Non classé

Decarboxylative Borylation of Stabilized and Activated Carbon Radicals

Decarboxylative Borylation of Stabilized and Activated Carbon Radicals

A general decarboxylative borylation protocol of aliphatic and aromatic carboxylic acids has been developed. Both stabilized and activated aryl and alkyl radicals could be generated from the leaving‐group‐assisted N‐hydroxybenzimidoyl chloride esters, even trifluoroethyl substrates could be activated for further elaboration.

Abstract

Redox‐active esters (RAEs) as active radical precursors have been extensively studied for C−B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single‐electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group‐assisted N‐hydroxybenzimidoyl chloride esters, even α‐CF3 substituted substrates could be activated for further elaboration.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Qiang Zhang, Xiaojuan Li, Weigang Zhang, Shengyang Ni, Yi Wang, Yi Pan
doi.org/10.1002/anie.202008138

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Refolding of Cold‐Denatured Barstar Induced by Radio‐Frequency Heating: A New Method to Study Protein Folding by Real‐Time NMR Spectroscopy

Refolding of Cold‐Denatured Barstar Induced by Radio‐Frequency Heating: A New Method to Study Protein Folding by Real‐Time NMR Spectroscopy

A state‐of‐the‐art temperature‐jump probe head is used in combination with real‐time 2D NMR experiments to study the kinetics of folding of a cold‐denatured protein. Barstar contains two prolines that adopt a mix of cis and trans conformations in the cold‐denatured state. The high time resolution measurements reported here show evidence for multiple folding pathways related to proline isomerization.

Abstract

The C40A/C82A double mutant of barstar has been shown to undergo cold denaturation above the water freezing point. By rapidly applying radio‐frequency power to lossy aqueous samples, refolding of barstar from its cold‐denatured state can be followed by real‐time NMR spectroscopy. Since temperature‐induced unfolding and refolding is reversible for this double mutant, multiple cycling can be utilized to obtain 2D real‐time NMR data. Barstar contains two proline residues that adopt a mix of cis and trans conformations in the low‐temperature‐unfolded state, which can potentially induce multiple folding pathways. The high time resolution real‐time 2D‐NMR measurements reported here show evidence for multiple folding pathways related to proline isomerization, and stable intermediates are populated. By application of advanced heating cycles and state‐correlated spectroscopy, an alternative folding pathway circumventing the rate‐limiting cis‐trans isomerization could be observed. The kinetic data revealed intermediates on both, the slow and the fast folding pathway.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: György Pintér, Harald Schwalbe
doi.org/10.1002/anie.202006945

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B‐Site Co‐Alloying with Germanium Improves the Efficiency and Stability of All‐Inorganic Tin‐Based Perovskite Nanocrystal Solar Cells

B‐Site Co‐Alloying with Germanium Improves the Efficiency and Stability of All‐Inorganic Tin‐Based Perovskite Nanocrystal Solar Cells

CsSn0.6Ge0.4I3 nanocrystals have been synthesized for the first time by a B‐site co‐alloying strategy. The introduction of Ge effectively decreases the high density of intrinsic Sn defects, resulting in an extended excitonic lifetime and enhanced solar cell performance. The stability of the new nanocrystals also improves owing to the effective protection of Sn2+ against oxidation.

Abstract

Colloidal lead‐free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size‐tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead‐free solar cells, yet showing highly unstable characteristics in ambient conditions. Here, we propose the synthesis of all‐inorganic mixture Sn‐Ge perovskite nanocrystals, demonstrating the role of Ge2+ in stabilizing Sn2+ cation while enhancing the optical and photophysical properties. The partial replacement of Sn atoms by Ge atoms in the nanostructures effectively fills the high density of Sn vacancies, reducing the surface traps and leading to a longer excitonic lifetime and increased photoluminescence quantum yield. The resultant Sn‐Ge nanocrystals‐based devices show the highest efficiency of 4.9 %, enhanced by nearly 60 % compared to that of pure Sn nanocrystals‐based devices.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Maning Liu, Hannu Pasanen, Harri Ali‐Löytty, Arto Hiltunen, Kimmo Lahtonen, Syeda Qudsia, Jan‐Henrik Smått, Mika Valden, Nikolai V. Tkachenko, Paola Vivo
doi.org/10.1002/anie.202008724

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Oral Insulin Delivery Platforms: Strategies To Address the Biological Barriers

Oral Insulin Delivery Platforms: Strategies To Address the Biological Barriers

Oral insulin delivery holds great promise as a convenient and economical means of diabetes treatment. This Minireview provides an overview of representative advances in facilitating oral insulin delivery by overcoming biological barriers, including strategies centered on moieties‐mediated transport, cell‐penetrating peptide assisted permeation, smart oral robotics transport, and microenvironment‐responsive release.

