From Nanoparticle Ensembles to Single Nanoparticles: Techniques for the Investigation of Plasmon Enhanced Electrochemistry

Par / 23 septembre 2022 / Non classé
From Nanoparticle Ensembles to Single Nanoparticles: Techniques for the Investigation of Plasmon Enhanced Electrochemistry

The progress of plasmon enhanced electrochemistry (PEEC) in terms of three types of electrochemical methods (macroscopic PEEC measurements, PEEC based on scanning electrochemical microscope, and PEEC based on nano-impact electrochemistry) is discussed in this Concept article.

Abstract

Plasmon enhanced electrochemistry (PEEC), where specific electrochemical reactions are promoted due to the reduced energy barrier of the reaction processes by the light excited “hot carriers” of the plasmonic nanoparticles, has aroused tremendous interest in recent years. A deep understanding of the PEEC process becomes a key issue for facilitating PEEC catalyst design and improving PEEC performance. This concept article begins with a brief discussion of the macroscopic electrochemical method of PEEC study of the plasmonic nanoparticle ensembles. Following that, we highlight two electrochemical techniques that may possess single nanoparticle sensitivity, i. e., scanning electrochemical microscope and nano-impact electrochemistry. The pros and cons of each technique are discussed and an outlook is given. We hope to provide the readers with the current status of PEEC to evoke reflections regarding the reaction mechanisms, performance improvement, and the utilizations to important systems.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Zerong Liang, Jian Li, Yi‐Ge Zhou
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202201489

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A Chemotactic Colloidal Motor

Par / 23 septembre 2022 / Non classé
A Chemotactic Colloidal Motor

Chemotactic colloidal motors can be served as excellent physical models of non-equilibrium complex systems and also have potential in active target delivery and other biomedical applications. In this Concept, both the recent experimental progress and theoretical opinion of chemotactic motors based on the torque-driven self-reorientation and alignment mechanism are discussed.

Abstract

Chemotaxis plays a crucial role in the realization of various functions of human life such as fertilization, immune function, inflammatory response, regeneration processes, etc. Inspired by the natural chemotaxis, colloidal motors with chemotactic ability can realize intelligent sense and targeted navigation, which bring a revolutionary method to biomedical applications like precision medicine. However, the application in the biomedical field requires the colloidal motors with submicrometer scale, strong chemotactic ability and clear chemotactic mechanism. In this Concept article, we introduce the recent progress of chemotactic colloidal motors, covering the fundamental theory behind experimental advancements. Particularly, the torque-driven reorientation motion of the submicrometer-sized colloidal motors during chemotaxis is discussed, and also their underlying mechanism is proposed. With the continuous research on chemotactic colloidal motors, it is believed that the emerging chemotactic colloidal motors will broaden practical applications in the biomedical field.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Chang Zhou, Ling Yang, Yingjie Wu, Mingcheng Yang, Qiang He
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202319

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Shedding Light on the Enigmatic TcO2 ⋅ xH2O Structure with Density Functional Theory and EXAFS Spectroscopy

Par / 23 septembre 2022 / Non classé
Shedding Light on the Enigmatic TcO2 ⋅ xH2O Structure with Density Functional Theory and EXAFS Spectroscopy**

What shape are you in? The structure of amorphous TcO2 ⋅ xH2O has been determined from DFT calculations and EXAFS measurements. Contrary to the generally accepted model, TcO2 ⋅ xH2O forms zigzag chains of cis-Tc(μ-O)4(H2O)2 units. A slow aging process results in increasing polymerization that might eventually lead to a new TcO2 polymorph. Formation of these phases with low solubility is highly relevant for the confinement of long-lived 99Tc in deep nuclear waste repositories.

Abstract

The β-emitting 99Tc isotope is a high-yield fission product in 235U and 239Pu nuclear reactors, raising special concern in nuclear waste management due to its long half-life and the high mobility of pertechnetate (TcO4−). Under the conditions of deep nuclear waste repositories, Tc is retained through biotic and abiotic reduction of TcO4− to compounds like amorphous TcO2 ⋅ xH2O precipitates. It is generally accepted that these precipitates have linear (Tc(μ-O)2(H2O)2)n chains, with trans H2O. Although corresponding Tc−Tc and Tc−O distances have been obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy, this structure is largely based on analogy with other compounds. Here, we combine density-functional theory with EXAFS measurements of fresh and aged samples to show that, instead, TcO2 ⋅ xH2O forms zigzag chains that undergo a slow aging process whereby they combine to form longer chains and, later, a tridimensional structure that might lead to a new TcO2 polymorph.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Augusto F. Oliveira, Agnieszka Kuc, Thomas Heine, Ulrich Abram, Andreas C. Scheinost
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202235

