Non classé – Page 2

Manganese‐Catalysed Transfer Hydrogenation of Quinolines under Mild Conditions

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A PNP pincer manganese complex was applied as catalyst for transfer hydrogenation of quinolines with ammonia borane as hydrogen source. 1,2,3,4-Tetrahydroquinolines were obtained under mild conditions with good to excellent yields. 1,2-Dihydroquinolines were detected by ¹H NMR in the progress and isotopic labelling experiments were performed to determine the destination of ammonia-borane hydrogen atoms.

Abstract

Herein, an efficient methodology for the homogeneous manganese-catalysed transfer hydrogenation of N-heterocycles by using ammonia-borane as a hydrogen source under mild reaction conditions is reported. Good to excellent isolated yields are achieved by applying a PNP manganese pincer complex. In the reaction, 1,2-dihydroquinoline is detected as intermediate by NMR spectra analysis and deuterium labelling experiment. The catalytic reaction likely proceeded by an outer-sphere pathway based on the bifunctional pincer complex.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Xiaoxiao Chu, Guoren Zhou, Maofu Pang, Hongwu Zhang
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202300597

Diastereoselective Dearomatization of Chalcone‐Based Quinolinium Salts to Assemble Bridged Quinobenzazepine Polycycles

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Herein, we designed and synthesized a range of multi-functional chalcone-based quinolinium salts and their synthetic application in the rapid and straightforward construction of oxa-bridged quinobenzazepine polycycles was successfully explored.

Abstract

Quinobenzazepines are useful in medicinal chemistry, but their synthesis is very challenging. Herein, we designed and synthesized a range of multi-functional chalcone-based quinolinium salts; their synthetic application in the rapid and straightforward construction of quinobenzazepines was successfully explored. A wide range of oxa-bridged quinobenzazepine polycycles were afforded serendipitously through a dearomative cascade reaction of our newly developed quinolinium salts and acetylacetone. This synthetic strategy features high bond- and ring-forming efficiency and complete regio- and diastereoselective control.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Chengxiang Luo, Chaoyang Li, Lijie Zhang, Xiongli Liu, Pengfei Cheng, Qilin Wang
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202300688

Tuning the Stacking Modes of Ultrathin Two‐Dimensional Metal–Organic Framework Nanosheet Membranes for Highly Efficient Hydrogen Separation

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

The stacking of two-dimensional metal–organic framework (MOF) nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. The unique binary stacking modes of the [Cu₂Br(IN)₂]_n nanosheets offers a chance to understand the relationship between nanosheet stacking behaviors and the gas separation performance of the resulting membranes.

Abstract

Two-dimensional (2D) metal–organic framework (MOF) membranes are considered potential gas separation membranes of the next generation due to their structural diversity and geometrical functionality. However, achieving a rational structure design for a 2D MOF membrane and understanding the impact of MOF nanosheet stacking modes on membrane separation performance remain challenging tasks. Here, we report a novel kind of 2D MOF membrane based on [Cu₂Br(IN)₂]_n (IN=isonicotinato) nanosheets and propose that synergetic stacking modes of nanosheets have a significant influence on gas separation performance. The stacking of the 2D MOF nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. Our 2D MOF nanosheet membranes exhibit high gas separation performances for H₂/CH₄ (selectivity >290 with H₂ permeance >520 GPU) and H₂/CO₂ (selectivity >190 with H₂ permeance >590 GPU) surpassing the Robeson upper bounds, paving a potential way for eco-friendly H₂ separation.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shizheng Song, Wei Wang, Yali Zhao, Wufeng Wu, Yanying Wei, Haihui Wang
onlinelibrary.wiley.com/doi/10.1002/anie.202312995

Tetracopper σ‐Bound μ‐Acetylide and ‐Diyne Units Stabilized by a Naphthyridine‐based Dinucleating Ligand

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Reaction of two equivalents of a dicopper(I) tert-butoxide species with an appropriate acetylide synthon allowed the rational synthesis of a molecular tetracopper(I) acetylide, which possesses an unusual μ₄–η¹:η¹:η¹:η¹ coordination mode. This geometry opens the door to higher nuclearity homo- or heterometallic architectures, as demonstrated by the formation of a pentacopper(I) complex.

Abstract

Reactions of a dicopper(I) tert-butoxide complex with alkynes possessing boryl or silyl capping groups resulted in formation of unprecedented tetracopper(I) μ-acetylide/diyne complexes that were characterized by NMR and UV/Vis spectroscopy, mass spectrometry and single-crystal X-ray diffraction. These compounds possess an unusual μ₄–η¹:η¹:η¹:η¹ coordination mode for the bridging organic fragment, enforced by the rigid and dinucleating nature of the ligand utilized. Thus, the central π system remains unperturbed and accessible for subsequent reactivity and modification. This has been corroborated by addition of a fifth copper atom, giving rise to a pentacopper acetylide complex. This work may provide a new approach by which metal-metal cooperativity can be exploited in the transformation of acetylide and diyne groups to a variety of substrates, or as a starting point for the controlled synthesis of copper(I) alkyne-containing clusters.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Pablo Ríos, Matthew S. See, Rex C. Handford, Jason K. Cooper, T. Don Tilley
onlinelibrary.wiley.com/doi/10.1002/anie.202310307

Adaptive Supramolecular Networks: Emergent Sensing from Complex Systems

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Combining three supramolecular sensing elements in a single solution forms an adaptive network of equilibrating sensors. Fingerprint sensor-sensor and sensor-analyte interactions results in emergent photophysical responses, allowing for the discrimination of highly similar challenging analytes.

