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991.
Nitrite Oxidation with Copper–Cobalt Nanoparticles on Carbon Nanotubes Doped Conducting Polymer PEDOT Composite
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Copper–cobalt bimetal nanoparticles (Cu?Co) have been electrochemically prepared on glassy carbon electrodes (GCEs), which were electrodeposited with conducting polymer nanocomposites of poly(3,4‐ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). Owing to their good conductivity, high mechanical strength, and large surface area, the PEDOT/CNTs composites offered excellent substrates for the electrochemical deposition of Cu?Co nanoparticles. As a result of their nanostructure and the synergic effect between Cu and Co, the Cu?Co/PEDOT/CNTs composites exhibited significantly enhanced catalytic activity towards the electrochemical oxidation of nitrite. Under optimized conditions, the nanocomposite‐modified electrodes had a fast response time within 2 s and a linear range from 0.5 to 430 μm for the detection of nitrite, with a detection limit of 60 nm . Moreover, the Cu?Co/PEDOT/CNTs composites were highly stable, and the prepared nitrite sensors could retain more than 96 % of their initial response after 30 days. 相似文献
992.
Preparation and Electrochemical Properties of Tin–Iron–Carbon Nanocomposite as the Anode of Lithium‐Ion Batteries 下载免费PDF全文
Dr. Xu Yang Dr. Rongyu Zhang Dr. Xiaofei Bie Prof. Chunzhong Wang Malin Li Dr. Nan Chen Prof. Yingjin Wei Prof. Gang Chen Dr. Fei Du 《化学:亚洲杂志》2015,10(11):2460-2466
Tin–iron–carbon nanocomposite is successfully prepared by a sol–gel method followed by a chemical vapor deposition (CVD) process with acetylene gas as the carbon source. The structural properties, morphology, and electrochemical performances of the nanocomposite are comprehensively studied in comparison with those properties of tin–carbon and iron–carbon nanocomposites. Sheet‐like carbon architecture and different carbon contents are induced thanks to the catalytic effect of iron during CVD. Among three nanocomposites, tin–iron–carbon demonstrates the highest reversible capacity of 800 mA h g?1 with 96.9 % capacity retention after 50 cycles. It also exhibits the best rate capability with a discharge capacity of 420 mA h g?1 at a current density of 1000 mA g?1. This enhanced performance is strongly related to the carbon morphology and content, which can not only accommodate the large volume change, but also improve the electronic conductivity of the nanocomposite. Hence, the tin–iron–carbon nanocomposite is expected to be a promising anode for lithium‐ion batteries. 相似文献
993.
Sodium‐Doped Mesoporous Ni2P2O7 Hexagonal Tablets for High‐Performance Flexible All‐Solid‐State Hybrid Supercapacitors 下载免费PDF全文
Dr. Chengzhen Wei Cheng Cheng Shanshan Wang Yazhou Xu Jindi Wang Prof. Huan Pang 《化学:亚洲杂志》2015,10(8):1731-1737
A simple hydrothermal method has been developed to prepare hexagonal tablet precursors, which are then transformed into porous sodium‐doped Ni2P2O7 hexagonal tablets by a simple calcination method. The obtained samples were evaluated as electrode materials for supercapacitors. Electrochemical measurements show that the electrode based on the porous sodium‐doped Ni2P2O7 hexagonal tablets exhibits a specific capacitance of 557.7 F g?1 at a current density of 1.2 A g?1. Furthermore, the porous sodium‐doped Ni2P2O7 hexagonal tablets were successfully used to construct flexible solid‐state hybrid supercapacitors. The device is highly flexible and achieves a maximum energy density of 23.4 Wh kg?1 and a good cycling stability after 5000 cycles, which confirms that the porous sodium‐doped Ni2P2O7 hexagonal tablets are promising active materials for flexible supercapacitors. 相似文献
994.
The particle-swarm optimization method has been used to predict the stable high pressure structures up to 300 GPa of hydrogen-rich group 17 chlorine (HnCl, n = 2–7) compounds. In comparison to the group 1 and 2 hydrides, the structural modification associated with increasing pressure and hydrogen concentration is much less dramatic. The polymeric HCl chains already present in the low temperature phase under ambient pressure persist in all the high pressure structures. No transfer of electrons from the chlorine atoms into the interstitial sites is found. This indicates the chemical bonding at high pressure in group 17 elements is fundamentally different from the alkali and alkaline elements. It is found that almost perfectly triangular H3
+ ions can be stabilized in the crystalline structure of H5Cl. 相似文献
995.
Lars Lauterbach Hongxin Wang Marius Horch Leland B. Gee Yoshitaka Yoda Yoshihito Tanaka Ingo Zebger Oliver Lenz Stephen P. Cramer 《Chemical science》2015,6(2):1055-1060
Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, which is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors. 相似文献
996.
