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avril 2023 – ChemDigest

Mois : avril 2023

Potential applications of Aggregation Induced Emission  active heterocyclic compounds

Potential applications of Aggregation Induced Emission  active heterocyclic compounds

Abstract

Heterocyclic compounds are used as a basic structural tool in medicinal chemistry and are very essential in our daily life. A wide range of heterocyclic compounds were reported to show in the literature with interesting biological and pharmacological properties. In their profound study on a series of several heterocyclic compounds shown to have bio applications, unfortunately, the aromatic π-conjugated heterocyclic molecules quench the emission intensity due to aggregation caused quenching due to π–π stacking. Owing to the disadvantages, the design and function of aggregation-induced emission (AIE) active heterocyclic materials were emerging abundantly. On the other note, AIE has often been used to further improve both the emission intensity and stability of compounds, with plenty of potential applications in chemical sensing and bioimaging. In this work, we comprehensively reviewed the recent progress in heterocyclic compounds with AIE characteristics that are effectively used in chemo-selective and bio-imaging or as highly selective sensors.

[EMIM]AlCl4‐ionic liquid catalyzed mechanochemically assisted synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐one and thione derivatives

[EMIM]AlCl4-ionic liquid catalyzed mechanochemically assisted synthesis of 3,4-dihydropyrimidin-2-(1H)-one and thione derivatives

Mechanochemically assisted [EMIM]AlCl4 catalyzed synthesis of DHPMs

Abstract

[EMIM]AlCl4 (1-ethyl-3-methylimidazolium tetrachloroaluminate) ionic liquid catalyzed mechanochemically assisted methodology for the Biginelli reaction has been developed successfully. One-pot, multicomponent reaction between ethyl/methyl acetoacetate, urea/thiourea, and various aromatic/aliphatic and heterocyclic aldehydes in presence of catalytic amount of [EMIM]AlCl4 under grinding conditions in ethanol affords 3,4-dihydropyrimidin-2-(1H)-one and its thione derivatives. Short reaction time, inclusion of eco-friendly solvent, moderate to high yield of the product, and operational simplicity are some of the noteworthy features of this protocol. In consequence, the described procedure finds an alternative way to existing methods for the synthesis of the titled compounds.

Chemoselective, Oxidation-Induced Macrocyclization of Tyrosine-Containing Peptides

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: E. Dalles Keyes, Marcus C. Mifflin, Maxwell J. Austin, Brighton J. Alvey, Lotfa H. Lovely, Andriea Smith, Tristin E. Rose, Bethany A. Buck-Koehntop, Jyoti Motwani, and Andrew G. Roberts
dx.doi.org/https://doi.org/10.1021/jacs.3c00210

Yb(OTf)3 Anchored on Crosslinked Chitosan Microsphere: A Green Heterogenized Catalyst for the Synthesis of Bispiro‐Fused Heterocycles

Yb(OTf)3 Anchored on Crosslinked Chitosan Microsphere: A Green Heterogenized Catalyst for the Synthesis of Bispiro-Fused Heterocycles

Yb(OTf)3 anchored on crosslinked chitosan microsphere (Yb(OTf)3@CCM) was prepared by facile processes. Using Yb(OTf)3@CCM as a green heterogeneous catalyst, the three-component [3+2] cycloaddition of isatins, tetrahydroisoquinolines and 5-alkenyl rhodanines was developed, which gave access to a suite of architecturally complex bispiro-fused heterocycles merging four pharmacophores.

