The reduction of different non-metallic reactants at the mercury/electrolyte interface inhibited by trialkylphosphine oxides

The reduction of HJO₃, HBrO₃ and S₂O²⁻₈ in the presence of hexyldiethyl- or octyldimethyl-phosphine oxide was studied dc polarographically at high surface coverages. Linear relationships between the logarithm of the rate constants and the film pressure of the surfactants were observed. From the slopes cross-sectional areas of the activated complexes of the inhibited electrode reactions could be determined. In the case of HJO₃, HBrO₃ and S₂O⁻²₈ reduction in alkaline solution the reactant seems to pass the adsorption layer without its hydratation shell, whereas the reduction of S₂O²⁻₈ in acid and neutral solutions apparently involves a mixed electron-ion transfer mechanism.     

Electrochemistry of surface grafted copper(II) benzoate complexes

Glassy carbon electrodes were grafted with carboxyphenyl groups by reduction of 4-carboxyphenyldiazonium tetrafluoroborate and these modified electrodes were characterised by cyclic voltammetry and ac impedance measurements. Cu(II) was reacted with the carboxyphenyl groups in the film to give a surface voltammetric response for the immobilised Cu(II)/Cu(I) couple. The results indicated an ECEC mechanism, in which the chemical steps correspond to the change of coordination environment following the electron transfer steps. The relaxation half-life time for the Cu(I) species formed after electron transfer was estimated at (140 ± 11) s. The large value of the peak width of 200 mV was analysed by modelling the voltammograms and the large value of the full width at half maximum (FWHM) could be explained by dispersion in the formal potentials of Cu centres present in a variety of environments in the films studied. An ECEC mechanism (scheme of square) is proposed for the electron transfer reaction considering that the chemical step after reduction of the Cu(II) complex corresponds to conformational changes within the attached layer. Experimental data clearly show that the oxidation of the reduced film can take place from different Cu(I) complexes formed along the reduction to the fully relaxed Cu(I) species.     

Crystal structures of palladium(II) and copper(II) complexes of meso-phenyl tripyrrinone

Meso-phenyl tripyrrinone (2), which is derived directly from N-confused porphyrin by Cu(II)-assisted oxygenolysis, can serve as a metal coordination ligand using three nitrogens and one oxygen in the core. The crystal structures of Pd(II) and Cu(II) complexes show the similar square-planar N₃O-coordination but the mode of oligomeric chains formed in the crystals by π–π stacking interaction is different: zig–zag for Cu(II) and straight for Pd(II) complex.     

Synthesis and characterization of telechelic phosphine oxide polyesters and cobalt(II) chloride complexes

A monofunctional phosphine oxide containing endcapping reagent, 4-carboxyphenyl biphenyl phosphine oxide, was synthesized for the preparation of telechelic polyester oligomers. The chemical structure of the endcapping reagent was verified using NMR spectroscopy, mass spectroscopy, and elemental analysis. Phosphine oxide telechelic polyesters were prepared for the first time via copolymerization of a low molar mass polyester oligomer precursor and the phosphine oxide endcapping reagent in the melt state. The quantitative incorporation of telechelic phosphine oxide functionality was confirmed using ¹H NMR spectroscopy and elemental analysis. The corresponding complexes of phosphine oxide terminated polyesters and cobalt(II) chloride were prepared via charging the cobalt salt at the onset of melt polymerization. ³¹P {¹H} NMR spectroscopy, FT-IR spectroscopy, and UV-vis spectroscopy indicated that the cobalt(II) ion preferentially coordinated with the phosphine oxide end groups. The complexes exhibited higher melt viscosity than their salt-free analogues due to the formation of coordinated polymers. The presence of the telechelic phosphine oxide end groups also aided in the homogeneous dispersion of the cobalt salt in a poly(ethylene terephthalate) (PET) matrix.     

Cathodic reduction and infrared reflectance spectroscopy of basic copper(II) salts on copper substrate

