Mechanism of Phosphine‐Catalyzed Allene Coupling Reactions: Advances in Theoretical Investigations

Organocatalysis has emerged as an effective strategy for chemical synthesis. Within this area, phosphine‐catalyzed coupling reactions have attracted considerable attention because of their versatility and wide range of applications in the construction of new C?C bonds. Recently, various experimental studies on the phosphine‐catalyzed coupling reaction of allenes have been reported, and mechanistic and computational studies have also progressed considerably. As a nucleophile, phosphine can react with an allene to form a zwitterionic phosphoniopropenide intermediate. After stepwise cycloaddition and proton transfer, the phosphine catalyst can be regenerated by C?P bond cleavage. Alternatively, the zwitterionic phosphoniopropenide intermediate could also be protonated by a Brønsted acid to generate a phosphonium intermediate, which can be used to construct new C?C bonds by electrophilic addition. In this review, we have summarized details of mechanistic studies of phosphine‐catalyzed allene coupling reactions that follow these two reaction modes. In addition to detailing the reaction pathway, the regioselectivity and diastereoselectivity of the phosphine‐catalyzed allene coupling reaction are also discussed in this review.     

Rhenium(I)‐Catalyzed ortho‐C−H Addition to Bicyclic Alkenes

Hydroarylation of bicyclic alkenes has been developed using a low‐valent Re^I‐catalyzed, directing group‐assisted C?H bond activation strategy. The addition of sodium acetate significantly improves the reaction efficiency; moreover, bicyclic alkenes such as 7‐oxa and aza benzonorbornadienes worked efficiently under this reaction condition. Preliminary mechanistic studies suggest that, after the alkene insertion, the rhenacycle preferentially undergoes protonolysis rather than reductive elimination.     

New borrelidin derivatives from an endophytic Streptomyces sp.

Three new borrelidin-type macrolactones, designated as borrelidins J?L (4–6), together with borrelidin A (1), borrelidin E (2), and 12-desnitrile-12-carboxyl-borrelidin (3) were isolated from a plant endophytic Streptomyces sp. NA06554. Their structures were determined by extensive spectroscopic analysis including HRESIMS, 1D and 2D NMR data. The antibacterial activities for compounds 1–6 were examined. Borrelidins A (1) and L (6) showed potent and moderate antibacterial activity against Micrococcus luteus, respectively, whereas other derivatives (2–5) are almost inactive, which allows us to propose a plausible structure-activity relationship.     

Preparation of 4-sulfonylcalix[6]arene modified Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> as adsorbent for adsorption of U(VI) from aqueous solution

The 4-sulfonylcalix[6]arene modified Fe₃O₄ (MFS) was characterized by FT-IR, SEM, VSM, TGA, etc., which showed that its saturation magnetization was 64.99 emu g^?1 with the particle size 10–40 nm. The maximum adsorption efficiency by MFS for 2.5 mg L^?1 U(VI) solution amounted to 94.39%, which was higher than that by Fe₃O₄ (65.22%) under its optimum adsorption conditions. The adsorption of MFS and Fe₃O₄ were both followed the pseudo-second order model and the Langmuir isotherm model. The Gibbs free energy change and enthalpy change revealed that the adsorption of U(VI) by MFS was a spontaneous and endothermic process.     

Floxuridine Homomeric Oligonucleotides “Hitchhike” with Albumin In Situ for Cancer Chemotherapy

Automated attachment of chemotherapeutic drugs to oligonucleotides through phosphoramidite chemistry and DNA synthesis has emerged as a powerful technology in constructing structure‐defined and payload‐tunable oligonucleotide–drug conjugates. In practice, however, in vivo delivery of these oligonucleotides remains a challenge. Inspired by the systemic transport of hydrophobic payloads by serum albumin in nature, we report the development of a lipid‐conjugated floxuridine homomeric oligonucleotide (LFU20) that “hitchhikes” with endogenous serum albumin for cancer chemotherapy. Upon intravenous injection, LFU20 immediately inserts into the hydrophobic cave of albumin to form an LFU20/albumin complex, which accumulates in the tumor by the enhanced permeability and retention (EPR) effect and internalizes into the lysosomes of cancer cells. After degradation, cytotoxic floxuridine monophosphate is released to inhibit cell proliferation.     