Abstract

Using renewable biomass chitosan as a raw material, crosslinked chitosan microsphere (CCM) was prepared by inverse suspension, which was then immersed in the ethanol solution of Yb(OTf)3 to fabricate CCM-supported Yb(OTf)3 (Yb(OTf)3@CCM). The three-component [3+2] cycloaddition of isatins, tetrahydroisoquinolines and 5-alkenyl rhodanines was developed with Yb(OTf)3@CCM as a green heterogeneous catalyst, which gave access to a suite of architecturally complex bispiro-fused heterocycles merging four pharmacophores with moderate to excellent yields (50–96 %) and diastereoselectivities (up to 99 : 1 dr). The reaction mechanism was preliminarily clarified by controlled experiments and dynamic high-resolution mass spectrometry studies. The synthetic potential of this protocol was proved by a gram-scale reaction which furnished the product with comparable results (85 % yield and 72 : 28 dr). Moreover, the catalyst could be recovered just through filtering, washing and drying process, and reused five times with the catalytic activity remaining in an acceptable range (from 93 % to 73 % yield).

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Lin Chen, Wen‐Ya Jiao
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202300041

Apolipoprotein E Recognizes Alzheimer’s Disease Associated 3‐O Sulfation of Heparan Sulfate

Apolipoprotein E Recognizes Alzheimer's Disease Associated 3-O Sulfation of Heparan Sulfate

The interaction of Apolipoprotein E (ApoE) with cell surface Heparan Sulfate (HS) is enhanced by a rare, Alzheimer’s Disease linked 3-O-Sulfo group. This binding motif is shared with tau protein, suggesting a mechanism for ApoE/tau interactions in the association of certain ApoE isoforms with AD.

Abstract

Apolipoprotein E (ApoE)’s ϵ4 alle is the most important genetic risk factor for late onset Alzheimer’s Disease (AD). Cell-surface heparan sulfate (HS) is a cofactor for ApoE/LRP1 interaction and the prion-like spread of tau pathology between cells. 3-O-sulfo (3-O-S) modification of HS has been linked to AD through its interaction with tau, and enhanced levels of 3-O-sulfated HS and 3-O-sulfotransferases in the AD brain. In this study, we characterized ApoE/HS interactions in wildtype ApoE3, AD-linked ApoE4, and AD-protective ApoE2 and ApoE3-Christchurch. Glycan microarray and SPR assays revealed that all ApoE isoforms recognized 3-O-S. NMR titration localized ApoE/3-O-S binding to the vicinity of the canonical HS binding motif. In cells, the knockout of HS3ST1-a major 3-O sulfotransferase-reduced cell surface binding and uptake of ApoE. 3-O-S is thus recognized by both tau and ApoE, suggesting that the interplay between 3-O-sulfated HS, tau and ApoE isoforms may modulate AD risk.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Dylan Mah, Yanan Zhu, Guowei Su, Jing Zhao, Ashely Canning, James Gibson, Xuehong Song, Eduardo Stancanelli, Yongmei Xu, Fuming Zhang, Robert J. Linhardt, Jian Liu, Lianchun Wang, Chunyu Wang
onlinelibrary.wiley.com/doi/10.1002/anie.202212636

Formation and Loading of a (2S)‐2‐Ethylmalonamyl Starter Unit in the Assembly Line of Polyketide‐Nonribosomal Peptide Hybrid Sanglifehrin A

Formation and Loading of a (2S)-2-Ethylmalonamyl Starter Unit in the Assembly Line of Polyketide-Nonribosomal Peptide Hybrid Sanglifehrin A

The process for forming and loading a (2S)-2-ethylmalonamyl starter unit in the assembly line of sanglifehrin A is uncovered. This process involves two unusual enzymatic reactions that occur on a discrete acyl carrier protein (ACP): an amide synthetase catalyzes (2S)-2-ethylmalonyl amidation, and a homolog of β-ketoacyl-ACP synthase III transfers resultant (2S)-2-ethylmalonamyl onto the assembly line to prime the biosynthesis of sanglifehrin A.

