Visible Light Photocatalytic Functional TiO2/PVDF Nanofibers for Dye Pollutant Degradation

The photodegradation of poly(vinylidene fluoride) (PVDF)/titanium oxide (TiO₂) nanofibers under visible light is described, something that has not been previously reported in the literature. Visible light photocatalytic electrospun PVDF/TiO₂ nanofiber webs with anatase TiO₂ concentration varying from 0% to 20% (0%, 1%, 3%, 5%, 10%, and 20%) are produced, and their ability to degrade a toxic pollutant, Rhodamine B (RhB), is studied. Photodegradation study using UV–vis spectroscopy on PVDF/TiO₂ nanofiber webs (with TiO₂ concentration of 20%) shows that 80% of RhB is degraded within 6 h at the wavelength of 546 nm, which clearly falls within the visible spectra. The color of RhB solvent catalyzed by PVDF/TiO₂ nanofiber webs gradually changes from red to orange, then to yellow, further to light yellow till colorless, which suggests the complete photodegradation of RhB under visible light. To estimate the rate of photodegradation, the reaction constant k is calculated. Based on the k value, PVDF/TiO₂ nanofiber webs with 20% TiO₂ concentration show the highest degradation rate compared to other PVDF/TiO₂ nanofiber webs and pure TiO₂ nanoparticles. This study proves the viability of TiO₂‐based nanofibers to have catalytic capabilities under low‐energy visible light.     

关于对数平均的上界和下界

利用广义对数平均，给出了对数平均的上界和下界控制     

An Unlocked Two-Dimensional Conductive Zn-MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production

Developing highly efficient catalytic sites for O₂ reduction to H₂O₂, while ensuring the fast injection of energetic electrons into these sites, is crucial for artificial H₂O₂ photosynthesis but remains challenging. Herein, we report a strongly coupled hybrid photocatalyst comprising polymeric carbon nitride (CN) and a two-dimensional conductive Zn-containing metal–organic framework (Zn-MOF) (denoted as CN/Zn-MOF(lc)/400; lc, low crystallinity; 400, annealing temperature in °C), in which the catalytic capability of Zn-MOF(lc) for H₂O₂ production is unlocked by the annealing-induced effects. As revealed by experimental and theoretical calculation results, the Zn sites coordinated to four O (Zn-O₄) in Zn-MOF(lc) are thermally activated to a relatively electron-rich state due to the annealing-induced local structure shrinkage, which favors the formation of a key *OOH intermediate of 2e⁻ O₂ reduction on these sites. Moreover, the annealing treatment facilitates the photoelectron migration from the CN photocatalyst to the Zn-MOF(lc) catalytic unit. As a result, the optimized catalyst exhibits dramatically enhanced H₂O₂ production activity and excellent stability under visible light irradiation.     

Enantio- and diastereoselective Michael addition reactions of unmodified aldehydes and ketones with nitroolefins catalyzed by a pyrrolidine sulfonamide

Chiral (S)-pyrrolidine trifluoromethanesulfonamide has been shown to serve as an effective catalyst for direct Michael addition reactions of aldehydes and ketones with nitroolefins. A wide range of aldehydes and ketones as Michael donors and nitroolefins as acceptors participate in the process, which proceeds with high levels of enantioselectivity (up to 99 % ee) and diastereoselectivity (up to 50:1 d.r.). The methodology has been employed successfully in an efficient synthesis of the potent H(3) agonist Sch 50917. In addition, a practical three-step procedure for the preparation of (S)-pyrrolidine trifluoromethanesulfonamide has been developed. The high levels of stereochemical control attending Michael addition reactions catalyzed by this pyrrolidine sulfonamide, have been investigated by using ab initio and density functional methods. Transition state structures for the rate-limiting C--C bond-forming step, corresponding to re- and si-face addition to the reactive conformation of the key enamine intermediates have been calculated. Analysis of these structures indicates that hydrogen bonding plays an important role in catalysis and that the energy barrier for si-face attack in reactions of aldehydes to form 2R,3S products is lower than that for the re-face attack leading to 2S,3R products. In contrast, the energy barrier for re-face addition is lower than that for si-face addition in reactions of ketones. The computational results, which are in good agreement with the experimental observations, are discussed in the context of the stereochemical course of these Michael addition reactions.     

Red luminescent polymeric cuprous organosulfide generated by solvothermal redox reaction

A new polymeric metal organosulfide [Cu(I)3(pymt)3]n(pymt = pyrimidine-2-thiolate) with strong red photoluminescence was synthesized through solvothermal redox reaction, and crystallographically characterized to be a one-dimensional chiral structure containing metal-metal interactions.     

Chemical biology of salinomycin

Cancer stem cells (CSC) have been shown to be refractory to conventional therapeutic agents, can promote metastasis, and have been linked to cancer relapse. The natural product Salinomycin has been identified by means of high throughput phenotypic screening as a selective killer of CSC in vitro and in vivo. In this article we comprehensively review the chemistry of Salinomycin, documenting early total syntheses, along with strategies that have been developed over the years to effectively modify this natural product at key positions with the view to establish a robust structure-activity-relationship and to delineate the complex mechanism of action of this fascinating molecule in the context of cancer research. Then, we document the biology of Salinomycin, putting forward phenotypic alterations that have been observed in the relevant biological models and highlighting how chemistry has been instrumental in discovering unprecedented physiological features of cancer stem cells that can be exploited for therapeutic benefits.     

吡啶团簇的飞秒光电离和从头计算研究

用飞秒激光电离飞行时间质谱研究了吡啶分子团簇在400 nm波长下的多光子光电离,实验观测到一系列的质子化和非质子化团簇离子.结果表明,质子转移也能发生在弱氢键结合的分子间.通过分析离子峰宽和离子信号强度随气源压力的变化,得到质子化团簇离子来源于大团簇离子的碎裂,而非质子化团簇离子是中性团簇直接电离的结果.从头计算结果表明,吡啶团簇是通过弱氢键C-H…N 结合在一起的,并且团簇离子离解倾向于生成质子化产物.     

1,3,2-二氮磷杂环戊-4-酮-2-硒(硫)代化合物的合成及生物活性

五元磷杂环;1;3;2-二氮磷杂环戊-4-酮-2-硒(硫)代化合物的合成及生物活性;烟草花叶病毒;除草活性;杀菌活性;抗药草花叶病毒活性     

染毒水样中神经性毒剂水解产物的分析

考察了对水中6种神经性毒剂水解产物固相萃取的萃取剂,洗脱剂等因素对萃取率的影响,以LC－CN小柱为萃取剂,1％冰醋 甲醇溶液为洗脱剂,测得萃取回收率为59．7％－100％,相对标准偏差为1．4％－7．2％,采用气相色谱和色质联用－选择离子检测法对水解产物三甲基硅烷（TMS）衍生物进行分析鉴定,水中水解产物最低检测浓度为0．002－0．02mg/L。为今后水中神经性毒剂未知样品分析提供了简便,快速的分析方法。