Cross‐Linked Aptamer–Lipid Micelles for Excellent Stability and Specificity in Target‐Cell Recognition

The specific binding ability of DNA–lipid micelles (DLMs) can be increased by the introduction of an aptamer. However, supramolecular micellar structures based on self‐assemblies of amphiphilic DLMs are expected to demonstrate low stability when interacting with cell membranes under certain conditions, which could lead to a reduction in selectivity for targeting cancer cells. We herein report a straightforward cross‐linking strategy that relies on a methacrylamide branch to link aptamer and lipid segments. By an efficient photoinduced polymerization process, covalently linked aptamer–lipid units help stabilize the micelle structure and enhance aptamer probe stability, further improving the targeting ability of the resulting nanoassembly. Besides the development of a facile cross‐linking method, this study clarifies the relationship between aptamer–lipid concentration and the corresponding binding ability.     

A Stable Quasi‐Solid‐State Sodium–Sulfur Battery

Ambient‐temperature sodium–sulfur (Na–S) batteries are considered a promising energy storage system due to their high theoretical energy density and low costs. However, great challenges remain in achieving a high rechargeable capacity and long cycle life. Herein we report a stable quasi‐solid‐state Na‐S battery enabled by a poly(S‐pentaerythritol tetraacrylate (PETEA))‐based cathode and a (PETEA‐tris[2‐(acryloyloxy)ethyl] isocyanurate (THEICTA))‐based gel polymer electrolyte. The polymeric sulfur electrode strongly anchors sulfur through chemical binding and inhibits the shuttle effect. Meanwhile, the in situ formed polymer electrolyte with high ionic conductivity and enhanced safety successfully stabilizes the Na anode/electrolyte interface, and simultaneously immobilizes soluble Na polysulfides. The as‐developed quasi‐solid‐state Na‐S cells exhibit a high reversible capacity of 877 mA h g^?1 at 0.1 C and an extended cycling stability.     

Case synthesis of a β-chloro bulky bis-pocket corrole: Crystallographic characterization and photophysical properties

A new bulky 2-chloro-5,10,15-tris(2,4,6-triphenylphenyl)-corrole was casually synthesized and the effect of mono-β-chlorination on its photophysical, electrochemical properties and light-induced singlet oxygen generation was investigated.     

萘酰亚胺-卟啉星型电子受体分子的构筑及其在非富勒烯太阳能电池中的应用

非富勒烯太阳能电池目前已经成为有机太阳能电池的研究热点,大量的共轭电子受体分子被开发,并成功应用到高性能光伏器件中。共轭分子作为非富勒烯电子受体,需要综合考虑吸收、能级、电子传输以及结晶性等,其中宽吸收光谱可以提高对太阳光谱的利用,是分子设计中重要因素之一。本工作中,我们设计一种新型电子受体分子,以卟啉为核、萘酰亚胺为端基以及炔为桥连基团。这种新型分子具有近红外的吸收光谱以及合适的能级。将一种具有吸收互补的共轭聚合物为电子给体,星型分子为电子受体应用到电池的活性层中,我们获得了1.8%的能量转换效率,电池的光谱响应为300–900 nm。实验结果证明了这种以卟啉为核的分子设计在实现近红外吸收的电子受体方面具有重要应用前景。     

A bioinspired strategy for assembling graphene oxide sheets into high-performance graphene films

正Since 2004, graphene has attracted intense attention from the scientific and industrial communities due to its extraordinary properties, such as ultrahigh strength and remarkable electrical conductivity. Mass production of high-quality graphene materials can be achieved by chemical vapor deposition and chemical exfoliation, and their applications have been widely explored [1–3]. The most common graphene derivative, graphene oxide (GO), can be synthesized in mass quantities by the oxidation and exfoliation of graphite, which has a low cost and is commercially available in market. One of the major applications for GO nanosheets is the construction of high-performance GO-based fibers,