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101.
Faqiong Zhao Liqin Liu Fei Xiao Jiangwen Li Rui Yan Shuangshuang Fan Baizhao Zeng 《Electroanalysis》2007,19(13):1387-1393
An ionic liquid (i.e., 1‐butyl‐3‐methylimidazolium hexafluorophosphate, BMIMPF6)‐single‐walled carbon nanotube (SWNT) gel modified glassy carbon electrode (BMIMPF6‐SWNT/GCE) is fabricated. At it the voltammetric behavior and determination of p‐nitroaniline (PNA) is explored. PNA can exhibit a sensitive cathodic peak at ?0.70 V (vs. SCE) in pH 7.0 phosphate buffer solution on the electrode, resulting from the irreversible reduction of PNA. Under the optimized conditions, the peak current is linear to PNA concentration over the range of 1.0×10?8–7.0×10?6 M, and the detection limit is 8.0×10?9 M. The electrode can be regenerated by successive potential scan in a blank solution for about 5 times and exhibits good reproducibility. Meanwhile, the feasibility to determine other nitroaromatic compounds (NACs) with the modified electrode is also tested. It is found that the NACs studied (i.e., p‐nitroaniline, p‐nitrophenol, o‐nitrophenol, m‐nitrophenol, p‐nitrobenzoic acid, and nitrobenzene) can all cause sensitive cathodic peaks under the conditions, but their peak potentials and peak currents are different to some extent. Their peak currents and concentrations show linear relationships in concentration ranges with about 3 orders of magnitude. The detection limits are 8.0×10?9 M for p‐nitroaniline, 2.0×10?9 M for p‐nitrophenol, 5.0×10?9 M for o‐nitrophenol, 5.0×10?9 M for m‐nitrophenol, 2.0×10?8 M for p‐nitrobenzoic acid and 8.0×10?9 M for nitrobenzene respectively. The BMIMPF6‐SWNT/GCE is applied to the determination of NACs in lake water. 相似文献
102.
103.
Wei Zeng 《Tetrahedron letters》2006,47(33):5923-5926
Vanadium(V) (5 mol %) and hydroxamic acid ligand (45 mol %) were found to promote the selective tert-butyl hydroperoxide-mediated oxidation of allylic and propargylic alcohols to the corresponding aldehydes and ketones. 相似文献
104.
生物,环境样品和食品中铅的痕量分析 总被引:2,自引:0,他引:2
主要根据近七年来发表的有关论文,综述了我国生物、环境样品和食品中铅和痕量分析技术进展,内容包括分子光谱、原子光谱、电化学和其他分析方法,以及联用技术和前处理等方面,收集文献393篇。 相似文献
105.
Xiaoqing Zeng Maofa Ge Zheng Sun Jiang Bian Dianxun Wang 《Journal of Molecular Structure》2007,840(1-3):59-65
Gaseous nitryl azide N4O2 is generated by the heterogeneous reaction of gaseous ClNO2 with freshly prepared AgN3 at −50 °C. The geometric and electronic structure of the molecule in the gas phase has been characterized by in situ photoelectron spectroscopy (PES) and quantum chemical calculations. The experimental first vertical ionization energy of N4O2 is 11.39 eV, corresponding to the ionization of an electron on the highest occupied molecular orbital (HOMO) {4a″(πnb(N4–N5–N6))}−1. An apparent vibrational spacing of 1600 ± 60 cm−1 (νasO1N2O3) on the second band at 12.52 eV (πnb(O1–N2–O3)) further confirms the preference of energetically stable chain structure in the gas phase. To complement the experimental results, the potential-energy surface of this structurally novel transient molecule is discussed. Both calculations and spectroscopic results suggest that the molecule adopts a trans-planar chain structure, and a five-membered ring decomposition pathway is more favorable. 相似文献
106.
复合氨基酸微量元素螯合物制备新工艺的研究 总被引:19,自引:0,他引:19
本文报道了以废羽毛为原料,采用矿物质硫酸盐的制备与中和脱酸、螯合反应结合的新工艺,以金属盐类作催化剂和硫酸水解法,制得了复合氨基酸微量元素螯合物。复合氮基酸生成率为71.7%,微量元素螯合率达到98%以上。该工艺简单易行,生产成本低。 相似文献
107.
Hongyang Su Lanlan Chen Yizhen Chen Prof. Rui Si Yuting Wu Xiaonan Wu Dr. Zhigang Geng Prof. Wenhua Zhang Prof. Jie Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20591-20596
Efforts have been devoted to achieving a highly efficient artificial synthesis of ammonia (NH3). Reported herein is a novel Fe-MoS2 catalyst with Fe atomically dispersed onto MoS2 nanosheets, imitating natural nitrogenase, to boost N2 electroreduction into NH3 at room temperature. The Fe-MoS2 nanosheets exhibited a faradic efficiency of 18.8 % with a yield rate of 8.63 μg mgcat.−1 h−1 for NH3 at −0.3 V versus the reversible hydrogen electrode. The mechanism study revealed that the electroreduction of N2 was promoted and the competing hydrogen evolution reaction was suppressed by decorating the edge sites of S in MoS2 with the atomically dispersed Fe, resulting in high catalytic performance for the electroreduction of N2 into NH3. This work provides new ideas for the design of catalysts for N2 electroreduction and strengthens the understanding about N2 activation over Mo-based catalysts. 相似文献
108.
A simple method was used to prepare a "switchable" electrode surface by using self-assembled monolayers of dodecanethiol on a gold electrode. The dodecane-modified electrode was electrochemically inactive until the monolayer was soaked in solutions of 1,10-phenanthroline or 2,2'-bipyridine. The electroactive form of the electrode could be reverted back to the nonelectroactive form by rinsing the electrode. Surface IR results showed that both dodecanethiol and 1,10-phenanthroline exist in the mixed monolayer. 相似文献
109.
(E)/(Z)-Isomeric allylic carbamate esters were deprotonated by n-butyllithium/(−)-sparteine in toluene. Trapping experiments with chlorotrimethylsilane afforded the α-substitution products, with (R)-configuration, revealing that the pro-S proton is removed predominantly to form the corresponding (S)-lithium·(−)-sparteine derivatives; kS/kR>15:1 and >7:1, respectively. A slow (S)→(R)-epimerization occurs at −78 °C (T1/2>60 min). The allylic double bond is stable to (Z)-(E) isomerization under these conditions. 相似文献
110.
It is known that silicon fullerenes cannot maintain perfect cage structures like carbon fullerenes. Previous density-functional theory calculations have shown that even with encapsulated species, nearly all endohedral silicon fullerenes exhibit highly puckered cage structures in comparison with their carbon counterparts. In this work, we present theoretical evidences that the tetrahedral fullerene cage Si(28) can be fully stabilized by encapsulating a tetrahedral metallic cluster (Al(4) or Ga(4)). To our knowledge, this is the first predicted endohedral silicon fullerene that can retain perfectly the same cage structure (without puckering) as the carbon fullerene counterpart (T(d)-C(28) fullerene). Density-functional theory calculations also suggest that the two endohedral metallosilicon fullerenes T(d)-M(4)@Si(28) (M=Al and Ga) can be chemically stable because both clusters have a large highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap ( approximately 0.9 eV), strong spherical aromaticity (nucleus-independent chemical shift value of -36 and -44), and large binding and embedding energies. 相似文献