Electrochemical ring-opening carboxylation of cyclic carbonate with carbon dioxide

Electroreductive ring-opening carboxylation of styrene carbonates with CO2 to achieve dicarboxylic acids and/or β-hydroxy acids has been developed via the selective cleavage of the C(sp3)-O bond in cyclic carbonates. The product selectivity is probably determined by the stability and reactivity of the key benzylic radical and carbanion intermediate.

Stereoregular poly(2-phenylthiirane) via cationic ring-opening polymerization

Herein, we describe an effective strategy for synthesizing polythioethers with a well-defined structure through the cationic polymerization of thiirane with electron-withdrawing substituents. This strategy allows for precisely controlling the regio- and stereochemistry of the ring-opening polymerization of 2-phenylthiirane, thus allowing for producing poly(2-phenylthiirane) with high stereoregularity using enantiomeric pure thiirane.

Innovative Approach to Chiral Polyurethanes: Asymmetric Copolymerization with Isocyanates

The introduction of nitrogen-containing functional groups to chiral polymer backbones enables the tailoring of physical properties and offers opportunities for further post-polymerization modification. However, the substrate scope of such polymers is extremely limited because monomers having nitrogen-containing groups can change coordination state with respect to the metal centers, thus decreasing the activity and enantioselectivity and even poisoning the catalyst completely. In this paper, we report our attempts to carry out the asymmetric copolymerization of meso-epoxide with highly reactive isocyanates. In particular, we found that biphenol-linked bimetallic Co(III) complexes with multiple chiral centers are very efficient in catalyzing this asymmetric copolymerization reaction, affording optically active polyurethanes with a completely alternating nature and a high enantioselectivity of up to 94% ee. Crucially, we identified that the steric hindrance at the phenolate ortho position of the ligand strongly influences the catalytic activity and product enantioselectivity. In addition, density functional theory calculations revealed that the highly sterically bulky substituents change the mechanism from bimetallic to monometallic, and result in the unexpected inversion of the chiral induction direction. Moreover, the high stereoregularity of the produced polyurethanes enhances their thermal stability. This study offers a versatile methodology for the synthesis of chiral polymers containing nitrogen functionalities.

A Powerful Strategy for Synthesizing Block Copolymers via Bimetallic Synergistic Catalysis

Block copolymers, comprising polyether and polyolefin segments, are an important and promising category of functional materials. However, the lack of efficient strategies for the construction of polyether-b-polyolefin block copolymers have hindered the development of these materials. Herein, we propose a simple and efficient method to obtain various block copolymers through the copolymerization of epoxides and acrylates via bimetallic synergistic catalysis. The copolymerization of epoxides and acrylates proceeds in a sequence-controlled manner, where the epoxides-involved homo- or copolymerization occurs first, followed by the homopolymerization of acrylates initiated by the alkoxide species from the propagating polymer chain, thus yielding copolymers with a block structure. Notably, the high monomer compatibility of this powerful strategy provides a platform for synthesizing various polyacrylate-based block copolymers comprising polyether, polycarbonate, polythiocarbonate, polyester, and polyurethane segments, respectively.

Iron-catalyzed selective construction of indole derivatives via oxidative C(sp3)-H functionalization of indolin-2-ones

Considering the importance of developing powerful catalysts and the pharmacophore characteristics of indole derivatives, we describe a switchable approach for the iron-catalyzed oxidative C(sp3)-H functionalization of indolin-2-ones. Selective transformations displayed excellent activity and chemoselectivity using FeCl2 as the catalyst, air as the oxidant, and alcohol as the solvent. By manipulating the reaction conditions, particularly the choice of solvent, catalyst loading, and reaction sequence, a series of valuable indole derivatives, including isatins and symmetrical and nonsymmetrical isoindigos, were selectively synthesized in good to excellent yields. Furthermore, the gram-scale synthesis of compounds with biological anticancer activity under simple conditions highlights their great potential in practical applications.