Dali Wang Chunlai Tu Yue Su Chuan Zhang Udo Greiser Xinyuan Zhu Deyue Yan Wenxin Wang 《Chemical science》2015,6(7):3775-3787
Despite of great advances of phospholipids and liposomes in clinical therapy, very limited success has been achieved in the preparation of smart phospholipids and controlled-release liposomes for in vivo drug delivery and clinical trials. Here we report a supramolecular approach to synthesize novel supramolecularly engineered phospholipids based on complementary hydrogen bonding of nucleosides, which greatly reduces the need of tedious chemical synthesis, including reducing the strict requirements for multistep chemical reactions, and the purification of the intermediates and the amount of waste generated relative more traditional approaches. These upgraded phospholipids self-assemble into liposome-like bilayer structures in aqueous solution, exhibiting fast stimuli-responsive ability due to the hydrogen bonding connection. In vitro and in vivo evaluations show the resulted supramolecular liposomes from nucleoside phospholipids could effectively transport drug into tumor tissue, rapidly enter tumor cells, and controllably release their payload in response to an intracellular acidic environment, thus resulting in a much higher antitumor activity than conventional liposomes. The present supramolecularly engineered phospholipids represent an important evolution in comparison to conventional covalent-bonded phospholipid systems. 相似文献
997.
Hui‐Ting Wang Qiang Li Lin Zhou 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(9):763-767
A cadmium–thiocyanate complex, poly[(1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κ4N)octakis‐μ2‐thiocyanato‐κ8N:S;κ8S:N‐tricadmium(II)], [Cd3(C8H14N3)2(NCS)8]n, was synthesized by the reaction of 1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane chloride, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, there are two independent types of CdII cation (one on a centre of inversion and one in a general position) and both are in distorted octahedral coordination environments, coordinated by N and S atoms from different ligands. Neighbouring CdII cations are linked together by thiocyanate bridges to form a two‐dimensional network. Hydrogen‐bonding interactions are involved in the formation of a three‐dimensional supramolecular network. 相似文献
998.
Xu Zhang Lei Zhang Meng‐Jie Wang Kou‐Lin Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(9):776-782
Two new coordination polymers (CPs) formed from 5‐iodobenzene‐1,3‐dicarboxylic acid (H2iip) in the presence of the flexible 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb) auxiliary ligand, namely poly[[μ2‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ2N3:N3′](μ3‐5‐iodobenzene‐1,3‐dicarboxylato‐κ4O1,O1′:O3:O3′)cobalt(II)], [Co(C8H3IO4)(C10H14N4)]n or [Co(iip)(bimb)]n, (1), and poly[[[μ2‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ2N3:N3′](μ2‐5‐iodobenzene‐1,3‐dicarboxylato‐κ2O1:O3)zinc(II)] trihydrate], {[Zn(C8H3IO4)(C10H14N4)]·3H2O}n or {[Zn(iip)(bimb)]·3H2O}n, (2), were synthesized and characterized by FT–IR spectroscopy, thermogravimetric analysis (TGA), solid‐state UV–Vis spectroscopy, single‐crystal X‐ray diffraction analysis and powder X‐ray diffraction analysis (PXRD). The iip2− ligand in (1) adopts the (κ1,κ1‐μ2)(κ1, κ1‐μ1)‐μ3 coordination mode, linking adjacent secondary building units into a ladder‐like chain. These chains are further connected by the flexible bimb ligand in a trans–trans–trans conformation. As a result, a twofold three‐dimensional interpenetrating α‐Po network is formed. Complex (2) exhibits a two‐dimensional (4,4) topological network architecture in which the iip2− ligand shows the (κ1)(κ1)‐μ2 coordination mode. The solid‐state UV–Vis spectra of (1) and (2) were investigated, together with the fluorescence properties of (2) in the solid state. 相似文献
999.
Shuyan Song Xiao Wang Sheling Li Zhuo Wang Qi Zhu Hongjie Zhang 《Chemical science》2015,6(11):6420-6424
Recent studies have further demonstrated that the conjugation of noble metal helical nanostructures could alter their optical and catalytic activities. However, the intrinsic isotropic crystal growth of Pt makes the synthesis of high-quality Pt NCs with unique porous or branched nanostructures difficult. In this work, a new, powerful capping agent, N,N-dimethyloctadecylammonium bromide acetate sodium, was synthesized and used to coordinate Pt ions, slowing down the reaction rate. As a result, in aqueous solution, Pt nanohelices with highly ordered horizontal pore channels were successfully fabricated. Importantly, the Pt nanohelices were composed of several sub-2 nm Pt nanowires coiled together around a central point. The as-obtained samples exhibited enhanced photothermal properties compared with the classic Pt nanoparticles. 相似文献
1000.
Nan Zhang Tao Bing Xiangjun Liu Cui Qi Luyao Shen Linlin Wang Dihua Shangguan 《Chemical science》2015,6(7):3831-3838
Guanine-rich oligonucleotides (GROs) have attracted considerable attention as anticancer agents, because they exhibit cancer-selective antiproliferative activity and can form G-quadruplex structures with higher nuclease resistance and cellular uptake. Recently, a GRO, AS1411 has reached phase II clinical trials for acute myeloid leukemia and renal cell carcinoma. The antiproliferative activity of GROs has been associated with various protein targets; however the real mechanisms of action remain unclear. In this study, we showed evidence that antiproliferative activity of GROs (including AS1411) is mainly contributed by the cytotoxicity of their guanine-based degradation products, such as monophosphate deoxyguanosine (dGMP), deoxyguanosine (dG) and guanine. The GROs with lower nuclease resistance exhibited higher antiproliferative activity. Among nucleotides, nucleosides and nucleobases, only guanine-based compounds showed highly concentration-dependent cytotoxicity. Our results suggest that it is necessary to reconsider the cancer-selective antiproliferative activity of GROs. Since guanine-based compounds are endogenous substances in living organisms, systematic studies of the cytotoxicity of these compounds will provide new information for the understanding of certain diseases and offer useful information for drug design. 相似文献