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Detection of Reactive Oxygen and Nitrogen Species by Upconversion Nanoparticle‐Based Near‐Infrared Nanoprobes: Recent Progress and Perspectives

Par / 23 septembre 2022 / Non classé
Detection of Reactive Oxygen and Nitrogen Species by Upconversion Nanoparticle-Based Near-Infrared Nanoprobes: Recent Progress and Perspectives

Accurate detection of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is of great significance. A variety of upconversion nanoparticles (UCNPs)-based near-infrared (NIR) nanoprobes for ROS and RNS detection is reviewed. Our focus is to describe how they are built and how do they work. Finally, the future opportunities and challenges for UCNPs-based NIR nanoprobes are briefly discussed, and how to improve the performance of UCNPs is also prospected.

Abstract

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are essential oxidative metabolites of organisms, which are closely related to physiological, pathological and pharmacological processes. The accurate detection of ROS/RNS is important for the understanding of biological processes, monitoring of pharmacological effects, and predicting the course of disease. The recently developed NIR nanoprobes based on upconversion nanoparticles (UCNPs) hold great prospects in sensitive and deep-tissue detection of ROS/RNS, and considerable progress has been achieved so far. In this review, we systematically summarize the up-to-date advances of UCNPs-based near-infrared (NIR) probes for ROS/RNS sensing, and the potential challenges and perspectives for further research are also highlighted. We envision that such a research field will have a bright future for modern biomedical applications.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Xiaokan Yu, Wenao Ouyang, Hao Qiu, Zhijun Zhang, Zhimin Wang, Bengang Xing
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202201966

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YfeX – A New Platform for Carbene Transferase Development with High Intrinsic Reactivity

Par / 23 septembre 2022 / Non classé
YfeX – A New Platform for Carbene Transferase Development with High Intrinsic Reactivity

YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases. WT YfeX catalyzes N−H insertion (including aliphatic and secondary amines) in high yield, cyclopropanation, and most excitingly, Si−H insertion of dimethylphenylsilane. QM/MM calculations reveal details of the mechanism of the unusual Si−H insertion reaction.

Abstract

Carbene transfer biocatalysis has evolved from basic science to an area with vast potential for the development of new industrial processes. In this study, we show that YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases, due to its high intrinsic reactivity, especially for the N−H insertion reaction of aromatic and aliphatic primary and secondary amines. YfeX shows high stability against organic solvents (methanol and DMSO), greatly improving turnover of hydrophobic substrates. Interestingly, in styrene cyclopropanation, WT YfeX naturally shows high enantioselectivity, generating the trans product with 87 % selectivity for the (R,R) enantiomer. WT YfeX also catalyzes the Si−H insertion efficiently. Steric effects in the active site were further explored using the R232A variant. Quantum Mechanics/Molecular Mechanics (QM/MM) calculations reveal details on the mechanism of Si−H insertion. YfeX, and potentially other peroxidases, are exciting new targets for the development of improved carbene transferases.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Victor Sosa Alfaro, Sodiq O. Waheed, Hannah Palomino, Anja Knorrscheidt, Martin Weissenborn, Christo Z. Christov, Nicolai Lehnert
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202201474

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Domino Reactions through Recursive Anionic Cascades: The Advantageous Use of Nitronates

Par / 23 septembre 2022 / Non classé
Domino Reactions through Recursive Anionic Cascades: The Advantageous Use of Nitronates

The evolving landscape of recursive nitronate cyclization, as a mechanistically distinct domino strategy employing nitroalkanes as dual-acting one-carbon lynchpins, is discussed in this review. Its advantageous use in rapid assembly of topologically diverse and functionally embellished carbo- and heterocycles is highlighted along with their applications in complex natural products synthesis.