Closed-loop recycling of sulfur-rich polymers with tunable properties spanning thermoplastics, elastomers, and vitrimers

The development of closed-loop recycling polymers that exhibit excellent performance is of great significance. Sulfur-rich polymers possessing excellent optical, thermal, and mechanical properties are promising candidates for chemical recycling but lack efficient synthetic strategies for achieving diverse structures. Herein, we report a universal synthetic strategy for producing polytrithiocarbonates, a class of sulfur-rich polymers, via the polycondensation of dithiols and dimethyl trithiocarbonate. This strategy has excellent compatibility with a wide range of monomers, including aliphatic, heteroatomic, and aromatic dithiols enabling the synthesis of polytrithiocarbonates with diverse structures. The present synthesis strategy offers a versatile platform for the construction of thermoplastics, elastomers, and vitrimers. Notably, these polytrithiocarbonates can be easily depolymerized via solvolysis into the corresponding monomers, which can be repolymerized to virgin polymers without changing the material properties.

Electroreductive Ring-Opening Carboxylation of 1,3-Oxazolidin-2-ones with CO2 for Accessing β-Amino Acids

Electrocarboxylation of the C(sp3)-O bond in 1,3-oxazolidin-2-ones with CO2 to achieve β-amino acids is developed. The C-O bond in substrates can be selectively cleaved via the single electron transfer on the surface of a cathode or through a CO2• - intermediate under additive-free conditions. A great diversity of β-amino acids can be obtained in a moderate to excellent yield and readily converted to various biologically active compounds.

Copolymerization Involving Sulfur-Containing Monomers

Incorporating sulfur (S) atoms into polymer main chains endows these materials with many attractive features, including a high refractive index, mechanical properties, electrochemical properties, and adhesive ability to heavy metal ions. The copolymerization involving S-containing monomers constitutes a facile method for effectively constructing S-containing polymers with diverse structures, readily tunable sequences, and topological structures. In this review, we describe the recent advances in the synthesis of S-containing polymers via copolymerization or multicomponent polymerization techniques concerning a variety of S-containing monomers, such as dithiols, carbon disulfide, carbonyl sulfide, cyclic thioanhydrides, episulfides and elemental sulfur (S8). Particularly, significant focus is paid to precise control of the main-chain sequence, stereochemistry, and topological structure for achieving high-value applications.

Azopolyesters with Intrinsic Crystallinity and Photoswitchable Reversible Solid-to-Liquid Transitions

Herein, we introduce a variety of azopolyesters (azobenzene-based polyesters) with remarkable intrinsic crystallinity and photoinduced reversible solid-to-liquid transition abilities from copolymerization of azobenzene-based epoxides with cyclic anhydrides. The length of the soft alkyl side-chain inlaid with azobenzenes and stereoregularity of main-chain of azopolymers have tremendous effects on crystallization properties of the resulting polyesters with melting temperature (Tm ) in the range of 51-251 °C. Moreover, some of azopolyesters possess excellently photoinduced reversible solid-to-liquid transition performance thanks to trans-cis photoisomerization of azobenzenes. Trans-azopolyesters are yellow solids with Tm s or glass transition temperatures (Tg s) above room temperature, whereas cis-polymers are red liquids with Tg s below -20 °C. These azopolyesters could be applied as novel light-switchable adhesives for quartz/quartz, wood/wood and quartz/wood adhesion, with the strength in the range of 0.73-0.89 MPa for trans-polymers. Conversely, the adhesion strength of liquefied cis-azopolyesters generated from the irradiation of trans-polymers by UV light was about 0.1 MPa, which shows light enable to control the adhesion process with high spatiotemporal resolution.

[Analysis of curative effect and short-term survival rate of plasma exchange and double plasma molecular adsorption combined with half-volume plasma exchange in the treatment of liver failure]