Abstract

Molecular differentiation by supramolecular sensors is typically achieved through sensor arrays, relying on the pattern recognition responses of large panels of isolated sensing elements. Here we report a new one-pot systems chemistry approach to differential sensing in biological solutions. We constructed an adaptive network of three cross-assembling sensor elements with diverse analyte-binding and photophysical properties. This robust sensing approach exploits complex interconnected sensor-sensor and sensor-analyte equilibria, producing emergent supramolecular and photophysical responses unique to each analyte. We characterize the basic mechanisms by which an adaptive network responds to analytes. The inherently data-rich responses of an adaptive network discriminate among very closely related proteins and protein mixtures without relying on designed protein recognition elements. We show that a single adaptive sensing solution provides better analyte discrimination using fewer response observations than a sensor array built from the same components. We also show the network’s ability to adapt and respond to changing biological solutions over time.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Allison J. Selinger, Fraser Hof
onlinelibrary.wiley.com/doi/10.1002/anie.202312407

Back Cover: Spatially Resolved Organic Whispering‐Gallery‐Mode Hetero‐Microrings for High‐Security Photonic Barcodes

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Whispering-gallery-mode (WGM) microcavities featuring distinguishable sharp peaks in a broadband exhibit enormous advantages in the field of miniaturized photonic barcodes. In their Research Article (e202310263), Zhenhua Gao, Yong Sheng Zhao et al. have developed a surface tension assisted heterogeneous assembly strategy to construct WGM hetero-microrings through regulating the charge-transfer (CT) interactions along circular boundaries, which remarkably promotes the security level and encoding capacity of the barcodes.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xingwei Feng, Ru Lin, Shuo Yang, Yuyu Xu, Tongjin Zhang, Shunwei Chen, Yingke Ji, Zifei Wang, Shiwei Chen, Chaofeng Zhu, Zhenhua Gao, Yong Sheng Zhao
onlinelibrary.wiley.com/doi/10.1002/anie.202313907

Photoinduced Cobalt Catalysis for the Reductive Coupling of Pyridines and Dienes Enabled by Paired Single‐Electron Transfer

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A mild, regioselective method for the hydropyridylation of diene feedstocks is reported, and is amenable to late-stage-functionalisation. Experiments and DFT calculations suggest a mechanism involving non-reversible hydrogen atom transfer, resulting in a reaction that is uniquely selective for dienes in the presence of other olefins.

Abstract

Selective hydroarylation of dienes has potential to provide swift access to useful building blocks. However, most existing methods rely on dienes stabilised by an aromatic group and transmetallation or nucleophilic attack steps require electron-rich aryl coupling partners. As such, there are few examples which tolerate wide-spread heteroarenes such as pyridine. Whilst allylic C−H functionalisation could be considered an alternative approach, the positional selectivity of unsymmetrical substrates is hard to control. Here, we report a general approach for selective hydropyridylation of dienes under mild conditions using metal catalysed hydrogen-atom transfer. Photoinduced, reductive conditions enable simultaneous formation of a cobalt-hydride catalyst and the persistent radical of easily-synthesised pyridyl phosphonium salts. This facilitates selective coupling of dienes in a traceless manner at the C4-position of a wide-range of pyridine substrates. The mildness of the method is underscored by its functional-group tolerance and demonstrated by applications in late-stage functionalisation. Based on a combination of experimental and computational studies, we propose a mechanistic pathway which proceeds through non-reversible hydrogen-atom transfer (HAT) from a cobalt hydride species which is uniquely selective for dienes in the presence of other olefins due to a much higher relative barrier associated with olefin HAT.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jingyang Qin, Manuel Barday, Samikshan Jana, Nil Sanosa, Ignacio Funes‐Ardoiz, Christopher J. Teskey
onlinelibrary.wiley.com/doi/10.1002/anie.202310639

Cover Picture: Regioselective and Stereospecific β‐Arabinofuranosylation by Boron‐Mediated Aglycon Delivery

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A highly efficient β-arabinofuranosylation utilizing boron-mediated aglycon delivery (BMAD) is presented by Kazunobu Toshima, Daisuke Takahashi, and co-workers in their Research Article (e202307015). The glycosylations proceeded smoothly for a variety of diols, triols, and unprotected sugar acceptors under mild conditions with predictable regioselectivity and complete β-stereoselectivity. Furthermore, the cover image shows that the regioselectivity in the BMAD reaction could be reversed by examining the reaction conditions and catalyst.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Kazuki Inaba, Yuna Naito, Mina Tachibana, Kazunobu Toshima, Daisuke Takahashi
onlinelibrary.wiley.com/doi/10.1002/anie.202313773

A Carbene Relay Strategy for Cascade Insertion Reactions

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

We streamline the synthesis of ketones and esters with multiple α-heteroatoms by sequentially generating two heteroatom metal carbenes using a designer I^(III)/S^(VI) reagent. This strategy enables the selective addition of oxygen, nitrogen, sulfur, or carbon atoms, incorporating up to three functional groups at the α-carbon of carbonyls in a single step.

