铜(II)/明胶(酶解明胶)络合物的制备及其络合形态的探讨

许多金属元素对于生物体是必需的,Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｃｕ、Ｍｏ和Ｚｎ在人体中的含量约３％;各种金属离子在生物体中具有不同的作用,其功能是很复杂的．铜在生物体内主要是进行氧化还原反应,起输送氧气和电子载体的作用．如果人体内缺乏铜,则...     

The electrochemical reactions of copper(II) and copper(I) chloride in n,n-dimethylformamide

Polarographic, voltammetric and controlled-potential coulometric studies of copper(II) and copper(I) chloride in dimethylformamide are reported. The two chloride complexes of copper(II) are reduced in a total of three electrochemical steps to two copper(I)-chloride complexes and to copper(0). The two copper(I)-chloride species are reduced to copper(0) and oxidized to copper(II)-chloride complexes. The dissociation constant of the tetrachlorocuprate(II) complex has been polarographically estimated to be 10^-25.     

Solvent and steric effects on the extraction of copper(II) with pivalic acid

The solvent extraction of copper(II) with trimethylacetic acid using benzene and 1-octanol as solvents was performed at 25 degrees C and 0.1 mole. dm(-3) ionic strength in the aqueous phase. In contrast to the extraction of copper(II) with a saturated straight-chain carboxylic acid in benzene, the dimeric copper(II) trimethylacetate was observed to dissociate into the monomer, even at a moderately high concentration of copper(II) in the benzene phase. In the system using 1-octanol as a solvent, both the monomeric and dimeric copper(II) species are suggested to be solvated by some 1-octanol molecules. It has been found that the dimerization and adduct formation of copper(II) species in benzene may more effectively enhance the extractability of copper(II) than the solvation by 1-octanol molecules.     

Properties of polyimide films doped with copper complexes

Polyimide films based on either 3, 3′, 4, 4′-benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride with 4,4′-oxydianiline have been doped with copper(I) and copper(II) complexes. High-quality, flexible, glass-cast films have been obtained which exhibit increased softening temperatures and lower polymer decomposition temperatures. The atmosphere and glass sides of the films are quite different. The copper(I) dopant is oxidized on the air side of the film, while the glass side contains predominantly copper (I). In the copper(II) case most of the copper appears on the air side as a silvery substance in the Cu(II) state. Chemical as well as ion etching can remove this material. Electrical resistivity of the copper(II)-doped films is decreased by three to five orders of magnitude relative to the polymer alone.     

Synthesis and characterization of 8-aminoquinolines,substituted by electron donating groups,as high-affinity copper chelators for the treatment of Alzheimer's disease

The deregulation of copper homeostasis generates copper–amyloid aggregation and strongly participates in neuron damage in the brains of patients with Alzheimer's disease. Therefore, copper chelators able to regulate copper homeostasis should be considered as potential therapeutic agents. On the basis of a bidentate amine side chain attached at the 2-position of an 8-aminoquinoline motif, a series of low-molecular-weight copper chelators have been designed to act as specific tetradentate Cu(II) chelators. The affinity of these ligands for Cu(II) and their selectivity for Cu(II) with respect to Zn(II) are reported. These ligands provide a square planar tetradentate coordination sphere that should be suitable to extract copper (II) from copper–amyloid complexes, and are therefore expected to regulate copper homeostasis in vivo.     

Experimental and computational study of species formed during electrochemical stripping oxidation of copper in chloride media determination of copper(II) in the ng l(-1) range by stripping potentiometry

A novel glassy carbon electrode design, permitting medium exchange in batch mode without loss of electrode potential control, has been used for the study of copper(I) and copper(II) species formed during constant current stripping oxidation of copper in chloride media. It was found that copper(II) species dominated at chloride concentrations below about 1 mM and that soluble copper(I) species dominated at chloride concentrations above about 100 mM. In the concentration range 1-100 mM, soluble copper(I) and copper(II) species are formed as well as solid copper(I) chloride, the latter giving rise to a split peak as it is further oxidised to copper(II). The experimental results agreed satisfactorily with computer calculated equilibria data using the haltafall program. The medium exchange procedure has, furthermore, been used for the determination of copper(II) in seawater reference samples, 7.5 M ammonium acetate/2.5 M acetic acid being used as stripping medium. The detection limit, after 15 min of electrolysis, was found to be 6 ng l(-1) (0.10 mM) and the relative precision 6-10%.     