Objective: To investigate how plasma exchange (PE) and double plasma molecular adsorption combined with half-volume plasma exchange (DPMAS + half-volume PE) affect the curative effect and short-term survival rate in liver failure. Methods: Data from 181 cases of liver failure caused by different etiologies from January 1, 2017 to September 31, 2020, were selected. Patients were divided into a PE treatment alone group and a DPMAS + half-dose PE treatment group. The laboratory indicators with different models of artificial liver before and after treatment and the survival rates of 7, 14, 28, and 90 days after discharge were observed in the two groups. Measurement data were analyzed by t-tests and rank sum tests. Categorical data were analyzed by χ (2) test. Results: Non-biological artificial liver therapy with different models improved the liver and coagulation function in the two groups of patients with liver failure (P < 0.05 in PTA% intra-group). The coagulation function was significantly improved in the PE treatment alone group compared with that in the DPMAS + half-dose PE group [PT after treatment: (20.15 ± 0.88) s in the PE treatment alone group, (23.43 ± 1.02) s, t = -2.44, P = 0.016 in the DPMAS+half-dose PE group; PTA: 44.72% ± 1.75% in the PE treatment alone group, 35.62% ± 2.25%, t = 3.215 P = 0.002 in the DPMAS + half-dose PE group]. Bilirubin levels were significantly decreased in the DPMAS+half-dose PE group compared to the PE treatment alone group [total bilirubin after treatment: (255.30 ± 15.64) μmol/L in the PE treatment alone group, (205.46 ± 9.03) μmol/L, t = 2.74, P = 0.07 in the DPMAS + half-dose PE group; direct bilirubin after treatment: (114.74 ± 7.11) μmol/L in the PE treatment alone group, (55.33 ± 3.18) μmol/L, t = 7.54, P < 0.001) in the DPMAS + half-dose PE group]. However, there was no significant effect on leukocytes and neutrophils after treatment with different models of artificial liver (P > 0.05) in the two groups, and platelets decreased after treatment, with no statistically significant difference between the groups (t = -0.15, P = 0.882). The inflammatory indexes of the two groups improved after treatment with different models of artificial liver (P < 0.05], and the 28 and 90 d survival rates were higher in the DPMAS+half-dose PE group than those of the PE treatment alone group (28 d: 60.3% vs. 75.0%, χ (2) = 4.315, P = 0.038; 90 d: 56.2% vs. 72.5%. χ (2) = 10.355 P < 0.001). DPMAS + half-dose PE group plasma saving was 1385 ml compared with PE treatment alone group (Z = -7.608, P < 0.05). Conclusion: Both DPMAS+half-dose PE and PE treatment alone have a certain curative effect on patients with liver failure. In DPMAS+half-dose PE, the 28-day survival rate is superior to PE treatment alone, and it saves plasma consumption and minimizes blood use in clinic.

[Research progress on the role of type II innate lymphoid cells in liver diseases]

Type II innate lymphoid cell (ILC2) is a newly identified innate immunological cell that belongs to the lymphocyte lineage in cell morphology, resides in the body's mucosal tissues, and has the dual functions of innate and adaptive immunity to promote tissue remodeling and repair after injury. Additionally, it is involved in the occurrence and development of a variety of liver diseases and plays an important role in maintaining the immunological homeostasis of the liver region. This article reviews the differentiation, development, and biological functions of ILC2, with particular attention to the research progress in liver diseases.

[Advances in anticoagulant therapy for cirrhosis combined with atrial fibrillation]

Relevant research in recent years has demonstrated that the atrial fibrillation occurrence rate is significantly higher in patients with cirrhosis. The most common indication for long-term anticoagulant therapy is chronic atrial fibrillation. The use of anticoagulant therapy greatly reduces the incidence rate of ischemic stroke. Patients with cirrhosis combined with atrial fibrillation have an elevated risk of bleeding and embolism during anticoagulant therapy due to cirrhotic coagulopathy. At the same time, the liver of such patients will go through varying levels of metabolism and elimination while consuming currently approved anticoagulant drugs, thereby increasing the complexity of anticoagulant therapy. This article summarizes the clinical studies on the risks and benefits of anticoagulant therapy in order to provide a reference for patients with cirrhosis combined with atrial fibrillation.