Abstract

Diabetes mellitus is a lifelong metabolic disease that requires frequent subcutaneous injections of insulin. However, this method of administration can be associated with patient discomfort and local tissue infection. Oral delivery of insulin has been pursued as a more convenient method for diabetes treatment, given its likely superior patient compliance and convenience as well as cost‐effectiveness. However, various biological barriers hinder the clinical translation of oral insulin. The rapid development of nanotechnology over the last decade offers great promise in improving the bioavailability of oral insulin. This Minireview provides an overview of biological barriers to oral insulin delivery, summarizes significant technological advances, and outlines future perspectives in oral insulin formulations as well as their hypoglycaemic effects.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yufen Xiao, Zhongmin Tang, Junqing Wang, Chuang Liu, Na Kong, Omid C. Farokhzad, Wei Tao
doi.org/10.1002/anie.202008879

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N‐Bridged Acyclic Trimeric Poly‐Cyclodiphosphazanes: Highly Tuneable Cyclodiphosphazane Building Blocks

N‐Bridged Acyclic Trimeric Poly‐Cyclodiphosphazanes: Highly Tuneable Cyclodiphosphazane Building Blocks

We have synthesized a completely new family of acyclic trimeric cyclodiphosphazane compounds comprising NH, NiPr, NtBu and NPh bridging groups. These species possess both a highly tuneable intra‐terminal N(H)R moiety distance that can be readily modulated by varying the steric bulk of the bridging groups, in addition to topological flexibility upon incorporation of weak non‐bonding interactions.

Abstract

We have synthesized a completely new family of acyclic trimeric cyclodiphosphazane compounds comprising NH, NiPr, NtBu and NPh bridging groups. In addition, the first NH‐bridged acyclic dimeric cyclophosphazane has been produced. The trimeric species display highly tuneable characteristics so that the distance between the terminal N(H)R moieties can be readily modulated by the steric bulk present in the bridging groups (ranging from ≈6 to ≈10 Å). Moreover, these species exhibit pronounced topological changes when a weak non‐bonding NH⋅⋅⋅π aryl interaction is introduced. Finally, the NH‐bridged chloride binding affinities have been calculated and benchmarked along with the existing experimental data available for monomeric cyclodiphosphazanes. Our results underscore these species as promising hydrogen bond donors for supramolecular host–guest applications.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaoyan Shi, Felix León, Ying Sim, Shina Quek, Gavin Hum, Yi Xin Joycelyn Khoo, Zi Xuan Ng, Mian Yang Par, How Chee Ong, Varun K. Singh, Rakesh Ganguly, Jack K. Clegg, Jesús Díaz, Felipe García
doi.org/10.1002/anie.202008214

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Fragment‐Based Stabilizers of Protein–Protein Interactions through Imine‐Based Tethering

Fragment‐Based Stabilizers of Protein–Protein Interactions through Imine‐Based Tethering

A novel concept for optimizing orthosteric protein–protein interaction (PPI) stabilization is reported. Increasing interactions with the protein partner that contributes less to the composite binding pocket of the stabilizer (NF‐κB, red surface) results in increased stabilization, whereas further enhancing the interaction with the dominant partner protein (14‐3‐3, white surface) does not contribute to the stabilizing effect.

Abstract

Small‐molecule stabilization of protein–protein interactions (PPIs) is a promising concept in drug discovery, however the question how to identify or design chemical starting points in a “bottom‐up” approach is largely unanswered. We report a novel concept for identifying initial chemical matter for PPI stabilization based on imine‐forming fragments. The imine bond offers a covalent anchor for site‐directed fragment targeting, whereas its transient nature enables efficient analysis of structure–activity relationships. This bond enables fragment identification and optimisation using protein crystallography. We report novel fragments that bind specifically to a lysine at the PPI interface of the p65‐subunit‐derived peptide of NF‐κB with the adapter protein 14‐3‐3. Those fragments that subsequently establish contacts with the p65‐derived peptide, rather than with 14‐3‐3, efficiently stabilize the 14‐3‐3/p65 complex and offer novel starting points for molecular glues.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Madita Wolter, Dario Valenti, Peter J. Cossar, Laura M. Levy, Stanimira Hristeva, Thorsten Genski, Torsten Hoffmann, Luc Brunsveld, Dimitrios Tzalis, Christian Ottmann
doi.org/10.1002/anie.202008585