Abstract

Recursive Anionic Cyclization (RAC) continues to proliferate as a mechanistically distinct domino strategy. Deployment of nitroalkanes as a source of recursive carbanions has created a niche operating space for generating molecular complexity and diversity. This new corollary i. e. recursive nitronate cyclization is the basis of a domino [5 C+1 C] cyclization strategy wherein nitroalkanes act as one-carbon lynchpin, providing rapid access to topologically intriguing, densely functionalized carbo- and heterocycles embodying multiple chiral centers with regio-, stereo- and enantioselectivity. Extension to aromatic domains, particularly via benzannulation reactions, has further consolidated the operating space. While leveraging the functional versatility of nitro group for post-domino modifications, such endeavors have culminated in total synthesis of diverse natural products. An incisive analysis of recursive nitronate cyclizations and their emergent potentials is delineated in this review. It is hoped that this focused narrative will enthuse and draw new practitioners to the arena to advance the field.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Saumitra Sengupta, Srihari Pabbaraja, Goverdhan Mehta
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202200945

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Hydrogen‐Bonded Organic Framework Ultrathin Nanosheets for Efficient Visible‐Light Photocatalytic CO2 Reduction

Par / 23 septembre 2022 / Non classé
Hydrogen-Bonded Organic Framework Ultrathin Nanosheets for Efficient Visible-Light Photocatalytic CO2 Reduction

Hydrogen-bonded organic framework (HOF) nanosheets (NSs) of HOF-25-Ni have been produced by the post-modification of robust guanine-quadruplex-linked metal-free 2,2′-pyridine-containing HOF-25 followed by exfoliation. With the help of a sensitizer, 10 wt% HOF-25-Ni NSs dispersed on graphene oxide promotes efficient and selective CO2-to-CO conversion under visible-light irradiation.

Abstract

Post-modification of robust guanine-quadruplex-linked 2,2′-pyridine-containing HOF-25 with Ni(ClO4)2 ⋅ 6 H2O followed by exfoliation using sonication method affords hydrogen-bonded organic framework (HOF) nanosheets (NSs) of HOF-25-Ni in the yield of 56 %. TEM and AFM technologies disclose the ultrathin nature of HOF-25-Ni NSs with thickness of 4.4 nm. STM observation determines the presence of sql segments assembled from HOF-25-Ni building blocks at the heptanoic acid/highly oriented pyrolytic graphite interface, supporting the simulated 2D supramolecular framework. ICP-MS, XAS, and XPS data prove the successful immobilization of atomic nickel sites on the 20 % total 2,2′-pyridine moieties in crystalline HOF-25-Ni. With the aid of [Ru(bpy)3]2+ and triisopropanolamine, 10 wt% HOF-25-Ni NSs dispersed on graphene oxide efficiently promotes visible-light-driven CO2 reduction, showing a 96.3 % CO selectivity with a prominent conversion rate up to 24 323 μmol g−1 h−1.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Baoqiu Yu, Ting Meng, Xu Ding, Xiaolin Liu, Hailong Wang, Baotong Chen, Tianyu Zheng, Wen Li, Qingdao Zeng, Jianzhuang Jiang
onlinelibrary.wiley.com/doi/10.1002/anie.202211482

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Anticancer Approach Inspired by the Hepatotoxic Mechanism of Pyrrolizidine Alkaloids with Glycosylated Artificial Metalloenzymes

Par / 23 septembre 2022 / Non classé
Anticancer Approach Inspired by the Hepatotoxic Mechanism of Pyrrolizidine Alkaloids with Glycosylated Artificial Metalloenzymes

Metabolic oxidation of pyrrolizidine alkaloids (PAs) by cytochrome P450 produces dehydro-PAs (DHPs), which leads to toxicities. We developed a therapeutic approach, in which a precursor is transformed into a synthetic DHP via 5–endo–dig cyclization catalyzed by a gold-based artificial metalloenzyme (ArM). In cell-based assays, the synthesis of the DHP by a glycosylated ArM suppressed cell growth of targeted cancer cells.

