排序方式: 共有134条查询结果,搜索用时 15 毫秒
51.
Dr. Biao Yang Kaifeng Niu Nan Cao Dr. Nitika Grover Wenchao Zhao Alexander Riss Prof. Dr. Jonas Björk Prof. Dr. Willi Auwärter Prof. Dr. Johannes V. Barth Prof. Dr. Mathias O. Senge 《Angewandte Chemie (International ed. in English)》2023,62(19):e202218211
Bicyclo[1.1.1]pentane (BCP) motifs are of growing importance to the pharmaceutical industry as sp3-rich bioisosteres of benzene rings and as molecular building blocks in materials science. Herein we explore the behavior of 1,3-disubstituted BCP moieties on metal surfaces by combining low-temperature scanning tunneling microscopy / non-contact atomic force microscopy studies with density functional theory modeling. We examine the configuration of individual BCP-containing precursors on Au(111), their supramolecular assembly and thermally activated dehalogenative coupling reactions, affording polymeric chains with incorporated electronically isolating units. Our studies not only provide the first sub-molecular insights of the BCP scaffold behavior on surfaces, but also extend the potential application of BCP derivatives towards integration in custom-designed surface architectures. 相似文献
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Guo Qiang Hu Li Li Hou Yong Yang Lei Yi Song Qiang Xie Guo Qiang Wang Nan Nan Duan Tie Yao Chao Xiao Yi Wen Wen Long Huang 《中国化学快报》2011,22(7):804-806
To further expand an effective modified route for the shift from an antibacterial fluoroquinolone(FQ) to an antitumor FQ,two series of title compounds based on an isostere of the FQ C3 carboxylic group with two fused heterocyclic rings,[1,2,4]triazolo[3,4- b][1,3,4]thiadiazine and pyrazolo[5,1-c][1,2,4]triazole,respectively,were designed and synthesized starting from the current antibacterial FQs,and their in vitro antitumor activity against L1210,CHO cell lines were evaluated via their respective IC50 values. 相似文献
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Tongbao Wang Lin Liang Runwei Wang Yanqiu Jiang Kaifeng Lin Jianmin Sun 《Adsorption》2012,18(5-6):439-444
Carbon materials such as activated carbons have been used in the field of water and wastewater treatments. However, the lack of mesopore and, particularly, the difficulty in recovering the spent carbon limited their applications. In this work, magnetic mesoporous carbon microspheres were synthesized by impregnating iron oxide precursors in the mesoporous carbon followed by the in situ conversion of the precursors into magnetite nanoparticles. The as-synthesized carbon microspheres with a high surface area of 742?m2/g and large mesopores of ~4.4?nm exhibited an excellent adsorption capacity for aqueous organic pollutants. The superparamagnetic microspheres with a saturation magnetization of 7.15 emu/g can be easily separated from the treated solution by external magnetic field. 相似文献
54.
Xi Fan Junhui Wang Kaifeng Wu Lei Zhang Jian Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1334-1337
Phase isomerism is a common and important phenomenon in inorganic materials, but the molecular isomerism of their nanocluster models is still rare. In this work, we report the first pair of isomeric titanium‐oxo clusters. Through combining pentagonal {Ti(Ti5)} building units in corner‐sharing or edge‐sharing forms, the two obtained Ti20‐oxo clusters take vertical and horizontal core configurations, respectively, which are both functionalized by the same organic ligands. More interestingly, the vertical type Ti20‐oxo core contains an identical {Ti8O14} moiety as anatase, making it the first molecular model of anatase TiO2. As a result, the vertical type cluster exhibits better photocatalytic H2 evolution activity, higher photocurrent response and faster charge transfer to external acceptors than its horizontal isomer. Thus, this work provides a cluster isomer method to understand the structure–property relationship of import titanium oxide materials. 相似文献
55.
Pengfei Wang Yueshuang Mao Lina Li Zhurui Shen Xiao Luo Kaifeng Wu Pengfei An Haitao Wang Lina Su Yi Li Sihui Zhan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11451-11456
A highly efficient Z‐scheme photocatalytic system constructed with 1D CdS and 2D CoS2 exhibited high photocatalytic hydrogen‐evolution activity of 5.54 mmol h?1 g?1 with an apparent quantum efficiency of 10.2 % at 420 nm. More importantly, its interfacial charge migration pathway was unraveled: The electrons are efficiently transferred from CdS to CoS2 through a transition atomic layer connected by Co–S5.8 coordination, thus resulting in more photogenerated carriers participating in surface reactions. Furthermore, the charge‐trapping and charge‐transfer processes were investigated by transient absorption spectroscopy, which gave an estimated charge‐separation yield of approximately 91.5 % and a charge‐separated‐state lifetime of approximately (5.2±0.5) ns in CdS/CoS2. This study elucidates the key role of interfacial atomic layers in heterojunctions and will facilitate the development of more efficient Z‐scheme photocatalytic systems. 相似文献
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57.