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Direct Intermediate Regulation Enabled by Sulfur Containers in Working Lithium–Sulfur Batteries

Direct Intermediate Regulation Enabled by Sulfur Containers in Working Lithium–Sulfur Batteries

Lithium polysulfide intermediates are directly regulated by the sulfur container PESn in working lithium sulfur batteries. Through reversible storage and release of the sulfur species, the container molecule converts small PSs into large organosulfur species, endowing changed electrochemical behaviors to lithium–sulfur batteries.

Abstract

Polysulfide intermediates (PSs), the liquid‐phase species of active materials in lithium–sulfur (Li‐S) batteries, connect the electrochemical reactions between insulative solid sulfur and lithium sulfide and are key to full exertion of the high‐energy‐density Li‐S system. Herein, the concept of sulfur container additives is proposed for the direct modification on the PSs species. By reversible storage and release of the sulfur species, the container molecule converts small PSs into large organosulfur species. The prototype di(tri)sulfide‐polyethylene glycol sulfur container is highly efficient in the reversible PS transformation to multiply affect electrochemical behaviors of sulfur cathodes in terms of liquid‐species clustering, reaction kinetics, and solid deposition. The stability and capacity of Li‐S cells was thereby enhanced. The sulfur container is a strategy to directly modify PSs, enlightening the precise regulation on Li‐S batteries and multi‐phase electrochemical systems.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jin Xie, Yun‐Wei Song, Bo‐Quan Li, Hong‐Jie Peng, Jia‐Qi Huang, Qiang Zhang
doi.org/10.1002/anie.202008911

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Suppressing Strong Exciton–Phonon Coupling in Blue Perovskite Nanoplatelet Solids by Binary Systems

Suppressing Strong Exciton–Phonon Coupling in Blue Perovskite Nanoplatelet Solids by Binary Systems

The effective suppression of exciton–phonon interactions of blue emissive CsPbBr3 nanoplatelets (NPLs) is realized by constructing binary NPL systems. The exciton–phonon coupling strength can be significantly reduced two times. Additionally, the energy transfer between binary NPLs originated from Förster resonance energy transfer (FRET) effect occurs within picoseconds, efficiently competing with the phonon interactions.

Abstract

Quasi‐two‐dimensional (2D) perovskites are promising candidates for light generation owing to their high radiative rates. However, strong exciton–phonon interactions caused by mechanical softening of the surface act as a bottleneck in improving their suitability for a wide range of lighting and display applications. Moreover, it is not easily available to tune the phonon interactions in bulk films. Here, we adopt bottom‐up fabricated blue emissive perovskite nanoplatelets (NPLs) as model systems to elucidate and as well as tune the phonon interactions via engineering of binary NPL solids. By optimizing component domains, the phonon coupling strength can be reduced by a factor of 2 driven by the delocalization of 2D excitons in out‐of‐plane orientations. It shows the picosecond energy transfer originated from the Förster resonance energy transfer (FRET) efficiently competes with the exciton–phonon interactions in the binary system.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shaomin Peng, Qi Wei, Bingzhe Wang, Zhipeng Zhang, Hongcheng Yang, Guotao Pang, Kai Wang, Guichuan Xing, Xiao Wei Sun, Zikang Tang
doi.org/10.1002/anie.202009193

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A Mechanochemical Reaction Cascade for Controlling Load‐Strengthening of a Mechanochromic Polymer

A Mechanochemical Reaction Cascade for Controlling Load‐Strengthening of a Mechanochromic Polymer

A mechanochemical reaction cascade for controlling load‐strengthening of a mechanochromic polymer is realized by using two comb polymers, each containing either spirothiopyran or a Diels–Alder adduct in the proximity of the branch points. The threshold force to trigger crosslinking is increased by ca. 1 nN and the minimum concentration of mechanophores required for crosslinking is decreased by 100‐fold compared to previous examples.