Abstract

Insertion reactions that involve stabilized electrophilic metallocarbenes are of great importance for installing α-heteroatoms to carbonyl compounds. Nevertheless, the limited availability of carbene precursors restricts the introduction of only a single heteroatom. In this report, we describe a new approach based on an I^(III)/S^(VI) reagent that promotes the cascade insertion of heteroatoms. This is achieved by sequentially generating two α-heteroatom-substituted metal carbenes in one reaction. We found that this mixed I^(III)/S^(VI) ylide reacts efficiently with a transition metal catalyst and an X−H bond (where X=O, N). This transformation leads to the sequential formation of a sulfoxonium- and an X-substituted Rh-carbenes, enabling further reactions with another Y−H bond. Remarkably, a wide range of symmetrical and unsymmetrical α,α-O,O-, α,α-O,N-, and α,α-N,N-subsituted ketones can be prepared under mild ambient conditions. In addition, we successfully demonstrated other cascades, such as CN/CN double amidation, C−H/C−S double insertion, and C−S/Y−H double insertion (where Y=S, N, O, C). Notably, the latter two cascades enabled the simultaneous installation of three functional groups to the α-carbon of carbonyl compounds in a single step. These reactions demonstrate the versatility of our approach, allowing for the synthesis of ketones and esters with multiple α-heteroatoms using a common precursor.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Li Li, Chenggang Mi, Guanwang Huang, Meirong Huang, Yuyi Zhu, Shao‐Fei Ni, Zhaofeng Wang, Yong Huang
onlinelibrary.wiley.com/doi/10.1002/anie.202312793

Electrocatalytic Synthesis of Pyridine Oximes using in Situ Generated NH2OH from NO species on Nanofiber Membranes Derived from NH2‐MIL‐53(Al)

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A novel strategy of converting NO into pyridine oximes utilizing in situ generated NH₂OH for organophpsphorus poisoning is realized by electrocatalysis over Al coordinated on nanofiber membrane, which offers great significance to synthesize medicine and multidisciplinary science, providing new insights for constructing new efficient system for NH₂OH production and utilization.

Abstract

Pyridine oximes produced from aldehyde or ketone with hydroxylamine (NH₂OH) have been widely applied in pharmaceutics, enzymatic and sterilization. However, the important raw material NH₂OH exhibits corrosive and unstable properties, leading to substantial energy consumption during storage and transportation. Herein, this work presents a novel method for directly synthesizing highly valuable pyridine oximes using in situ generated NH₂OH from electrocatalytic NO reduction with well-design nanofiber membranes (Al-NFM) derived from NH₂-MIL-53(Al). Particularly, 2-pyridinealdoxime, the precursor of antidote pralidoxime (2-PAM) for nerve agents suffering from scarcity and high cost, was achieved with a Faraday efficiency up to 49.8 % and a yield of 92.1 %, attributing to the high selectivity of NH₂OH production on Al-NFM, further easily reacted with iodomethane to produce 2-PAM. This study proposes a creative approach, having wide universality for synthesizing pyridine and other oximes with a range of functional groups, which not only facilitates the conversion of exhaust gas (NO) and waste water (NO₂⁻) into valuable chemicals especially NH₂OH production and in situ utilization through electrochemistry, but also holds significant potential for synthesis of neuro detoxifying drugs to humanity security.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Runan Xiang, Shihan Wang, Peisen Liao, Fangyan Xie, Jiawei Kang, Suisheng Li, Jiahui Xian, Linna Guo, Guangqin Li
onlinelibrary.wiley.com/doi/10.1002/anie.202312239

A Photolabile Curcumin‐Diazirine Analogue Enables Phototherapy with Physically and Molecularly Produced Light for Alzheimer’s Disease Treatment

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A photolabile curcumin analogue CRANAD-147 is reported. It could lead to changes in properties, structures (sequences) and neurotoxicity of amyloid beta (Aβ) species in vitro and in transgenic 5xFAD mice in vivo with molecularly generated light (dubbed as “molecular light”) from chemiluminescence probe ADLumin-4. It has great potential as an alternative approach for AD drug discovery.

