Oligomerization of the Cu(II) and Ni(II) tetraazaannulene complexes: A pulse radiolysis study of the associated reaction mechanism

The oligomerization of [Cu^II(H_x(tmdnTAA))]^x+ (x = 0, 1, 2 and (tmdnTAA))²⁻ is 2,4,9,11-tetramethyl-dinaphto[14]-2,4,6,9,11,13-hexaeneN₄) was initiated in homogeneous solution via the reaction of this Cu(II) complex with pulse radiolytically generated radicals. The reaction produces Cu(III) intermediates which are rapidly converted to Cu(II) ligand-radical species. In contrast to the mechanism proposed for the electrochemical oligomerization, where the local concentration of radicals is probably high, the reaction kinetics in homogeneous solution is propagated by a process where the Cu(II) ligand-radical precursors react with [Cu^II(H_x(tmdnTAA))]^x+.     

Cu3P Binary Phosphide: Synthesis via a Wet Mechanochemical Method and Electrochemical Behavior as Negative Electrode Material for Lithium‐Ion Batteries

Mechanochemical synthesis of Cu₃P in the presence of n‐dodecane results in a material with a secondary particle size distribution of 10 μm, secondary particles which consist of homogeneously agglomerated 20 nm primary particles. The electrochemical performance of Cu₃P with lithium is influenced by the reaction depth, in other words by the lower potential cut‐off. During the electrochemical reaction, the displacement of copper by lithium from the Cu₃P structure until the formation of Li₃P and Cu deteriorates the capacity retention. Improved performance was obtained when the charge potential was limited to 0.50 V (vs. Li/Li⁺) and the formation of the Li_xCu_3‐xP phase (0 ≤ × ≤ 2). In this case, when the potential is limited to 0.5 V, the capacity is stable for more than 50 cycles. Acceptable electrochemical performances in Li‐ion cells within the voltage range 0.50–2.0 V (vs. Li/Li⁺) were shown when Cu₃P was used as an anode and Li_1.2(Ni_0.13Mn_0.54Co_0.13)O₂ and LiNi_0.5Mn_1.5O₄ as positive electrode materials.     

Changes in pulmonary Cu−Zn contents in superior mesenteric artery occlusion shock of rabbit

Contents of Cu and Zn of into-pulmonary blood (IPB), out-pulmonary blood (OPB), Lung tissue, and supernatant and macrophages of Lung Lavage were determined in superior mesenteric artery occlusion (SMAO) shock of rabbits. Zn of pulmonary tissue was 11.42 +/- 0.60 and 14.52 +/- 1.78 (micrograms/g wet wt) in SMAO shock and control groups, respectively. Content of Zn was found to be lower, Cu was not changed, and Cu/Zn ratio increased in lung tissue in SMAO shock. Contents of Cu and Zn in other samples were not changed. The results suggest that lower Zn in lung tissue related to acute lung injury.     

Selective adaptation to copper of populations ofAgrostis tenuis andFestuca rubra (Poaceae)

Populations ofAgrostis Tenuis andFestuca rubra, tolerant and non-tolerant towards Zn and Pb, were studied in regard to their adaptability by natural selection, towards a third metal (Cu) and the time required for the appearance of such tolerance. It was found that Zn and Pb tolerant and non-tolerant populations are likely to select the character of Cu-tolerance within the course of only one generation. More specifically, Zn and Pb tolerant populations show a better adaptability compared with non-tolerant ones. The amount of tolerance to copper obtained by artificial selection is comparable with that of populations growing naturally on copper mines.     

Cu2+对菱叶片生理指标及超微结构的毒理学效应分析

研究了不同Cu²⁺处理浓度(0、0.002、0.004、0.006、0.008 mmol.L^-1)对菱叶片叶绿素含量和叶绿素荧光参数、膜脂过氧化和抗氧化系统等的影响,并用透射电镜观察了其叶细胞超微结构的变化。试验结果表明:随着Cu²⁺浓度的增加:(1)叶绿素含量、Fv/Fo和Fv/Fm显著下降,Fo显著上升;(2)活性氧(AOS)产生速率、丙二醛(MDA)含量、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性逐渐升高;超氧化物歧化酶(SOD)、游离脯氨酸(Pro)和可溶性糖含量显著下降;抗坏血酸(AsA)、还原型谷胱甘肽(GSH)和谷胱甘肽还原酶(GR)含量呈先升后降趋势,且始终高于对照;(3)电镜观察发现,Cu²⁺对叶片细胞器的超微结构特别是叶绿体、线粒体和细胞核造成严重损伤。以上结果表明,本试验过量Cu²⁺的胁迫破坏了菱正常生理生化活动,并造成功能紊乱,最终导致菱的死亡。     

铜胁迫对穿心莲幼苗生长及生理特性的影响

通过对盆栽穿心莲(Andrographis paniculata)幼苗浇灌Cu SO4溶液实验,研究外施Cu2+对穿心莲幼苗的生理特性和药效成分含量的影响。结果显示,外施Cu2+对穿心莲幼苗的生长、生理生化指标和穿心莲内酯、脱水穿心莲内酯的含量均有显著影响。当Cu SO4溶液浓度超过6.25 mmol/L时,Cu2+能显著抑制穿心莲幼苗株高、叶长、叶宽的增长,且随胁迫时间的延长和Cu2+浓度的增大抑制作用增强;穿心莲叶片中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量均随Cu2+浓度增大和胁迫时间的延长而升高,当Cu SO4溶液浓度达到12.5 mmol/L且胁迫20 d和30 d时,叶片中SOD活性达到对照组的168.3%和171.18%;过氧化物酶(POD)、过氧化氢酶(CAT)活性则随Cu2+浓度的增大呈先升高后下降的趋势;当外施Cu SO4溶液浓度大于1.25 mmol/L时,与对照相比,穿心莲药效成分穿心莲内酯和脱水穿心莲内酯的含量均显著降低(P0.05)。研究结果表明,外施Cu SO4溶液浓度高于6.25 mmol/L时,能显著影响穿心莲幼苗的生理特性和有效成分含量,从而降低穿心莲药材的产量和质量。     

