David B

Frontispiece: Molecular Engineering of Metal Alkoxides for Solution Phase Synthesis of High‐Tech Metal Oxide Nanomaterials

Frontispiece: Molecular Engineering of Metal Alkoxides for Solution Phase Synthesis of High‐Tech Metal Oxide Nanomaterials

The bottom‐up synthesis of inorganic nanomaterials with precision at the atomic/molecular level offers many opportunities for the design and betterment of the nanomaterials for various applications. Molecular engineering during soft chemical processing for the synthesis of functional nanomaterials enables the desired chemical and physical properties of the precursors, such as solubility or volatility, clean decomposition, control of stoichiometry for multimetallic species. For more information, see the Minireview by S. Mishra and S. Daniele on doi.org/10.1002/chem.202000534page 9292 ff.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Shashank Mishra, Stéphane Daniele
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202084272

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Frontispiece: Low‐Temperature Miniemulsion‐Based Routes for Synthesis of Metal Oxides

Frontispiece: Low‐Temperature Miniemulsion‐Based Routes for Synthesis of Metal Oxides

The use of miniemulsions containing chemical precursors in the disperse phase is a versatile method to produce nanoparticles and nanostructures of different chemical nature, including not only polymers, but also a variety of inorganic materials. The focus is on materials in which nanostructures of metal oxides are synthesized in processes that involve the miniemulsion technique in any of the steps. For more information, see the Minireview by R. Muñoz‐Espí and K. Landfester on doi.org/10.1002/chem.202001246page 9304 ff.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Rafael Muñoz‐Espí, Katharina Landfester
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202084273

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Solution Combustion Synthesis: Towards a Sustainable Approach for Metal Oxides

Solution Combustion Synthesis: Towards a Sustainable Approach for Metal Oxides

SCS : Solution combustion synthesis (SCS) is a low cost, simple, fast and energy efficient method to produce oxides with desired morphology. The final properties of the oxide materials can be fine‐tuned by controlling crucial parameters (fuel type, metal precursors, stoichiometry, pH). The growing application of printed metal oxide thin films at low temperature in electronic devices is a clear evidence that SCS is a vital step for next‐generation large‐scale electronics (see figure).

Abstract

Solution combustion synthesis (SCS) has been widely used to produce simple and complex oxides with a desired morphology (size and shape). SCS is valuable due to low cost, simplicity and energy efficient synthesis. To guarantee the best molecular‐level mixing of reactants in an aqueous or solvent‐based solution some parameters need to be controlled, such as fuel type, metal cations precursors, stoichiometry ratio (φ ), pH effect, atmosphere and initiation type. These determine the final properties of the oxide materials, providing the potential to reach different morphologies, which are essential for their final applications. This Review article focuses on the crucial parameters in SCS and how these affect the overall materials properties from nanostructures to thin films. To finalize, special attention is given to the application of SCS to form metal oxide thin films at low temperature and their application in thin film transistors (TFTs).

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Emanuel Carlos, Rodrigo Martins, Elvira Fortunato, Rita Branquinho
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000678

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Liquid‐Phase Synthesis of Iron Oxide Nanostructured Materials and Their Applications

Liquid‐Phase Synthesis of Iron Oxide Nanostructured Materials and Their Applications

Nanostructured iron oxides : This review article summarizes the liquid‐phase synthetic methods for iron oxide nanostructured materials, such as the co‐precipitation method, microemulsion method, conventional hydrothermal and solvothermal methods, microwave‐assisted heating method, sonochemical method, and other methods. In addition, the biomedical, environmental, and electrochemical energy storage applications of iron oxide nanostructured materials are discussed to emphasize their promising applications.

