The eradication of Pseudomonas aeruginosa infections is becoming increasingly complex due to the emergence of multidrug-resistant strains, underscoring the urgent need for novel therapeutic strategies. Currently, no vaccine is available to prevent P. aeruginosa infections and the development of glycoconjugate vaccines based on P. aeruginosa lipopolysaccharides (LPS) presents significant challenges. To explore the immunological activity of the serotype O17 O-antigen, we present the first chemical synthesis of two hexasaccharides derived from the O17 O-antigen of P. aeruginosa, which possess distinct sequences. The synthesis of these two target hexasaccharides was accomplished using a chemoselective one-pot [2+2+2] assembly strategy and a common step-wise synthesis, respectively. The formation of β-mannosamine glycosidic linkages in products 1 and 2, was achieved through a direct stereoselective 1, 2- cis-glycosylation involving 4, 6- O-benzylidene-induced conformational locking facilitated by Ph 2SO/Tf 2O pre-activation, and an indirect 1, 2- trans-β-glycosylation alongside S N2 substitution of azide groups at C2, respectively. The efficient synthesis of these conjugation-ready oligosaccharides from the O-antigen of P. aeruginosa serotype O17 will provide foundational materials for identifying key antigens and developing glycoconjugate vaccines.
The synthesis of titanium oxo clusters (TOCs) with both chirality and photoactivity is urgently needed to expand their applications. However, this remains a significant challenge due to synthetic difficulties and limitations in chiral ligand selection. In this work, we have isolated two pairs of enantiomeric TOCs, [Ti 3(µ 3-O)( R/S-L1) 2( iPrO) 6] ( R/S-Ti3; iPrOH = isopropanol, R/ S-L1 = R/ S-2’-hydroxy-[1, 1’- binaphthalen]-2-yl isopropyl hydrogenphosphate) and [Ti 4(µ 2-O)(µ 4-O)( R/ S-L2) 2(EtO) 8] ( R/S-Ti4; EtOH = ethanol, R/ S-L2 = R/ S-2’-hydroxy-[1, 1’-binaphthalen]-2-yl ethyl hydrogenphosphate), via an in situ ligand transformation approach. The R/ S-L1 and R/ S-L2 ligands were obtained by alcoholysis of R/ S-L ( R/ S-1, 1’-binaphthyl-2, 2’-diyl hydrogenphosphate) in different reaction solvents. These ligands, with additional coordination sites, facilitated the formation of novel TOCs and improved their stability. Importantly, these clusters exhibited exceptional stability in solid state and maintained appreciable stability in solution. Furthermore, the introduction of chiral ligands not only imparts a homochiral nature to R/S-Ti3 and R/S-Ti4 but also confers upon them superior photoelectric properties due to ligand-to-metal charge transfer (LMCT) phenomena, as confirmed by theoretical calculations. This study offers a valuable synthetic strategy for preparing photoactive chiral TOCs, and we anticipate it will inspire new discoveries in the field of chiral metal nanoclusters.
The frequent occurrence of oil spills not only results in the waste of petroleum resources, but also poses a serious threat to the marine ecological environment. Considering the large amount of crude oils with high viscosity, it is urgent to develop a sorbent capable of efficiently reducing the viscosity for the cleanup of oil spills. Inspired by the “lotus effect” and “poikilotherm which utilize the solar energy for thermoregulation”, the low surface energy material polydimethylsiloxane (PDMS) and polypyrrole (PPy) were loaded over the island nonwoven fabric to fabricate a novel crude oil sorbent material. The nonwoven fabric achieved an efficient photothermal conversion. Wherein, the fluorine-free PDMS was used to hydrophobically modify the nonwoven fabric, endowing it with excellent oil-water separation performance, with a separation efficiency of up to 95%. After 10 cycles, the separation efficiency of PPy/PDMS modified nonwoven fabric (PPy/PDMS@NF) was still above 90%, demonstrating superior recyclability. In addition, the PPy/PDMS@NF possessed the self-cleaning capabilities. Under light conditions, the PPy/PDMS@NF was rapidly heated up, reducing the viscosity of crude oil and enabling the effective recovery of oil spills. Under one sun illumination (1.0 kW·m –2), the surface temperature of the PPy/PDMS@NF reached 60.7 °C, and its sorption capacity for high-viscosity crude oil reached 7 g crude oil·g sorbent –1. Thanks to its environmental friendliness and excellent sorption capacity, this work provides a new option for dealing with the high-viscosity marine oil spills.