Abstract

The development of Alzheimer’s disease (AD) drugs has recently witnessed substantial achievement. To further enhance the pool of drug candidates, it is crucial to explore non-traditional therapeutic avenues. In this study, we present the use of a photolabile curcumin-diazirine analogue, CRANAD-147, to induce changes in properties, structures (sequences), and neurotoxicity of amyloid beta (Aβ) species both in cells and in vivo. This manipulation was achieved through irradiation with LED light or molecularly generated light, dubbed as “molecular light”, emitted by the chemiluminescence probe ADLumin-4. Next, aided by molecular chemiluminescence imaging, we demonstrated that the combination of CRANAD-147/LED or CRANAD-147/ADLumin-4 (molecular light) could effectively slow down the accumulation of Aβs in transgenic 5xFAD mice in vivo. Leveraging the remarkable tissue penetration capacity of molecular light, phototherapy employing the synergistic effect of a photolabile Aβ ligand and molecular light emerges as a promising alternative to conventional AD treatment interventions.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shi Kuang, Biyue Zhu, Jing Zhang, Fan Yang, Bo Wu, Weihua Ding, Liuyue Yang, Shiqian Shen, Seven H. Liang, Prasenjit Mondal, Mohanraja Kumar, Rudolph E. Tanzi, Can Zhang, Hui Chao, Chongzhao Ran
onlinelibrary.wiley.com/doi/10.1002/anie.202312519

Sulfonium Salt Reagents for the Introduction of Deuterated Alkyl Groups in Drug Discovery

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Versatile deuterated reagents, namely, d_n-alkyl sulfonium salts, d_n-alkyl halides, a d_n-alkyl azide, and a d_n-alkyl amine, were prepared and used to efficiently introduce d_n-alkyl groups into drug candidates and their analogues with complex skeletons. A liver microsomal metabolism study using 7-(d₂-ethoxy)flavone as a model compound revealed a significant deuterium kinetic isotope effect due to the installed d₂-ethoxy group.

Abstract

The pharmacokinetics of pharmaceutical drugs can be improved by replacing C−H bonds with the more stable C−D bonds at the α-position to heteroatoms, which is a typical metabolic site for cytochrome P450 enzymes. However, the application of deuterated synthons is limited. Herein, we established a novel concept for preparing deuterated reagents for the successful synthesis of complex drug skeletons with deuterium atoms at the α-position to heteroatoms. (d_n-Alkyl)diphenylsulfonium salts prepared from the corresponding nondeuterated forms using inexpensive and abundant D₂O as the deuterium source with a base, were used as electrophilic alkylating reagents. Additionally, these deuterated sulfonium salts were efficiently transformed into d_n-alkyl halides and a d_n-alkyl azide as coupling reagents and a d_n-alkyl amine as a nucleophile. Furthermore, liver microsomal metabolism studies revealed deuterium kinetic isotope effects (KIE) in 7-(d₂-ethoxy)flavone. The present concept for the synthesis of deuterated reagents and the first demonstration of a KIE in a d₂-ethoxy group will contribute to drug discovery research based on deuterium chemistry.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Kazuho Ban, Keisuke Imai, Shuki Oyama, Jin Tokunaga, Yui Ikeda, Hiromasa Uchiyama, Kazunori Kadota, Yuichi Tozuka, Shuji Akai, Yoshinari Sawama
onlinelibrary.wiley.com/doi/10.1002/anie.202311058

Rapidly Synthesized Single‐Ion Conductive Hydrogel Electrolyte for High‐Performance Quasi‐Solid‐State Zinc‐ion Batteries

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

Utilized sulfonic acid-modified COFs (TCOF-S) photo-catalyst to generate free radicals to trigger the rapid in situ light solidification of acrylamide in the pore channels of COFs. Formed TCOF-S-Gel has combined polymer gel electrolytes (PGE) with single-ion conductors (SICs) and make them complement each other.

Abstract

Single-ion conductive electrolytes can largely eliminate electrode polarization, reduce the proportion of anion migration and inhibit side reactions in batteries. However, they usually suffer from insufficient ion conductivity due to the strong interaction between cations and cationic receptors. Here we report an ultrafast light-responsive covalent organic frameworks (COF) with sulfonic acid groups modification as the acrylamide polymerization initiator. Benefiting from the reduced electrostatic interaction between Zn²⁺ and sulfonic acid groups through solvation effects, the as-prepared COF-based hydrogel electrolyte (TCOF-S-Gel) receives an ion conductivity of up to 27.2 mS/cm and Zn²⁺ transference number of up to 0.89. In addition, sufficient hydrogen bonds endow the single-ion conductive TCOF-S-Gel electrolyte to have good water retention and superb mechanical properties. The assembled Zn||TCOF-S-Gel||MnO₂ full zinc-ion battery exhibits high discharge capacity (248 mAh/g at 1C), excellent rate capability (90 mAh/g at 10C) and superior cycling performance. These enviable results enlist the instantaneously photocured TCOF-S-Gel electrolyte to be qualified to large-scaled flexible high-performance quasi-solid-state zinc-ion batteries.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Tianyu Qiu, Tonghui Wang, Wensi Tang, Yingqi Li, Yangguang Li, Xingyou Lang, Qing Jiang, Huaqiao Tan
onlinelibrary.wiley.com/doi/10.1002/anie.202312020

On‐Demand Activation of Transesterification by Chemical Amplification in Dynamic Thiol‐Ene Photopolymers

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

The potential of chemical amplification has been explored for the on-demand release of hydroxy groups in dynamic covalent thiol-ene photopolymers by controlled activation of a photoacid. In a domino effect fashion, a single photon event leads to a cascade of reactions, which ultimately endow the polymers with the ability to flow as a result of thermo-activated transesterification.