Abstract

Owing to their high natural abundance, low cost, easy availability, and excellent magnetic properties, considerable interest has been devoted to the synthesis and applications of iron oxide nanostructured materials. Liquid‐phase synthesis methods are economical and environmentally friendly with low energy consumption and volatile emissions, and as such have received much attention for the preparation of iron oxide nanostructured materials. Herein, the liquid‐phase synthesis methods of iron oxide nanostructured materials including the co‐precipitation method, microemulsion method, conventional hydrothermal and solvothermal methods, microwave‐assisted heating method, sonolysis method, and other methods are summarized and reviewed. Many iron oxide nanostructured materials, self‐assembled nanostructures, and nanocomposites have been successfully prepared, which are of great significance to enhance their structure‐dependent properties and applications. The specific roles of liquid‐phase chemical reaction parameters in regulating the chemical composition, structure, crystallinity, morphology, particle size, and dispersive behavior of the as‐prepared iron oxide nanostructured materials are emphasized. The biomedical, environmental, and electrochemical energy storage applications of iron oxide nanostructured materials are discussed. Finally, challenges and perspectives are proposed for future investigations on the liquid‐phase synthesis and applications of iron oxide nanostructured materials.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Heng Li, Ying‐Jie Zhu
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000679

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Photochemistry in the Low‐Temperature Processing of Metal Oxide Thin Films by Solution Methods

Photochemistry in the Low‐Temperature Processing of Metal Oxide Thin Films by Solution Methods

Photochemistry has emerged as a powerful tool for the low‐temperature processing of metal oxide thin films prepared by solution methods leading to 1) the synthesis of low‐temperature liquid precursors, 2) an enhanced decomposition of metal precursors, 3) a high degree of condensation and densification of the metal‐oxygen network, and 4) a prompt nucleation and growth of the crystalline phase.

Abstract

Photochemistry has emerged in the last few years as a powerful tool for the low‐temperature processing of metal oxide thin films prepared by solution methods. Today, its implementation into the fabrication procedure makes possible the integration of amorphous semiconductors or functional crystalline oxides into flexible electronic systems at temperatures below 350 °C. In this review, the effects of UV irradiation at the different stages of the chemical solution deposition of metal oxide thin films are presented. These stages include from the synthesis of the precursor solution to the formation of the amorphous metal‐oxygen network in the film and its subsequent crystallization into the oxide phase. Photochemical reactions that can be induced in both the solution deposited layer and the irradiation atmosphere are first described, highlighting the role of the potential reactive chemical species formed in the system under irradiation, such as free radicals or oxidizing compounds. Then, the photochemical effects of continuous UV light on the film are shown, focusing on the decomposition of the metal precursors, the condensation and densification of the metal‐oxygen network, and the nucleation and growth of the crystalline oxide. All these processes are demonstrated to advance the formation and crystallization of the metal oxide thin film to an earlier stage, which is ultimately translated into a lower temperature range of fabrication. The reduced energy consumption of the process upon decreasing the processing temperature, and the prospect of using light instead of heat in the synthesis of inorganic materials, make photochemistry as a promising technique for a sustainable future ever more needed in our life.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Iñigo Bretos, Ricardo Jiménez, Jesús Ricote, M. Lourdes Calzada
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000244

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Aqueous Chemical Solution Deposition of Functional Double Perovskite Epitaxial Thin Films

Aqueous Chemical Solution Deposition of Functional Double Perovskite Epitaxial Thin Films

Slow films : The use of polymers to control the growth of ceramic thin films can make it easier to produce materials for spintronic applications, which use electron spin instead of charge to carry information. Water‐soluble polymers bind to metal cations and slow down crystallization rates so that the most thermodynamically favored double perovskite structure films, with an optimal orientation and high magnetism for device applications, are formed.