Infrared reflectance spectroscopy and cathodic reduction have been used for the characterization of copper corrosion products formed by atmospheric corrosion. The following basic copper(II) salts were synthesized: atacamite and paratacamite (Cu₂Cl(OH)₃), brochantite (Cu₄SO₄(OH)₆), posnjakite (Cu₄SO₄(OH)₆.H20), malachite (Cu₂CO₃(OH)₂), gerhardite (Cu₂NO₃(OH)₃). The samples for analysis were obtained by incrustation of submicron particles of the compound on the surface of OFHC copper coupons. Infrared reflectance spectroscopy shows that, unlike copper oxides, the reflection spectra of thin layers of basic copper(II) salts on copper are similar to those obtained by the usual KBr-pellet method for the location of the bands. However, some differences occur in the intensities of the bands between the two modes. Infrared reflectance spectroscopy allows an easy identification of basic copper(II) salts: chlorides can be identified by their Cu-O-H bending modes; sulfates, sulfite, nitrate and carbonate by the internal mode of the corresponding anion (v ₃ region). The cathodic reduction analyses of the salts on copper display only a wide peak in the range from –0.6 to –0.55 V vs SCE, indicating that one step is involved. The potential of this cathodic reduction peak is distinguishable from the one of copper(I) oxides (–0.9 V vs SCE). Thereby the relative proportions of copper(II)) salts and copper(I) oxides present in the corrosion layer can be determined.     

Synthesis,spectral and structural study of sulfur-containing copper(II) complexes

A series of four new copper(II) complexes [Cu(H₂L)(L¹)] 1, [Cu(H₂L)(PMDT)] 2, [Cu(H₂L)(Dien)] 3 and [Cu(H₂L)(L²)] 4 have been synthesized by template condensation (H₂L=thiodiglycolic acid, L¹=N-[(1)-1-(4-methylphenyl)ethylidene]benzohydrazide, PMDT=N,N,N′,N′,N ^′′-pentamethyldiethylene- triamine, Dien=diethylenetriamine L²=N-[(1)-pyridin-2-ylmethylidene]benzohydrazide). The bonding and stereochemistry of the complexes have been characterized by molar conductance, elemental analysis, magnetic susceptibility, infrared, UV–visible, electron paramagnetic resonance structural studies and electrochemical studies. g-Values were calculated for all complexes in polycrystalline form as well as in DMSO solution. The magnetic and spectral data indicate square pyramidal geometry for 1 and octahedral geometry for 2–4 complexes. Cyclic voltammograms for all the complexes are similar and involve two irreversible redox processes. Their biological properties have also been studied. The thio complexes show more antibacterial activity than the controlled one. The antibacterial activities of the compounds have also been tested against Escherichia coli with different concentrations.     

Stability constants of adipate complexes of copper(II), nickel(II), zinc(II), cobalt(II), uranyl(II) and thorium(IV) determined by electrophoresis

Stability constants of Copper(II), Nickel(II), Cobalt(II), Zinc(II), Uranyl(II) and Thorium(IV) adipates have been determined by paper electrophoresis. Adipic acid (0.005 mol dm^?3) was added to the background electrolyte: 0.1 mol dm^?3 HClO₄. The proportions of (CH₂)₄COOH COO^? and (CH₂)₄C₂O⁼₂ were varied by changing the pH of the electrolyte. These anions yielded the complexes Zn(CH₂)₄COOH COO⁺, Co(CH₂)₄COOH COO⁺, Ni(CH₂)₄COOH COO⁺, Th(CH₂)₄COOH COO³⁺, Th[(CH₂)₄COOH COO]₄, Cu(CH₂)₄ C₂O₄ and UO₂[(CH₂)₄(C₂O₄)]^2?₂, whose stability constants are found to be 10^2.8, 10^2.8, 10^3.2, 10^5.2, 10^15.3, 10^2.7 and 10^11.8 respectively (μ = 0.1, temp. 40°C).     

两种不同电去离子技术处理含铜金属离子废水的研究

研究了倒极电渗析技术(EDIR)和电去离子技术(EDI)过程中淡出水和浓水室的电导率、p H值、铜离子浓度和膜堆电流,以及运行后离子交换膜和树脂的表面形态。结果表明:EDIR运行15 h的淡出水的电导率为30μS/cm,16 h的铜离子去除率为97.2%。EDI过程中15 h淡出水的电导率550μS/cm,16 h的铜离子去除率为77.8%。EDIR使淡出水的电导率降低,铜离子去除率升高。EDIR淡出水的p H值长期维持碱性,EDI淡出水则由碱性变成酸性、再变成碱性。然而,EDIR和EDI过程中浓水室的电导率和p H值基本接近。EDIR降低了膜堆电流、消除了浓水室阴离子交换膜表面氢氧化铜沉淀,抑制了淡水室中混合树脂表面沉淀。本质上,EDIR通过周期性改变淡水室和浓水室的相对数量和离子迁移方向而消除了膜表面氢氧根离子富集,并缓和了树脂表面水解现象,从而改善了EDIR过程的稳定性。     

