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961.
Yuewei Wu Chaoxian Yan Dongxu Li Chengshan Yuan Jibin Sun Shuyun Zhou Hao‐Li Zhang Xiangfeng Shao 《化学:亚洲杂志》2019,14(10):1860-1869
Four tetraphenylethylenes ( 2 a – d ) containing an electron‐rich 2,3,4,6‐tetrahydro‐1,6‐dithia‐3a‐azaphenalene (THDTAP) moiety have been synthesized. The 2 a – d show aggregation‐induced emission (AIE) with yellowish green photoluminescence (PL) in THF‐H2O (v/v, 1:9) solution and in the solid state. Compounds 2 a – d undergo 1,2‐migratory shift in oxidative cyclodehydrogenation reactions to afford the unexpected products 3 a – d which display green PL in CH2Cl2 solution and are non‐emissive in the solid state. The PL intensities of 3 a – d are clearly enhanced in the presence of meta‐chloroperoxybenzoic acid (mCPBA) owing to the oxidation of the S‐atoms on the THDTAP moiety. In contrast, the PL of 2 a – d in THF‐H2O (v/v, 1:9) solution is quenched by adding mCPBA, ascribable to the oxidation of the C=C bond on the ethylene moiety. It is found that the absorption of 3 a – d is distinctly red‐shifted from the UV/Vis region to the NIR region upon acidification, arising from the protonation of the N‐atom on the THDTAP moiety. Furthermore, 3 a – d display nonlinear optical response (NLO) and optical limiting (OL) behaviour which is superior to that of the well‐known OL material C60. 相似文献
962.
Ashish Chalana Ramesh Karri Shyama Charan Mandal Biswarup Pathak Gouriprasanna Roy 《化学:亚洲杂志》2019,14(24):4582-4587
Methylation and demethylation of mercury compounds are two important competing processes that control the net production of highly toxic mercury alkyls, methylmercury (MeHg+) and dimethylmercury (Me2Hg), in environment. Although the microbial and the photochemical methylation and demethylation processes are well studied in recent years but the chemical methylation and demethylation processes have not been studied well. Herein, we report for the first time that the CuSe nanosheet has remarkable ability to activate the highly inert Hg?C bonds of various MeHg+ and Me2Hg compounds at room temperature (21 °C). It facilitates the conversion of MeHg+ into Me2Hg in the absence of any proton donors. Whereas, in the presence of any proton source, it has unique ability to degrade MeHg+ into CH4 and inorganic mercury (Hg2+). Detailed studies revealed that the relatively fast Hg?C bond cleavage was observed in case of MeHgSPh or MeHgI in comparison to MeHgCl, indicating that the Hg?C bond in MeHgCl is relatively inert in nature. On the other hand, the Hg?C bond in Me2Hg is considered to be exceedingly inert and, thus, difficult to cleave at room temperature. However, CuSe nanosheets showed unique ability to degrade Me2Hg into CH4 and Hg2+, via the formation of MeHg+, under acidic conditions at room temperature. DFT calculations revealed that the Hg?C bond activation occurs through adsorption on the surface of (100)‐faceted CuSe nanosheets. 相似文献
963.
《Arabian Journal of Chemistry》2019,12(7):1474-1478
The present study was carried out in order to determine the phytochemical composition of the marine brown alga Cystoseira foeniculacea collected off the coasts of Algeria. After a preliminary fractionation of its organic crude extracts by column chromatography, the resulting fractions were further analysed by 1H NMR. Even though algal species of the genus Cystoseira are commonly known to produce a wide variety of meroditerpenoids, in the case of C. foeniculacea none of the fractions were found to contain such compounds: most of the fractions showed typical 1H NMR signals of fatty acids and derivatives (mainly glycerolipids and glycolipids). Nevertheless, the thorough analysis of a sterol-enriched fraction by RP-C8 HPLC led to the isolation, for the first time from this species, of fucosterol (1) and a mixture of saringosterols (2 and 3). The NMR data of compounds 1–3 were fully determined with the help of 1D and 2D experiments which allowed the reassignment of some attributions in comparison with those reported in the literature. This work also confirms evidence of the oxidative degradation of fucosterol into a C-24 epimeric mixture of saringosterols. 相似文献
964.
Yun Yang Wenjuan Liu Yunhui Zhao Tianlong Huang Jiale Cui 《Journal of Macromolecular Science: Physics》2019,58(2):209-218
Synthesized biodegradable polymers with controlled degradability and good biological safety would be useful in biomedical applications. In this work a novel maleated poly(D,L-lactide-co-glycolide) (MPLGA) was melt copolymerized from maleic anhydride, D,L-lactide and glycolide monomers. The degradation behavior in phosphate-buffered solution (PBS) was investigated and the biological properties were studied by using fibroblastic cells cultured in an extract of MPLGA and by an in-vitro cell cytotoxicity test. The results indicated that the MPLGA was successfully obtained using the melt-copolymerization method. The maleic anhydride groups in the MPLGA led to a faster degradation in PBS than PLGA. Fibroblastic cells showed normal morphologies in MPLGA extracts, and the MPLGA materials showed no cell cytotoxicity. The in-vitro biological properties indicated that the obtained MPLGA had good biocompatibility and would be useful for medical applications. 相似文献
965.
