芳香烃氯甲基化反应的综述

芳香烃氯甲基化是有机合成中的重要反应。本文综述了芳香烃氯甲基化的反应，并按不同类型的氯甲基化试剂、不同活性的反应催化剂、不同极性的反应介质，及采用相转移催化技术等四方面分别予以讨论     

Recent Development in the Synthesis of Natural Saponins and Their Derivatives

Naturally occurring saponins are attractive candidates or lead compounds for new drug design and development and thus have become important synthetic targets. This short account reviews the recent progress in the chemical synthesis and structure-activity relationship (SAR) studies of naturally occurring saponins and their derivatives.     

Acid‐treated g‐C3N4‐Cu2O composite catalyst with enhanced photocatalytic activity under visible‐light irradiation

Acid‐treated g‐C₃N₄‐Cu₂O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as‐synthesized samples were characterized using a range of techniques, such as X‐ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible‐light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo‐generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid‐treated g‐C₃N₄‐Cu₂O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge‐transfer resistance. Furthermore, the g‐C₃N₄‐Cu₂O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and ?O₂^? could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high‐performance photocatalysts, and facilitate their application in addressing environmental protection issues.     

Nitrogen doping effects on the structure of graphene

Graphene and nitrogen doped graphene have been prepared by modified Hummers’ method and the following ammonia heat-treatment process, respectively. The effects of N-doping on the structure of graphene have been systematically investigated by various characterization techniques. SEM, TEM, BET, Raman and XRD analysis were used to distinguish the difference of the microstructures; and FT-IR, XPS, especially XANES were performed to elucidate the bonding information such as C-N. The effect of nitrogen doping on the structure of graphene has been obtained. More defects are present on nitrogen doped graphene as elucidated by BET, XRD, Raman, and XANES characterizations. XANES analysis also indicates that the N-doping decreases the surface oxygen-containing groups.     

Study on the Interaction Between Bovine Serum Albumin and Potassium Perfluoro Octane Sulfonate

The interactions between potassium perfluorooctanesulfonate (PFOS) and bovine serum albumin (BSA) were studied by fluorescence spectroscopy. The association constants between PFOS and BSA were obtained by fluorescence enhancing and fluorescence quenching respectively. Furthermore, fluorescence quenching was studied at different temperatures, and the binding constant was also determined by the method of fluorescence quenching. According to the thermodynamic parameters, the main binding force could be judged. The experimental results revealed that BSA and PFOS had strong interactions. The mechanism of quenching belonged to dynamic quenching and the main sort of binding force was hydrophobic force. IR-spectra proved the interaction changed the conformation of BSA.     

Effects of Ag–La codoping on structure and electrical properties of BaTiO3 powder

Ag–La codoped BaTiO₃ powders were prepared by sol–gel technology after the preparation of Ag-doped and La-doped BaTiO₃ powders. Variations in the structure, constitution, morphology, and electrical properties of the modified BaTiO₃ powders were characterized. It can be concluded that Ag–La codoping decreases the resistivity of the modified powders more significantly than Ag doping and La doping, respectively. The sample with the lowest resistivity was obtained by codoping with 0.1 at.% Ag and 0.3 at.% La, where the resistivity decreased to 7.13 × 10² Ω m from the value of 4.30 × 10⁹ Ω m of the undoped powder. X-ray diffractometry (XRD) and Fourier-transform infrared (FTIR) analyses indicate that the main phase of the codoped powders transitions from tetragonal to cubic with increasing La doping content. Scanning electron microscopy (SEM) observations illustrate that codoping makes the particles distribute more equably. The relationship between the resistivity and the structure of the doped BaTiO₃ powders is discussed based on defect chemistry.     

In situ self-assembly synthesis of gold nanoparticle arrays on polystyrene microspheres and their surface plasmon resonance

Gold (Au) nanoparticle arrays with tunable morphology and optical characteristics were synthesized by in-situ self-assembly process that occurred on the surface of aniline-modified polystyrene (PS) microspheres. The method can be used to control the growth of both single and aggregated Au nanoparticle arrays on PS microsphere surface. This method could also be adapted for synthesis of other noble metals hybrid materials, which opens exciting opportunities for their practical applications.