Abstract

Double perovskite structure (A2BB′O6) oxides exhibit a breadth of multifunctional properties with a huge potential range of applications in fields as diverse as spintronics, magneto‐optic devices, or catalysis, and most of these applications require the use of thin films and heterostructures. Chemical solution deposition techniques are appearing as a very promising methodology to achieve epitaxial oxide thin films combining high performance with high throughput and low cost. In addition, the physical properties of these materials are strongly dependent on the ordered arrangement of cations in the double perovskite structure. Thus, promoting spontaneous cationic ordering has become a relevant issue. In this work, our recent achievements by using polymer‐assisted deposition (PAD) of environmentally friendly, water‐based solutions for the growth of epitaxial ferromagnetic insulating double perovskite La2CoMnO6 and La2NiMnO6 thin films on SrTiO3 and LaAlO3 single‐crystal substrates are presented. It is shown that the particular crystallization and growth process conditions of PAD (very slow rate, close to thermodynamic equilibrium conditions) promote high crystallinity and quality of the films, as well as favors spontaneous B‐site cationic ordering.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Hailin Wang, Carlos Frontera, Javier Herrero‐Martín, Alberto Pomar, Pere Roura, Benjamín Martínez, Narcis Mestres
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000129

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Cross‐Linked Polymers as Scaffolds for the Low‐Temperature Preparation of Nanostructured Metal Oxides

Cross‐Linked Polymers as Scaffolds for the Low‐Temperature Preparation of Nanostructured Metal Oxides

Linking up : An overview is presented on the current state of the art in the use of crosslinked organic polymers in the preparation of hybrid materials containing metal oxide nanoparticles into them. Both insoluble crosslinked polymers (resins) and soluble ones (micro‐ and nanogels) are considered. The review focuses on the synthetic strategies that have been proposed and sketches the current applications of the resulting materials.

Abstract

The current state of the art of the use of cross‐linked organic polymers, both insoluble (resins or gels) and soluble (micro‐ and nanogels), as aids for the low‐temperature preparation of stable metal oxide nanoparticles or nanostructured metal oxides is reviewed herein. Synthetic strategies for inorganic oxide nanomaterials of this kind can greatly benefit from the use of cross‐linked polymers, which may act as scaffolds/exotemplates during inorganic nanoparticle synthesis, or as stabilizers following post‐synthetic modification of the nanoparticles. Furthermore, the peculiar properties of the organic cross‐linked polymers add to those of the inorganic oxide nanoparticles, producing materials with combined properties. The potential applications of such highly promising composite nanomaterials will be also briefly sketched.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Paolo Centomo, Marco Zecca, Andrea Biffis
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000815

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Hierarchical Mn3O4 Anchored on 3D Graphene Aerogels via C−O−Mn Linkage with Superior Electrochemical Performance for Flexible Asymmetric Supercapacitor

Hierarchical Mn3O4 Anchored on 3D Graphene Aerogels via C−O−Mn Linkage with Superior Electrochemical Performance for Flexible Asymmetric Supercapacitor

Carbon nanohorns : An asymmetric supercapacitor was constructed by using graphene aerogels reacted either with Mn(AC)2 to form the anode or CNH to form the cathode (see scheme).

Abstract

Flexible asymmetric supercapacitors are more appealing in flexible electronics because of high power density, wide cell voltage, and higher energy density than symmetric supercapacitors in aqueous electrolyte. In virtues of excellent conductivity, rich porous structure and interconnected honeycomb structure, three dimensional graphene aerogels show great potential as electrode in asymmetric supercapacitors. However, graphene aerogels are rarely used in flexible asymmetric supercapacitors because of easily re‐stacking of graphene sheets, resulting in low electrochemical activity. Herein, flower‐like hierarchical Mn3O4 and carbon nanohorns are incorporated into three dimensional graphene aerogels to restrain the stack of graphene sheets, and are applied as the positive and negative electrode for asymmetric supercapacitors devices, respectively. Besides, a strong chemical coupling between Mn3O4 and graphene via the C‐O‐Mn linkage is constructed and can provide a good electron‐transport pathway during cycles. Consequently, the asymmetric supercapacitor device shows high rate cycle stability (87.8 % after 5000 cycles) and achieves a high energy density of 17.4 μWh cm−2 with power density of 14.1 mW cm−2 (156.7 mW cm−3) at 1.4 V.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Lishuang Fan, Yu Zhang, Zhikun Guo, Bing Sun, Da Tian, Yujie Feng, Naiqing Zhang, Kening Sun
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.201903947

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Solution‐Based, Anion‐Doping of Li4Ti5O12 Nanoflowers for Lithium‐Ion Battery Applications

Solution‐Based, Anion‐Doping of Li4Ti5O12 Nanoflowers for Lithium‐Ion Battery Applications

Flower power : Solution‐based, anionic doping represents a convenient strategy with which to improve upon the conductivity of candidate anode materials such as Li4Ti5O12. Here, Cl doping was optimized and fully characterized, with the resulting materials tested for application in lithium ion batteries.