Abstract

Chemical amplification is a well-established concept in photoresist technology, wherein one photochemical event leads to a cascade of follow-up reactions that facilitate a controlled change in the solubility of a polymer. Herein, we transfer this concept to dynamic polymer networks to liberate both catalyst and functional groups required for bond exchange reactions under UV irradiation. For this, we exploit a photochemically generated acid to catalyse a deprotection reaction of an acid-labile tert-butoxycarbonyl group, which is employed to mask the hydroxy groups of a vinyl monomer. At the same time, the released acid serves as a catalyst for thermo-activated transesterifications between the deprotected hydroxy and ester moieties. Introduced in an orthogonally cured (450 nm) thiol-click photopolymer, this approach allows for a spatio-temporally controlled activation of bond exchange reactions, which is crucial in light of the creep resistance versus reflow ability trade-off of dynamic polymer networks.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Walter Alabiso, Bernhard Sölle, David Reisinger, Gema Guedes de la Cruz, Max Schmallegger, Thomas Griesser, Elisabeth Rossegger, Sandra Schlögl
onlinelibrary.wiley.com/doi/10.1002/anie.202311341

Design of an Oxygen‐Tolerant Photo‐RAFT System for Protein‐Polymer Conjugation Achieving High Bioactivity

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

This study explores the effects of ROS on protein activity and secondary structure during photocatalysis. Specifically, it offers valuable insights into synthesizing protein-polymer conjugates while preserving high enzymatic activity under mild and aerobic conditions. The EY/TEOA system is identified as the optimal method for preparing conjugates, offering a simple and robust strategy with excellent oxygen tolerance in a minimal reaction volume.

Abstract

Protein-polymer conjugates have significant potential in pharmaceutical and biomedical applications. To enable their widespread use, robust conjugation techniques are crucial. This study introduces a photo-initiated reversible addition-fragmentation chain-transfer (Photo-RAFT) polymerization system that exhibits excellent oxygen tolerance. This system allows for the synthesis of protein-polymer conjugates with high bioactivity under mild and aerobic conditions. Three photocatalytic systems utilizing Eosin Y (EY) as the photocatalyst with two different cocatalysts (ascorbic acid and triethanolamine) were investigated, each generating distinct reactive oxygen species (ROS) such as singlet oxygen, superoxide, hydrogen peroxide, and hydroxyl radicals. The impact of these ROS on three model proteins (lysozyme, albumin, and myoglobin) was evaluated, demonstrating varying bioactivities based on the ROS produced. The EY/TEOA system was identified as the optimal photo-RAFT initiating system, enabling the preparation of protein-polymer conjugates under aerobic conditions while maintaining high protein enzymatic activity. To showcase the potential of this approach, lysozyme-poly(dimethylaminoethyl acrylate) conjugates were successfully prepared and exhibited enhanced antimicrobial property against Gram-positive and Gram-negative bacteria.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Tong Zhang, Zilong Wu, Gervase Ng, Cyrille Boyer
onlinelibrary.wiley.com/doi/10.1002/anie.202309582

Hydrogen‐Bonded Organic Framework to Upgrade Cycling Stability and Rate Capability of Li‐CO2 Batteries

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A cyano hydrogen-bonded organic framework has been applied to a Li-CO₂ battery for the first time. The HOF endows Li-CO₂ batteries with significantly enhanced electrochemical performance in terms of rate capability and cycling stability.

Abstract

Elaborately designed multifunctional electrocatalysts capable of promoting Li⁺ and CO₂ transport are essential for upgrading the cycling stability and rate capability of Li-CO₂ batteries. Hydrogen-bonded organic frameworks (HOFs) with open channels and easily functionalized surfaces hold great potential for applications in efficient cathodes of Li-CO₂ batteries. Herein, a robust HOF_S (HOF-FJU-1) is introduced for the first time as a co-catalyst in the cathode material of Li-CO₂ batteries. HOF-FJU-1 with cyano groups located periodically in the pore can induce homogeneous deposition of discharge products and accommodate volumetric expansion of discharge products during cycling. Besides, HOF-FJU-1 enables effective interaction between Ru⁰ nanoparticles and cyano groups, thus forming efficient and uniform catalytic sites for CRR/CER. Moreover, HOF-FJU-1 with regularly arranged open channels are beneficial for CO₂ and Li⁺ transport, enabling rapid redox kinetic conversion of CO₂. Therefore, the HOF-based Li-CO₂ batteries are capable of stable operation at 400 mA g⁻¹ for 1800 h and maintain a low overpotential of 1.96 V even at high current densities up to 5 A g⁻¹. This work provides valuable guidance for developing multifunctional HOF-based catalysts to upgrade the longevity and rate capability of Li-CO₂ batteries.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Zhibin Cheng, Yanlong Fang, Yisi Yang, Hao Zhang, Zhiwen Fan, Jindan Zhang, Shengchang Xiang, Banglin Chen, Zhangjing Zhang
onlinelibrary.wiley.com/doi/10.1002/anie.202311480

