非水体系中苯并三唑在铜电极上吸附的电化学表面增强拉曼光谱研究

采用电化学现场表面增强拉曼光谱(SERS)研究了非水体系中苯并三唑(BTAH)在铜电极上的吸附及成膜行为, 结果表明非水体系中BTAH的吸附行为随电位变化而不同. 较负电位区间主要以中性分子形式吸附; 中间电位区间主要以BTA^－吸附并不可逆成膜; 而在氧化电位区间主要表现为铜的氧化. 随中性配体三苯基膦(pph₃)的加入, 在中间电位区间, 由于易溶的Cu(pph₃)_n⁺的生成而使铜的溶解速度加快, 最终该阳离子在溶液中和BTA^-作用而生成了多核铜的配合物. 采用直接电化学方法模拟电极表面过程合成了相应的吸附产物, 并对其组成进行了相关表征.     

Biological study and electrochemical characterization of Cu(II) and 1,8-bis-(2-pyridyl)-3,6-dithiaoctane (pdto) complex

Preliminary proliferation assays in human tumor cervix line HeLa, using the coordination compound [Cu(pdto)H₂O]²⁺ (pdto = 1,8-bis-(2-pyridyl)-3,6-dithiaoctane) and its precursors Cu(NO₃)₂ · 2.5H₂O and pdto, were carried out. The results showed that the copper complex has a behavior similar to that of the reference drug cis-platin. No biological activity for the non-coordinated ligand and the copper salt was found. It was established by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy, that the complex [Cu(pdto)H₂O]²⁺ presents an electrochemical reversible Cu(II)/Cu(I) reduction, in acetonitrile solution, meanwhile, the copper salt Cu(NO₃)₂ · 2.5H₂O exhibited an electrochemical irreversible behavior. A comparison between biological and electrochemical results corresponding to [Cu(pdto)H₂O]²⁺ and Cu(NO₃)₂ · 2.5H₂O let us to proposed, the electrochemical reversibility, as one important factor in the antitumoral activity of the copper complex. Due to the nature of the studies presented in this work, other factors like intercalation properties with DNA cannot be neglected in the antitumoral activity of the complex.     

Electrochemical study of Cu2O/CuO composite coating produced by annealing and electrochemical methods

The electrochemical behavior of a copper oxide electrode produced by annealing and electrochemical methods was studied in an acetonitrile solvent by means of the cyclic voltammetry method. The presence of different peaks of oxidation and reduction produced by repeating the potential scans, numerous variations in the current, and shifts of peak potentials in consecutive cycles have been justified. Voltammograms proved that various oxidation species can be produced in solid-deposited forms of Cu₂O_s and CuO_s and dissolved forms of Cu(II)_sol and Cu(I)_sol ions. The experimental results indicated that higher amounts of Cu₂O_s than CuO_s can be produced in the process of copper electrode annealing. Also, the nature of copper species is responsible for different peak currents in the cyclic voltammograms, characterized by UV–Vis and XRD spectrometric methods.

     

Renewable New Copper Complex Bulk‐Modified Carbon Paste Electrode: Preparation,Electrochemistry, and Electrocatalysis

A conductive carbon paste electrode (CPE) comprised of a new copper‐complex of [Cu₂(Dpq)₂(Ac)₂(H₂O)₂](ClO₄)₂?H₂O (Dpq=dipyrido[3,2‐d : 2′,3′‐f]quinoxaline, Ac=acetate) and carbon powder, was fabricated by the direct mixing method. The electrochemical behavior and electrocatalysis of the new copper‐complex modified CPE (Cu‐CPE) have been studied in detail. Cyclic voltammograms showed that the Cu‐CPE had a favorable electrochemical response of a reversible redox couple of Cu(II)/Cu(I). The Cu‐CPE showed good electrocatalytic activity toward the reduction of the bromate, nitrite and hydrogen peroxide. The electrocatalytic reduction peak current of KBrO₃, KNO₂ and H₂O₂ showed a linear dependent on their concentrations. All of the results revealed that the Cu‐CPE had a good reproducibility, remarkable long term stability and especially good surface renewability by simple mechanical polishing in the event of surface fouling, which is important for practical application.     