Ratiometric fluorescent detection of Cu2+ based on dual‐emission ZIF‐8@rhodamine‐B nanocomposites

Zeolitic imidazolate framework‐8 (ZIF‐8) loading rhodamine‐B (ZIF‐8@rhodamine‐B) nanocomposites was proposed and used as ratiometric fluorescent sensor to detect copper(II) ion (Cu²⁺). Scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray powder diffraction, nitrogen adsorption/desorption isotherms and fluorescence emission spectroscopy were employed to characterize the ZIF‐8@rhodamine‐B nanocomposites. The results showed the rhodamine‐B was successfully assembled on ZIF‐8 based on the π‐π interaction and the hydrogen bond between the nitrogen atom of ZIF‐8 and –COOH of rhodamine‐B. The as‐obtained ZIF‐8@rhodamine‐B nanocomposites were octahedron with size about 150–200 nm, had good water dispersion, and exhibited the characteristic fluorescence emission of ZIF‐8 at 335 nm and rhodamine‐B at 575 nm. The Cu²⁺ could quench fluorescence of ZIF‐8 rather than rhodamine‐B. The ZIF‐8 not only acted as the template to assemble rhodamine‐B, but also was employed as the signal fluorescence together with the fluorescence of rhodamine‐B as the reference to construct a novel ratiometric fluorescent sensor to detect Cu²⁺. The resulted ZIF‐8@rhodamine‐B nanocomposite fluorescence probe showed good linear range (68.4 nM to 125 μM) with a low detection limit (22.8 nM) for Cu²⁺ combined with good sensitivity and selectivity. The work also provides a better way to design ratiometric fluorescent sensors from ZIF‐8 and other fluorescent molecules.     

Ratiometric and selective fluorescent chemodosimeter for Cu(II) by Cu(II)‐induced oxidation

A new rhodamine derivative, rhodamine B 4‐N,N‐dimethylaminobenzaldehyde hydrazone (1), was designed for ratiometric sensing of Cu(II) selectively. A red‐shift from 515 to 585 nm was observed in the fluorescence spectrum when Cu(II) was added to 1 in acetonitrile. Other metal ions of interest showed no ratiometric response. The interaction between Cu(II) and 1 was found to be the Cu(II)‐induced oxidation of 1. Copyright © 2008 John Wiley & Sons, Ltd.     

Copper(II) complexes of Neobelliera Bullata Trypsin Modulating Oostatic Factor and its analogues

The stoichiometry, stability constants and solution structure of the complexes formed in the reaction of copper(II) with hexapeptide NPTNLH, i.e. the Neobelliera Bullata Trypsin Modulating Oostatic Factor (Neb-TMOF), and its analogues DPTNLH, Ac-NPTNLH and Ac-DPTNLH have been determined by potentiometric, UV-visible, CD and EPR spectroscopic methods. Upon raising pH for Ac-NPTNLH and Ac-DPTNLH peptides, copper(II) coordination starts from the imidazole nitrogen of the His⁶; afterwards three deprotonated amide nitrogens are progressively involved in metal ions coordination. In a wide pH range of 4.5-8.5 for the NPTNLH and DPTNLH ligands the CuL complex dominates with the imidazole nitrogen of His⁶ coordinated to form a macrochelate. The N-terminal amino group of the NPTNLH and DPTNLH peptides takes part in the coordination of the metal ion in the CuL, CuH₋₁L and CuH₋₂L complexes. However, at pH above 9 the CuH₋₃L complex with the {N_Im, 3N⁻} coordination mode is formed. For the CuH₋₂L complex the spectroscopic data clearly indicate the 4N {NH₂, CO or COO⁻, 2N⁻, N_Im} bonding mode with the axial coordination of the N-terminal amine group to the metal ion.     

The possible role of metallothioneins in copper tolerance of Silene cucubalus

Growth and copper-binding of a copper-tolerant and a copper-sensitive population of Silene cucubalus (L.) Wib. have been studied. The copper-tolerant plants showed a much lower uptake and a proportionally higher transport of copper from root to shoot. A copper-binding protein with an apparent M_r of 8500 resembling metallothionein has been isolated from the roots of copper-treated plants of the tolerant population. After 20 d, the protein was observed to be inducible upon copper supply in the copper-tolerant plants, but not yet in the sensitive ones. This could be an indication of a difference in metalregulated synthesis of the protein. Ion-exchange chromatography of the 8500 protein yielded a major copper-containing fraction eluting at high ionic strength. Other characteristics such as UV absorption and amino-acid composition resembled strongly those of metallothioneins. The involvement of metallothioneins in the detoxification of copper within Cu-tolerant plants is discussed in relation to other mechanisms.Abbreviation DEAE diethyloaminoethyl