Abstract

We demonstrate an intermolecular reaction cascade to control the force which triggers crosslinking of a mechanochromic polymer of spirothiopyran (STP). Mechanochromism arises from rapid reversible force‐sensitive isomerization of STP to a merocyanine, which reacts rapidly with activated C=C bonds. The concentration of such bonds, and hence the crosslinking rate, is controlled by force‐dependent dissociation of a Diels–Alder adduct of anthracene and maleimide. Because the adduct requires ca. 1 nN higher force to dissociate at the same rate as that of STP isomerization, the cascade limits crosslinking to overstressed regions of the material, which are at the highest rate of material damage. Using comb polymers decreased the minimum concentration of mechanophores required to crosslinking by about 100‐fold compared to previous examples of load‐strengthening materials. The approach described has potential for controlling a broad range of reaction sequences triggered by mechanical load.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yifei Pan, Huan Zhang, Piaoxue Xu, Yancong Tian, Chenxu Wang, Shishuai Xiang, Roman Boulatov, Wengui Weng
doi.org/10.1002/anie.202010043

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Electrochemically Induced Metal–Organic‐Framework‐Derived Amorphous V2O5 for Superior Rate Aqueous Zinc‐Ion Batteries

Electrochemically Induced Metal–Organic‐Framework‐Derived Amorphous V2O5 for Superior Rate Aqueous Zinc‐Ion Batteries

In situ electrochemical induction of crystalline V2O3‐containing MIL‐88B(V) and carbon material yields a composite termed a‐V2O5@C. The a‐V2O5@C composites displays appreciable electrochemical performance due to the unique amorphous structure of V2O5 and its composite state with carbon.

Abstract

The electrochemical performance of vanadium‐oxide‐based cathodes in aqueous zinc‐ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal–organic‐framework‐derived composite of amorphous V2O5 and carbon materials (a‐V2O5@C) for the first time, where V2O5 is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V2O5 with more isotropic Zn2+ diffusion routes and active sites, resulting in fast Zn2+ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a‐V2O5@C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shenzhen Deng, Zishun Yuan, Zhiwei Tie, Changda Wang, Li Song, Zhiqiang Niu
doi.org/10.1002/anie.202010287

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Pb18O8Cl15I5: A Polar Lead Mixed Oxyhalide with Unprecedented Architecture and Excellent Infrared Nonlinear Optical Properties

Pb18O8Cl15I5: A Polar Lead Mixed Oxyhalide with Unprecedented Architecture and Excellent Infrared Nonlinear Optical Properties

Noncentrosymmetric Pb18O8Cl15I5, the first mixed oxyhalide in the PbO–PbCl2–PbI2 system, was found to have an unprecedented structural architecture featuring two types of oxocentered Pb–O units with different dimensionality (see picture). Characterization based on the large single crystal revealed that Pb18O8Cl15I5 outperformed AgGaS2 in key properties for high‐performance infrared nonlinear optical materials (see picture).

Abstract

To develop high‐performance nonlinear optical (NLO) materials for infrared (IR) applications, we have applied a rational element‐composition design strategy and investigated the unexplored PbO–PbCl2–PbI2 system. By doing so, we discovered a new polar lead mixed oxyhalide, Pb18O8Cl15I5, the first synthetic metal oxyhalide combining both Cl and I. Pb18O8Cl15I5 reveals an unprecedented structural feature with two different dimensional types of oxocentered Pb–O units, namely, [O4Pb8]8+ clusters and [OPb2]2+ chains. Centimeter‐sized single crystals of Pb18O8Cl15I5 have been successfully grown under ambient conditions. Remarkably, Pb18O8Cl15I5 satisfies all fundamental yet rigorous criteria for high‐performance IR NLO materials, exhibiting the widest IR transparency (up to 16.0 μm) among oxide‐based crystals, strong second‐harmonic generation response (1.05×AgGaS2), superior birefringence (0.086 at 636 nm), and a high laser‐induced damage threshold (8.5×AgGaS2).

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xinglong Chen, Qun Jing, Kang Min Ok
doi.org/10.1002/anie.202009541

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An Overview on the Chemical N‐Functionalization of Sugars and Formation of N‐Glycosides

An Overview on the Chemical N‐Functionalization of Sugars and Formation of N‐Glycosides

The aim of this review is to present the advancement that took place in the field of N‐functionalization or N‐glycosylation by describing all the possible mechanistic pathways that had been followed till date and their outstanding applications. This review may also guide the readers to further explore this field.