Building Block‐Inspired Hybrid Perovskite Derivatives for Ferroelectric Channel Layers with Gate‐Tunable Memory Behavior

Par admin / 27 septembre 2023 27 septembre 2023 / Non classé

A building block assembling method allows a series of ferroelectric semiconductors of 2D hybrid perovskites to be constructed. The resulting species have unprecedent gate-tunable memory behaviors potentially boosting future non-volatile memory applications.

Abstract

Ferroelectric photovoltaics driven by spontaneous polarization (P_s) holds a promise for creating the next-generation optoelectronics, spintronics and non-volatile memories. However, photoactive ferroelectrics are quite scarce in single homogeneous phase, owing to the severe P_s fatigue caused by leakage current of photoexcited carriers. Here, through combining inorganic and organic components as building blocks, we constructed a series of ferroelectric semiconductors of 2D hybrid perovskites, (HA)₂(MA)_n-1Pb_nBr_3n+1 (n=1–5; HA=hexylamine and MA=methylamine). It is intriguing that their Curie temperatures are greatly enhanced by reducing the thickness of inorganic frameworks from MAPbBr₃ (n=∞, T_c=239 K) to n=2 (T_c=310 K, ΔT=71 K). Especially, on account of the coupling of room-temperature ferroelectricity (P_s≈1.5 μC/cm²) and photoconductivity, n=3 crystal wafer was integrated as channel field effect transistor that shows excellent a large short-circuit photocurrent ≈19.74 μA/cm². Such giant photocurrents can be modulated through manipulating gate voltage in a wide range (±60 V), exhibiting gate-tunable memory behaviors of three current states (“-1/0/1” states). We believe that this work sheds light on further exploration of ferroelectric materials toward new non-volatile memory devices.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Haojie Xu, Fapeng Sun, Wuqian Guo, Shiguo Han, Yi Liu, Qingshun Fan, Liwei Tang, Wei Liu, Junhua Luo, Zhihua Sun
onlinelibrary.wiley.com/doi/10.1002/anie.202309416

Sulfur Changes the Electrochemical CO2 Reduction Pathway over Cu Electrocatalysts

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

S atoms adsorbed on metallic Cu surfaces can significantly inhibit CO₂ reduction to CO while promoting formate formation in the electrochemical reduction of CO₂.

Abstract

Electrochemical CO₂ reduction to value-added chemicals or fuels offers a promising approach to reduce carbon emissions and alleviate energy shortage. Cu-based electrocatalysts have been widely reported as capable of reducing CO₂ to produce a variety of multicarbon products (e.g., ethylene and ethanol). In this work, we develop sulfur-doped Cu₂O electrocatalysts, which instead can electrochemically reduce CO₂ to almost exclusively formate. We show that a dynamic equilibrium of S exists at the Cu₂O-electrolyte interface, and S-doped Cu₂O undergoes in situ surface reconstruction to generate active S-adsorbed metallic Cu sites during the CO₂ reduction reaction (CO₂RR). Density functional theory (DFT) calculations together with in situ infrared absorption spectroscopy measurements show that the S-adsorbed metallic Cu surface can not only promote the formation of the *OCHO intermediate but also greatly suppress *H and *COOH adsorption, thus facilitating CO₂-to-formate conversion during the electrochemical CO₂RR.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shuyu Liang, Jiewen Xiao, Tianyu Zhang, Yue Zheng, Qiang Wang, Bin Liu
onlinelibrary.wiley.com/doi/10.1002/anie.202310740

BiBr3‐Mediated Intramolecular Aza‐Prins Cyclization of Aza‐Achmatowicz Rearrangement Products: Asymmetric Total Synthesis of Suaveoline and Sarpagine Alkaloids

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

An intramolecular Prins cyclization of aza-Achmatowicz rearrangement products was developed to construct the versatile 9-azabicyclo[3.3.1]nonane (9-ABN) ring system with a variety of substitution patterns and then applied to the asymmetric total synthesis of six suaveoline and sarpagine alkaloids: macrophylline, suaveoline, norsuaveoline, affinisine, normacusine B and N_a-Me-16-epipericyclivine.