Abstract

Sanglifehrin A (SFA) is a spirolactam-conjugated, 22-membered macrolide with remarkable immunosuppressive and antiviral activities. This macrolide is a result of a hybrid polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) assembly line that utilizes (2S)-2-ethylmalonamyl as a starter unit. Here, we report that the formation and loading of this starter unit in the SFA assembly line involve two unusual enzymatic reactions that occur on a discrete acyl carrier protein (ACP), SfaO. An amide synthetase, SfaP, catalyzes the amidation of (2S)-2-ethylmalonyl in a SfaO-dependent manner. Then, a β-ketoacyl-ACP synthase III-like protein, SfaN, transfers resultant (2S)-2-ethylmalonamyl from SfaO onto the loading ACP domain of the hybrid PKS-NRPS assembly line to prime SFA biosynthesis. Both SfaP and SfaN display promiscuous activities. This study furthers the appreciation of assembly line chemistry, as a new paradigm for unusual building block formation and incorporation is provided.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Zhijun Tang, Bo Pang, Chang Liu, Shengjie Guo, Xudong Qu, Wen Liu
onlinelibrary.wiley.com/doi/10.1002/anie.202217090

Inducing Covalent Atomic Interaction in Intermetallic Pt Alloy Nanocatalysts for High‐Performance Fuel Cells

Inducing Covalent Atomic Interaction in Intermetallic Pt Alloy Nanocatalysts for High-Performance Fuel Cells

By constructing covalent interaction bonding between Pt and Ga atoms, the developed L10−Pt2CuGa/C ORR catalyst shows efficient and stable performance in practical fuel cells. This work may provide a new strategy to enhance the performance of electrocatalysts via tuning the type of chemical bonds for electrochemical energy conversion.

Abstract

The harsh working environments of proton exchange membrane fuel cells (PEMFCs) pose huge challenges to the stability of Pt-based alloy catalysts. The widespread presence of metallic bonds with significantly delocalized electron distribution often lead to component segregation and rapid performance decay. Here we report L10−Pt2CuGa intermetallic nanoparticles with a unique covalent atomic interaction between Pt−Ga as high-performance PEMFC cathode catalysts. The L10−Pt2CuGa/C catalyst shows superb oxygen reduction reaction (ORR) activity and stability in fuel cell cathode (mass activity=0.57 A mgPt−1 at 0.9 V, peak power density=2.60/1.24 W cm−2 in H2-O2/air, 28 mV voltage loss at 0.8 A cm−2 after 30 000 cycles). Theoretical calculations reveal the optimized adsorption of oxygen intermediates via the formed biaxial strain on L10−Pt2CuGa surface, and the durability enhancement stems from the stronger Pt−M bonds than those in L11−PtCu resulted from Pt−Ga covalent interactions.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xuan Liu, Zhonglong Zhao, Jiashun Liang, Shenzhou Li, Gang Lu, Cameron Priest, Tanyuan Wang, Jiantao Han, Gang Wu, Xiaoming Wang, Yunhui Huang, Qing Li
onlinelibrary.wiley.com/doi/10.1002/anie.202302134

Molecule Saturation Boosts Acetylene Semihydrogenation Activity and Selectivity on a Core‐Shell Ruthenium@Palladium Catalyst

Molecule Saturation Boosts Acetylene Semihydrogenation Activity and Selectivity on a Core-Shell Ruthenium@Palladium Catalyst

An effective catalyst for semihydrogenation of acetylene was created by layering Pd on large Ru nanoparticles with terrace sites and a smaller lattice constant. The catalyst stabilizes unsaturated acetylene as it undergoes semihydrogenation while promoting ethylene desorption, thereby achieving high activity and selectivity at the same time.

Abstract

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

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Chuwei Zhu, Wenlong Xu, Fang Liu, Jie Luo, Junling Lu, Wei‐Xue Li
onlinelibrary.wiley.com/doi/10.1002/anie.202300110

A Fused [5]Helicene Dimer with a Figure‐Eight Topology: Synthesis, Chiral Resolution, and Electronic Properties

A Fused [5]Helicene Dimer with a Figure-Eight Topology: Synthesis, Chiral Resolution, and Electronic Properties

A Suzuki coupling-mediated macrocyclization followed by a Bi(OTf)3-catalyzed cyclization of a vinyl ether has led to the synthesis of a fused [5]helicene dimer with a figure-eight geometry, as confirmed by X-ray crystallographic analysis. The fully conjugated electronic structure and D2 symmetry results in the isolated enantiomers showing persistent chirality and large dissymmetric factors.

