship and synergy in HIRI. UDP featured excellent sensitivity, selectivity, and reversibility in response to O2•– and ATP, which rendered UDP suitable for detecting O2•– and ATP and generating independent responses in the blue and red fluorescence channels without spectral crosstalk. Notably, in situ imaging with UDP revealed for the first time synchronous O2•– bursts and ATP depletion in hepatocytes and mouse livers during the process of HIRI. Surprisingly, a slight increase in ATP was observed during reperfusion. More importantly, intracellular O2•–─succinate dehydrogenase (SDH)─mitochondrial (Mito) reduced nicotinamide adenine dinucleotide (NADH)─Mito ATP─intracellular ATP cascade signaling pathway in the HIRI process was unveiled which illustrated the correlation between O2•– and ATP for the first time. This research confirms the potential of UDP for the dynamic monitoring of HIRI and provides a clear illustration of HIRI pathogenesis.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c04303 https://pubs.acs.org/doi/10.1021/jacs.3c04303

Hierarchical self-assembly of Pt(II) metallacycles for the construction of functional materials has received considerable research interest, owing to their potential to meet increasing complexity and functionality demands while being based on well-defined scaffolds. However, the fabrication of long-range-ordered Pt(II) metallacycle-based two-dimensional hierarchical self-assemblies (2D HSAs) remains a challenge, primarily because of the limitations of conventional orthogonal noncovalent interaction (NCI) motifs and the intrinsic characteristics of Pt(II) metallacycles, making the delicate self-assembly processes difficult to control. Herein, we prepare well-regulated Pt(II)-metallacycle-based 2D HSAs through a directed strategy involving double cation−π interactions derived from C3-symmetric hexagonal Pt(II) metallacycles and C2-symmetric sodium phenate monomers. Spatially confined arrays of planar Pt(II) metallacycles and the selective growth of self-assemblies at desired locations are achieved by employing strong cation−π driving forces with well-defined directionality as the second orthogonal NCI, realizing the bottom-up, three-stage construction of Pt(II)-metallacycle-based 2D HSAs. The resultant 2D HSAs are applied as dual-mode catalysis platforms, which are loaded with two different nanocatalysts, one promoting catalytic oxidation and the other promoting photocatalytic reduction.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05143 https://pubs.acs.org/doi/10.1021/jacs.3c05143

A central goal of chemical and drug delivery sciences is to maximize the therapeutic efficacy of a given drug at the lowest possible dose. Here, we report a generalizable strategy that can be utilized to improve the delivery of mRNA drugs using lipid nanoparticles (LNPs), the clinically approved chemistry platforms utilized in the Moderna and Pfizer/BioNTech COVID-19 vaccines. In brief, our strategy updates the chemistry of LNPs to incorporate adenosine triphosphate (ATP) alongside mRNA, a modification that results in upward of a 79-fold increase in LNP-delivered mRNA-encoded protein expression in vitro and a 24-fold increase in vivo when compared to parent mRNA LNP formulations that do not contain ATP. Notably, we find that our ATP co-delivery strategy increases LNP-delivered mRNA-encoded protein expression across eight different LNP chemistries and three different cell lines, under normoxia and hypoxia, and in a well-tolerated fashion. Notably, our strategy also improves the expression of mRNA encoding for intracellular and secreted proteins both in vitro and in vivo, highlighting the utility of leveraging ATP co-delivery within mRNA LNPs as a means to increase protein expression. In developing this strategy, we hope that we have provided a simple yet powerful approach to improving mRNA LNPs that may one day be useful in developing therapies for human disease.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05574 https://pubs.acs.org/doi/10.1021/jacs.3c05574

Singlet exciton fission in organic chromophores has received much attention during the past decade. Inspired by numerous spectroscopic studies in the solid state, there have been vigorous efforts to study singlet exciton fission dynamics in covalently bonded oligomers, which aims to investigate underlying mechanisms of this intriguing process in simplified model systems. In terms of through-space orbital interactions, however, most of covalently bonded pentacene oligomers studied so far fall into weakly interacting systems since they manifest chain-like structures based on various (non)conjugated linkers. Therefore, it remains as a compelling question to answer how through-space interactions in the solid state intervene this photophysical process since it is hypersensitive to displacements and orientations between neighboring chromophores. Herein, as one of experimental studies to answer this question, we introduced a tight-packing dendritic structure whose mesityl-pentacene constituents are coupled via moderate through-space orbital interactions. Based on the comparison with a suitably controlled dendritic structure, which is in a weak coupling regime, important mechanistic viewpoints are tackled such as configurational mixings between singlet, charge-transfer, and triplet pair states and the role of chromophore multiplication. We underscore that our through-space-coupled dendritic oligomer in a quasi-intermediate coupling regime provides a hint on the interplay of multiconfigurational excited-states, which might have drawn complexity in singlet exciton fission kinetics throughout numerous solid-state morphologies.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c05660 https://pubs.acs.org/doi/10.1021/jacs.3c05660

Azonium ions formed by the protonation of tetra-ortho-methoxy-substituted aminoazobenzenes photoisomerize with red light under physiological conditions. This property makes them attractive as molecular tools for the photocontrol of physiological processes, for example, in photopharmacology. However, a mechanistic understanding of the photoisomerization process and subsequent thermal relaxation is necessary for the rational application of these compounds as well as for guiding the design of derivatives with improved properties. Using a combination of sub-ps/ns transient absorption measurements and quantum chemical calculations, we show that the absorption of a photon by the protonated E–H+ form of the photoswitch causes rapid (ps) isomerization to the protonated Z–H+ form, which can also absorb red light. Proton transfer to solvent then occurs on a microsecond time scale, leading to an equilibrium between Z and Z–H+ species, the position of which depends on the solution pH. Whereas thermal isomerization of the neutral Z form to the neutral E form is slow (∼0.001 s–1), thermal isomerization of Z–H+ to E–H+ is rapid (∼100 s–1), so the solution pH also governs the rate at which E/E–H+ concentrations are restored after a light pulse. This analysis provides the first complete mechanistic picture that explains the observed intricate photoswitching behavior of azonium ions at a range of pH values. It further suggests features of azonium ions that could be targeted for improvement to enhance the applicability of these compounds for the photocontrol of biomolecules.

]]> Fri, 01 Sep 2023 00:00:00 GMT 10.1021/jacs.3c06157 https://pubs.acs.org/doi/10.1021/jacs.3c06157

Aqueous dispersions of microporous nanocrystals with dry, gas-accessible pores─referred to as “microporous water”─enable high densities of gas molecules to be transported through water. For many applications of microporous water, generalizable strategies are required to functionalize the external surface of microporous particles to control their dispersibility, stability, and interactions with other solution-phase components─including catalysts, proteins, and cells─while retaining as much of their internal pore volume as possible. Here, we establish design principles for the noncovalent surface functionalization of hydrophobic metal–organic frameworks with amphiphilic polymers that render the particles dispersible in water and enhance their hydrolytic stability. Specifically, we show that block co-polymers with persistence lengths that exceed the micropore aperture size of zeolitic imidazolate frameworks (ZIFs) can dramatically enhance ZIF particle dispersibility and stability while preserving porosity and >80% of the theoretical O2 carrying capacity. Moreover, enhancements in hydrolytic stability are greatest when the polymer can form strong bonds to exposed metal sites on the external particle surface. More broadly, our insights provide guidelines for controlling the interface between polymers and ```