Dr. Jinpeng Liu Dr. Nali Zhu Dr. Haiming Xu Jinwu Bai Dr. Chaofeng Shao Prof. Meiting Ju Prof. Qilin Yu Prof. Lu Liu 《ChemistryOpen》2019,8(10):1309-1315
Bismuth oxybromide (BiOBr) nanosheets are exciting photocatalysts for microbial disinfection and organic dye degradation. However, it remains a great challenge to easily recycle these nanomaterials and improve their photocatalytic ability. Herein, we constructed a novel photocatalytic BiOBr@PAG gel containing BiOBr nanosheets and polyacrylamide gel (PAG), based on peroxydisulfate-induced polymerization reaction. The photocatalytic gel had equally distribution of BiOBr nanosheets on the surface, and could be easily recycled from water. More strikingly, the gel could also rapidly kill all tested pathogenic bacteria (i. e., Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) under irradiation. Its disinfection activity is attributed to remarkable intracellular ROS production and oxidative cell damage. Furthermore, the gel had higher photocatalytic activity than BiOBr nanosheets alone during degradation of organic dyes. This study developed a novel strategy for preparation of easy-recycling and high-efficiency photocatalytic systems for practical application in environmental treatment and medicinal disinfection. 相似文献
966.
采用溶胶凝胶法合成了钛硅纳米复合氧化物(TiO2-SiO2),并以其为载体用原位合成技术或浸渍法负载Keggin结构磷钼酸(HPMo)制备了复合催化剂,使用扫描电子显微镜(SEM)、傅里叶红外光谱仪(FT-IR)、紫外可见光谱仪(UV-Vis)、X射线衍射光谱(XRD)和比表面分析仪(BET)等测试手段对催化剂的结构进行表征。 结果表明,采用原位法合成的催化剂为纳米粒子,纳米晶骨架内存在微孔和介孔共存的孔道结构。 原位合成技术或浸渍法制备的催化剂中HPMo保持Keggin骨架结构。以模拟油品(二苯并噻吩、苯并噻吩或噻吩的正辛烷溶液)的氧化脱硫为探针反应,在选定的条件下:硫含量为200.0 g/g的正辛烷溶液和无水乙醇各10.0 mL,反应温度60 ℃,催化剂质量0.15 g,n(H2O2)∶n(S)=5∶1,二苯并噻吩的脱除率高于96.0%,产物中硫含量低于10.0 μg/g。 在相同的实验条件下,受电子云密度的影响,脱硫由易到难的顺序为二苯并噻吩>苯并噻吩>噻吩。 催化剂循环使用4次后活性未见明显降低,是一类绿色的模型有机硫化物氧化脱除工艺用催化剂。 相似文献
967.
蛋白质蛋氨酸亚砜化是一种重要的氧化还原依赖的蛋白质翻译后修饰,不仅是氧化应激的重要标志物之一,也是一种蛋白质功能调控开关可影响活性氧信号转导,与一系列疾病尤其是神经退行性疾病的发生发展密切相关。 在许多生物体中,蛋氨酸亚砜还原酶是目前已经发现的唯一能将蛋白质蛋氨酸亚砜还原为蛋氨酸的物质,可以修复氧化损伤蛋白,恢复蛋白质功能,调控细胞氧还平衡,对相关疾病的治疗具有非常重要的意义。 本文重点介绍蛋氨酸亚砜和蛋氨酸亚砜还原酶的结构和催化机理,综述蛋氨酸亚砜和蛋氨酸亚砜还原酶荧光探针的部分研究进展,对该领域的研究前景进行展望。 相似文献
968.
GAO Biao LUO Yajun MIAO Changxi YUE Yinghong YANG Weimin HUA Weiming GAO Zi 《高等学校化学研究》2018,34(4):609-615
A series of Cr-SiO2 catalysts with a Cr content(mass fraction) ranging from 0.5% to 9% was prepared by a sol-gel method. The catalysts were characterized by XRD, N2 adsorption, EDX elemental mapping, Raman spectroscopy, UV-Vis spectroscopy, XPS and H2-TPR, and their catalytic behavior in the dehydrogenation of 1-butene to 1,3-butadiene(BD) using CO2 as a soft oxidant was studied. The initial BD yield is well correlated with the amount of Cr6+ in the fresh catalysts. The highest BD yield of ca. 34% is achieved on the catalysts with 5%-9% Cr at 600℃ and weight hourly space velocity(WHSV) of 4.5 g·gcat-1·h-1. The promoting effect of CO2 on the BD yield was observed, which can be attributed to the reaction coupling between a simple dehydrogenation of 1-butene and the reverse water-gas shift reaction as well as regaining the oxidation state(lattice oxygen) of reduced Cr3+ species due to the mild oxidation ability of CO2. The Cr-SiO2 catalyst exhibits higher BD yield than the Cr catalyst supported on SBA-15, which is attributed to the higher amount of Cr6+ present on the former catalyst. 相似文献
969.
970.
A multifunctional Cu2O/Ag micro-nanocomposite, which has the characteristics of high catalytic activities under the visible light and high surface-enhanced Raman scattering (SERS) activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO3 concentration, Ag content on the Cu2O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanoparticles form on the Cu2O nanoframes to obtain the Cu2O/Ag nanocomposite, which can act as an excellent bifunctional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS. 相似文献