The invention of novel linkers is a long-lasting task in the area of the sulfur(VI) fluoride exchange reaction (SuFEx). Compared with the most frequently investigated sulfonyl fluorides, synthetic accessibility toward its mono-aza isostere, i.e., sulfonimidoyl fluorides is still limited. Herein, we report an electrochemical carbonfluorination of the readily available N-sulfinylamines to access various aryl and alkyl sulfonimidoyl fluorides. The transformation is characterized by the ready availability of starting materials, mild reaction conditions, and obviating metal catalysts and chemical oxidants.
Inspired by the molecular mechanism of mussel adhesion, here, we developed a class of injectable and self-healing hydrogels based on natural polysaccharide hyaluronic acid (HA). The dynamic property of hydrogels is derived from histidine-metal coordination, which widely exists in the mussel adhesive plaque. To mimic components of mussel byssal threads, we first grafted histidine-containing peptides onto the HA chains. Followed by the addition of Zn 2+ ions, the modified HA could then transform into a pH-sensitive hydrogel network (HA-His-Zn) with tunable sol-gel transitions. The dynamic metal-ligand coordination could significantly enhance the mechanical properties of HA hydrogels and also endow them with self-healing and injectable abilities. In addition, the HA-His-Zn hydrogels could also exhibit antibacterial and immunoregulatory activities due to the bioactive Zn 2+ ions. These results, together with the dynamic properties and good biocompatibility, indicated that the HA-His-Zn hydrogels could be applied as a class of easy-to-handle scaffold materials for regeneration medicine, particularly for tissue traumas with chronic inflammations and infections.
Stereoselective construction of 2-deoxy-glycosidic linkages has been achieved by the 1, 2-sulfur migration/glycosylation and desulfurization strategy; however, current protocols suffer from harsh reaction conditions and unsatisfactory stereoselectivity, particularly during the 1, 2- S-migration/glycosylation step. With 2- O-resided ( o-alkynyl)benzoate and anomeric p-methoxyphenylsulfenyl groups as the initiating and migrating groups, respectively, a novel protocol for the efficient synthesis of 2-deoxy-glycosides via the 1, 2-sulfur migration/glycosylation-desulfurization strategy has been established, which is featured by the mild and catalytic reaction conditions, expanded substrate scope, as well as good to excellent diastereoselectivity. Mechanism studies determined hyperconjugation-stabilized oxocarbenium ion as the key intermediate, achieving high 1, 2- trans stereocontrol through thermodynamic, steric, as well as electrostatic effects. This provides the fresh insight for the operative mechanism of the 1, 2-sulfur migration/glycosylation and desulfurization strategy, further corroborated by the elaborately designed testing reactions and DFT calculations. Moreover, the synthetic potential of the newly established protocol was examined by the practical synthesis of natural product, culminating in the acquisition of digoxin from acetylated digoxigenin in 25% overall yield through an 8-step longest linear sequence.
Photothermal hydrogenation of carbon monoxide (CO) holds the potential to generate valuable C 2+ chemicals using renewable solar energy. However, its activity and selectivity towards C 2–C 3 alkanes are limited compared to conventional thermal catalysis. In this study, we developed a robust catalyst consisting of Cu/Fe 3O 4 nanoparticles on Mo 2C Tx MXene, showing enhanced photothermal C 2–C 3 production. The Cu component plays a crucial role in H 2 dissociation and subsequent H spillover, facilitating the in situ generation of Fe 0 in Fe 5C 2 active sites and thus efficiently promoting photothermal CO hydrogenation. As a result, we achieved a 51.3% C 2+ selectivity and 78.5% CO conversion at a high gas hourly space velocity (GHSV) of 12000 mL·g cat −1·h −1 and 2.5 MPa in a flow reactor at 320 °C. The overall C 2–C 3 yield reached 23.6% with Cu/Fe 3O 4/Mo 2C Tx catalysts, marking a 2.8-fold increase compared to the performance of the bare Fe 3O 4/Mo 2C Tx catalyst.