Synthesis,structure, spectroscopic,magnetic and electrochemical studies of a rare syn–anti acetate-bridged copper(II) complex

The structure, spectroscopy and electrochemical properties of a novel dinuclear copper(II) complex, [{Cu(phen)₂}₂(μ-CH₃COO)][PF₆]₃ where phen = 1,10-phenanthroline, is reported. The crystal structure contains two independent Cu(II) ions, with different geometry around each copper center, which are bridged by an acetate anion. The acetate-bridged ligand shows a syn–anti coordination mode with a trigonal bipyramidal geometry for the Cu(1) center and a distorted square-based pyramidal geometry for the Cu(2) center. The angular structural index parameter τ for Cu(1) and Cu(2) is 0.9 and 0.33, respectively. The copper(II) atoms display a different geometry with a N₄O chromophore group and with Cu–O distances of 1.993(5)–1.996(5) Å and Cu–N distances which vary from 1.980(5) to 2.161(6) Å. The intra Cu…Cu separation is 4.9904(5) Å. The effective magnetic moment (μ_eff) of the complex was measured by the Evans method. The cyclic voltammogram of [{Cu(phen)₂}₂(μ-CH₃COO)][PF₆]₃ shows two waves at positive potential which are assigned to the two Cu(II/I) reduction couples.     

Electrochemical,chemical and spectrophotometric investigation of the copper(II)-bicinchoninic acid reagent used for protein measurements

The use of a reagent containing copper (II), bicinchoninic acid (BCA) and tartrate buffered at pH 11.25 was studied voltammetrically, coulometrically, spectrophotometrically and chemically. The reagent exhibits three cathodic waves at rotating platinum disk and rotating glassy carbon electrodes. The two more-positive cathodic waves correspond to electrochemical reduction to copper (I)-bisbicinchoninate, Cu(BCA)₂^3?. The third cathodic wave is caused by reduction to metallic copper. A reaction mechanism is proposed that shows the major chemical species in the solution and the electrochemical reaction products. Voltammetric and chemical studies indicate that the reagent should be used with care for protein assays because it is subject to multiple chemical interferences.     

Electrochemical behavior of copper in 1-butyl-3-methylimidazolium bromide-copper(II) bromide binary ionic liquid

The methods of potentiometry, voltammetry, and gravimetry are used to study the electrochemical behavior of copper in the BMImBr-CuBr₂ ionic liquid (0?C30.5 mol % CuBr₂). It is shown that electrochemical reduction of copper(II) occurs irreversibly, in two one-electron stages (transfer coefficient ?? of the cathodic process are 0.58 and 0.46, accordingly, for the first and second stages). Diffusion coefficients of copper-containing ions D _Cu(II) at 60°C are 1.3 × 10^?7 and 1.6 × 10^?7 cm² s^?1 in melts with the CuBr₂ concentration of 0.1 and 1.5 mol kg^?1 of BMImBr, accordingly. High (up to 98%) deposition efficiency and high-quality copper deposit can be obtained in the potential range of ?2.0 to ?1.8 V (vs. a platinum quasireference electrode). It is found that the copper corrosion rate grows at an increase in the CuBr₂ concentration in the binary melt and is comparable with that in aqueous solutions of H₂SO₄-CuSO₄.     

Mechanistic studies on the electrochemically lithiated spinel LiCuVO4

The lithiation mechanism of the spinel LiCuVO₄ was studied by X-ray diffraction, XPS, and electrochemical measurements using the lithium cell with the spinel cathode. The lithiation proceeded by the following steps: (1) in the multiphasic reaction for x < 1.5 in Li_1+xCuVO₄, the LiCuVO₄ spinel transforms to a new phase, Li_2.5Cu_0.5VO₄, and Cu metal; (2) in the monophasic electrochemical displacement reaction for 1.5 < x < 2.0, the copper ions extrude from Li_2.5Cu_0.5VO₄ with lithium intercalation, which forms Li₃VO₄ and Cu metal; (3) in the intercalation reaction for 2.0 < x < 5.0, lithium ions intercalate into Li₃VO₄ with several reaction steps. The new phase, Li_2.5Cu_0.5VO₄, lithiated reversibly with the electrochemical displacement between copper and lithium ions.     

Poly(vinylpyrrolidone)‐based films grown on copper surfaces

The influence of molecular weight and the amount of the poly(vinylpyrrolidone) (PVP) on the growth of poly(vinylpyrrolidone)–based films on copper surfaces was studied by electrochemical, infrared and electronic spectroscopy, and thermogravimetric methods. Complex polymer/metal ions were deposited onto a copper surface, as the result of the electrochemically generated reaction of copper cations with PVP and SCN^?, in sulfuric acid media. Spontaneous film growth on copper surfaces was generated and characterized as a Cu(II)/PVP/SCN^? complex. Infrared spectra and thermal gravimetric curves of the films generated at + 0.7 V were compared with the chemically synthesized complex, and show the same patterns. The oxidation process can be described as: Cu(0)→Cu(I) and Cu(I)→Cu(II), and the copper complex formed at more positive potentials was characterized as Cu(II)/PVP/SCN^?, with copper bonded to the oxygen atom of PVP and thiocyanate ligand N‐linked. This study focuses on the complex formation on a copper surface in acid media and its characterization through electrochemical and spontaneously generated reactions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2206–2214, 2009     

