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71.
Two new complexes, (CoIII)2(H3L?)2(0.5H2O)2(ClO4)4 (I) and (MnIII)2(H3L?)2(0.5H2O)2 (ClO4)4 (II), were synthesized and crystallographically characterized [H4L = 1,4,7,10‐tetra‐(2‐hydroxypropyl)‐l,4,7,10‐tetraazacyclododecane] using electrospray ionization mass spectrometry and X‐ray photoelectron spectrometery. The characterizations confirmed that the valences of the metal ions increased from divalent to trivalent due to deprotonation of one OH group (H4L was in the form of H3L?). Owing to the instability of Co(III) and Mn(III) in both air and in solution, they preferred to exist in divalent form. The two heptadentate complexes are extraordinary in that the chiral pendants of the complexes are different in configuration. Spectroscopic studies, viscosity measurements, thermal denaturation experiments and circular dichroism spectra demonstrated that the complexes were prone to interact with DNA by groove binding. At micromolar concentrations and under physiological conditions, the two complexes were able to oxidatively cleave the supercoiled pUC19 plasmid DNA into its nicked and linear forms. Mechanistic studies using various additives suggest the complexes had structures different from those of other inorganic complexes. These are the first reported inorganic complexes not containing planar aromatic ligands and yet binding at the major groove. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
72.
73.
Synthesis of ethylene/vinyl ester copolymers with pendent linear branches via ring‐opening metathesis polymerization of fatty acid‐derived cyclooctenes 下载免费PDF全文
Yuchen Feng Suyun Jie Bo‐Geng Li 《Journal of polymer science. Part A, Polymer chemistry》2017,55(13):2211-2220
Fatty acid‐derived cyclooctenes, including n‐hexanoic acid ( M1 ), n‐octanoic acid ( M2 ), lauric acid ( M3 ), and palmitic acid ( M4 ), were prepared as monomers and polymerized by ring‐opening metathesis polymerization (ROMP) using Grubbs second‐generation catalyst ( G2 ). In all the cases, the regio‐irregular unsaturated polymers with pendent linear branches were obtained, which could be saturated by chemical hydrogenation with TSH/TPA in high conversion, yielding ethylene/vinyl ester copolymers with pendent linear branches on precisely every eighth backbone carbon. Both unsaturated and saturated polymers were amorphous, and their structures were characterized by FTIR, 1H and 13C NMR spectra, and elemental analysis. Differential scanning calorimetry (DSC) and thermo‐gravimetric analysis (TGA) were used to study their thermal properties. The chain length of branches greatly affected the thermal properties of polymers. After hydrogenation, the thermal degradation stability of polymers was relatively improved. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2211–2220 相似文献
74.
Lan Lei Xianya Geng Shuchao Li Yingjun Peng Yuantian Yu 《International journal of quantum chemistry》2019,119(24):e26044
Let denote a molecular graph of linear [n] phenylene with n hexagons and n squares, and let the Möbius phenylene chain be the graph obtained from the by identifying the opposite lateral edges in reversed way. Utilizing the decomposition theorem of the normalized Laplacian characteristic polynomial, we study the normalized Laplacian spectrum of , which consists of the eigenvalues of two symmetric matrices ℒ R and ℒ Q of order 3n. By investigating the relationship between the roots and coefficients of the characteristic polynomials of the two matrices above, we obtain an explicit closed-form formula of the multiplicative degree-Kirchhoff index as well as the number of spanning trees of . Furthermore, we determine the limited value for the quotient of the multiplicative degree-Kirchhoff index and the Gutman index of . 相似文献
75.
Mingfang Li Rong Geng Meichuan Liu Dongming Li 《International journal of environmental analytical chemistry》2013,93(8):571-582
Bovine serum albumin (BSA) was covalently attached to glassy carbon electrode (GCE) surface by the electrochemical method. An enhancement for the redox of hydroquinone (HQ) on BSA/GCE was confirmed by cyclic voltammetry and electrochemical impedance spectroscopy measurement. The electron transfer rate constant (k s) on the BSA/GCE electrode is almost three orders of magnitude higher than that on bare GCE. The enhancing effect can be attributed to the electrostatic force between the positively charged HQ and negatively charged BSA. It is found that the enhanced redox process of HQ can be used to determine HQ sensitively. The oxidation current can reach 95% of its steady-state value within 30 s. The linear range for HQ determination is from 2.5 × 10?8 M to 1.325 × 10?6 M with a detection limit of 8.6 × 10?9 M at a signal-to-noise ratio of 3. The study may provide a simple, rapid and sensitive method for determination of HQ which is present in the natural environment and in chemical industry effluent. 相似文献
76.
Yun-Hai Wang Guo Li Qing-Yun Chen Xin Geng Wei Yan 《Journal of Solid State Electrochemistry》2013,17(7):1985-1989
The present work investigated the drying period effect on the activity, morphology, crystallinity, and other properties of antimony-doped tin dioxide-coated titanium electrodes prepared by coating pyrolysis method. The drying period is found to be an important factor affecting the electrode activity. The antimony content in the electrode decreased when the drying period increased. Simultaneously, crack width, Sn3d5/2 binding energy, crystallite size, catalyst loading, and resistivity increased with the drying time. The results showed that the electrode prepared with the drying time of 10 min had the highest activity towards phenol degradation in the series under study. 相似文献
77.