Sequence Control in Asymmetric Terpolymerizations of meso-Epoxides, CO2, and Phthalic Anhydride: Unprecedented Statistical Ester-Carbonate Distributions

The statistical terpolymerization of epoxides, CO2 and cyclic anhydrides remains challenging, mainly because epoxide/CO2 and epoxide/anhydride copolymerizations typically proceed at considerably different rates. Herein, we report the syntheses of novel chiral terpolymers with unprecedented statistical distributions of carbonate and ester units (up to 50% junction units) via the one-pot reaction of cyclohexene oxide, phthalic anhydride, and CO2 under mild conditions using enantiopure bimetallic aluminum-complex-based catalyst systems. Notably, all resulting terpolymers exhibited excellent enantioselectivities (≥96% ee) that were independent of the carbonate-ester distribution. The statistical compositions of the carbonate and ester units in the resulting terpolymers were determined via 1H and 13C NMR spectroscopies. Furthermore, thermal properties were tuned by altering the ester content of the chiral terpolymer without influencing the enantioselective ring-opening step involving the meso-epoxide. This asymmetric terpolymerization methodology is also compatible with a variety of meso-epoxides to afford the corresponding terpolymers with 17%-25% junction units and excellent enantioselectivities (94%-99% ee). The present study is expected to provide new guidelines for preparing a broad range of biodegradable polymers with excellent enantioselectivities and adjustable properties.

Electrocarboxylation Reactions Using CO2 Both as Promoter and Carboxylative Reagent

Electrocarboxylation reaction, which employs organic electrosynthesis to achieve the utilization of CO2 as a carboxylative reagent, provides a powerful and efficient tool for the preparation of organic carboxylic acid. In some electrocarboxylation reactions, CO2 also acts as a promoter to facilitate the desired reaction. This concept mainly highlights recent CO2-promoted electrocarboxylation reactions via CO2•- intermediate or transiently protective carboxylation of active intermediate with CO2.

Favorable Propylene-Incorporated Terpolymerization of Ethylene with CO Mediated by Cationic [P,O]-Pd and Ni Complexes

Commercial polyketone materials are generally produced by palladium-catalyzed terpolymerization of ethylene and α-olefin with carbon monoxide (CO), and rare examples were reported regarding the incorporation of propylene into an ethylene/CO copolymer chain using a cost-effective nickel catalyst. In this study, we have developed a series of [P,O]-type cationic Pd and Ni complexes supported by a diphosphazane monoxide (PNPO) platform, and the electronic and steric effect on phosphine, amine, and phosphine oxide moieties is systematically investigated for terpolymerization in terms of activity, propylene/CO (C3) incorporation, and molecular weight control. It is observed that the melting temperature (T_m) is proportional to the number of C3 incorporations present in the polymer chain, and the incorporated propylene does not affect the degradation temperature substantially, thus broadening the processing temperature window of the resultant polyketones. Notably, in comparison with dppp-type catalysts, PNPO catalysts exhibited a higher preference for propylene consumption, which is of great importance for making more efficient use of α-olefin resources.

Emerging Trends in Closed-Loop Recycling Polymers: Monomer Design and Catalytic Bulk Depolymerization

Plastics are indispensable materials in modern society; however, their extensive use has contributed to the depletion of finite natural resources and caused severe environmental issues. One end-of-use solution for plastics involves the chemical recycling of polymers back to monomers for repolymerization to virgin polymers without changing the material properties, allowing the establishment of a circular material economy. This concept focuses on the critical advantages of chemically recyclable polymers in terms of monomer design, material properties, and the feasibility of bulk depolymerization. The recyclability via bulk thermolysis of various polyesters, CO₂ -based polycarbonates, and polyacetals produced via ring-opening polymerization is highlighted through discussions regarding rational monomer design and efficient catalyst development. An outlook and perspective are provided to delineate the future challenges in the rational design of monomer and polymer structures that deliver the desired materials performance while being suitable for bulk thermolysis with high (de)polymerization activity and selectivity.

Preparation of Poly(β-malic acid) via Direct Carbonylative Polymerization of Benzyl Glycidate

Poly(malic acid) (PMLA) is a water-soluble, biodegradable, biocompatible, and nontoxic polyester in the poly(hydroxyalkanoate) (PHA) family. it features various applications in pharmaceutical field. Herein, NaCo(CO)₄ and pyridine derivatives are employed for direct carbonylative polymerization of benzyl glycidate (BG) for poly(β-malic acid) production. Further investigation on reaction mechanism reveals that this polymerization undergoes a direct chain growth, rather than a sequential process involving β-lactone intermediate. The low cost and facile preparation of epoxide substrate render this methodology extremely appealing that avoids the rather tedious procedures for β-malolactonate synthesis required toward ring opening polymerization. This study also represents an alternative strategy over traditional methods for poly(β-malic acid) production using step growth polycondensation of malic acid.

