Latest ArticlesPolycyclic compounds are widely found in natural products and drug molecules with important biological activities, which attracted the attention of many chemists. Phosphine-catalyzed nucleophilic addition is one of the most powerful tools for the construction of various cyclic compounds with the advantages of atom economy, mild reaction conditions and simplicity of operation. Allenolates, Morita−Baylis−Hillman (MBH) alcohols and their derivatives (MBHADs), electron-deficient olefins and alkynes are very efficient substrates in phosphine mediated annulations, which formed many phosphonium species such as β-phosphonium enolates, β-phosphonium dienolates and vinyl phosphonium ylides as intermediates. This review describes the reactivities of these phosphonium zwitterions and summarizes the synthesis of polycycle compounds through phosphine-mediated intramolecular and intermolecular sequential annulations. Thus, a systematic summary of the research process based on the phosphine-mediated sequential annulations of allenolates, MBH alcohols and MBHADs, electron-deficient olefins and alkynes are presented in Chapters 2–6, respectively.
The separation of alicyclic ketones and alicyclic alcohols is one of the challenges in the field of petrochemical industry. However, traditional separation methods suffer from excessive energy consumption, complicated operation, and unsatisfactory separation efficiency for substances with similar boiling points. Herein, we offer an innovative method for the separation of alicyclic ketones and alicyclic alcohols employing nonporous adaptive crystals (NACs) of perethylated pillar[5]arene (EtP5) and perethylated pillar[6]arene (EtP6). NACs of EtP5 cannot adsorb either alicyclic ketones or alicyclic alcohols because of the small cavity size of EtP5. By contrast, NACs of EtP6 can separate cyclopentanone from the vapor mixture of cyclopentanone/cyclopentanol (v:v = 1:1) and cyclohexanone from the vapor mixture of cyclohexanone/cyclohexanol (v:v = 1:1) with purities of 99.1% and 100%, respectively. Density functional theory calculations show that the selectivity comes from the thermodynamic stability of the newly formed crystal structure after adsorption of the preferred guest molecule. Moreover, NACs of EtP6 can be reused without losing selectivity and performance.
With the rapid development of electric vehicles, hybrid electric vehicles and smart grids, people's demand for large-scale energy storage devices is increasingly intense. As a new type of secondary battery, potassium ion battery is promising to replace the lithium-ion battery in the field of large-scale energy storage by virtue of its low price and environmental friendliness. At present, the research on the anode materials of potassium ion batteries mainly focuses on carbon materials and the design of various nanostructured metal-based materials. Problems such as poor rate performance and inferior cycle life caused by electrode structure comminution during charge and discharge have not been solved. Quantum dots/nanodots materials are a new type of nanomaterials that can effectively improve the utilization of electrode materials and reduce production costs. In addition, quantum dots/nanodots materials can enhance the electrode reaction kinetics, reduce the stress generated in cycling, and effectively alleviate the agglomeration and crushing of electrode materials. In this review, we will systematically introduce the synthesis methods, K+ storage properties and K+ storage mechanisms of carbon quantum dots and carbon-based transition metal compound quantum dots composites. This review will have significant references for potassium ion battery researchers.
Aromatic nitro compounds present substantial health and environmental concerns due to their toxic nature and potential explosive properties. Consequently, the development of host–guest molecular recognition systems for these compounds serves a dual-purpose: enabling the fabrication of high-performance sensors for detection and guiding the design of efficient adsorbents for environmental remediation. This study investigated the host–guest recognition behavior of perethylated pillar[n]arenes toward two aromatic nitro molecules, 1-chloro-2,4-dinitrobenzene and picric acid. Various techniques including 1H NMR, 2D NOESY NMR, and UV-vis spectroscopy were employed to explore the binding behavior between pillararenes and aromatic nitro guests in solution. Moreover, valuable single crystal structures were obtained to elucidate the distinct solid-state assembly behaviors of these guests with different pillararenes. The assembled solid-state supramolecular structures observed encompassed a 1:1 host–guest inclusion complex, an external binding complex, and an exo-wall tessellation complex. Furthermore, based on the findings from these systems, a pillararene-based test paper was developed for efficient picric acid detection, and the removal of picric acid from solution was also achieved using pillararenes powder. This research provides novel insights into the development of diverse host–guest systems toward hazardous compounds, offering potential applications in environmental protection and explosive detection domains.
A cobalt pincer complex bearing both P and C-stereogenic centers has been designed and synthesized, allowing for the development of the first cobalt-catalyzed asymmetric hydrogenation of quinoxalines under relatively mild conditions. Valuable chiral 1,2,3,4-tetrahydroquinoxalines could be obtained with high yields and excellent enantioselectivities (35 examples, up to > 99% ee).
