Palladium and Ruthenium Dual-Single-Atom Sites on Porous Ionic Polymers for Acetylene Dialkoxycarbonylation: Synergetic Effects Stabilize the Active Site and Increase CO Adsorption

Heterogeneous single-metal-site catalysts usually suffer from poor stability, thereby limiting industrial applications. Dual Pd₁−Ru₁ single-atom-sites supported on porous ionic polymers (Pd₁−Ru₁/PIPs) were constructed using a wetness impregnation method. The two isolated metal species in the form of a binuclear complex were immobilized on the cationic framework of PIPs through ionic bonds. Compared to the single Pd- or Ru-site catalyst, the dual single-atom system exhibits higher activity with 98 % acetylene conversion and near 100 % selectivity to dialkoxycarbonylation products, as well as better cycling stability for ten cycles without obvious decay. Based on DFT calculations, it was found that the single-Ru site exhibited a strong CO adsorption energy of −1.6 eV, leading to an increase in the local CO concentration of the catalyst. Notably, the Pd₁−Ru₁/PIPs catalyst had a much lower energy barrier of 2.49 eV compared to 3.87 eV of Pd₁/PIPs for the rate-determining step. The synergetic effect between neighboring single sites Pd₁ and Ru₁ not only enhanced the overall activity, but also stabilized Pd^II active sites. The discovery of synergetic effects between single sites can deepen our understanding of single-site catalysts at the molecular level.     

利用空间位阻和氢溢流协同作用促进5-羟甲基糠醛选择性加氢制备5-甲基糠醛

Selective hydrogenation is a vital class of reaction. Various unsaturated functional groups in organic compounds, such as aromatic rings, alkynyl (C≡C), carbonyl (C＝O), nitro (-NO₂), and alkenyl (C＝C) groups, are typical targets in selective hydrogenation. Therefore, selectivity is a key indicator of the efficiency of a designed hydrogenation reaction. 5-(Hydroxymethyl)furfural (HMF) is an important platform compound in the context of biomass conversion, and recently, the hydrogenation of HMF to produce fuels and other valuable chemicals has received significant attention. Controlling the selectivity of HMF hydrogenation is paramount because of the different reducible functional groups (C＝O, C-OH, and C＝C) in HMF. Moreover, the exploration of new routes for hydrogenating HMF to valuable chemicals is becoming attractive. 5-Methylfurfural (MF) is also an important organic compound; thus, the selective hydrogenation of HMF to MF is an essential synthetic route. However, this reaction has challenging thermodynamic and kinetic aspects, making it difficult to realize. Herein, we propose a strategy to design a highly efficient catalytic system for selective hydrogenation by exploiting the synergy between steric hindrance and hydrogen spillover. The design and preparation of the Pt@PVP/Nb₂O₅ catalyst (PVP = polyvinyl pyrrolidone; Nb₂O₅ = niobium(V) oxide) were also conducted. Surprisingly, HMF could be converted to MF with 92% selectivity at 100% HMF conversion. The reaction pathway was revealed through the combination of control experiments and density functional theory calculations. Although PVP blocked HMF from accessing the surface of Pt, hydrogen (H₂) could be activated on the surface of Pt due to its small molecular size, and the activated H₂ could migrate to the surface of Nb₂O₅ through a phenomenon called H₂ spillover. The Lewis acidic surface of Nb₂O₅ could not adsorb the C＝O group but could adsorb and activate the C-OH group of HMF; therefore, when HMF was adsorbed on Nb₂O₅, the C-OH groups were hydrogenated by the spilled over H₂ to form MF. The high selectivity of this reaction was realized because of the unique combination of steric effects, hydrogen spillover, and tuning of the electronic states of the Pt and Nb₂O₅ surfaces. This new route for producing MF has great potential for practical application owing to its discovered advantages. We believe that this novel strategy can be used to design catalysts for other selective hydrogenation reactions. Furthermore, this study demonstrates a significant breakthrough in selective hydrogenation, which will be of interest to researchers working on the utilization of biomass, organic synthesis, catalysis, and other related fields.      