Abstract

Solution‐based, anionic doping represents a convenient strategy with which to improve upon the conductivity of candidate anode materials such as Li4Ti5O12 (LTO). As such, novel synthetic hydrothermally‐inspired protocols have primarily been devised herein, aimed at the large‐scale production of unique halogen‐doped, micron‐scale, three‐dimensional, hierarchical LTO flower‐like motifs. Although fluorine (F) doping has been explored, the use of chlorine (Cl) dopants is the primary focus here. Several experimental variables, such as dopant amount, lithium hydroxide concentration, and titanium butoxide purity, were probed and perfected. Furthermore, the Cl doping process did not damage the intrinsic LTO morphology. The analysis, based on interpreting a compilation of SEM, XRD, XPS, and TEM‐EDS results, was used to determine an optimized dopant concentration of Cl. Electrochemical tests demonstrated an increased capacity via cycling of 12 % for a Cl‐doped sample as compared with pristine LTO. Moreover, the Cl‐doped LTO sample described in this study exhibited the highest discharge capacity yet reported at an observed rate of 2C for this material at 143mAh g−1. Overall, these data suggest that the Cl dopant likely enhances not only the ion transport capabilities, but also the overall electrical conductivity of our as‐prepared structures. To help explain these favorable findings, theoretical DFT calculations were used to postulate that the electronic conductivity and Li diffusion were likely improved by the presence of increased Ti3+ ion concentration coupled with widening of the Li migration channel.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Kenna L. Salvatore, Diana M. Lutz, Haoyue Guo, Shiyu Yue, Joceline Gan, Xiao Tong, Ping Liu, Esther S. Takeuchi, Kenneth J. Takeuchi, Amy C. Marschilok, Stanislaus S. Wong
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202002489

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High‐Activity Organocatalysts for Polyether Synthesis via Intramolecular Ammonium Cation Assisted SN2 Ring‐Opening Polymerization

High‐Activity Organocatalysts for Polyether Synthesis via Intramolecular Ammonium Cation Assisted SN2 Ring‐Opening Polymerization

A new organocatalyst that has unprecedented reactivity for ring‐opening polymerization of epoxides follows a novel intramolecular ammonium cation assisted mechanism. The bifunctional catalyst incorporates two 9‐borabicyclo[3.3.1]nonane centers on the two ends as Lewis acidic sites for epoxide activation and a quaternary ammonium halide in the middle as the initiating site.

Abstract

This manuscript describes a kind of bifunctional organocatalyst with unprecedented reactivity for the synthesis of polyethers via ring‐opening polymerization (ROP) of epoxides under mild conditions. The bifunctional catalyst incorporates two 9‐borabicyclo[3.3.1]nonane centers on the two ends as Lewis acidic sites for epoxide activation and a quaternary ammonium halide in the middle as the initiating site. The catalyst could be easily prepared in two steps from commercially available stocks on up to kilogram scale with ≈100 % yield. The organoboron catalyst mediated ROP of epoxides displays living behavior with low catalyst loading (5 ppm) and enables the synthesis of polyethers with molecular weights of over a million grams per mole (>106 g mol−1). Based on the investigations on crystal structure of catalyst, MALDI‐TOF, and 11B NMR spectroscopy, an intramolecular ammonium cation assisted SN2 mechanism is proposed and verified by DFT calculations.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Guan‐Wen Yang, Yao‐Yao Zhang, Rui Xie, Guang‐Peng Wu
doi.org/10.1002/anie.202002815

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Exploring the Labile Nature of 2,4,6‐Trimethoxyphenyl Moiety in Allylic Systems under Acidic Conditions