Selective separation of phenanthrene (PHE) from aromatic isomer mixtures poses a significant challenge in industry due to the similar physical properties of PHE and its isomer anthracene (ANT). Herein, we report the self-assembly of a water-soluble Pd2L2 cage 1 with a large hydrophobic cavity, formed from novel macrocyclic ligands (L) and cis-Pd(Ⅱ). Cage 1 can selectively encapsulate PHE instead of ANT. Based on host-guest recognition followed by extraction, we achieve a remarkable 99% purity of PHE separation from an equimolar mixture of PHE and ANT using cage 1 in aqueous solution. Importantly, the separation performance of PHE using cage 1 remains unaffected even after five extraction cycles, demonstrating its robustness. This work highlights the potential of supramolecular cages for efficient and cost-effective PHE separation from the isomer ANT in aqueous solutions using such promising host-guest strategy.
The rapid emergence of drug-resistant bacterial strains undermines the efficacy of conventional antibiotics, necessitating the development of alternative therapies. Antimicrobial photodynamic therapy (PDT) is a promising approach, but its effectiveness is often limited by the suboptimal photocatalytic activity of photosensitizers. In this study, we introduce a novel photoresponsive carbon-based antibacterial agent, Ce6/g-C3N4, which combines the photocatalytic properties of graphite-phase carbon nitride (g-C3N4) with the photodynamic attributes of chlorin e6 (Ce6). This agent, with an average particle size of 250.7 nm, demonstrates significantly enhanced photocatalytic activity. Additionally, the strong affinity of Ce6/g-C3N4 for bacteria and efficient delivery of Ce6 result in an inhibition rate exceeding 99% against Gram-positive bacteria and excellent biofilm eradication under light irradiation. In vivo experiments reveal that Ce6/g-C3N4 effectively inhibits bacterial growth on wounds, and promotes wound healing post-light treatment, while maintaining good biocompatibility. Overall, the Ce6/g-C3N4 antibacterial agent synergizes photodynamic and photocatalytic mechanisms, offering a new avenue for the photo-mediated, multi-strategic treatment of bacterial infections and wound healing.
Inspired by the light-dependent signal transduction in nature, we herein report a fully synthetic receptor AZO with the capacity of transmembrane signaling, working by photo-induced change of molecular conformation. Our receptor has an anchoring group, a rigid and photoresponsive transmembrane unit and a precatalyst tailgroup. After doping in lipid membranes, AZO is membrane anchored and the extended trans-isomer enables the tailgroup to bind with intravesicular Zn2+, thereby achieving enzyme activation and triggering downstream events (ester hydrolysis). However, the shortened cis-isomer pulls the tailgroup into lipids, thereby preventing the complexation and all transduction processes. Upon alternative irradiation of ultraviolet (UV) and visible light, the transduction process can be reversible switch between "ON" and "OFF", achieving light signal transduction. This study provides a new strategy for future design of artificial signal transduction receptors.
Two thioamino acids and four fluorinated amino acids were employed to substitute either partially or entirely the Ile2, Ser3, Ile6, and Ser7 residues of Leu10-teixobactin to prepare ten analogues and the bioactivity of them was investigated. The SAR studies revealed that Ile6 was tolerable for both thioamidation and fluoridation, while Ser7 was identified as the most tolerable site for thioamidation. Analogue 1a demonstrated comparable or slightly improved antibacterial activity, superior protease stability compared to Leu10-teixobactin, while not exhibiting obvious cytotoxicity against mammalian cells.
Liquid-liquid phase separation (LLPS) of proteins and nucleic acids is a common phenomenon in cells that underlies the formation of membraneless organelles. Although the macroscopic behavior of biomolecular coacervates has been elucidated by microscopy, the detailed dynamic properties of proteins/peptides during the LLPS process remain poorly characterized. Here, site-directed spin labeling-electron paramagnetic resonance (SDSL-EPR) spectroscopy was employed to characterize the dynamic properties of a minimal model LLPS system consisting of positively charged peptides and RNA. The degree of phase separation, indicated by broadening of the EPR spectrum of the spin-labeled peptide due to slow molecular tumbling, was monitored by EPR. In addition, three distinct populations with varying molecular motion during LLPS, featuring different spectral lineshapes, were identified. These populations included a fast motion component (Ⅰ), a slower motion component (Ⅱ) associated with peptides in the dispersed phase and an immobile component (Ⅲ) observed in the dense phase. With gradual titration of the peptides to RNA, the EPR spectrum gradually shifted, reflecting changes in the populations of the components. Together, SDSL-EPR method not only provides new insights into the dynamic behavior of biomolecules during LLPS, but also offers a sensitive method for biomolecular phase separation processes at the molecular level.
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