Here, we show a cost-effective and environmentally friendly method for synthesizing iminofuranones using visible light and the photocatalyst 2-bromoanthraquinone. Our approach uses only oxygen as the oxidant, avoiding the need for additional transition metals and strong oxidizing agents. By employing a mixed solvent system of DMF and CHCl 3 under ambient conditions, we have achieved highly diastereoselective conversions of various 2-vinyl benzamides and alkenyl amides into functionalized iminoisobenzofuranones and iminofuranones. This versatile process is broadly applicable and enables late-stage structural modifications of complex substrates with bioactive moieties.
Dendronized polymers (DenPols) with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials. However, it still has lacked a rapid and efficient approach to the facile synthesis of DenPols with high-generation and well-defined structures. Herein, we report a “ m+n ” grafting-onto strategy combined with the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction with reaction-enhanced reactivity of intermediates (RERI) mechanism for synthesizing DenPols G m+ n by attaching n-generation dendrons (G n) onto the m-generation DenPols G m. In this “ m+n” grafting-onto strategy, the DenPols G m ( m = 1, 2) bearing 1, 3-triazido branches on the repeating unit were capable of RERI effect that guaranteed the CuAAC reaction in an extremely efficient way with ultrafast kinetics to synthesize third-, fourth- and fifth-generation DenPols (G 1+2, G 1+3, G 1+4, G 2+2, and G 2+3) with near quantitative grafting density and narrow distribution. Moreover, these resultant DenPols G m+ n had more terminal groups per repeating unit due to the three branches of 1, 3-triazido structure, exhibiting valuable potential opportunities for molecular surface engineering. The development of this “ m+ n” grafting-onto strategy with RERI mechanism not only presents a new avenue for ultrafast preparing DenPols but also holds great promise for preparing unimolecular materials with more functional terminal groups.
The ion-selective porous membrane is the key component in osmotic energy conversion, and optimizing its permeability and selectivity is crucial for improving output performance. Here, to construct a permeability and selectivity synergistically enhanced osmotic energy generator, the surface and space charge synergistically enhanced 3D composite membrane is prepared by inserting sulfonated hydrogels into the 3D ion channels with tunable surface charge. The membrane’s selectivity is improved from 0.66 to 0.94 by increasing the charge density on the membrane surface and the spatial charge density of the membrane. The experimental and simulation results showed that the synergistic enhancement of the spatial and surface charges significantly improved the electrostatic interactions between the ions and the ion channels, which led to the enhancement of selectivity, net ionic fluxes, and output performance. The space charge improved composite membrane presents an advanced power density of about 6.4 W·m –2 under a 50-fold concentration gradient, which is nearly 2 times that of the phase inversion membrane without hydrogels. Our study provides a promising solution for constructing high-performance osmotic energy generators.
Ni-rich cathode materials, exemplified by LiNi 1– x– yC o xMnyO 2 (NCM), have significantly propelled Li-ion battery (LIB) technology forward owing to their high energy density. However, the long-term storage stability of these materials remains a critical challenge that must be addressed. This review provides a comprehensive analysis of the storage failure mechanisms in both polycrystalline (PC-NCM) and single crystal (SC-NCM) forms, a topic that has been seldom reviewed. It delves into the microstructural changes and performance degradation that occur during storage, emphasizing the effects of environmental factors on NCM materials, including the formation of surface impurities and structural deterioration. Additionally, the review discusses various enhancement strategies, such as surface coatings, doping, and gas treatments, which are designed to improve storage stability. Furthermore, the review projects insights from current polycrystalline studies to suggest future research directions aimed at enhancing the air stability of SC-NCM, which is vital for improving the safety and durability of LIBs.
As well known, cilia play an irreplaceable role in sensing and movement of natural organisms because they can respond to external signals and generate net flow in complex environments. Based on these findings, scientists further explored the functions of natural cilia and have developed many artificial cilia in the past nearly thirty years. This review provides an overview of recent progress of artificial cilia. Firstly, we summarize the characteristics of natural cilia. Subsequently, we introduce the fabrication methods including template, magnetic assembly, lithography, and 3D printing. Then we discuss the stimulus actuation of artificial cilia from two major modes: contact control and remote control. In addition, five typical types of applications, including adhesion regulation, intelligent control, mobile microrobot, biological sensor and anti-counterfeiting, were reviewed in detail. Finally, we present the challenges and future development in the fields of advanced artificial cilia.