Abstract

Metabolic oxidation of pyrrolizidine alkaloids (PAs) from herbal and dietary supplements by cytochrome P450 produces dehydro-PAs (DHPs), which leads to toxicities. A highly reactive cation species generated from the active pyrrole ring of DHPs readily reacts with various cellular components, causing hepatotoxicity and cytotoxicity. Inspired by PA-induced hepatic damage, we developed a therapeutic approach based on a cyclization precursor that can be transformed into a synthetic DHP under physiological conditions through gold-catalyzed 5–endo–dig cyclization using a gold-based artificial metalloenzyme (ArM) instead of through metabolic oxidation by cytochrome P450. In cell-based assays, the synthesis of the DHP by a cancer-targeting glycosylated gold-based ArM substantially suppressed cell growth of the targeted cancer cells without causing cytotoxicity to untargeted cells, highlighting the potential of the strategy to be used therapeutically in vivo.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Michitaka Kurimoto, Tsung‐che Chang, Yoshitake Nishiyama, Takehiro Suzuki, Naoshi Dohmae, Katsunori Tanaka, Satoshi Yokoshima
onlinelibrary.wiley.com/doi/10.1002/anie.202205541

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Simultaneous Photoactivation of cGAS‐STING Pathway and Pyroptosis by Platinum (II) Triphenylamine Complexes for Cancer Immunotherapy

Par / 23 septembre 2022 / Non classé
Simultaneous Photoactivation of cGAS-STING Pathway and Pyroptosis by Platinum (II) Triphenylamine Complexes for Cancer Immunotherapy

The first small molecule that can activate cGAS-STING in a photocontrollable way is reported. Upon irradiation, Pt1 and Pt2 can damage mitochondrial DNA, the nuclear envelope and nuclear DNA sequentially, which effectively releases DNA into cytoplasm to activate the cGAS-STING pathway both in vitro and in vivo.

Abstract

Activation of the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway is a potent anticancer immunotherapeutic strategy, and the induction of pyroptosis is a feasible way to stimulate the anticancer immune responses. Herein, two PtII complexes (Pt1 and Pt2) were designed as photoactivators of the cGAS-STING pathway. In response to light irradiation, Pt1 and Pt2 could damage mitochondrial/nuclear DNA and the nuclear envelope to activate the cGAS-STING pathway, and concurrently induce pyroptosis in cancer cells, which evoked an intense anticancer immune response in vitro and in vivo. Overall, we present the first photoactivator of the cGAS-STING pathway, which may provide an innovative design strategy for anticancer immunotherapy.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yu‐Yi Ling, Xiao‐Yu Xia, Liang Hao, Wen‐Jin Wang, Hang Zhang, Liu‐Yi Liu, Wenting Liu, Zhi‐Yuan Li, Cai‐Ping Tan, Zong‐Wan Mao
onlinelibrary.wiley.com/doi/10.1002/anie.202210988

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Pyrazine Alkylation with Aldehydes and Haloalkanes Using N,N’‐Bis(trimethylsilyl)‐1,4‐dihydropyrazine Derivatives

Par / 23 septembre 2022 / Non classé
Pyrazine Alkylation with Aldehydes and Haloalkanes Using N,N’-Bis(trimethylsilyl)-1,4-dihydropyrazine Derivatives

N,N’-Bis(trimethylsilyl)-1,4-dihydropyrazines serves as starting materials for introducing alkyl groups into the parent pyrazine skeletons upon combined with aldehydes and nBu4NF as well as electron-deficient alkyl halides. In this reaction, activation of the trimethylsilyl moiety by fluoride is the key step for generating electron-rich silicate intermediates, while reduction of electron-deficient alkyl halides by 1 a produces radical cation [1 a]⋅+ for further C−C bond formation.

Abstract

N,N’-Bis(trimethylsilyl)-1,4-dihydropyrazines are useful starting materials for synthesizing alkylpyrazines upon combination with aldehydes and tetra(n-butyl)ammonium fluoride. Various aryl, heteroaryl, and alkyl aldehydes are utilized as sources of the alkyl substituents; reactions with electron-rich aldehydes afford the corresponding alkylpyrazines in good yields. The overall reaction sequence was clarified by DFT calculations; in this reaction, activation of the N-trimethylsilyl moiety by fluoride, forming the electron-rich silicate intermediate Int-1, is the key step for the subsequent C−C bond formation with aldehydes, and the following 1,3-proton transfer from Int-3 to Int-4 is the rate-determining step. In addition, treatment of N,N’-bis(trimethylsilyl)-2,5-dimethyl-1,4-dihydropyrazines (1 a) with electron-deficient alkyl halides under fluoride-free conditions affords the corresponding alkylated pyrazines.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Hayato Tsurugi, Minami Matsuno, Tomomi Kawakami, Kazushi Mashima
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202200862

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In Situ Imaging of Ion Motion in a Single Nanoparticle: Structural Transformations in Selenium Nanoparticles

Par / 23 septembre 2022 / Non classé
In Situ Imaging of Ion Motion in a Single Nanoparticle: Structural Transformations in Selenium Nanoparticles

In situ and real-time visualization of ion motions in a single nanoparticle was achieved by dark-field microscopy and disclosed the transformation of amorphous SeNPs into polycrystalline Hg3Se2Cl2.