Its even more than a centennial that the systematic researches of chemical alteration of sugars have been advancing. Out of all the interest in the field of N‐glycoside has assembled pace over the past few years. Therefore, N‐functionalization of sugar is one of the most fundamental modifications along with other group like azide, amide etc also play a remarkable role in the field of glycoscience. Different approaches to access structurally modified N‐glycosides in carbohydrate derivatives are reviewed. The goal of this review is to provide an overview of different way of N‐functionalization of amino sugar and induction of nitrogen scaffolds for the synthesis of various orthogonal protective groups of the N‐glycoside. The N‐functionalization of sugars designate as follows: (a) glycosylamine, (b) glycosyl azide, and (c) introduction of N‐functionality to the sugar for formation of N‐glycosides. This is the first review focus on N‐functionalization of sugars which will be a future scope that influence the readers to work in this area further.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Rekha Sangwan, Ariza Khanam, Pintu Kumar Mandal
doi.org/10.1002/ejoc.202000813

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Asymmetric α‐Chlorination of β‐Keto Esters Using Hypervalent Iodine‐Based Cl‐Transfer Reagents in Combination with Cinchona Alkaloid Catalysts

Asymmetric α‐Chlorination of β‐Keto Esters Using Hypervalent Iodine‐Based Cl‐Transfer Reagents in Combination with Cinchona Alkaloid Catalysts

Simple Cinchona alkaloids serve as nucleophilic organocatalysts to facilitate the enantioselective α‐chlorination of β‐keto esters by using hypervalent iodine‐based Cl‐transfer reagents

We herein report an unprecedented strategy for the asymmetric α‐chlorination of β‐keto esters with hypervalent iodine‐based Cl‐transfer reagents using simple Cinchona alkaloid catalysts. Our investigations support an α‐chlorination mechanism where the Cinchona species serves as a nucleophilic catalyst by reacting with the chlorinating agent to generate a chiral electrophilic Cl‐transfer reagent in situ. Using at least 20 mol‐% of the alkaloid catalyst allows for good yields and enantioselectivities for a variety of different β‐keto esters under operationally simple conditions.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Lotte Stockhammer, Johannes Schörgenhumer, Christopher Mairhofer, Mario Waser
doi.org/10.1002/ejoc.202001217

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Efficient Fused‐Ring Extension of A–D–A‐Type Non‐Fullerene Acceptors by a Symmetric Replicating Core Unit Strategy

Efficient Fused‐Ring Extension of A–D–A‐Type Non‐Fullerene Acceptors by a Symmetric Replicating Core Unit Strategy

Smart move! The extension of an aromatic fused‐ring core structure by the symmetric replicating core unit strategy is an effective approach to promoting the photovoltaic performance of A–D–A‐type non‐fullerene acceptors (NFAs; see figure). Upon pairing the extended structure LC81 with a wide‐bandgap polymer donor (PBT1‐C), the corresponding organic solar cells showed a much high power conversion efficiency (12.71 %) than that of the device based on the reference NFA, TPTT‐4F.

Abstract

The extension of fused aromatic ring core structures is beneficial for enhancing intramolecular charge transfer and effective π conjugation in A–D–A‐type (A=acceptor; D=donor) non‐fullerene acceptors (NFAs). In this work, a novel strategy involving the extension of a fused‐ring core by symmetrically replicating the core unit has been developed, and a novel symmetric fused‐12‐ring NFA, LC81, has been synthesized. When paired with the wide‐bandgap polymer donor PBT1‐C, the corresponding organic solar cells (OSCs) showed a high power conversion efficiency of 12.71 %, much higher than that of the device based on the reference NFA, TPTT‐4F. Moreover, the LC81‐based OSC displayed a lower energy loss and a better ambient stability than the TPTT‐4F‐based device. Our results indicate that the extension of the fused‐ring core by the symmetric replicating core unit strategy is an effective approach to promoting the photovoltaic characteristics of A–D–A‐type NFAs.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Tian Xia, Chao Li, Hwa Sook Ryu, Jing Guo, Jie Min, Han Young Woo, Yanming Sun
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000889

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Effect of Site‐Specific O‐Glycosylation on the Structural Behavior of NOTCH1 Receptor Extracellular EGF‐like Domains 11 and 10

Effect of Site‐Specific O‐Glycosylation on the Structural Behavior of NOTCH1 Receptor Extracellular EGF‐like Domains 11 and 10

Chemical synthesis facilitated construction of four EGF11 and five EGF10 modules having key O‐glycosylation states in NOTCH1 extracellular EGF‐like domains 11 and 10 (see figure). Comprehensive NMR studies highlighted the structural importance of the new type “sugar bridge” crosslinking Thr‐O‐GlcNAc in the consensus sequence C5‐X‐X‐G‐X‐(T/S)‐G‐X‐X‐C6 and an amino acid in the hinge region between the domains, 445Thr‐O‐GlcNAc—IIe451 in domain 11 and 405Thr‐O‐GlcNAc—Gln411 in domain 10, respectively.