高效医学传感钙钛矿材料研究进展

卤化物钙钛矿材料作为一种新型半导体材料,具有优异的光电转换特性、能级结构可调、易于加工、结构和尺寸以及形貌可调、改性后优异的生物相容性等优点,在医学检测传感器中具有广阔的应用前景。本综述讨论了钙钛矿材料在生物医学传感领域的研究进展,钙钛矿医学传感器能通过光电转换、全光转换、电催化等多种物理或化学机制实现传感,具有可灵活选择的器件结构、性能指标和信号传递方式,用于人体代谢物质、神经递质、癌症相关物质和药物等医学物质的检测。钙钛矿医学传感器将为未来的医工多学科融合提供新希望,加快医工融合发展。     

Chemical profiling of Ziziphi spinosae semen using on-line comprehensive two-dimensional liquid chromatography-mass spectrometry based on a novel phthalic anhydride bonded stationary phase

Ziziphi spinosae semen has been widely used to treat insomnia and anxiety. To profile its chemical components, an online comprehensive two-dimensional liquid chromatography-mass spectrometry was developed. In this two-dimensional liquid chromatography system, a novel phthalic anhydride-bonded stationary phase column was combined with a C18 column. As a result, this new stationary phase exhibited remarkable differences in separation selectivity from C18, achieving a good orthogonality of 83.3%. Moreover, this new stationary phase with weaker hydrophobicity than C18 realized solvent compatibility in the online configuration. Coupled with tandem MS, 154 compounds were identified, including 51 unreported compounds. Compared with one-dimensional liquid chromatography-mass spectrometry, this online two-dimensional liquid chromatography-mass spectrometry system exhibited a much higher resolving power in isomer separation. This work provided an effective separation and characterization method for the material basis of Ziziphi spinosae semen. This strategy provides ideas for the material basis research of other traditional Chinese medicines.     

Simple high-performance liquid chromatography-ultraviolet method for simultaneous separation and detection of 14 bisphenol pollutants in building materials

A high-performance liquid chromatography-ultraviolet method was developed for rapidly and simultaneously analyzing novel and typical bisphenols in building materials, including bisphenol S, diphenolic acid, bisphenol F, bisphenol E, bisphenol A, bisphenol B, bisphenol AF, bisphenol AP, bisphenol C, bisphenol FL, bisphenol Z, bisphenol BP, bisphenol M, and bisphenol P. By using a Kromasil 100–5 C18 column, these bisphenols were completely separated in 40 min via gradually increasing the concentration of methanol in the mobile phase from 45 to 80% during the elution process. In particular, this method achieved the synchronous analysis of bisphenol S, diphenolic acid, bisphenol FL, bisphenol BP, and bisphenol M through HPLC, which were difficult to separate and had to be identified and detected through mass spectrometry. The limits of detection of the method ranged from 0.002 to 0.040 mg/L for these 14 bisphenols, with a precision of less than 4.9% (n = 7, c = 0.05 mg/L). The analytical results for five types of building materials (phenolic, epoxy, polycarbonate, polyester, and polysulfone resins) indicated that the proposed method is appropriated for the rapid measurement of bisphenols in real samples.     

Microinjection Molded Biopolymeric Airway Stent with Antibacterial and Anti-Hyperplastic Properties

Central airway stenosis is a condition that the diameter of the trachea or main bronchus shrinkage is caused by external compression or internal tissue hyperplasia, which can cause difficulty breathing, asphyxia, and even death. Airway stenting is an easy way to restore the patency of the central airway, but airway stents commonly used in clinical practice can lead to complications such as mucus plugging, bacterial infection, and granulation tissue hyperplasia. Moreover, the non-degradable characteristic makes it requires a second operation to remove, which has the potential to cause tissue damage. In this study, a biodegradable airway stent is fabricated by microinjection molding using the bioelastomer of poly (L-lactide-co-ε-caprolactone) as the matrix material. The airway stent has excellent mechanical properties and an appropriate degradation rate. The hydrophilic surface of the airway stent can inhibit mucus plugging. The loading of silver nanoparticles and cisplatin endows the stent with antibacterial and anti-hyperplastic functions. In vitro and in vivo experiments demonstrate that this study provides an antibacterial and anti-hyperplastic biodegradable airway stent with elastic properties to avoid secondary removal operation and reduce complications associated with mucus plugging, bacterial infection, and granulation tissue hyperplasia.     