In situ synthesis and dielectric properties of copper(II) and nickel(II) chiral Schiff base complexes

Two chiral Schiff base-containing complexes, [Cu(L¹)](ClO₄)₂·H₂O (1, L¹ = (S,S)-N1,N2-bis((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) and [Ni(L²)₂](ClO₄)₂ (2, L² = (S,S)-N1-((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) were synthesized from the reaction mixture of 1H-imidazole-4-carbaldehyde, (S,S)-1,2-diaminocyclohexane and Cu(ClO₄)₂·6H₂O or Ni(ClO₄)₂·6H₂O in methanol. Single-crystal X-ray diffraction analyses reveal that the in situ generated chiral Schiff base ligands L¹ and L² are bisubstituted and monosubstituted, respectively, corresponding to the different metal ions Cu^II and Ni^II. Variable-frequency and -temperature dielectric properties of 1 and 2 have been studied.     

Copper(I) and copper(II) complexes in solution and the crystalline state

Model studies on the copper-protein interaction that may catalyze lipid oxidation have been made by studying the copper complexes of glycyl-L-histidyl-glycine and ε-aminocaproic acid. The compositions of the complexes in solution were measured by emf methods. The structures of solid complexes were determined by x-ray diffraction techniques. The results indicate that all the solid complexes have their counterparts by species formed in solution. One of 28 papers presented at the Symposium, “Metal-Catalyzed Lipid Oxidation,” ISF-AOCS World Congress, Chicago, September 1970.     

Diimine copper(II) complexes as building blocks for microporous catalytic materials

New copper(II) complexes with tridentate diimine ligands, containing imidazolate-bridging groups, have been prepared as precursors of supramolecular-coordination-chemistry-based assemblies, designed to act as oxidation catalysts. These complexes were isolated as mono-, di- and polymeric or cyclic supramolecular species. In solution, solvent- and pH-dependent equilibria between the mono- and dinuclear complexes, or the mono- and the corresponding polymeric species were detected. Those species were characterized by different spectroscopic techniques (UV/Vis, IR, Raman and EPR), and the X-ray crystallographic structure was determined for one of them. The catalytic activity of the dinuclear and polymeric species in the oxidation of phenol substrates by molecular oxygen were verified, by monitoring the corresponding quinone formation. Cyclic hexa- or tetranuclear copper(II) species, exhibiting imidazolate-bridge groups between the copper centres, were observed to be better catalysts then the analogous dinuclear ones, mainly due the interaction of the substrate with the catalyst hydrophobic cavity. A modulation of the cavity size seems strongly affect the reactivity of these systems.     

Caffeine in copper(II) complexes: crystal and molecular structure of di(caffeine)tetrakis(naproxenato)dicopper(II)

The crystal and molecular structure of di(caffeine)tetrakis(naproxenato)- dicopper(II) was determined by direct method and Fourier techniques. The structure was refined by full-matrix least-squares methods to a weighted R factor of 0.0705. The compound is binuclear with square pyramidal geometry at each copper(II) centre. The two copper(II) atoms are bridged by four carboxylate groups, while the apical ligands are caffeine molecules. The Cu–Cu distance is 2.649(2) Å. The Cu atoms are displaced by 0.217 Å from the plane containing four oxygen atoms bonded to Cu towards the apical caffeine molecules. The structural data are compared with those found in similar [Cu₂(RCOO)₄(caf)₂] (caf = caffeine) complexes.     

Facile hydrothermal synthesis of vanadium oxides nanobelts by ethanol reduction of peroxovanadium complexes

V₃O₇·H₂O and VO₂(B) nanobelts were successfully synthesized by a one-pot hydrothermal approach using peroxovanadium (V) complexes, ethanol and water as the starting materials. Some parameters, such as the ratio of ethanol/water, the reaction temperature and the reaction time, were briefly discussed to reveal the formation of vanadium oxides nanobelts. It was found that the ethanol was oxidized to aldehyde confirmed by the silver mirror reaction and gas chromatography. V₃O₇·H₂O and VO₂(B) nanobelts could be selectively synthesized by controlling the quantity of ethanol. The possible formation mechanism of the synthesis of vanadium oxides nanobelts was proposed. The electrochemical properties of V₃O₇·H₂O and VO₂(B) nanobelts were studied, and they exhibited a high initial discharge capacity of 350 mAh/g and 190 mAh/g, respectively. VO₂(M) nanobelts were prepared by the irreversible transformation of VO₂(B) nanobelts at 700 °C for 2 h under the inert atmosphere. The phase transition properties of VO₂(M) nanobelts were investigated by DSC and variable-temperature IR, which revealed that the as-obtained VO₂(M) nanobelts could be applied to the optical switching devices.     

