Latest ArticlesThe practical application of high-energy-density lithium-sulfur (Li-S) batteries have been highly praised for energy storage devices, while are largely hindered by the "shuttling effect". Herein, core-shell carbon spheres composed of interlinked porous core and lamellar shell were designed to restrain the polysulfide shuttling. The microporous structure with pore size of around 1 nm effectively trap lithium polysulfides. Furthermore, the interconnected porous core shortens the ion transfer distance and the lamellar carbon shell endows the carbon spheres with fast electron conduction, finally facilitating polysulfide conversion kinetics. Therefore, the Li-S batteries with the carbon spheres as the interlayer show high discharge specific capacity of 1002 mAh/g at 2 C with 574 mAh/g remaining after 600 cycles, and high areal capacity of 5.48 mAh/cm2 with sulfur loading of 4.67 mg/cm2 at 0.1 C. The corresponding pouch cells also exhibit stable cycling stability with an initial discharge specific capacity of 1082 mAh/g at 0.1 C.
Ynones are important skeletons in bioactive molecules and valuable building blocks for organic synthesis, thus great efforts have been devoted to their preparation. While, introducing prochiral substrates to construct ynones bearing a chiral framework is unrealized to date. Herein, we reported the first example of Pd/SOP-catalyzed asymmetric carbonylative alkynylation via a non-classical carbonylative Sonogashira-type approach (acyl-Pd(Ⅱ) species generated from nucleophiles). By using cyclic diaryliodonium salts as prochiral substrates, various axial chiral ynones with good functional group tolerance (39 examples), satisfied yields (71%-96%) and excellent enantioselectivities (generally 94%-99% ee) were produced. Synthesis of bioactive compounds, scale-up experiment and useful transformations were also conducted to demonstrate the utility of this process.
The classification of π-/σ-aromaticity depends on the electrons with the dominating contributions. Traditionally, π- and σ-aromaticity are used to describe the unsaturated and saturated systems, respectively. Thus, it is rarely reported that π-aromaticity is dominated in a saturated system. Here we demonstrate that π-aromaticity could be dominating in several fully saturated four-membered rings (4MRs), supported by various aromaticity indices including ΔBL, NICS, EDDB, MCI, and AdNDP. The origin of such π-aromaticity in saturated rings could be attributed to an introduction of two additional electrons into the π-type LUMO of the parent neutral species. Our findings represent a novel approach to achieve π-aromaticity into a fully saturated system which has traditionally been dominated by σ-aromaticity.
An amphiphilic derivative with a large Stokes shift by introducing flexible hydrophilic long chains into a rigid ethylene-pyrene compound have been successfully synthesized. The alkylated compound exhibited a notable change in charge distribution, facilitating cation-π interactions. Through the process of amphiphilic self-assembly, the formation of highly ordered aggregates enabled effective photo-dimerization under 449 nm LED irradiation. Notably, this photo-responsive technology not only exhibited advanced multi-color emission effects, including white light emission but also exhibited environmentally friendly behavior in the aqueous phase.
Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm. Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters complex energy landscapes, leading to the potential occurrence of misfolding issues. While non-covalent crosslinking can circumvent this issue, the resulting single-chain nanoparticles exhibit lower structural stability compared to their covalently crosslinked counterparts. In this study, we present a novel approach for the synthesis of single-chain nanoparticles, achieved through the combination of non-covalent and covalent intramolecular crosslinking. Cyanostilbenes grafted onto the linear polymer form intrachain non-covalent stacks aided by hydrogen bonds, leading to the formation of non-covalently crosslinked single-chain nanoparticles. These nanoparticles undergo conversion to covalently crosslinked nanostructures through subsequent photo-irradiation using [2 + 2] photocycloaddition, a process facilitated by the supramolecular confinement effect. Consequently, the resulting single-chain nanoparticles demonstrate both intrachain folding efficiency and substantial stability, offering significant potential for advancing applications across diverse fields.
Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways. However, most reactive intermediates are unstable and present at low concentrations; their short lifetimes make them difficult to detect and characterize. Supramolecular containers offer opportunities for the stabilization and characterization of those labile species, through isolation from the media and protection inside the cavity of the host. In this review, we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers. The container compounds include carcerands, deep cavitands and amide naphthotubes. We focus on unstable guest species – cyclobutadiene, benzocyclopropenone, o-benzyne, 1,2,4,6-cycloheptatetraene, anti-Bredt's olefin, fluorophenoxycarbene, O-acylisoamide, and hemiaminal – that act as intermediates in certain organic reactions
The seven-membered ring motifs are found in bioactive pharmaceuticals and a wide range of natural products, including alkaloids and terpenoids, which hold significant importance in synthetic chemistry and has garnered considerable attention from both academia and industry. Despite the challenges faced in the past decade, the total synthesis of natural products incorporating the non-aromatic cycloheptane skeletons remains a compelling pursuit. Recently, numerous elegant strategies for constructing the seven-membered ring system have been successfully developed. This review focuses on the recent advancements in this field from 2017 to April 2023, highlighting key transformations utilized to construct the non-aromatic cycloheptane core structures and serves as a valuable guide for synthetic chemists engaged in the total synthesis of natural products containing seven-membered ring motifs.
Selenium is an essential trace element for humans and animals. As the active center of selenoproteins, the addition of selenium is beneficial to enhance the antioxidant ability. However, the high cost limits the application of organic Se in agriculture animal production. Selenized glucose (SeGlu) is a newly invented organoselenium material with good stability, low toxicity and low cost. This assay found that SeGlu was able to increase selenium deposition in liver of newborn broilers, and enhance the antioxidant capacity of liver by elevating the activities of antioxidant enzymes such as total superoxide dismutase and glutathione peroxidase. This paper as the first example clarifying the mechanism of SeGlu to enhance the antioxidant ability of chicks, shows that SeGlu can be used as an organic selenium enrichment additive for early nutrition of poultry. As a cross-discipline study involving chemistry, biology and agriculture animal science, the work may be beneficial for studies in related fields and prompt the development of the selenium science.
Tryptophan (Trp) carries a unique heteroaromatic indole side chain and plays a critical role in peptide or protein modification. Herein, we have reported a metal-free photoinduced N-H alkylation strategy using N-aryl glycines for specific modification of tryptophan-containing peptides. The robustness of our approach is demonstrated by its wide substrate scope, excellent isolated yields, as well as almost unobservable side effects. Using this highly efficiently metal-free condition, alkylated Trp-containing peptides can be smoothly assembled. This study provides a reliable and practical tool for the chemo-selective modification of various tryptophan containing oligopeptides.
The H-bond promoted electrochemical [2 + 2 + 1] annulation of benzo[d]isothiazole 1,1-dioxides, N-arylglycines and paraformaldehyde for the synthesis of various benzo[d]imidazo[1,5-b]isothiazole 5,5-dioxide derivatives under redox mediator, catalyst and electrolyte-free conditions was developed.
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