Exploring the Labile Nature of 2,4,6‐Trimethoxyphenyl Moiety in Allylic Systems under Acidic Conditions

A study aimed to comprehend the labile behavior of electron‐rich aryl groups connected to allylic framework under acidic medium is carried out. Reveresible protonation and deprotonation at the ipso‐carbon was found to be a driving factor in the C–C bond breaking reaction

An investigation of the unexpected lability of the Csp³–Csp² bond connecting 2,4,6‐trimethoxyphenyl group and an allylic moiety is carried out. We observed that the catalytic presence of either Lewis or Brønsted acid can render such 2,4,6‐trimethoxyphenyl group labile. Several nucleophiles were found to substitute the labile C–C bond in mild reaction conditions resulting in very good yields of the allylated products. Even in the absence of a nucleophile, intramolecular cyclization of the parent substrate under acidic activation caused the labile C–C bond to cleave. A major motivation of this study is to understand the lability of electron‐rich aryl group in acidic medium, employing 2,4,6‐trimethoxyphenyl moiety as a case study. A plausible mechanism is proposed after carrying out several control reactions as well as UV/Vis and 1H NMR spectroscopic studies. This work provides an insight into the activation of electron‐rich arenes as a labile entity in acidic medium while also adding a conceptually novel C–C bond breaking approach to the vast literature of allylation of arenes.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Dipankar Paul, Paresh Nath Chatterjee
doi.org/10.1002/ejoc.202000631

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ZIF‐Induced d‐Band Modification in a Bimetallic Nanocatalyst: Achieving Over 44 % Efficiency in the Ambient Nitrogen Reduction Reaction

ZIF‐Induced d‐Band Modification in a Bimetallic Nanocatalyst: Achieving Over 44 % Efficiency in the Ambient Nitrogen Reduction Reaction

A kinetically driven ambient nitrogen reduction reaction has a Faradaic efficiency of over 44 % and an ammonia yield rate of over 161 μg mgcat−1 h−1. It employs a zeolitic imidazole framework to induce electron‐deficient sites on the catalyst and a lower d‐band to weaken catalyst–H interactions whilst promoting the catalyst–N2 interaction.

Abstract

The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d‐band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat−1 h−1 under ambient conditions. The strategy lowers electrocatalyst d‐band position to weaken H adsorption and concurrently creates electron‐deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44‐fold compared to without ZIF (ca. 1 %). The Pt/Au‐NZIF interaction is key to enable strong N2 adsorption over H atom.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Howard Yi Fan Sim, Jaslyn Ru Ting Chen, Charlynn Sher Lin Koh, Hiang Kwee Lee, Xuemei Han, Gia Chuong Phan‐Quang, Jing Yi Pang, Chee Leng Lay, Srikanth Pedireddy, In Yee Phang, Edwin Kok Lee Yeow, Xing Yi Ling
doi.org/10.1002/anie.202006071

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MOFs Conferred with Transient Metal Centers for Enhanced Photocatalytic Activity

MOFs Conferred with Transient Metal Centers for Enhanced Photocatalytic Activity

Passing through : Highly effective photocatalysts for hydrogen evolution, driven by visible light, were developed by conferring the metal–organic framework (MOF) NH2‐MIL‐125(Ti) with active copper centers. The transient copper centers allow highly effective charge transfer, dramatically improving the carrier density, lifetime of the photogenerated charge, and photocatalytic activity.