Reactions of phenylbis(2-pyridyl)phosphine with oxorhenium(v) complexes

[ReOCl₃(PPh₃)₂] reacts with phenylbis(2-pyridyl)phosphine (PPhpy₂) in boiling THF under the formation of the rhenium(III) compound [ReCl₃(PPh₃)(OPPhpy₂-O,N)]. Reduction of the metal can be avoided by milder reaction conditions, and an asymmetric, oxo-bridged rhenium(V) dimer of the composition (NBu₄)[Re₂O₂Cl₅(μ-PPhpy₂-P,N,N′)(μ-O)] is obtained from the reaction of PPhpy₂ and (NBu₄)[ReOCl₄] in THF at room temperature. The products have been characterized spectroscopically and by X-ray structure analyses.     

Studies on immobilized polymer-bound imidazole copper(II) complexes as catalysts. Part II. immobilization of copper(II) complexes of poly(styrene-co-n-vinylimidazole) by quaternization or adsorption on silica and their catalyses of oxidative coupling of 2,6-disubstituted phenols

Copper(II) complexes of poly(styrene-co-N-vinylimidazole) (Cu(II)-PS-im) were immobilized on modified silica by quaternization or on unmodified silica by adsorption and these immobilized polymer-bound complexes were applied as catalysts for oxidative coupling polymerization of 2,6-dimethylphenol (DMP) in toluene / methanol (13 / 2 v / v). Higher average chain loading (α) of PS-im with imidazole groups, e.g. a ⩾ 17%, was essential for successful adsorption. A main role of hydroxide appears to be production of more reactive phenolate anions from DMP. A rise in reaction rate was not observed for high ligand / Cu, which probably resulted from too high viscosity of the silica suspension at high ligand / Cu. In a batch process under comparable conditions both types of immobilized polymer catalysts were found to have the same preference for poly-2,6-dimethyl-1,4-phenyleneoxide formation as non-immobilized Cu(II)-PS-im and their low molar mass analogue. However, they were five times less active than non-immobilized ones, which was explained primarily in terms of a reduced effective ligand / Cu ratio after the immobilization of polymeric ligands. Application of both types of immobilized polymer catalysts in a continuous stirred tank reactor (CSTR) for oxidative coupling of 2,6-di-tert-butylphenol was successful. A stable phenol conversion was obtained in CSTR under suitable conditions for at least 120 hours.     

2-取代苯并咪唑与铜（II）配合物的微波合成与表征

采用2-取代基苯并咪唑化合物、氯化铜为原料、丙酮或2-丁酮为溶剂,在微波辐射下合成了2-苄基苯并咪唑(BIm_a)和1-(对甲氧基苄基)-2-(对甲氧基苯基)苯并咪唑(BIm_b)的铜配合物,收率分别为80%和75%.测得BIm_a和BIm_b铜配合物熔点分别为144.7～145.8 ℃和224.5～226.0℃.应用摩尔电导率、XRD、紫外光谱、SEM和热分析测试对目标配合物进行表征,摩尔电导率、紫外和红外光谱解析表明,2-取代苯并咪唑配体与Cu(Ⅱ) 发生了配合反应;XRD和SEM表征证明晶型为单斜晶系;热分析得出BIm_a、BIm_b和氯化铜的配位数分别为1和1/2.     

The kinetics of copper dissolution in acetonitrile-water copper(II) solutions

The rate of dissolution of rotating copper discs in acidified copper(II) solutions prepared in an acetonitrile-water solvent (mole fraction ACETONITRILE = 0.·25) was measured in the temperature range 270–360 K. The rate of dissolution was found to be proportional to the square root of the rotation speed and to have an activation energy of 18 ± 2kJ mol⁻¹. The reaction is therefore considered to be diffusion controlled.

The reduction of copper(II) to copper(I) on a rotating platinum electrode, and the oxidation of copper(O) to copper(I) on a rotating copper electrode, were investigated. These two reactions together make up the dissolution reaction. From the intersection of the polarization curves, it was confirmed that the dissolution reaction was diffusion controlled. Dissolution rates calculated from the electrochemical measurements agreed with the kinetic measurements. Estimates of some electrochemical parameters in the acetonitrile mixed solvent were made.

The surface characteristics of annealed and unannealed copper discs which had been etched in the copper(II) solution are discussed briefly.