Determination of stability constants of metal(II)-methionine and metal(II)-methionine-cystiene (binary and mixed) complexes using the Paper Ionophoretic Technique

Mixed complexation reactions of methionine and cysteine with copper(II) and cobalt(II) have been studied in solution phase using the paper electrophoretic technique at ionic strength 0.1 M and temperature 35°C. The binary equilibria copper(II)-methionine and cobalt(II)-methionine have also been studied, since this is a prerequisite to the investigation of mixed complexes. The stability constants of copper(II)-methionine-cysteine and cobalt(II)-methionine-cysteine mixed complexes were found to be 2.80 ± 0.07 and 2.44 ± 0.11 (logarithm of stability constant values), respectively.     

Catalytic reduction currents in the stripping voltammetry of solutions of the system copper(II)-ascorbic acid and their application in analytical chemistry

It has been found that the analytical signal from copper(II), cadmium(II), and zinc(II) in alternating-current stripping voltammetry in the presence of ascorbic acid (AA) increases only for copper(II) ions, which have significant oxidative potential. It is associated with the appearance of a catalytic current of the reducer in stripping voltammetry, where the reducer is AA. A scheme has been proposed for this process. The rate constant has been calculated for the chemical reduction of copper(I) ions, electrochemically produced in the diffusion layer as a result of the electrochemical oxidation of copper atoms, with AA. A procedure has been developed for the determination of copper in model solutions using the catalytic current of AA; the limit of copper detection is 0.01 μg/L, which is one order lower than the one achieved without AA.     

Novel Michael addition products of bis(amino acidato)metal(II) complexes: synthesis, characterization, dye degradation, and oxidation properties

Michael addition reactions of bis(amino acidato)metal(II) complexes (metal = copper, nickel, zinc; amino acid = glycine, dl-alanine, l-alanine) with acrylonitrile have been carried out under various experimental conditions in the absence of a base, resulting in mono- and disubstituted products in high yield, including partially hydrolyzed products. A reaction mechanism for the Michael addition on the nitrogen atom of the coordinated amino acid moiety, replacing the amino hydrogen atom(s), is proposed. All of the products have been characterized by Fourier transform infrared spectroscopy, electron paramagnetic resonance spectra, and elemental and electrochemical analyses. The single-crystal structures of bis( N-cyanoethylglycinato)copper(II) monohydrate ( 1a), diaquabis( N-cyanoethylglycinato)nickel(II), aquabis( N, N-dicyanoethylglycinato)copper(II) ( 2a), and bis[( N-propionamido- N-cyanoethyl)glycinato]copper(II) dihydrate ( 4a) have been confirmed by X-ray diffraction techniques. The products 1a, 2a, 4a, and bis( N-propionamidoglycinato)copper(II) monohydrate ( 3a) have been used as catalysts for the degradation of a phenol red dye and mild oxidation of various organic substrates in the presence of hydrogen peroxide. The monosubstituted complexes have been found to catalyze the reactions to a greater extent than the disubstituted complexes.     

Determination of Stability Constants of Metal(II)-Methionine and Metal(II)-Methionine-Cysteine (Binary and Mixed) Complexes with a Paper Ionophoretic Technique

A mixed complexation reaction of methionine and cysteine with copper(II) and cobalt(II) has been studied in solution phase using the paper electrophoretic technique at ionic strength 0.1 M and a temperature of 35°C. The binary equilibria copper(II)-methionine and cobalt(II)-methionine have also been studied, since this is prerequisite for the investigation of mixed complexes. The stability constants of copper(II)-methionine-cysteine and cobalt(II)-methionine-cysteine mixed complexes were found to be 2.80 ± 0.07 and 2.44 ± 0.11 (logarithm of stability constant values), respectively. This article was submitted by the authors in English.     

Kupfer(II)-Komplexe mit monofunktionellen dreizähnigenSchiffbasen mit O,N,O-Sequenzen

A few complexes of copper(II) have been prepared by reacting copper(II) acetate with salicylidene methyl anthranilates in alcohol medium. Analytical data indicate 1 : 2 stoichiometry. These copper(II) complexes show normal magnetic moments indicating no spin interactions. With the help of electronic and infrared spectral evidences it has been suggested that in these complexes copper(II) exhibits coordination number six.     