Abstract

Human NOTCH1 receptor contains 36 epidermal growth factor (EGF)‐like repeating domains, in which O‐glycosylation status of EGF12 domain regulates the interaction with Notch ligands. Our interest is focused on the effect of specific O‐glycosylation states on the structural behavior of EGF11 and EGF10, because they appeared to affect molecular mechanism in receptor–ligand interactions by inducing some conformational alterations in these domains and/or the regions connecting two domains. To understand the structural impact of various O‐glycosylation patterns on the pivotal EGF‐like repeats 10, 11, and 12, we performed chemical synthesis and NMR studies of site‐specifically O‐glycosylated EGF11 and EGF10. Our strategy enabled us to synthesize four EGF11 and five EGF10 modules. The specific O‐glycosylation states affected in vitro folding of EGF10 more than EGF11, while calcium ion had a larger effect on EGF11 folding. Comprehensive NMR studies shed light on the new type “sugar bridges” crosslinking Thr‐O‐GlcNAc in the consensus sequence C5‐X‐X‐G‐X‐(T/S)‐G‐X‐X‐C6 and an amino acid in the hinge region between the domains, 445Thr‐O‐GlcNAc—IIe451 in domain 11 and 405Thr‐O‐GlcNAc—Gln411 in domain 10, respectively.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Yasuhiro Yokoi, Shin‐Ichiro Nishimura
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202002652

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Pseudocapacitive Lithium Storage of Cauliflower‐Like CoFe2O4 for Low‐Temperature Battery Operation

Pseudocapacitive Lithium Storage of Cauliflower‐Like CoFe2O4 for Low‐Temperature Battery Operation

Anode materials with a wide operating temperature are highly desirable for lithium‐ion batteries. A CoFe2O4 anode with a hierarchical cauliflower‐like structure (see figure) is presented that shows high specific capacities of 907.5 and 664.5 mAh g−1 at 0.1 A g−1 at 0 and −25 °C. The full‐cell battery assembled using cl‐CoFe2O4 as the anode and commercial LiFePO4 as the cathode displays a high capacity of 612.7 mAh g−1 at 0.3 A g−1 after 140 cycles and can be used to successfully turn on an LED light.

Abstract

Binary transition‐metal oxides (BTMOs) with hierarchical micro–nano‐structures have attracted great interest as potential anode materials for lithium‐ion batteries (LIBs). Herein, we report the fabrication of hierarchical cauliflower‐like CoFe2O4 (cl‐CoFe2O4) via a facile room‐temperature co‐precipitation method followed by post‐synthetic annealing. The obtained cauliflower structure is constructed by the assembly of microrods, which themselves are composed of small nanoparticles. Such hierarchical micro–nano‐structure can promote fast ion transport and stable electrode–electrolyte interfaces. As a result, the cl‐CoFe2O4 can deliver a high specific capacity (1019.9 mAh g−1 at 0.1 A g−1), excellent rate capability (626.0 mAh g−1 at 5 A g−1), and good cyclability (675.4 mAh g−1 at 4 A g−1 for over 400 cycles) as an anode material for LIBs. Even at low temperatures of 0 °C and −25 °C, the cl‐CoFe2O4 anode can deliver high capacities of 907.5 and 664.5 mAh g−1 at 100 mA g−1, respectively, indicating its wide operating temperature. More importantly, the full‐cell assembled with a commercial LiFePO4 cathode exhibits a high rate performance (214.2 mAh g−1 at 5000 mA g−1) and an impressive cycling performance (612.7 mAh g−1 over 140 cycles at 300 mA g−1) in the voltage range of 0.5–3.6 V. Kinetic analysis reveals that the electrochemical performance of cl‐CoFe2O4 is dominated by pseudocapacitive behavior, leading to fast Li+ insertion/extraction and good cycling life.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Honghong Fan, Farzaneh Bahmani, Yusuf Valentino Kaneti, Yanna Guo, Asma A. Alothman, Xinglong Wu, Yusuke Yamauchi, Wenliang Li, Jingping Zhang
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202001858

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