Electroreductive Ring-Opening Carboxylation of Cycloketone Oxime Esters with Carbon Dioxide

Electroreductive ring-opening carboxylation of cycloketone oxime esters with atmospheric carbon dioxide is reported. This reaction proceeded under simple constant current conditions in an undivided cell using glassy carbon as the cathode and magnesium as the sacrificial anode, providing substituted γ- and δ-cyanocarboxylic acids in moderate to good yields. Electrochemically generated cyanoalkyl radicals and cyanoalkyl anion are proposed as the key intermediates.

[Sero-epidemiological characteristics of the hepatitis D virus infection among hepatitis B virus infected-patients at a single center in Xinjiang region]

Objective: To investigate the sero-epidemiological characteristics of the hepatitis D virus (HDV) infection among hepatitis B virus (HBV)-infected patients in Xinjiang region. Methods: A single-center cross-sectional analysis method was used to select 264 cases of hepatitis B virus infection who were hospitalized in the Center for Infectious Diseases and Liver Diseases of the First Affiliated Hospital of Xinjiang Medical University from August 2021 to January 2022. All patients were tested for HDV Ag, HDV IgM, HDV IgG, and HDV RNA. The infection status of hepatitis D virus was analyzed by grouping according to their clinical type, HBV viral load, and HBsAg level. A paired t-test was used for data with measurement data conforming to normal distribution. A paired rank sum test was used for data that did not conform to normal distribution before and after treatment. Results: A total of 36 cases (13.64%) and 26 cases (9.85%) were positive for HDV serological markers and HDV RNA. According to clinical type grouping, the positive rates of HDV serum markers in patients with chronic hepatitis B, hepatitis B-related cirrhosis, liver cancer, and liver failure were 13.46%, 12.43%, and 20.83%, respectively, and there was no statistically significant difference among the three groups (χ²=0.86, P=0.649). The positive rates of HDV RNA were 11.54%, 8.11%, and 20.83%, respectively, and there was no statistically significant difference among the three groups (χ²=4.015, P=0.134). According to HBV viral load grouping, the positive rates of HDV serum markers among patients with viral loads <20, 20-2 000, and >2 000 IU/ml were 17.15%, 7.81%, and 6.67%, respectively, and the difference was not statistically significant among the three groups (χ²=4.846, P=0.089). The positive rates of HDV RNA were 9.47%, 10.94%, and 10%, respectively, and the difference was not statistically significant among the three groups (χ²=0.113, P=0.945). According to HBsAg level grouping, the positive rates of HDV serum markers in HBsAg<0.05, 0.05~250, and >250 IU/ml were 14.29%, 16.67%, and 10.85%, respectively, and there was no statistically significance between the three groups (χ²=1.745, P=0.418). The positive rates of HDV RNA were 4.76%, 8.77%, and 11.63%, respectively, and there was no statistically significant difference among the three groups (χ²=1.221, P=0.543). Clinical outcome, disease course, HBV DNA, serological markers of viral hepatitis, routine blood test, biochemical indicators, coagulation function, and other laboratory indicators were compared between HDV serum marker and/or nucleic acid positive and negative patients, and there was no statistically significant difference (P>0.05). Conclusion: The positive rate of HDV serological markers and HDV RNA is 13.64% and 9.85%, respectively, at a single center in the Xinjiang region, and there is still a high HDV infection rate among the HBV-infected patients with low levels of viral load and HBsAg.