Abstract

Intraparticle ion motions are critical to the structure and properties of nanomaterials, but rarely disclosed. Herein, in situ visualization of ion motions in a single nanoparticle is presented by dark-field microscopy imaging, which shows HgCl2-induced structural transformation of amorphous selenium nanoparticles (SeNPs) with the main composition of Se8. Owing to the high binding affinity with selenium and coulomb interactions, Hg2+ ions can permeate into the interior of SeNPs, making the amorphous Se8 turn to polycrystalline Hg3Se2Cl2. As a proof of concept, SeNPs then serve as a highly effective scavenger for selective removal of Hg2+ ions from solution. This new finding offers visual proof for the photophysical process involving intraparticle ion motion, demonstrating that tracking the ion motions is a novel strategy to comprehend the formation mechanism with the purpose of developing new nanostructures like nanoalloys and nano metal compounds.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Bin Bin Chen, Meng Li Liu, Hong Yan Zou, Yang Liu, Yuan Fang Li, Mark T Swihart, Cheng Zhi Huang
onlinelibrary.wiley.com/doi/10.1002/anie.202210313

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Ultrasmall Copper Nanoclusters in Zirconium Metal‐Organic Frameworks for the Photoreduction of CO2

Par / 23 septembre 2022 / Non classé
Ultrasmall Copper Nanoclusters in Zirconium Metal-Organic Frameworks for the Photoreduction of CO2

A room-temperature synthetic strategy is reported for incorporation of ultrasmall Cu nanoclusters into a series of robust Zr-metal–organic frameworks. The resultant core–shell composites mediate CO2 photoreduction selectively and outperform similar composites even with variable Cu spatial distribution.

Abstract

Encapsulating ultrasmall Cu nanoparticles inside Zr-MOFs to form core–shell architecture is very challenging but of interest for CO2 reduction. We report for the first time the incorporation of ultrasmall Cu NCs into a series of benchmark Zr-MOFs, without Cu NCs aggregation, via a scalable room temperature fabrication approach. The Cu NCs@MOFs core–shell composites show much enhanced reactivity in comparison to the Cu NCs confined in the pore of MOFs, regardless of their very similar intrinsic properties at the atomic level. Moreover, introducing polar groups on the MOF structure can further improve both the catalytic reactivity and selectivity. Mechanistic investigation reveals that the CuI sites located at the interface between Cu NCs and support serve as the active sites and efficiently catalyze CO2 photoreduction. This synergetic effect may pave the way for the design of low-cost and efficient catalysts for CO2 photoreduction into high-value chemical feedstock.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shan Dai, Takashi Kajiwara, Miyuki Ikeda, Ignacio Romero‐Muñiz, Gilles Patriarche, Ana E. Platero‐Prats, Alexandre Vimont, Marco Daturi, Antoine Tissot, Qiang Xu, Christian Serre
onlinelibrary.wiley.com/doi/10.1002/anie.202211848

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Regioselective Transition‐Metal‐Free C(sp2)−H Borylation: A Subject of Practical and Ongoing Interest in Synthetic Organic Chemistry

Par / 23 septembre 2022 / Non classé
Regioselective Transition-Metal-Free C(sp2)−H Borylation: A Subject of Practical and Ongoing Interest in Synthetic Organic Chemistry

Recent developments in strategies for transition-metal-free regioselective C−H borylation are summarized in this Review. Strategies developed to control the regioselectivity of the electrophilic borylation, such as approaches controlled by electronic effects, auxiliaries, and steric factors, are also discussed. EDG=electron donating group, DG=directing group, TM=transition metal.