Abstract

Highly effective photocatalysts for the hydrogen‐evolution reaction were developed by conferring the linkers of NH2‐MIL‐125(Ti), a metal–organic framework (MOF) constructed from TiOx clusters and 2‐aminoterephthalic acid (linkers), with active copper centers. This design enables effective transfer of electrons from the linkers to the transient Cu2+/Cu+ centers, leading to 7000‐fold and 27‐fold increase of carrier density and lifetime of photogenerated charges, respectively, as well as high‐rate production of H2 under visible‐light irradiation. This work provides a novel design of a photocatalyst for hydrogen evolution using non‐noble Cu2+/Cu+ as co‐catalysts.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaolang Chen, Shuning Xiao, Hao Wang, Wenchao Wang, Yong Cai, Guisheng Li, Minghua Qiao, Jian Zhu, Hexing Li, Dieqing Zhang, Yunfeng Lu
doi.org/10.1002/anie.202002375

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Improving Cancer Immunotherapy Outcomes Using Biomaterials

Improving Cancer Immunotherapy Outcomes Using Biomaterials

Immunotherapy is a promising strategy to treat tumors, but its low response rate and side effects are major challenges in clinical applications. This Minireview highlights a range of biomaterials with the potential to alter the tumor microenvironment to improve effectiveness and outcomes of cancer immunotherapy.

Abstract

Immunotherapy has made great strides in improving clinical outcomes in cancer treatment. However, few patients exhibit adequate response rates for key outcome measures and desired long‐term responses, and they often suffer systemic side effects due to the dynamic nature of the immune system. This has motivated a search for alternative strategies to improve unsatisfactory immunotherapeutic outcomes. In recent years, biomaterial‐assisted immunotherapy has shown promise in cancer treatment with improved therapeutic efficacy and reduced side effects. These biomaterials have illuminated fundamental mechanisms underlying the immunoediting process, while greatly improving the efficacy of chimeric antigen receptor (CAR) T‐cell therapy, cancer vaccine therapy, and immune checkpoint blockade therapy. This Minireview discusses recent advances in engineered biomaterials that address limitations associated with conventional cancer immunotherapies.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shuangqian Yan, Zichao Luo, Zhenglin Li, Yu Wang, Jun Tao, Changyang Gong, Xiaogang Liu
doi.org/10.1002/anie.202002780

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Hierarchical Structure of NiMo Hydrodesulfurization Catalysts Determined by Ptychographic X‐Ray Computed Tomography

Hierarchical Structure of NiMo Hydrodesulfurization Catalysts Determined by Ptychographic X‐Ray Computed Tomography

Ptychographic X‐ray computed tomography was used to investigate the structural make‐up of supported hydrodesulfurization catalysts. The results will allow for a better rationale of current generation catalyst performance as well as a better distribution of the active phase in next‐generation hydrodesulphurization catalysts.

Abstract

Hydrodesulphurization, the removal of sulphur from crude oils, is an essential catalytic process in the petroleum industry safeguarding the production of clean hydrocarbons. Sulphur removal is critical for the functionality of downstream processes and vital to the elimination of environmental pollutants. The effectiveness of such an endeavour is among other factors determined by the structural arrangement of the heterogeneous catalyst. Namely, the accessibility of the catalytically active molybdenum disulphide (MoS2) slabs located on the surfaces of a porous alumina carrier. Here, we examined a series of pristine sulfided Mo and NiMo hydrodesulphurization catalysts of increasing metal loading prepared on commercial alumina carriers using ptychographic X‐ray computed nanotomography. Structural analysis revealed a build consisting of two interwoven support matrix elements differing in nanoporosity. With increasing metal loading, approaching that of industrial catalysts, these matrix elements exhibit a progressively dissimilar MoS2 surface coverage as well as MoS2 cluster formation at the matrix element boundaries. This is suggestive of metal deposition limitations and/ or catalyst activation and following prohibitive of optimal catalytic utilization. These results will allow for diffusivity calculations, a better rationale of current generation catalyst performance as well as a better distribution of the active phase in next‐generation hydrodesulphurization catalysts.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Johannes Ihli, Leonid Bloch, Frank Krumeich, Klaus Wakonig, Mirko Holler, Manuel Guizar‐Sicairos, Thomas Weber, Julio Cesar Silva, Jeroen Anton Bokhoven
doi.org/10.1002/anie.202008030

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Observation of Collective Photoswitching in Free‐Standing TATA‐Based Azobenzenes on Au(111)

Observation of Collective Photoswitching in Free‐Standing TATA‐Based Azobenzenes on Au(111)

Photoswitching in a well‐ordered self‐assembled monolayer of freestanding azobenzene derivatives was studied on the molecular scale with in situ scanning tunneling microscopy, infrared absorption spectroscopy, and ab initio calculations, revealing cooperative effects. Although the intermolecular distances prevent direct contact, trans cis photoisomerization is enhanced by cis neighbors because the light‐induced excitation is localized.