Abstract

Chiral shape-persistent molecular nanocarbons are promising chiroptical materials; their synthesis, however, remains a big challenge. Herein, we report the facile synthesis and chiral resolution of a double-stranded figure-eight carbon nanobelt 1 in which two [5]helicene units are fused together. Two synthetic routes were developed, and, in particular, a strategy involving Suzuki coupling-mediated macrocyclization followed by Bi(OTf)3-catalyzed cyclization of vinyl ether turned out to be the most efficient. The structure of 1 was confirmed by X-ray crystallographic analysis. The isolated (P,P)- and (M,M)- enantiomers show persistent chiroptical properties with relatively large dissymmetric factors (|gabs|=5.4×10−3 and |glum|=1.0×10−2), which can be explained by the effective electron delocalization along the fully conjugated belt and the unique D2 symmetry. 1 exhibits local aromatic character with a dominant structure containing eight Clar’s aromatic sextet rings.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Qifeng Zhou, Xudong Hou, Jinyi Wang, Yong Ni, Wei Fan, Zhengtao Li, Xiao Wei, Ke Li, Wei Yuan, Zhuofan Xu, Manzhou Zhu, Yanli Zhao, Zhe Sun, Jishan Wu
onlinelibrary.wiley.com/doi/10.1002/anie.202302266

X‐Ray‐triggered Carbon Monoxide and Manganese Dioxide Generation based on Scintillating Nanoparticles for Cascade Cancer Radiosensitization

X-Ray-triggered Carbon Monoxide and Manganese Dioxide Generation based on Scintillating Nanoparticles for Cascade Cancer Radiosensitization

X-ray-triggered carbon monoxide and manganese dioxide generation nanocomposites were fabricated with UV-responsive manganese carbonyl and radioluminescent scintillating nanoparticles. The glycolytic inhibition of carbon monoxide, coupled with the Mn2+-mediated Fenton-like activity of manganese dioxide, greatly boost the effect of radiotherapy.

Abstract

Carbon monoxide (CO) is an endogenous signaling molecule with broad therapeutic effects. Here, a multifunctional X-ray-triggered carbon monoxide (CO) and manganese dioxide (MnO2) generation nanoplatform based on metal carbonyl and scintillating nanoparticles (SCNPs) is reported. Attributed to the radioluminescent characteristic of SCNPs, UV-responsive Mn2(CO)10 is not only indirectly activated to release CO by X-ray but can also be degraded into MnO2. A high dose of CO can be used as a glycolytic inhibitor for tumor suppression; it will also sensitize tumor cells to radiotherapy. Meanwhile MnO2, as the photolytic byproduct of Mn2(CO)10, has both glutathione (GSH) depletion and Fenton-like Mn2+ delivery properties to produce highly toxic hydroxyl radical (⋅OH) in tumors. Thus, this strategy can realize X-ray-activated CO release, GSH depletion, and ⋅OH generation for cascade cancer radiosensitization. Furthermore, X-ray-activated Mn2+ in vivo demonstrates an MRI contrast effect, making it a potential theranostic nanoplatform.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Zhen Du, Xin Wang, Xiao Zhang, Zhanjun Gu, Xiaoyi Fu, Shaoju Gan, Ting Fu, Sitao Xie, Weihong Tan
onlinelibrary.wiley.com/doi/10.1002/anie.202302525

The Indenyl Effect: Accelerated C−H Amidation of Arenes via Ind*RhIII Nitrene Transfer Catalysis

The Indenyl Effect: Accelerated C−H Amidation of Arenes via Ind*RhIII Nitrene Transfer Catalysis**

The acyl silane directed C−H amidation of benzoyl silanes via nitrene transfer catalysis using 1,4,2-dioxazol-5-ones as the N-donor source was significantly accelerated in the presence of a heptamethylindenyl-rhodium catalyst (Ind*RhIII).