Abstract

An intramolecular aza-Prins cyclization of aza-Achmatowicz rearrangement products was developed in which bismuth tribromide (BiBr₃) plays a dual role as an efficient Lewis acid and source of the bromide nucleophile. This approach enables the facile construction of highly functionalized 9-azabicyclo[3.3.1]nonanes (9-ABNs), which are valuable synthetic building blocks and a powerful platform for the synthesis of a variety of alkaloid natural products and drug molecules. Suitable substrates for the aza-Prins cyclization include 1,1-disubstituted alkenes, 1,2-disubstituted alkenes, alkynes, and allenes, with good to excellent yields observed. Finally, we showcase the application of this new approach to the enantioselective total synthesis of six indole alkaloids: (−)-suaveoline (1), (−)-norsuaveoline (2), (−)-macrophylline (3), (+)-normacusine B (4), (+)-N_a-methyl-16-epipericyclivine (5) and (+)-affinisine (6) in a total of 9–14 steps. This study significantly expands the synthetic utility of the aza-Achmatowicz rearrangement, and the strategy (aza-Achmatowicz/aza-Prins) is expected to be applicable to the total synthesis of other members of the big family of macroline and sarpagine indole alkaloids.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Wai Fung Cheng, Shiqiang Ma, Yin Tung Lai, Yuen Tsz Cheung, Kornkamon Akkarasereenon, Yiqin Zhou, Rongbiao Tong
onlinelibrary.wiley.com/doi/10.1002/anie.202311671

Efficient Intersystem Crossing and Long‐lived Charge‐Separated State Induced by Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole‐Bodipy Dyad

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

Through space intramolecular charge transfer, a compact electron donor-acceptor (cabazole-bodipy) dyad with face-to-face geometry exhibits long-lived charge-separated state (τ_CSS=24 ns) and efficient intersystem crossing (Φ_Δ=61 %). This discovery opens a new avenue for designing efficient photosensitizers and photonic applications that depend on long-lived excited states generation.

Abstract

The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (Φ_Δ=61 %) and long-lived triplet excited state (τ_T=186 μs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (Φ_Δ=0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τ_CSS=24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Hui Liang, Manlin Lu, Zafar Mahmood, Zheng Li, Zeduan Chen, Guowei Chen, Ming‐De Li, Yanping Huo, Shaomin Ji
onlinelibrary.wiley.com/doi/10.1002/anie.202312600

Nucleic Acid‐to‐Small Molecule Converter through Amplified Hairpin DNA Circuits

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

We realize the conversion of nucleic acid input into small molecule output using hairpin DNA circuits. The systems are combined with the biorthogonal Staudinger reduction to release fluorophore, dye, and anticancer agent triggered by oncogenic miR-21. Our approach would have great potential for efficient detection and chemotherapy of cancers based on nucleic acid expression profiles.

Abstract

Many microRNAs (miRNAs) are characteristically found in cancer cells, making miRNAs promising marker biomolecules for cancer diagnosis and therapeutics. However, it is challenging to use miRNA as a cancer signature because it is difficult to convert the nucleic acid sequence information into molecular functionality. To address this challenge, we realize nucleic acid-to-small molecule converters using hairpin DNA circuits. Harnessing a Staudinger reduction as a trigger for the conversion, we constructed hybridization chain reaction (HCR) and catalytic hairpin assembly (CHA) circuits that respond to oncogenic miR-21. Fluorophore and dye molecules were released in response to miR-21 through the HCR, providing fluorogenic and chromogenic readouts. Selective cytotoxicity in miR-21-abundant cells was realized by the CHA to release the anticancer drug SN-38. This would be the first example of selective activation of a small-molecule prodrug triggered by oncogenic miRNA in human living cells.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Kunihiko Morihiro, Yasuhiro Tomida, Daisuke Fukui, Manami Hasegawa, Akimitsu Okamoto
onlinelibrary.wiley.com/doi/10.1002/anie.202306587

Unravelling the Molecular Structure and Confining Environment of an Organometallic Catalyst Heterogenized within Amorphous Porous Polymers

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

Structural elucidation of active sites in amorphous host materials is demonstrated by combining cutting-edge NMR techniques with pair distribution function analysis and computational chemistry. The detailed structure of the heterogenized organometallic complex and its confinement within two amorphous porous organic polymers is revealed by computation and confirmed by dedicated NMR techniques.

Abstract

The catalytic activity of multifunctional, microporous materials is directly linked to the spatial arrangement of their structural building blocks. Despite great achievements in the design and incorporation of isolated catalytically active metal complexes within such materials, a detailed understanding of their atomic-level structure and the local environment of the active species remains a fundamental challenge, especially when these latter are hosted in non-crystalline organic polymers. Here, we show that by combining computational chemistry with pair distribution function analysis, ¹²⁹Xe NMR, and Dynamic Nuclear Polarization enhanced NMR spectroscopy, a very accurate description of the molecular structure and confining surroundings of a catalytically active Rh-based organometallic complex incorporated inside the cavity of amorphous bipyridine-based porous polymers is obtained. Small, but significant, differences in the structural properties of the polymers are highlighted depending on their backbone motifs.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Ribal Jabbour, Christopher W. Ashling, Thomas C. Robinson, Arafat Hossain Khan, Dorothea Wisser, Pierrick Berruyer, Ashta C. Ghosh, Alisa Ranscht, David A. Keen, Eike Brunner, Jérôme Canivet, Thomas D. Bennett, Caroline Mellot‐Draznieks, Anne Lesage, Florian M. Wisser
onlinelibrary.wiley.com/doi/10.1002/anie.202310878

