997 resultados para Cu atoms
Resumo:
Nearly monodisperse Cu-In-S ternary nanocrystals with tunable composition, crystalline structure, and size were synthesized by a hot-injection method using mixed generic precursors. Such ternary nanocrystals with zincblende and wurtzite structure were reported for the first time.
Resumo:
In this work, we report the first application of water-soluble fluorescent Ag nanoclusters in fluorescent sensors. The fluorescence of poly(methacrylic acid) (PMAA)-templated Ag nanoclusters was found to be quenched effectively by Cu2+, but not when other common metal ions were present. By virtue of the specific response toward the analyte, a new, simple, and sensitive fluorescent method for detecting Cu2+ has been developed based on Ag nanoclusters.
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Novel channel structures based on [M(bpdo)(3)](2+) and p-sulfonatocalix[4]arene nanocapsules have been established; these are sustained exclusively by charge-assisted pi...pi interactions and sorption experiments show the porous materials have selective guest sorption properties.
Resumo:
A supramolecular complex [Cu(phen)(2)H2O]{[Cu(phen)(H2O)](2)[C6AS]}center dot 2.5H(2)O (phen = 1,10'-phenanthroline and C6AS = p-sulfonatocalix[6]arene) has been synthesized under hydrothermal condition, and characterized by IR spectroscopy, TG analysis and single crystal X-ray diffraction. In the structure, unprecedented 1D ({[Cu(phen)(H2O)](2)[C(6)AS]}(2-))(n) coordination chains (exactly being belts) are stacked into some 2D layers by the pi center dot center dot center dot pi stacking interactions, which are further interconnected into a 3D extended structure by hydrogen bonding.
Resumo:
A novel diimine Cu(I)complex [Cu(ABPQ)(DPEphos)]BF4 [ABPQ and DPEphos are acenaphtho[1,2-b]bipyrido[2,3-h:3,2-f]quinoxaline and bis(2-(diphenylphosphanyl)phenyl) ether, respectively] is synthesized, and its photophysical properties are experimentally and theoretically characterized. The emission bands centered at ca. 400/470 and 550 nm of [Cu(ABPQ)(DPEphos)]BF4 are attributed to the ligand-centered pi -> pi* transition and the metal-to-ligand charge transfer d pi(Cu) -> pi*(N-N) transition, respectively. The luminescence quantum yield of [Cu(ABPQ)(DPEphos)]BF4 in CHCl3 is found to be about five times higher than that of [Cu(Phen)(DPEphos)]BF4.
Resumo:
A new polyoxotungstate complex [Na-2(H2O)(8)][Na-8(H2O)(20)][Cu(en)(2)][W12O42] center dot 3 H2O (1) (en = ethylenediamine) has been synthesized in aqueous solution and characterized by elemental analysis, IR spectroscopy and TG analysis, together with a single crystal X-ray diffraction study. In compound 1, the Cu(en)(2)(2+) complex cation links the [W12O42](12-) anions to form a I D chain, and the ID chains are further interconnected with Na-8(H2O)(20)(8+) and Na-2(H2O)(8)(2+) cations to construct a new 3D framework.
Resumo:
In the mixed-metal complex catena-poly[bis[diaquasilver(I)] [bis[aquacopper(II)]-mu(3)-pyridine-2,5-dicarboxylato-2': 1: 1'kappa N-5,O-2: O-5: O-5, O-5'-mu-pyridine-2,5-dicarboxylato-2: 1 kappa(4) N, O-2: O-5, O-5'-disilver(I)-mu(3)-pyridine-2,5-dicarboxylato-1: 1': 2 '' kappa(5) O-5, O-5': O-5: N, O-2-mu pyridine-2,5-dicarboxylato-1': 20 ''kappa(4) O-5, O-5': N, O-2] hexahydrate], {[Ag(H2O)(2)][AgCu(C7H3NO4)(2)(H2O)] center dot 3H(2)O}(n), a square-pyramidal Cu-II center is coordinated by two N atoms and two O atoms from two pyridine-2,5-dicarboxylate (2,5-pydc) ligands and a water molecule, forming a [Cu(2,5-pydc)(2)-( H2O)](2-) metalloligand. One Ag I center is coordinated by five O atoms from three 2,5-pydc ligands and, as a result, the [Cu(2,5-pydc)(2)(H2O)](2-) metalloligands act as linkers in a unique mu(3)-mode connecting Ag-I centers into a one-dimensional anionic double chain along the [101] direction.
Resumo:
The title mixed-metal complex, {(NH4)(2)[Cu(C7H3NO4)(2)(H2O)(2)][CdCu(C7H3NO4)(2)(H2O)(6)]center dot 6H(2)O}(n), contains one octahedrally coordinated Cd-II center and two octahedrally coordinated Cu-II centers, each lying on an inversion center. The two Cu-II atoms are each coordinated by two O atoms and two N atoms from two 2,4-pydc (2,4-H(2)pydc = pyridine-2,4-dicarboxylic acid) ligands in the equatorial plane and two water molecules at the axial sites, thus producing two crystallographically independent [Cu(2,4-pydc)(2)(H2O)(2)](2-) metalloligands. One metalloligand exists as a discrete anion and the other connects the Cd(H2O)(4) units, forming a neutral chain.