Abstract

Considerable advances have been made in the area of C−H functionalization in the last few decades. A number of approaches including both directed and nondirected strategies have been developed thus far. Among the various C−H functionalizations, C−H borylation is of special interest due to the wide applications of organoboron compounds. In this regard, various transition-metal-catalyzed regioselective strategies have been developed. However, the major concern regarding metal-catalyzed C−H borylation procedures is the requirement of a precious metal as well as the contamination by metal precursors in the desired products, which limit the application of this process in large-scale synthesis. Therefore, recent trends have involved the use of transition-metal-free systems. We summarize recent developments in transition-metal-free regioselective C−H borylation. We believe that this Review will help to increase interest in this field and stimulate further progress.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Supriya Rej, Naoto Chatani
onlinelibrary.wiley.com/doi/10.1002/anie.202209539

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Quantifying the Solution Structure of Metal Nanoclusters Using Small‐Angle Neutron Scattering

Par / 23 septembre 2022 / Non classé
Quantifying the Solution Structure of Metal Nanoclusters Using Small-Angle Neutron Scattering

Small-angle neutron scattering (SANS) can directly quantify the overall structure parameters of nanoclusters in solution without the requirement of crystallization or gas phase ionization. A series of silver and gold nanoclusters were studied with SANS demonstrating good agreement with crystallographic data in both the shape, size and the molecular weight information.

Abstract

Metal nanoclusters are a unique class of synthetic material, as their crystal structures can be resolved using X-ray diffraction, and their chemical formula can be precisely determinated from mass spectroscopy. However, a complete structure characterization by these two techniques is often a challenging task. Here, we utilize small-angle neutron scattering (SANS) to directly quantify the key structure parameters of a series of silver and gold nanoclusters in solution. The results not only correlate well to their crystallographic structures, but also allow the quantification of the counterions layer surrounding charged nanoclusters in solution. Furthermore, when combining with X-ray scattering, it is possible to estimate the molecular weight of both the metal core and the ligand shell of nanoclusters. This work offers an alternative characterization tool for nanoclusters without the requirement of crystallization or gas phase ionization.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xindi Liu, Huayan Yang, Yuxiang Chen, Ye Yang, Lionel Porcar, Aurel Radulescu, Stefan Guldin, Rongchao Jin, Francesco Stellacci, Zhi Luo
onlinelibrary.wiley.com/doi/10.1002/anie.202209751

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Understanding the Nature and Strength of Noncovalent Face‐to‐Face Arene–Fullerene Interactions

Par / 23 septembre 2022 / Non classé
Understanding the Nature and Strength of Noncovalent Face-to-Face Arene–Fullerene Interactions

We synthesized a new series of fullerene-based molecular torsion balances and examined their folding equilibrium to understand the nature and strength of noncovalent face-to-face arene−fullerene interactions. The contributions of polarizabilities, anionic charges, electronic dipole moments, and the number of arene rings to the interactions were experimentally quantified by analyzing the folding equilibrium of the molecular torsion balances.

Abstract

Face-to-face noncovalent arene−fullerene interactions are important in several research fields such as synthetic chemistry, materials chemistry, and medicinal chemistry; however, their nature and strength are still poorly understood. In this study, we prepare a fullerene-based torsion balance containing thioanisole, phenol, naphthalene, azulene, and pyrene moieties as a unimolecular model system. Moreover, we compare the folding free energies between the folded and the unfolded conformers of a series of the molecular torsion balances to quantify noncovalent interactions between arenes and the fullerene surface. This work demonstrates that the contributions of polarizabilities, anionic charges, electronic dipole moments, and the number of arene rings to the interactions can be experimentally measured by analyzing the folding equilibrium of the molecular torsion balances.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Michio Yamada, Yukiyo Kurihara, Masaaki Koizumi, Kasumi Tsuji, Yutaka Maeda, Mitsuaki Suzuki
onlinelibrary.wiley.com/doi/10.1002/anie.202212279

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Modular Construction of a Tessellated Octahedron, its Hierarchical Spherical Aggregate Behavior, and Electrocatalytic CO2 Reduction Activity

Par / 23 septembre 2022 / Non classé
Modular Construction of a Tessellated Octahedron, its Hierarchical Spherical Aggregate Behavior, and Electrocatalytic CO2 Reduction Activity

The self-assembly of a tessellated triangle T1 and the construction of a tessellated octahedron O1 containing metal-organic modules as the panels are demonstrated. O1 has a diameter on the order of 10.9 nm and a molecular weight greater than 84 kDa. After hybridization with carbon nanotubes, the supramolecules exhibit electrochemical reduction activity for CO2 to CO.