Materials Space-Tectonics: Atomic-level Compositional and Spatial Control Methodologies for Synthesis of Future Materials

Reactions occurring at surfaces and interfaces necessitate the creation of well-designed surface and interfacial structures. To achieve a combination of bulk material (i.e., framework) and void spaces, a meticulous process of “nano-architecting” of the available space is necessary. Conventional porous materials such as mesoporous silica, zeolites, and metal–organic frameworks lack advanced cooperative functionalities owing to their largely monotonous pore geometries and limited conductivities. To overcome these limitations and develop functional structures with surface-specific functions, the novel materials space-tectonics methodology has been proposed for future materials synthesis. This review summarizes recent examples of materials synthesis based on designing building blocks (i.e., tectons) and their hybridization, along with practical guidelines for implementing materials syntheses and state-of-the-art examples of practical applications. Lastly, the potential integration of materials space-tectonics with emerging technologies, such as materials informatics, is discussed.     

Iron-Catalyzed Trifluoromethylation of Indole-Tethered Alkene Enables Synthesis of CF3-Containing Spiroindolenines and Tetrahydrocarbazoles

An iron-catalyzed trifluoromethylation of indole-tethered alkene with Togni's reagent to construct CF₃-containing spiro[indole-3,3′-pyrrolidine] and tetrahydrocarbazole derivatives under mild and convenient conditions has been disclosed. Mechanistic studies indicate that the reaction proceed through a CF₃ radical addition to the alkene, followed by sequential dearomatizing spiocyclization of the indole and oxidation to afford the spiro[indole-3,3′-pyrrolidine] derivatives. Meanwhile, when the substituent at the C2 position of the indole is hydrogen, the CF₃-containing tetrahydrocarbazole is obtained through trifluoromethylation of alkene and cyclization of indole.     

Polyphenol-Based Nanosystems for Next-Generation Cancer Therapy: Multifunctionality,Design, and Challenges

With the continuous updating of cancer treatment methods and the rapid development of precision medicine in recent years, there are higher demands for advanced and versatile drug delivery systems. Scientists are committed to create greener and more effective nanomedicines where the carrier is no longer limited to a single function of drug delivery. Polyphenols, which can act as both active ingredients and fundamental building blocks, are being explored as potential multifunctional carriers that are efficient and safe for design purposes. Due to their intrinsic anticancer activity, phenolic compounds have shown surprising expressiveness in ablation of tumor cells, overcoming cancer multidrug resistance (MDR), and enhancing immunotherapeutic efficacy. This review provides an overview of recent advances in the design, synthesis, and application of versatile polyphenol-based nanosystems for cancer therapy in various modes. Moreover, the merits of polyphenols and the challenges for their clinical translation are also discussed, and it is pointed out that the novel polyphenol delivery system requires further optimization and validation.     

Photosynthesis of Benzonitriles on BiOBr Nanosheets Promoted by Vacancy Associates

Photocatalytic organic functionalization reactions represent a green, cost-effective, and sustainable synthesis route for value-added chemicals. However, heterogeneous photocatalysis is inefficient in directly activating ammonia molecules for the production of high-value-added nitrogenous organic products when compared with oxygen activation in the formation of related oxygenated compounds. In this study, we report the heterogeneous photosynthesis of benzonitriles by the ammoxidation of benzyl alcohols (99 % conversion, 93 % selectivity) promoted using BiOBr nanosheets with surface vacancy associates. In contrast, the main reaction of catalysts with other types of vacancy sites is the oxidation of benzyl alcohol to benzaldehyde or benzoic acid. Experimental measurements and theoretical calculations have demonstrated a specificity of vacancy type with respect to product selectivity, which arises from the adsorption and activation of NH₃ and O₂ that is required to promote subsequent C−N coupling and oxidation to nitrile. This study provides a better understanding of the role of vacancies as catalytic sites in heterogeneous photocatalysis.