Resumo:
The title compound, [Cu(C5H3N2O2)(2)(H2O)(2)], is a new polymorph of the previously reported compound [Klein et al. (1982). Inorg. Chem. 21, 1891-1897]. The Cu-II atom, lying on an inversion center, is coordinated by two N atoms and two O atoms from two pyrazine-2-carboxylate ligands and by two water molecules in a distorted octahedral geometry with the water molecules occupying the axial sites. Intermolecular O-H center dot center dot center dot O, O-H center dot center dot center dot N and C-H center dot center dot center dot O hydrogen bonds connect the complex molecules into a two-dimensional layer parallel to (10 (1) over bar), whereas the previously reported polymorph exhibits a three-dimensional hydrogen-bonded network.
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The catalytic mechanism for the oxidation of primary alcohols catalyzed by the two functional models of galactose oxidase (GOase), M-II L (M = Cu, Zn; L = N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)1-2-diiminoquinone)), has been studied by use of the density functional method B3LYP The catalytic cycle of Cu- and Zn-catalysts consists of two parts, namely, substrate oxidation (primary alcohol oxidation) and O-2 reduction (catalyst regeneration). The catalytic mechanisms have been studied for the two reaction pathways (route 1 and route 2). The calculations indicate that the hydrogen atom transfer within the substrate oxidation part is the rate-determining step for both catalysts, in agreement with the experimental observation.
Resumo:
将三肽Gly-Gly-His(GGH)共价键合到MPA修饰的微悬臂梁表面,研究了肽与Cu2+的相互作用过程。研究发现,在Cu2+浓度较高时,Cu2+能快速与不同肽链上的羧基和咪唑环配位,并通过连锁反应诱导悬臂梁向镀金面偏转;而后肽链上的氮原子与Cu2+配位,同时构象发生变化,由直链转变成折叠状,进而增加链间的作用力使悬臂梁反向偏转;而Cu2+浓度低时不能实现连锁反应诱导悬臂梁表面快速的形成向内的拉力,直接通过构象变化推动悬臂梁反向偏转。考察了溶液pH值、Cl-浓度对GGH与Cu2+作用的影响,结果表明,在pH7.0的条件下GGH与Cu2+作用导致悬臂梁偏转最大。Cl-的存在会与Cu2+形成CuCl2x?x配合物不易与肽链结合。
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A new hydrogen-bonded dinuclear copper(II) coordination compound has been synthesized from the Schiff-base ligand 6-(pyridine-2-ylhydrazonomethyl)phenol (Hphp). The molecular structure of [Cu-2(php)(2)(H2O2)(2)(ClO4)](ClO4)- (H2O) (1), determined by single-crystal X-ray diffraction, reveals the presence of two copper(II) centers held together by means of two strong hydrogen bonds, with O center dot O contacts of only 2.60-2.68 angstrom. Temperature-dependent magnetic susceptibility measurements down to 3 K show that the two metal ions are antiferromagnetically coupled (J = -19.8(2) cm(-1)). This exchange is most likely through two hydrogen-bonding pathways, where a coordinated water on the first Cu, donates a H bond to the O atoms of the coordinated php at the other Cu. This strong O center dot H (water) bonding interaction has been clearly evidenced by theoretical calculations. In the relatively few related cases from the literature, this exchange path, mediated by a (neutral) coordinated water molecule, was not recognized.
Resumo:
制备了TiO2-CuO修饰Cu电极,并对CO2在该复合光电电极上的还原行为进行了研究。光电化学测试表明,TiO2有助于电极的光电转换,能注入更多的电子促进CO2还原。TiO2-CuO/Cu复合电极在光照条件下对CO2具有很好的光电催化还原活性,使还原电位正移约100 mV,同时有效地抑制了水的光电分解。Mott-Schottky曲线测定表明,TiO2-CuO/Cu复合电极具有n型半导体性质,其平带电位随光照时间的增加而负移。光谱及色质谱测试证明,CO2在TiO2-CuO/Cu复合电极上的光电化学还原产物为甲酸和甲醛,还有少量乙烯和甲烷。在-1.2 V条件下光照3 h,CO2的转化率可达32%。基于实验结果对CO2光电还原机理进行了推断。
Resumo:
The reaction mechanisms of the H-2 with the homonuclear dimers M-2 (Cu, Ag, Au) and the heteronuclear dimers PdM (M = Cu, Ag, Au) were studied by use of density functional theory. For the H-2 reactions with homonuclear dimers M-2 (Cu, Ag, Au), it was found that it is easier for Au-2 to dissociate the hydrogen molecule compared with Cu-2 and Ag-2. For H-2 reactions with the heteronuclear dimers PdM (M = Cu, Ag, An), the hydrogen molecule can be easily dissociated at Pd site, rather than at noble metal site.