Fan Yang Lu Xu Guodong Dai Lin Luo Kaifeng Yang Churui Huang Dong Tian Fei Shen 《Molecules (Basel, Switzerland)》2022,27(5)
The valorization of cellulose and lignin residues in an integrated biorefinery is of great significance to improve the overall economics but has been challenged by their structural recalcitrance, especially for lignin residue. In this work, a facile chemical conversion route to fabricating functional UV-blocking cellulose/lignin composite films through a facile dissolution–regeneration process using these biomass residues was proposed. Three representative lignin residues, i.e., aspen and poplar wood lignin, and corn stover (CS) lignin were assessed for their feasibility for the film fabrication. The UV-blocking performance of the composite films were comparatively investigated. Results showed that all these three lignin residues could enhance the UV-blocking property of the composite films, corresponding to the reduction in the optical energy band gap from 4.31 to 3.72 eV, while poplar lignin had a considerable content of chromophores and showed the best UV-blocking enhancement among these three assessing lignins. The enhancement of UV-blocking property was achieved without compromising the visible-light transparency, mechanical strength and thermal stability of the composite films even at 4% lignin loading. This work showed the high promise of integrating biomass residue conversion into lignocellulose biorefinery for a multi-production purpose. 相似文献
58.
Xinjiang Zhang Meng He Yongzhong Zhan Wenchao Yang Kaifeng Wu 《Molecules (Basel, Switzerland)》2022,27(19)
Copper matrix composites have a wide application as magnetic conductive materials, electromagnetic materials, electrical discharge machining materials, etc. Such materials are expected to have a good combination of excellent electrical conductivity and good mechanical strength. In this work, micro/nano hybrid reinforcements with Fe microspheres and reduced graphene oxide (rGO) nanosheets were developed for copper matrix composites. The rGO/Fe/Cu powders were firstly wet-mixed and then densified by the vacuum hot-pressing sintering to obtain the bulk compacts. Microstructure, electrical conductivity and mechanical properties of such compacts were investigated. Microstructural result of as-sintered compacts shows that the Fe microspheres could distribute in the matrix uniformly, and rGO nanosheets exhibit both agglomerated and dispersed states. The grain size of Cu matrix decreased with the increase of the rGO content. Hardness, compression and tensile 0.2% yield strength of the as-sintered compacts were improved evidently by the addition of the hybrid Fe/rGO, comparing with pure Cu and single Fe-added composites. However, a lower electrical conductivity appeared in the more rGO-added composites, but still reached more than 33.0% international annealing copper standard (IACS). These performance change could be sought in the spatially geometrical distribution and characteristics of such micro/nano Fe/rGO hybrid addition, and the relevant mechanisms were discussed. 相似文献
59.
Coacervate behavior of polyelectrolyte complexes has been studied by many papers. Few studies have focused on the coacervate behavior of amphoteric polymer. In this study, amphoteric copolymer of diallyldimethylammonium chloride (DM) and sodium styrenesulfonate (SS) (the copolymer was noted as DMS) was synthesized with the mole content of SS to DM ranged from 0 to 10%. Firstly, DMS was characterized by static light scattering, FTIR, 1H-NMR, TGA and DSC. Then, its phase and coacervate behaviors were studied. Turbidity was utilized as an indicator for the coacervate formation. It was found that when the SS content was more than 4 mol%, DMS coacervate would be formed in deionized water at a certain concentration. Temperature and pH have no effect on the formation of DMS coacervate. Meanwhile, salts has a great influence on the DMS coacervation. Unlike the results of the other polyelectrolyte complexes, Na2SO4, Na2HPO4, NaCOOCH3, sodium citrate and NaI cannot prevent the DMS coacervate formation. However, the addition of NaCl, NaNO3, NaBr and NaSCN can prevent the coacervate formation. The influence cannot be described by Hofmeister-like behavior. Results of surface tension and fluorescence spectrum presented that the driving forces to formation of DMS coacervate are the electrostatic interaction and the intermolecular hydrophobic interaction. 相似文献
60.
XU HongTao WANG XinShou TAO LeiMing & WU SiXin Key Laboratory for Special Functional Materials of Ministry of Education Henan University Kaifeng China 《中国科学:化学》2010,(3)
MCM-41-type mesoporous silica nanospheres(MSN) have been prepared using n-cetyltrimethylammonium bromide(CTAB) as a soft template.The pseudo-moire' rotational pattern inside the MSN results in many interior defects.Hollow mesoporous silica(HMS) spheres were synthesized by solvent extraction of the template from MSN.The morphology and structure of MSN and HMS were studied by TEM,XRD and nitrogen sorption techniques.A model drug,bromocresol green dye,was packed inside different regions of HMS through impregna... 相似文献