Efficient and Selective Chemical Recycling of CO2 -Based Alicyclic Polycarbonates via Catalytic Pyrolysis

Chemical recycling of polymers to their constituent monomers is the foremost challenge in building a sustainable circular plastics economy. Here, we report a strategy for highly efficient depolymerization of various CO₂ -based alicyclic polycarbonates to epoxide monomers in solvent-free conditions by a simple Cr^III -Salen complex mediated catalytic pyrolysis process. The chemical recycling of the widely studied poly(cyclohexene carbonate) exhibits excellent reactivity (TOF up to 3000 h^-1 , 0.1 mol % catalyst loading) and high epoxide monomer selectivity (>99 %). Mechanistic investigation reveals that the process proceeds in a sequential fashion via a trans-carbonate intermediate.

[Analysis of pathogenic bacteria in cirrhotic patients complicated with bacterial infection in a tertiary hospital in Xinjiang]

Objective: To understand the species, distribution, and extent of drug resistance of pathogenic bacteria in patients with liver cirrhosis combined with bacterial infection in a tertiary hospital in Xinjiang. Methods: 1 271 cases with liver cirrhosis combined with infection were analyzed retrospectively for pathogenic bacterial species and drug resistance condition in different bacterial strain. Results: Among the 1 271 cases with liver cirrhosis, 480 were combined with infection, and the infection rate was 37.8%. The majority of infected patients had decompensated cirrhosis (438 cases). Peritoneum (327 cases, 60.8%) was the common infection site, followed by lungs (16.9%). 343 strains of pathogens were isolated from 480 infected cases, of which 289 strains were among the top 10 common distinct bacteria, accounting for 76.5% and 23.5% of Gram-negative and positive bacteria. The first top three strains were Escherichia coli. (33.2%), Klebsiella pneumoniae (11.4%), and Enterococcus faecium (11.1%), and there were differences in the drug resistance rates of each strain. Conclusion: In a tertiary hospital in Xinjiang, patients with decompensated cirrhosis have a high rate of bacterial infection. The pathogenic bacteria are diverse, mainly Gram-negative bacteria; however, the infection rate of Gram-positive bacteria such as Enterococcus is gradually increasing. Additionally, according to the bacterial properties, they are divided into four categories: Enterobacter, Enterococcus, glucose non-fermenting bacteria and Staphylococcus, and it is found that even the same species of bacteria have different drug resistance rates.

Direct and Selective Electrocarboxylation of Styrene Oxides with CO2 for Accessing β-Hydroxy Acids

Highly selective and direct electroreductive ring-opening carboxylation of epoxides with CO2 in an undivided cell is reported. This reaction shows broad substrate scopes within styrene oxides under mild conditions, providing practical and scalable access to important synthetic intermediate β-hydroxy acids. Mechanistic studies show that CO2 functions not only as a carboxylative reagent in this reaction but also as a promoter to enable efficient and chemoselective transformation of epoxides under additive-free electrochemical conditions. Cathodically generated α-radical and α-carbanion intermediates lead to the regioselective formation of α-carboxylation products.

Cationic P,O-Coordinated Nickel(II) Catalysts for Carbonylative Polymerization of Ethylene: Unexpected Productivity via Subtle Electronic Variation

Transition-metal-catalyzed copolymerization of ethylene with carbon monoxide affords polyketones materials with excellent mechanical strength, photodegradability, surface and barrier properties. Unlike the widely used and rather expensive Pd catalysts, Ni-catalyzed carbonylative polymerization is very difficult since the strong binding affinity of CO to Ni deactivates the highly electrophilic metal center easily. In this study, various cationic P,O-coordinated Ni complexes were synthesized using the electronic modulation strategy, and the catalyst with strong electron-donating substituents exhibits an excellent productivity of 10⁴  g polymer (g Ni)^-1 , which represents a rare discovery that a Ni complex could operate with such exceptional efficiency in comparison with Pd catalysts. Notably, those Ni catalysts were also efficient for terpolymerization of ethylene, propylene with CO for producing commercial polyketone materials with low melting temperatures and easy processibility.