Abstract

Light‐induced transitions between the trans and cis isomer of triazatriangulenium‐based azobenzene derivatives on Au(111) surfaces were observed directly by scanning tunneling microscopy, allowing atomic‐scale studies of the photoisomerization kinetics. Although the azobenzene units in these adlayers are free‐standing and spaced at uniform distances of 1.26 nm, their photoswitching depends on the isomeric state of the surrounding molecules and, specifically, is accelerated by neighboring cis isomers. These collective effects are supported by ab initio calculations indicating that the electronic excitation preferably localizes on the n –π* state of trans isomers with neighboring cis azobenzenes.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Talina R. Rusch, Alexander Schlimm, Nicolai R. Krekiehn, Tobias Tellkamp, Šimon Budzák, Denis Jacquemin, Felix Tuczek, Rainer Herges, Olaf M. Magnussen
doi.org/10.1002/anie.202003797

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Modular and Versatile Trans‐Encoded Genetic Switches

Modular and Versatile Trans‐Encoded Genetic Switches

Switch‐hitter : A bacterial genetic switch that accepts RNAs, small molecules, and proteins as inputs was developed based on a tRNA‐mimicking structure. The switch is trans‐encoded, which makes manipulation of the target mRNA redundant. It is stable to RNase, shows a strong dynamic response, and exhibits a high level of orthogonality.

Abstract

Current bacterial RNA switches suffer from lack of versatile inputs and are difficult to engineer. We present versatile and modular RNA switches that are trans‐encoded and based on tRNA‐mimicking structures (TMSs). These switches provide a high degree of freedom for reengineering and can thus be designed to accept a wide range of inputs, including RNA, small molecules, and proteins. This powerful approach enables control of the translation of protein expression from plasmid and genome DNA.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Avishek Paul, Eliza M. Warszawik, Mark Loznik, Arnold J. Boersma, Andreas Herrmann
doi.org/10.1002/anie.202001372

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Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Just a little magic : Single‐ensemble CdTeSe magic‐size clusters (MSC‐399) evolved at room temperature when binary CdTe and CdSe induction period samples were mixed and dispersed into a mixture of toluene (Tol) and octylamine (OTA). The OTA amount affects the rate of the apparent transformation from CdTe MSC‐371 into CdTeSe MSC‐399 through Steps 5/1, 3, and 6.

Abstract

Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F↔CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Hai Zhang, Chaoran Luan, Dong Gao, Meng Zhang, Nelson Rowell, Maureen Willis, Meng Chen, Jianrong Zeng, Hongsong Fan, Wen Huang, Xiaoqin Chen, Kui Yu
doi.org/10.1002/anie.202005643

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Photoactivated Polymersome Nanomotors: Traversing Biological Barriers

Photoactivated Polymersome Nanomotors: Traversing Biological Barriers

Delivery driver : Photo‐activated polymersome nanomotors (PNMs) composed of a biodegradable polymersome system coated with a hemisphere gold layer were utilized for intracellular delivery of molecular cargo via the assistance of a NIR laser. The active penetration of the cell membrane by the nanomotors allowed both encapsulated payloads and surrounding cargo to be delivered into cells.