Abstract

Investigations into C−H amidation reactions catalysed by cationic half-sandwich d6 metal complexes revealed that the indenyl-derived catalyst [Ind*RhCl2]2 significantly accelerated the directed ortho C−H amidation of benzoyl silanes using 1,4,2-dioxazol-5-ones. Ring slippage involving a haptotropic η5 to η3 rearrangement of the indenyl complex proposedly enables ligand substitution at the metal centre to proceed via associative, rather than dissociative pathways, leading to significant rate and yield enhancements. Intriguingly, this phenomenon appears specific for C−H amidation reactions involving weakly coordinating carbonyl-based directing groups with no acceleration observed for the corresponding reactions involving strongly coordinating nitrogen-based directing groups.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Liselle Atkin, Daniel L. Priebbenow
onlinelibrary.wiley.com/doi/10.1002/anie.202302175

A Sustainable Wood‐Based Iron Photocatalyst for Multiple Uses with Sunlight: Water Treatment and Radical Photopolymerization

A Sustainable Wood-Based Iron Photocatalyst for Multiple Uses with Sunlight: Water Treatment and Radical Photopolymerization

A photocatalyst was made from demethylated lignin as sustainable source and Fe3O4. It can be used in environmental sciences to clean wastewater and in material sciences as a radical photoinitiator, resulting in crosslinking of vinyl monomers by radical photopolymerization. Films obtained showed good water repelling and no tackiness even in an aerobic surrounding.

Abstract

A sustainable photocatalyst for use with multiple purpose comprising demethylated lignin (Fe3O4@D-wood) was made by treatment of wood and iron oxide. Characterization followed by XRD, UV/Vis, photo-current studies, and electrochemical measurements. This material became subject of photocatalytic explorations for water treatment and material synthesis by radical photopolymerization. Exposure of Fe3O4@D-wood with artificial sunlight showed an improved activity considering photochemical oxidation of organic pollutants in the presence of H2O2. The efficient generation of reactive radicals brought this system also to photopolymerization. Here, radicals based on reactive oxygen species (ROS) generated in the catalytic cycle can be seen as the dominating species to initiate radical polymerization. A mixture of UDMA and TPGDA showed good reactivity with cumene hydroperoxide (CHP). Photocatalyst used for water treatment facilitates reuse for photopolymerization.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaolin Guo, Xinpeng Zhao, Xiongfei Luo, Yulian Pang, Bing Tian, Shouxin Liu, Shujun Li, Jian Li, Bernd Strehmel, Zhijun Chen
onlinelibrary.wiley.com/doi/10.1002/anie.202301242

Unveiling the Critical Role of Ion Coordination Configuration of Ether Electrolytes for High Voltage Lithium Metal Batteries

Unveiling the Critical Role of Ion Coordination Configuration of Ether Electrolytes for High Voltage Lithium Metal Batteries

A new ether solvent (1,3-dimethoxypropane, DMP) is used for the configuration of the electrochemical behavior of electrolytes in lithium metal batteris. The six-membered Li+-chelating ring greatly improves the oxidation stability of the ether-based electrolyte compared to the conventional five-membered chelate ring. The cathode-electrolyte interphase enriched in LiF effectively protects the nickel-rich cathode from corrosion by electrolyte side reactions.

Abstract

Albeit ethers are favorable electrolyte solvents for lithium (Li) metal anode, their inferior oxidation stability (<4.0 V vs. Li/Li+) is problematic for high-voltage cathodes. Studies of ether electrolytes have been focusing on the archetype glyme structure with ethylene oxide moieties. Herein, we unveil the crucial effect of ion coordination configuration on oxidation stability by varying the ether backbone structure. The designed 1,3-dimethoxypropane (DMP, C3) forms a unique six-membered chelating complex with Li+, whose stronger solvating ability suppresses oxidation side reactions. In addition, the favored hydrogen transfer reaction between C3 and anion induces a dramatic enrichment of LiF (a total atomic ratio of 76.7 %) on the cathode surface. As a result, the C3-based electrolyte enables greatly improved cycling of nickel-rich cathodes under 4.7 V. This study offers fundamental insights into rational electrolyte design for developing high-energy-density batteries.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shunqiang Chen, JiaJia Fan, Zhuangzhuang Cui, Lijiang Tan, Digen Ruan, Xin Zhao, Jinyu Jiang, Shuhong Jiao, Xiaodi Ren
onlinelibrary.wiley.com/doi/10.1002/anie.202219310