Controlled Disassembly of Elemental Sulfur: An Approach to the Precise Synthesis of Polydisulfides

The usage of elemental sulfur (S₈ ) for constructing sulfur-containing polymers is of great significance in terms of sulfur resource utilization or fabrication of high-performance polymers. Currently, the random disassembly of S₈ hinders its direct use in the precise synthesis of sulfur-containing polymers. Herein, we provide an effective strategy for controlling the dismantlement of S₈ to synthesize polydisulfides, a promising category of dynamic bonds containing polymers. In this strategy, the completely alternating copolymerization of one sulfur atom, which is orderly derived from S₈ , with episulfides is achieved with MTBD (7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene) as catalyst and [PPN]SbF₆ ([PPN]⁺ is bis(triphenylphosphine)iminium) as cocatalyst. Delightedly, the living- polymerization feature, and the good monomer compatibility allows for the access to diverse polydisulfides. Furthermore, the density functional theory (DFT) was employed to elaborate the copolymerization process.

Capsid protein from red-spotted grouper nervous necrosis virus induces incomplete autophagy by inactivating the HSP90ab1-AKT-MTOR pathway

As a highly important fish virus, nervous necrosis virus (NNV) has caused severe economic losses to the aquaculture industry worldwide. Autophagy, an evolutionarily conserved intracellular degradation process, is involved in the pathogenesis of several viruses. Although NNV can induce autophagy to facilitate infection in grouper fish spleen cells, how it initiates and mediates autophagy pathways during the initial stage of infection is still unclear. Here, we found that red-spotted grouper NNV (RGNNV) induced autophagosome formation in two fish cell lines at 1.5 and 3 h post infection, indicating that autophagy is activated upon entry of RGNNV. Moreover, autophagic detection showed that RGNNV entry induced incomplete autophagy by impairing the fusion of autophagosomes with lysosomes. Further investigation revealed that binding of the RGNNV capsid protein (CP) to the Lateolabrax japonicus heat shock protein HSP90ab1 (LjHSP90ab1), a cell surface receptor of RGNNV, contributed to RGNNV invasion-induced autophagy. Finally, we found that CP blocked the interaction of L. japonicus protein kinase B (AKT) with LjHSP90ab1 by competitively binding the NM domain of LjHSP90ab1 to inhibit the AKT-mechanistic target of the rapamycin (MTOR) pathway. This study provides novel insight into the relationship between NNV receptors and autophagy, which may help clarify the pathogenesis of NNV.

Sustainable Approach for Synthesis and Completely Recycle of Cyclic CO2-based Polycarbonates

It is highly desirable to reduce the environmental pollution related to the disposal of end-of-life plastics. Polycarbonates derived from the copolymerization of CO₂ and epoxides have attracted much attention since they can enable CO₂-fixation and furnish biorenewable and degradable polymeric materials. So far, only linear CO₂-based polycarbonates have been reported and typically degraded to cyclic carbonates. Here we synthesize a homogeneous dinuclear methyl zinc catalyst ((BDI-ZnMe)₂, 1) to rapidly copolymerize meso-CHO and CO₂ into poly(cyclohexene carbonate) (PCHC) with an unprecedentedly cyclic structure. Moreover, in the presence of trace amounts of water, a heterogeneous multi-nuclear zinc catalyst ((BDI-(ZnMe₂·xH₂O))_n, 2) is prepared and shows up to 99% selectivity towards the degradation of PCHC back to meso-CHO and CO₂. This strategy not only achieves the first case of cyclic CO₂-based polycarbonate but also realizes the complete chemical recycling of PCHC back to its monomers, representing closed-loop recycling of CO₂-based polycarbonates.

It is highly desirable to reduce the environmental pollution related to the disposal of end-of-life plastics.

Facile synthesis, structure and properties of CO2-sourced poly(thioether-co-carbonate)s containing acetyl pendants via thio-ene click polymerization

Synthetic transformation of CO2 into di- and trivinyl carbonates allows for photo-initiated thio-ene polymerization leading to sequence controlled poly(thioether-carbonate)s.