Kupfer(II)-Komplexe von N-Benzoyl-O-methyl-N′-phenyl-isoharnstoffen

Copper(II) Complexes of N-Benzoyl-O-methyl-N′-phenyl-isoureas By reaction of N-benzoyl-N′-(p-nitro/p-bromphenyl)thioureas with copper(II)acetate-monohydrate in methanole insoluble copper(I)precipitates have been obtained, from which filtrates bis[N-benzoyl-O-methyl-N′-(p-nitrophenyl)-isoureato]copper(II) 1 and bis[N-benzoyl-O-methyl-(p-bromphenyl)-isoureato]copper(II) 2 were isolated. The moleculare structure of 1 with planar trans coordination has been determined by single crystal X-ray diffraction methods. The N-benzoyl-O-methyl- N′-(o-nitrophenyl)-isourea 3 and N-benzoyl-O-methyl-N′-(p-bromphenyl)-isourea 4 have been prepared by reaction of the corresponding N-benzoyl-N′-phenyl-thioureas with mercury(II)acetate in methanolic solution. The molecular structure of 3 has been determined by single crystal X-ray diffraction methods. The NH-tautomeric form is stabilized by a bifurcated intramolecular hydrogen bond to an oxygen atom of the o-nitro group and the benzoyl oxygen atom. XPS, NMR and mass-spectrometric investigations also confirm the structures.     

Reactivity of mononuclear alkylperoxo copper(II) complex. O-O bond cleavage and C-H bond activation

A detailed reactivity study has been carried out for the first time on a new mononuclear alkylperoxo copper(II) complex, which is generated by the reaction of copper(II) complex supported by the bis(pyridylmethyl)amine tridentate ligand containing a phenyl group at the 6-position of the pyridine donor groups and cumene hydroperoxide (CmOOH) in CH3CN. The cumylperoxo copper(II) complex thus obtained has been found to undergo homolytic cleavage of the O-O bond and induce C-H bond activation of exogenous substrates, providing important insights into the catalytic mechanism of copper monooxygenases.     

Spectrophotometric Determination of Ziram by Coprecipitating the Corresponding Copper(II) or Palladium(II) Complex with Naphthalene

A spectrophotometric method has been developed for the determination of zinc dimethyldithiocarbamate (ziram) by converting it into dimethyldithiocarbamate and coprecipitating its copper(II) and palladium(II) dimethyldithiocarbamate complexes and coprecipitating onto microcrystalline naphthalene. Palladium(II) and copper(II) complexes absorb strongly at 395 nm and 430 nm, respectively. The interference of various ions has been studied and the method has been applied to determine ziram in commercial samples and grains.     

Synthesis, spectral and electrochemical studies of Cu(II) and Ni(II) complexes with new N2O2 ligands: a new precursor capable of depositing copper nanoparticles using thermal reduction

Cu(II) and Ni(II) complexes of the general type [M(N2O2)] are described. The N2O2 ligands used are [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48nm were formed by thermal reduction of [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles.     

Copper(II) coordination chemistry of westiellamide and its imidazole, oxazole, and thiazole analogues

The copper(II) coordination chemistry of westiellamide (H(3)L(wa)), as well as of three synthetic analogues with an [18]azacrown-6 macrocyclic structure but with three imidazole (H(3)L(1)), oxazole (H(3)L(2)), and thiazole (H(3)L(3)) rings instead of oxazoline, is reported. As in the larger patellamide rings, the N(heterocycle)-N(peptide)-N(heterocycle) binding site is highly preorganized for copper(II) coordination. In contrast to earlier reports, the macrocyclic peptides have been found to form stable mono- and dinuclear copper(II) complexes. The coordination of copper(II) has been monitored by high-resolution electrospray mass spectrometry (ESI-MS), spectrophotometric and polarimetric titrations, and EPR and IR spectroscopies, and the structural assignments have been supported by time-dependent studies (UV/Vis/NIR, ESI-MS, and EPR) of the complexation reaction of copper(II) with H(3)L(1). Density functional theory (DFT) calculations have been used to model the structures of the copper(II) complexes on the basis of their spectroscopic data. The copper(II) ion has a distorted square-pyramidal geometry with one or two coordinated solvent molecules (CH(3)OH) in the mononuclear copper(II) cyclic peptide complexes, but the coordination sphere in [Cu(H(2)L(wa))(OHCH(3))](+) differs from those in the synthetic analogues, [Cu(H(2)L)(OHCH(3))(2)](+) (L = L(1), L(2), L(3)). Dinuclear copper(II) complexes ([Cu(II) (2)(HL)(mu-X)](+); X = OCH(3), OH; L = L(1), L(2), L(3), L(wa)) are observed in the mass spectra. While a dipole-dipole coupled EPR spectrum is observed for the dinuclear copper(II) complex of H(3)L(3), the corresponding complexes with H(3)L (L = L(1), L(2), L(wa)) are EPR-silent. This may be explained in terms of strong antiferromagnetic coupling (H(3)L(1)) and/or a low concentration of the dicopper(II) complexes (H(3)L(wa), H(3)L(2)), in agreement with the mass spectrometric observations.     