Crystallinity Regulation and Defects Passivation for Efficient and Stable Perovskite Solar Cells Using Fully Conjugated Porous Aromatic Frameworks

Crystallinity Regulation and Defects Passivation for Efficient and Stable Perovskite Solar Cells Using Fully Conjugated Porous Aromatic Frameworks

Fully conjugated porous aromatic frameworks (PAFs) were constructed through Gilch reaction. The obtained PAFs have rigid conjugated backbones with high specific surface area and excellent stability. The PAFs were successfully applied in the perovskite solar cells (PSCs) by doping into the perovskite layer, and the power conversion efficiencies and stability significantly increased.

Abstract

Fully conjugated porous aromatic frameworks (PAFs) have been constructed through Gilch reaction. The obtained PAFs have rigid conjugated backbones, high specific surface area, and excellent stability. The prepared PAF-154 and PAF-155 have been successfully applied in the perovskite solar cells (PSCs) by doping into the perovskite layer. The champion PSC devices afford a power conversion efficiency of 22.8 % and 22.4 %. It is found that the PAFs can be used as an efficient nucleation template, thus regulating the perovskite crystallinity. Meanwhile, PAFs can also passivate defects and promote carriers transporting in the perovskite film. By the comparative study with their linear counterpart, we unravel that the efficacy of PAFs is highly related to their porous structure and rigid fully conjugated networks. The unencapsulated devices with PAFs doping exhibit outstanding long-term stability, retaining 80 % of their initial efficiencies after half-year storage in ambient conditions.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yege Jing, Chen Wang, Yi Chen, Lin Liu, Liying Yin, Fengchao Cui, Ning Zhang, Shanpeng Wen, Guangshan Zhu
onlinelibrary.wiley.com/doi/10.1002/anie.202301234

Multi‐Site Conformational Exchange in the Synthetic Neomycin‐Sensing Riboswitch Studied by 19F NMR

Multi-Site Conformational Exchange in the Synthetic Neomycin-Sensing Riboswitch Studied by 19F NMR

Molecular motions are tightly coupled with function. Here we use a unique combination of five different fluorine NMR relaxation methods to reveal the dynamics in three structurally similar riboswitch:ligand complexes. Our data displays unexpectedly complex exchange topologies with up to four structurally different states. Importantly, the associated kinetic and thermodynamics parameters could be accurately determined.

Abstract

The synthetic neomycin-sensing riboswitch interacts with its cognate ligand neomycin as well as with the related antibiotics ribostamycin and paromomycin. Binding of these aminoglycosides induces a very similar ground state structure in the RNA, however, only neomycin can efficiently repress translation initiation. The molecular origin of these differences has been traced back to differences in the dynamics of the ligand:riboswitch complexes. Here, we combine five complementary fluorine based NMR methods to accurately quantify seconds to microseconds dynamics in the three riboswitch complexes. Our data reveal complex exchange processes with up to four structurally different states. We interpret our findings in a model that shows an interplay between different chemical groups in the antibiotics and specific bases in the riboswitch. More generally, our data underscore the potential of 19F NMR methods to characterize complex exchange processes with multiple excited states.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jan H. Overbeck, Jennifer Vögele, Felix Nussbaumer, Elke Duchardt‐Ferner, Christoph Kreutz, Jens Wöhnert, Remco Sprangers
onlinelibrary.wiley.com/doi/10.1002/anie.202218064

Divergent Total Syntheses of (+)‐Vulgarisins A–E

Divergent Total Syntheses of (+)-Vulgarisins A–E

The asymmetric total syntheses of (+)-vulgarisins A–E, which share a rare [5-6-4-5] tetracyclic core structure, have been achieved for the first time in a divergent manner. Key features of the strategy involve a catalytic asymmetric intramolecular cyclopropanation, a one-pot borylation/conjugate addition process, a Wolff ring contraction and a stereocontrolled pinacol cyclization.