Tissue distribution and excretion study of neopanaxadiol in rats by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry 下载免费PDF全文
Cong Geng Jian‐yuan Yin Xiu‐hua Yu Jing‐yan Liu Yu‐xia Yang De‐ya Sun Qin Meng Zhong‐lin Wei Ji‐hua Liu 《Biomedical chromatography : BMC》2015,29(3):333-340
Neopanaxadiol (NPD), a major ginsenoside in Panax ginseng C. A. Meyer (Araliaceae), was reported to have neuroprotective effect. In this study, a method of ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry (UPLC/QTOF‐MS) was developed and validated for quantitative analysis of NPD in tissues, urine and feces, using liquid–liquid extraction (LLE) to isolate NPD from different biological samples, and chromatographic separation was performed on an Agilent Zorbax Stable Bond C18 (2.1 × 50 mm, 1.8 µm) column with 0.1% formic acid in water and acetonitrile. All standard calibration curves were linear (all r2 > 0.995) within the test range. After oral administration, NPD was extensively distributed to most of the tissues without long‐term accumulation. The higher levels were observed in stomach and intestine, followed by kidney and liver. Approximately 64.56 ± 20.32% of administered dose in feces and 0.0233 ± 0.0356% in urine were found within 96 h, which indicated that the major elimination route was fecal excretion. This analytical method was applied to the study of NPD distribution and excretion in rats after oral intake for the first time. The results we found here are helpful for us to understand the pharmacological effects of NPD, as well as its toxicity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
78.
Raghida Bou Zerdan Zhishuai Geng Benjaporn Narupai Yvonne J. Diaz Morgan W. Bates David S. Laitar Biswas Souvagya Antony K. Van Dyk Craig J. Hawker 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1989-1997
The utility of pentafluorophenyl esters for the selective introduction of functional units and branch points in well-defined poly(acrylic acid) (PAA) derivatives is demonstrated using a combination of controlled radical polymerization and postpolymerization modification. Reversible addition-fragmentation chain transfer enables the synthesis of well-defined copolymers—poly(pentafluorophenyl acrylate-co-tert-butyl acrylate)—with the active ester repeat units serving as attachment points for reaction with primary amines, specifically tris(2-(t-butoxycarbonyl)ethyl)methyl amine (Behera's amine). Deprotection using trifluoroacetic acid removes both the backbone and side chain t-butyl esters to give a series of branched PAA derivatives containing novel tricarboxylic acid side chains that are well suited to complexation and multidentate interactions. Surprisingly, the active ester homopolymer is shown to have the highest reactivity with Behera's amine when compared to copolymers with lower incorporation of pentafluorophenyl esters, suggesting an intriguing interplay of neighboring group effects and steric interactions. The ability to tune the efficiency of postpolymerization modification gives a library of PAA derivatives. 相似文献
79.
Shang Chen Shuiyin Chen Dengji Han Christopher W. Bielawski Jianxin Geng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(51):e202201580
Lithium (Li) metal has attracted significant attention in areas that range from basic research to various commercial applications due to its high theoretical specific capacity (3860 mA h g−1) and low electrochemical potential (−3.04 vs. standard hydrogen electrode). However, dendrites often form on the surfaces of Li metal anodes during cycling and thus lead to battery failure and, in some cases, raise safety concerns. To overcome this problem, a variety of approaches that vary the electrolyte, membrane, and/or anode have been proposed. Among these efforts, the use of three-dimensional frameworks as Li hosts, which can homogenize and minimize the current density at the anode surface, is an effective approach to suppress the formation of Li dendrites. Herein, we describe the development of using carbon-based materials as Li hosts. While these materials can be fabricated into a variety of porous structures, they have a number of intrinsic advantages including low costs, high specific surface areas, high electrical conductivities, and wide electrochemical stabilities. After briefly summarizing the formation mechanisms of Li dendrites, various methods for controlling structural and surface chemistry will be described for different types of carbon-based materials from the viewpoint of improving their performance as Li hosts. Finally, we provide perspective on the future development of Li host materials needed to meet the requirements for their use in flexible and wearable devices and other contemporary energy storage techniques. 相似文献
80.
Nan Jiang Xiao-Yu Yang Guo-Liang Ying Ling Shen Jing Liu Wei Geng Ling-Jun Dai Shao-Yin Liu Jian Cao Ge Tian Tao-Lei Sun Shi-Pu Li Bao-Lian Su 《Chemical science》2015,6(1):486-491
Self-repair is nature''s way of protecting living organisms. However, most single cells are inherently less capable of self-repairing, which greatly limits their wide applications. Here, we present a self-assembly approach to create a nanoshell around the cell surface using nanoporous biohybrid aggregates. The biohybrid shells present self-repairing behaviour, resulting in high activity and extended viability of the encapsulated cells (eukaryotic and prokaryotic cells) in harsh micro-environments, such as under UV radiation, natural toxin invasion, high-light radiation and abrupt pH-value changes. Furthermore, an interaction mechanism is proposed and studied, which is successful to guide design and synthesis of self-repairing biohybrid shells using different bioactive molecules. 相似文献