EPR study of copper(II) complexes in the matrix of titania gel modified with powder cellulose

The character of the copper(II) distribution over the surface of titania gel modified with powder cellulose has been studied by EPR. Three types of copper(II) compounds have been identified: mononuclear complexes, magnetic associates, and copper(II) compounds that do not give rise to an observable EPR spectrum at the used frequency and temperature. The modification of titania gel has been shown to have an effect on the relative contents of these compounds.     

Kinetic-spectrophotometric determination of Cu(II) and pyridine by use of the aerial oxidation of dimedone bisguanylhydrazone

The synthesis and analytical properties of dimedone bisguanylhydrazone (DIBG) are described for the first time. DIBG is oxidized by aerial oxygen and the reaction is catalysed by copper(II). The catalytic effect of copper(II) is increased by the presence of pyridine. Kinetic methods are described for determining trace amounts of copper(II) and pyridine. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 550 nm. The calibration graphs are linear in the range 0.6-9.5 mug for copper(II) and 0.2-8.8 mg for pyridine. The methods have been applied to the determination of copper in galena and of pyridine in piperidine and isoamyl alcohol. The kinetic parameters of the reaction have been determined.     

Tetraalkoxyaluminates of nickel(II), copper(II), and copper(I)

The syntheses and structural details of tetraisopropoxyaluminates and tetra-tert-butoxyaluminates of nickel(II), copper(I), and copper(II) are reported. Within the nickel series, either Ni[Al(OiPr)4]2.2HOiPr, with nickel(II) in a distorted octahedral oxygen environment, or Ni[Al(OiPr)4]2.py, with nickel(II) in a square-pyramidal O4N coordination sphere, or Ni[(iPrO)(tBuO)3Al]2, with Ni(II) in a quasi-tetrahedral oxygen coordination, has been obtained. Another isolated complex is Ni[(iPrO)3AlOAl(OiPr)3].3py (with nickel(II) being sixfold-coordinated), which may also be described as a "NiO" species trapped by two Al(OiPr)3 Lewis acid-base systems stabilized at nickel by three pyridine donors. Copper(I) compounds have been isolated in three forms: [(iPrO)4Al]Cu.2py, [(tBuO)4Al]Cu.2py, and Cu2[(tBuO)4Al]2. In all of these compounds, the aluminate moiety behaves as a bidentate unit, creating a tetrahedrally distorted N2O2 copper environment in the pyridine adducts. In the base-free copper(I) tert-butoxyaluminate, a dicopper dumbbell [Cu-Cu 2.687(1) A] is present with two oxygen contacts on each of the copper atoms. Copper(II) alkoxyaluminates have been characterized either as Cu[(tBuO)4Al]2, {Cu(iPrO)[(iPrO)4Al]}2, and Cu[(tBuO)3(iPrO)Al]2 (copper being tetracoordinated by oxygen) or as [(iPrO)4Al]2Cu.py (pentacoordinated copper similar to the nickel derivative). Finally, a copper(II) hydroxyaluminate has been isolated, displaying pentacoordinate copper (O4N coordination sphere) by dimerization, with the formula {[(tBuO)4Al]Cu(OH).py}2. The formation of all of these isolated products is not always straightforward because some of these compounds in solution are subject to decomposition or are involved in equilibria. Besides NMR [copper(I) compounds], UV absorptions and magnetic moments are used to characterize the compounds.     

A proposed structure for the copper(ii) salts of α-acyloin oximes

The behavior of the copper (II) salts of the a-isomers of some acyloin oximes towards a series of selected amines was examined in order to study the unusual solubility relationships which these copper salts exhibit towards ammonium hydroxide. The insolubility in ammonium hydroxide of these copper salts of acyloin oximes has been attributed to their being inner complex salts. Evidence is presented which is contra y to this view. Based on the solubilities of the copper (II) salts investigated, a polymeric structure for copper (II) acyloin oximes is proposed. The study included the following α-isomers of acyloin oximes: benzoin oxime, 2,2'-furoin oxime, phenylbenzoin oxime, methylbenzoin oxime, 2,2'thenoin oxime, a-hydroxyisobutyrophenone oxime, and α-hydroxyacetophenone oxime. The last four compounds had not been examined previously as to their ability to form copper (II) salts.