Enantioselective Synthesis of Arylglycines via Pd‐Catalyzed Coupling of Schöllkopf Bis‐Lactim Ethers with Aryl Chlorides

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

Catalytic methylnaphthyl(XPhos)-palladium bromide promote the coupling of chiral tert-leucine-derived Schöllkopf bis-lactim ether with cheap aryl chlorides at room temperature in yields up to 95 % and >25 : 1 dr. This enables a convenient access to non-natural tertiary arylglycines, which are key structural motifs in several top-selling drugs. This protocol is also suitable for the late-stage functionalization of common pharmaceuticals.

Abstract

Arylglycines are important pharmacophores present in several top-selling drugs. This compound class has now been made accessible from abundant aryl chlorides by a Pd-catalyzed Schöllkopf-type amino acid synthesis. In the presence of the catalyst methylnaphthyl(XPhos)-palladium bromide, the base lithium 2,2,6,6-tetramethylpyrrolidide and the additive ZnCl₂, tert-leucine-derived bis-lactim ethers were efficiently arylated at room temperature, reaching yields of 95 % and diastereoselectivities of 98 : 2. Hydrolysis gave the corresponding arylglycines in high enantiomeric excess.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Daniel Sowa Prendes, Florian Papp, Nagesh Sankaran, Nardana Sivendran, Frederike Beyer, Christian Merten, Lukas J. Gooßen
onlinelibrary.wiley.com/doi/10.1002/anie.202309868

Frontier Molecular Orbital Engineering: Constructing Highly Efficient Narrowband Organic Electroluminescent Materials

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

This Minireview summarizes the research endeavors of narrowband organic electroluminescent materials, highlighting the tremendous contribution of frontier molecular orbital engineering strategy.

Abstract

It is of great strategic significance to develop highly efficient narrowband organic electroluminescent materials that can be utilized to manufacture ultra-high-definition (UHD) displays and meet or approach the requirements of Broadcast Television 2020 (B.T.2020) color gamut standards. This motif poses challenges for molecular design and synthesis, especially for developing generality, diversity, scalability, and robustness of molecular structures. The emergence of multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters has ingeniously solved the problems and demonstrated bright application prospects in the field of UHD displays, sparking a research boom. This Minireview summarizes the research endeavors of narrowband organic electroluminescent materials, with emphasis on the tremendous contribution of frontier molecular orbital engineering (FMOE) strategy. It combines the outstanding advantages of MR framework and donor-acceptor (D−A) structure, and can achieve red-shift and narrowband emission simultaneously, which is of great significance in the development of long-wavelength narrowband emitters with emission maxima especially exceeding 500 nm. We hope that this Minireview would provide some inspiration for what could transpire in the future.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yincai Xu, Qingyang Wang, Xinliang Cai, Chenglong Li, Shimei Jiang, Yue Wang
onlinelibrary.wiley.com/doi/10.1002/anie.202312451

Total Biosynthesis of Melleolides from Basidiomycota Fungi: Mechanistic Analysis of the Multifunctional GMC Oxidase Mld7

Par admin / 26 septembre 2023 26 septembre 2023 / Non classé

Investigation of the total biosynthesis of the melleolide sesquiterpenoids produced by Basidiomycota fungi revealed that the glucose-methanol-choline oxidase enzyme Mld7 is a key enzyme that catalyzes multistep reactions leading to two different types of melleolides. Notably, these two reactions are highly regulated by interaction with the cell membrane.

Abstract

Mushroom terpenoids are biologically and chemically diverse fungal metabolites. Among them, melleolides are representative sesquiterpenoids with a characteristic protoilludane skeleton. In this study, we applied a recently established hot spot knock-in method to elucidate the biosynthetic pathway leading to 1α-hydroxymelleolide. The biosynthesis of the sesquiterpene core involves the cytochrome P450 catalyzing stepwise hydroxylation of the Δ⁶-protoilludene framework and a stereochemical inversion process at the C5 position catalyzed by short-chain dehydrogenase/reductase family proteins. The highlight of the biosynthesis is that the flavoprotein Mld7 catalyzes an oxidation-triggered double-bond shift accompanying dehydration and acyl-group-assisted substitution with two different nucleophiles at the C6 position to afford the Δ⁷-protoilludene derivatives, such as melleolide and armillarivin. The complex reaction mechanism was proposed by DFT calculations. Of particular importance is that product distribution is regulated by interaction with the cell membrane.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Mitsunori Fukaya, Shota Nagamine, Taro Ozaki, Yaping Liu, Miina Ozeki, Taro Matsuyama, Kazunori Miyamoto, Hirokazu Kawagishi, Masanobu Uchiyama, Hideaki Oikawa, Atsushi Minami
onlinelibrary.wiley.com/doi/10.1002/anie.202308881