Abstract

Coordination-driven self-assembly has led to the formation of various aesthetical polyhedrons and compounds with advanced functions. Whereas two-dimensional supramolecules with complex and giant skeletons are plentiful, the constructions of polyhedrons are limited by using basic polygons as the panels. Herein, we report the modular synthesis of a tessellated triangle and tessellated octahedron with metal-organic modules as the panels and formed via template-driven self-assembly. These architectures have diameters on the order of 10.9 nm and molecular weights greater than 84 kDa. Interestingly, fiber and spherical-like nanostructures could be formed from the tessellated triangles and octahedrons, respectively, through hierarchical self-assembly. In addition, after hybridization with carbon nanotubes, the supramolecules exhibit electrochemical reduction activity for CO2 to CO.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Guotao Wang, Yunna Yang, Hui Liu, Mingzhao Chen, Zhiyuan Jiang, Qixia Bai, Jie Yuan, Zhilong Jiang, Yiming Li, Pingshan Wang
onlinelibrary.wiley.com/doi/10.1002/anie.202205851

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First Synthesis, Confirmation of Stereochemistry, and Cytotoxic Activity of Oxyfungiformin

Par / 23 septembre 2022 / Non classé
First Synthesis, Confirmation of Stereochemistry, and Cytotoxic Activity of Oxyfungiformin

The marine sesquiterpenoid oxyfungiformin was obtained in a concise synthetic sequence starting from the chiral precursor guaiol. The absolute configuration of oxyfungiformin was established by a combination of X-ray analysis and comparison of the values for specific optical rotation. Oxyfungiformin and a diastereoisomer showed cytotoxic activity in a panel of human cancer cell models.

Abstract

The relative configuration of the marine sesquiterpenoid oxyfungiformin, isolated from the soft coral Capnella fungiformis, was confirmed by synthesis using the natural product guaiol as chiral precursor. The absolute configuration of oxyfungiformin could be assigned by combination of X-ray diffraction and comparison of the values for the specific optical rotation. Oxyfungiformin and a diastereoisomer showed cytotoxic activity in cells originating from cancers of the lung, breast, and cervix.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Marie Pascaline Rahelivao, Ingmar Bauer, Tilo Lübken, Olga Kataeva, Anne Vehlow, Nils Cordes, Hans‐Joachim Knölker
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202200809

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Mechanistic Insights into Lewis Acid‐Controlled Torquoselective Nazarov Cyclization of Activated Dienones Bearing a Chiral Sulfoxide

Par / 23 septembre 2022 / Non classé
Mechanistic Insights into Lewis Acid-Controlled Torquoselective Nazarov Cyclization of Activated Dienones Bearing a Chiral Sulfoxide

Two diastereoisomeric tetrahydrocyclopentapyranones can be diastereodivergently obtained from a common activated dienone bearing a chiral sulfoxide through a Nazarov cyclization. The diastereoselectivity switch of both reactions is controlled by the nature of the Lewis acid used as promoter. Density functional theory investigations shed light on the reaction mechanism.

Abstract

This work provides a switchable strategy to access, through a Nazarov cyclization, two diastereomeric disubstituted 3,4,5,6-tetrahydrocyclopenta[b]pyran-7(2H)-ones from an activated dienone bearing a chiral sulfoxide. The switch in the torquoselectivity is controlled by the nature of the Lewis acid used as promoter. From the four possible stereoisomers, only the two trans were observed. The Lewis acids employed were achiral and the diastereoselectivities were dictated by the sulfinyl auxiliary. Density functional theory investigations shed light on the reaction mechanism. The experimental torquoselectivities were very closely reproduced and their inversion could be linked back to a change in the binding mode of the substrate.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Erwann Grenet, Raphaël Robidas, Arie Lee, Claude Y. Legault, Xavier J. Salom‐Roig
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202200828

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Chain-to-Layer Dimensionality Engineering of Chiral Hybrid Perovskites to Realize Passive Highly Circular-Polarization-Sensitive Photodetection

Par / 23 septembre 2022 / Non classé

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Tingting Zhu, Wen Weng, Chengmin Ji, Xinyuan Zhang, Huang Ye, Yunpeng Yao, Xinling Li, Junlin Li, Wenxiong Lin, and Junhua Luo
dx.doi.org/https://doi.org/10.1021/jacs.2c07891

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