Abstract

The asymmetric total syntheses of (+)-vulgarisins A–E, which share a rare and highly oxygenated [5-6-4-5] tetracyclic core structure that were isolated from P. vulgaris Linn., have been described for the first time in a divergent manner. Key transformations include: 1) a catalytic asymmetric intramolecular cyclopropanation to forge the A ring bearing desired stereochemistry at C14; 2) a one-pot borylation/conjugate addition process for creation of the C1−C11 bond; 3) a Wolff ring contraction to assemble the bicyclo[3.2.0]heptane subunit (CD rings); and 4) a stereocontrolled pinacol cyclization for construction of the central B ring of the natural products.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Kaixiang Xu, Shan Mu, Huijuanzi Rao, Jialei Hu, Hanfeng Ding
onlinelibrary.wiley.com/doi/10.1002/anie.202303668

Resolidified Chalcogen Precursors for High‐Quality 2D Semiconductor Growth

Resolidified Chalcogen Precursors for High-Quality 2D Semiconductor Growth

Chalcogen powder is pre-melted and resolidified to give a stable chalcogen precursor for the chemical vapor deposition growth of transition metal dichalcogenides. The obtained monolayer tungsten disulfide is uniform and shows high optical and structural quality.

Abstract

Two-dimensional (2D) semiconductors including transition metal dichalcogenides (TMDCs) have gained attention in optoelectronics for their extraordinary properties. However, the large amount and locally distributed lattice defects affect the optical properties of 2D TMDCs, and the defects originate from unstable factors in the synthesis process. In this work, we develop a method of pre-melting and resolidification of chalcogen precursors (sulfur and selenium), namely resolidified chalcogen, as precursor for the chemical vapor deposition growth of TMDCs with ultrahigh quality and uniformity. Taking WS2 as an example, the monolayer WS2 shows uniform fluorescence intensity and a small full-width at half-maximum of photoluminescence peak at low temperatures with an average value of 13.6±1.9 meV. The defect densities at the interior and edge region are both low and comparable, i.e., (9±3)×1012 cm−2 and (10±4)×1012 cm−2, indicating its high structural quality and uniformity. This method is universal in growing high quality monolayer MoS2, WSe2, MoSe2, and will benefit their applications.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Qinke Wu, Huiyu Nong, Rongxu Zheng, Rongjie Zhang, Jingwei Wang, Liusi Yang, Bilu Liu
onlinelibrary.wiley.com/doi/10.1002/anie.202301501

Boosting the Efficiency of Dye‐Sensitized Solar Cells by a Multifunctional Composite Photoanode to 14.13 %

Boosting the Efficiency of Dye-Sensitized Solar Cells by a Multifunctional Composite Photoanode to 14.13 %

A new strategy to fabricate a multifunctional composite photoanode containing TiO2 hollow spheres, Au nanoparticles and upconversion nanoparticles is presented. A champion power conversion efficiency of 14.13 % is obtained, which is a record for N719 dye-based dye-sensitized solar cells.

Abstract

We report a new strategy to fabricate a multifunctional composite photoanode containing TiO2 hollow spheres (TiO2-HSs), Au nanoparticles (AuNPs) and novel NaYF4 : Yb,Er@NaLuF4 : Eu@SiO2 upconversion nanoparticles (UCNPs). The AuNPs are grown on the photoanode film including TiO2-HSs and UCNPs by a simple in situ plasmonic treatment. As a result, an impressive power conversion efficiency of 14.13 % is obtained, which is a record for N719 dye-based dye-sensitized solar cells, demonstrating great potential for the solar cells toward commercialization. This obvious enhancement is ascribed to a collaborative mechanism of the TiO2-HSs exhibiting excellent light-scattering ability, of the UCNPs converting near-infrared photons into visible photons and of the AuNPs presenting outstanding surface plasmon resonance effect. Notably, a steady-state experiment further reveals that the champion cell exhibits 95.33 % retainment in efficiency even after 180 h of measurements, showing good device stability.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Siqi Zhang, Fuhua Huang, Xugeng Guo, Ye Xiong, Yafei Huang, Hans Ågren, Li Wang, Jinglai Zhang
onlinelibrary.wiley.com/doi/10.1002/anie.202302753