Abstract

Synthetic nanomotors are appealing delivery vehicles for the dynamic transport of functional cargo. Their translation toward biological applications is limited owing to the use of non‐degradable components. Furthermore, size has been an impediment owing to the importance of achieving nanoscale (ca. 100 nm) dimensions, as opposed to microscale examples that are prevalent. Herein, we present a hybrid nanomotor that can be activated by near‐infrared (NIR)‐irradiation for the triggered delivery of internal cargo and facilitated transport of external agents to the cell. Utilizing biodegradable poly(ethylene glycol)‐b‐poly(d,l ‐lactide) (PEG‐PDLLA) block copolymers, with the two blocks connected via a pH sensitive imine bond, we generate nanoscopic polymersomes that are then modified with a hemispherical gold nanocoat. This Janus morphology allows such hybrid polymersomes to undergoing photothermal motility in response to thermal gradients generated by plasmonic absorbance of NIR irradiation, with velocities ranging up to 6.2±1.10 μm s−1. These polymersome nanomotors (PNMs) are capable of traversing cellular membranes allowing intracellular delivery of molecular and macromolecular cargo.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jingxin Shao, Shoupeng Cao, David S. Williams, Loai K. E. A. Abdelmohsen, Jan C. M. Hest
doi.org/10.1002/anie.202003748

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Dual‐Defects Adjusted Crystal‐Field Splitting of LaCo1−xNixO3−δ Hollow Multishelled Structures for Efficient Oxygen Evolution

Dual‐Defects Adjusted Crystal‐Field Splitting of LaCo1−xNixO3−δ Hollow Multishelled Structures for Efficient Oxygen Evolution

Vacant and distorted : The microstructure of hollow multishelled structure (HoMS) perovskite oxides combined with the dual‐defects of surface oxygen vacancies and lattice distortion tuned the crystal‐field splitting energy, which promotes the thermodynamic and kinetic processes for the oxygen evolution reaction (OER).

Abstract

To boost the performance for various applications, a rational bottom‐up design on materials is necessary. The defect engineering on nanoparticle at the atomic level can efficiently tune the electronic behavior, which offers great opportunities in enhancing the catalytic performance. In this paper, we optimized the surface oxygen vacancy concentration and created the lattice distortion in rare‐earth‐based perovskite oxide through gradient replacement of the B site with valence alternated element. The dual defects make the electron spin state transit from low spin state to high spin state, thus decreasing the charge transport resistance. Furthermore, assembly the modified nanoparticle subunits into the micro‐sized hollow multishelled structures can provide porous shells, abundant interior space and effective contact, which enables an enhanced mass transfer and a shorter charge transport path. As a result, the systemic design in the electronic and nano‐micro structures for catalyst has brought an excellent oxygen evolution performance.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Huan Wang, Jian Qi, Nailiang Yang, Wei Cui, Jiangyan Wang, Qinghao Li, Qinghua Zhang, Xiqian Yu, Lin Gu, Jiong Li, Ranbo Yu, Keke Huang, Shuyan Song, Shouhua Feng, Dan Wang
doi.org/10.1002/anie.202007077

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Jin Xie

Jin Xie

A good day at work starts with a fast read of just published papers … My favorite time of day is the morning when I discuss chemistry with my students in the labs … ” Find out more about Jin Xie in his Author Profile.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors:
doi.org/10.1002/anie.202009673

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Highly Enantioselective Iridium-Catalyzed Coupling Reaction of Vinyl Azides and Racemic Allylic Carbonates

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Min Han‡, Min Yang‡, Rui Wu, Yang Li, Tao Jia, Yuanji Gao, Hai-Liang Ni, Ping Hu, Bi-Qin Wang, and Peng Cao*
feedproxy.google.com/~r/acs/jacsat/~3/4KEreIh18ck/jacs.0c01766

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Intrinsically Active Surface in a Pt/?-Mo2N Catalyst for the Water–Gas Shift Reaction: Molybdenum Nitride or Molybdenum Oxide?

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Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Zhe-Shan Zhang†#, Qiang Fu†#, Kai Xu†, Wei-Wei Wang†, Xin-Pu Fu†, Xu-Sheng Zheng?, Ke Wu?, Chao Ma*§, Rui Si*‡, Chun-Jiang Jia*†, Ling-Dong Sun?, and Chun-Hua Yan?
feedproxy.google.com/~r/acs/jacsat/~3/yzxKw2mRt_4/jacs.9b11088

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