Carbonylative Polymerization of Epoxides Mediated by Tri-metallic Complexes: A Dual Catalysis Strategy for Synthesis of Biodegradable Polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs) are a unique class of commercially manufactured biodegradable polyesters with properties suitable for partially substituting petroleum-based plastics. However, high costs and low volumes of production have restricted their application as commodity materials. In this study, tri-metallic complexes were developed for carbonylative polymerization of epoxides via a dual catalysis strategy, affording 17 products of novel PHAs with up to 38.2 kg/mol M n values. The polymerization proceeds in a sequential fashion, which entails the carbonylative ring expansion of epoxide to β -lactone and its subsequent ring-opening polymerization that occurs selectively at the O- alkyl bond via carboxylate species. The wide availability and structural diversity of epoxide monomers provide PHAs with various structures, excellent functionalities, and tunable properties. This study represents a rare example of the preparation of PHAs using epoxides and carbon monoxide as raw materials.

COS-triggered oxygen/sulfur exchange of isatins: chemoselective synthesis of functionalized isoindigos and spirothiopyrans via self-condensation and the thio-Diels-Alder reaction

Herein, we present the first organocatalytic oxygen/sulfur atom exchange reaction (O/S ER) of isatins by employing carbonyl sulfide (COS) as a novel sulfuring reagent under mild reaction conditions. 8-Diazabicyclo[5.4.0]undec-7-ene (DBU) exhibited excellent activity in this approach. Remarkably, the chemical transformations of in situ generated 3-thioisatins can be tuned via the judicious choice of reaction solvents in a one pot process, enabling the selective formation of either functionalized isoindigos in CH₃CN via a self-condensation process or spirothiopyrans in DMSO in the presence of conjugated dienes via the thio-Diels-Alder reaction. Mechanistic studies with experimental and density functional theory approaches revealed that the O/S ER between isatins and COS results in the formation of 3-thioisatins as the key intermediates, which further undergo solvent-controlled transformations to generate isoindigos or spirothiopyrans, respectively. The easily-accessible substrates and operational simplicity make the process suitable for further exploration. The practicality of this transformation was demonstrated by the gram-scale synthesis of isoindigo-based drug molecules and donor-acceptor conjugated polymers.

Photoinduced Reversible Semicrystalline-to-Amorphous State Transitions of Stereoregular Azopolyesters

We report the synthesis of isotactic azobenzene-based polyesters (azopolyesters) with main-chain chirality via highly enantioselective resolution copolymerization of racemic azobenzene-containing epoxides with cyclic anhydrides. All polyesters with trans-azobenzene moieties were found to be semicrystalline materials with melting temperatures of 153-231 °C, while the corresponding isotactic cis-azopolyesters were amorphous. The azobenzene groups in the copolymers exhibited reversible trans-to-cis and cis-to-trans photoisomerization upon irradiation with light. This demonstrates that the crystallinity of isotactic azopolyesters can be manipulated via photoinduced reversible isomerization. In addition, mixing isotactic trans-polyesters with different enantiomeric configurations in a 1:1 mass ratio afforded crystalline stereocomplexes for which the crystalline behavior differed significantly from those of the component enantiomer. Also, photoinduced reversible transitions between semicrystalline and amorphous states were observed in various stereocomplexes of isotactic trans-azopolyesters, similar to the isotactic azopolyesters themselves.

Synthesis of Nonalternating Polyketones Using Cationic Diphosphazane Monoxide-Palladium Complexes

Copolymerization of olefin with carbon monoxide has received considerable interest from both academia and industry, and the introduction of polar carbonyl group renders the resultant polyketones with excellent mechanical strength, crystallinity, photodegradability, hydrophilicity, surface, and barrier properties. However, most of the reported polyketones are difficult to be processed because of limited solubility in common solvents and high melting temperature (T_m ∼ 260 °C) resulting from the strictly alternative structure. Nonalternating copolymerization of ethylene with CO is a very promising method to circumvent the problem of processability of traditional perfectly alternating polyketone. In the contribution, the palladium coordinated diphosphazane monoxide substituted by strong electron-donating groups is discovered to be highly reactive for producing nonalternating polyketones, and up to 24.2% extra ethylene incorporation has lowered T_m values to 147 and 165 °C and further improved thermal stability (T_d ∼ 339 °C) of the resultant materials. Our data demonstrates that cationic palladium complexes can also exhibit excellent reactivity and an unprecedented nonalternating degree in this copolymerization.