Construction of Axially Chiral Arylpyrroles via Atroposelective Diyne Cyclization

Construction of Axially Chiral Arylpyrroles via Atroposelective Diyne Cyclization

A novel copper-catalyzed atroposelective diyne cyclization enables the efficient synthesis of a range of axially chiral arylpyrrole biaryls in good to excellent yields with generally excellent enantioselectivities via oxidation and X−H insertion of vinyl cations. This method gives the first synthesis of mono-substituted 3-arylpyrrole atropisomers and the first atroposelective diyne cyclization.

Abstract

Axially chiral biaryls widely exist in natural products and pharmaceuticals and are used as chiral ligands and catalysts in asymmetric synthesis. Compared to the well-established axially chiral 6-membered biaryl skeletons, examples of 5-membered biaryls have been quite scarce, and mono-substituted 3-arylpyrrole atropisomers have not been reported. Here, we disclose a copper-catalyzed atroposelective diyne cyclization for the construction of a range of axially chiral arylpyrrole biaryls in good to excellent yields with generally excellent enantioselectivities via oxidation and X−H insertion of vinyl cations. Importantly, this protocol not only represents the first synthesis of mono-substituted 3-arylpyrrole atropisomers, but also constitutes the first example of atroposelective diyne cyclization and the first atropisomer construction via vinyl cations. Theoretical calculations further support the mechanism of vinyl cation-involved cyclization and elucidate the origin of enantioselectivity.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yang‐Bo Chen, Li‐Gao Liu, Can‐Ming Chen, Yi‐Xi Liu, Bo Zhou, Xin Lu, Zhou Xu, Long‐Wu Ye
onlinelibrary.wiley.com/doi/10.1002/anie.202303670

Selective Photocatalytic Oxidative Coupling of Methane via Regulating Methyl Intermediates over Metal/ZnO Nanoparticles

Selective Photocatalytic Oxidative Coupling of Methane via Regulating Methyl Intermediates over Metal/ZnO Nanoparticles

Transition-metal-loaded ZnO has been investigated for photocatalytic oxidative coupling of methane, among which Au/ZnO exhibited a C2-C4 hydrocarbon production rate of 683 μmol g−1 h−1 with 83 % selectivity. Photogenerated methyl active groups can be selectively coupled on Au but tend to be over-oxidized into CO2 on other transition metals mainly because of the deference in *CH3-metal interaction.

Abstract

Methane conversion to higher hydrocarbons requires harsh reaction conditions due to high energy barriers associated with C−H bond activation. Herein, we report a systematic investigation of photocatalytic oxidative coupling of methane (OCM) over transition-metal-loaded ZnO photocatalysts. A 1 wt % Au/ZnO delivered a remarkable C2-C4 hydrocarbon production rate of 683 μmol g−1 h−1 (83 % C2-C4 selectivity) under light irradiation with excellent photostability over two days. The metal type and its interaction with ZnO strongly influence the selectivity toward C−C coupling products. Photogenerated Zn+-O sites enable CH4 activation to methyl intermediates (*CH3) migrating onto adjacent metal nanoparticles. The nature of the *CH3-metal interaction controls the OCM products. In the case of Au, strong d-σ orbital hybridization reduces metal-C−H bond angles and steric hindrance, thereby enabling efficient methyl coupling. Findings indicate the d-σ center may be a suitable descriptor for predicting product selectivity during OCM over metal/ZnO photocatalysts.

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