Synthesis,crystal structure,and DNA-binding studies of a one-dimensional copper(II) polymer bridged both by oxamidate and thiocyanato ligands

A new one-dimensional copper(II) polymer, [Cu₄(dmapox)₂(SCN)₄(CH₃OH)₂] _n , where dmapox is the dianion of N,N′-bis[3-(dimethylamino)propyl]oxamide, was synthesized and characterized by elemental analysis, conductivity measurement, IR, and electronic spectral studies. The crystal structure of the copper(II) complex has been determined by X-ray single-crystal diffraction. The complex crystallizes in triclinic, space group P ? 1 and exhibits infinite one-dimensional copper(II) polymeric chain bridged both by bis-tridentate μ-trans-dmapox and μ-1,3-thiocyanato ligand. The environment around the copper(II) atom can be described as distorted square-pyramid. The Cu···Cu separations through the oxamidate and thiocyanato bridges are 5.246(2) Å (Cu1–Cu1ⁱ), 5.2649(14) Å (Cu2–Cu2ⁱⁱ), and 5.8169(15) Å (Cu1–Cu2), respectively. The interaction of the copper(II) complex with herring sperm DNA (HS-DNA) has been investigated by using absorption and emission spectral and electrochemical techniques and viscometry. The results reveal that the copper(II) complex may interact with DNA in the mode of groove binding with the intrinsic binding constant of 2.56 × 10⁵ M^?1.     

Syntheses and characterization of new tetraazamacrocyclic copper(II) complexes as a dual functional mimic enzyme (catalase and superoxide dismutase)

A series of macrocyclic complexes, [Cu(TAAP)]X₂, X?=?ClO₄ and CH₃COO; [Cu(TAAP)X]X, X?=?NO₃, Cl, and Br, have been synthesized by self-condensation of 5-amino-3-methyl-l-phenylpyrazole-4-carbaldehyde (AMPC) in the presence of copper(II). Elemental analyses and conductivity measurements confirm the stoichiometry of the ligand and complexes, while the characteristic absorption bands in IR spectra confirmed the formation of ligand framework around copper. Square-pyramidal and square-planar stereochemistries have been proposed for the five-coordinate (nitrato and halogeno) and four-coordinate (perchlorate and acetate) complexes. The electrochemical properties and thermal behaviors have been studied by cyclic voltammetry and TGA. Mimetics of antioxidant enzymes such as superoxide dismutase (SOD) and catalase demonstrated that there is a correlation between the observed redox properties and the SOD and catalase biomimetic catalytic activities of the copper(II) complexes.     

Electrical conductivity of solutions of copper(II) nitrate crystalohydrate in dimethyl sulfoxide

Conductometry is used to investigate the electric conductivity of Cu(NO₃)₂ ? 3Н₂О solutions in dimethyl sulfoxide in the 0.01–2.82 M range of concentrations and at temperatures of 288–318 K. The limiting molar conductivity of the electrolyte and the mobility of Cu²⁺ and NO₃^- ions, the effective coefficients of diffusion of copper(II) ions and nitrate ions, and the degree and constant of electrolytic dissociation are calculated for different temperatures from the experimental results. It is established that solutions containing 0.1–0.6 M copper nitrate trihydrate in DMSO having low viscosity and high electrical conductivity can be used in electrochemical deposition.     

Use of the photoluminescence intensity variation as an in-situ probe for electrochemical copper deposition on a p-type GaAs electrode

Photoluminescence was used as an in-situ method for following the electrodeposition of copper on p-type GaAs electrodes from a 0.5 M H₂SO₄ solution containing Cu(II) sulphate. The method appeared to be very sensitive to copper coating and to be able to detect a copper amount of the monolayer range. Moreover, during anodic polarisation of the metallised electrode, photoluminescence measurements showed the complete dissolution of the copper layer. In-situ photoluminescence measurements were confirmed by ex-situ analyses at different stages of the electrochemical treatment of the GaAs electrode.     

A new two-dimensional polymeric copper(II) complex bridged both by oxamidate and azide groups: synthesis,structure and DNA binding properties

A new two-dimensional polymeric copper(II) complex, [Cu₂(heae)(N₃)₂] _n , where heae stands for the dianion of N,N′-bis(N-hydroxyethylaminoethyl)oxamide, has been synthesized and characterized by elemental analysis, molar conductivity measurement, IR, electronic spectral studies and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, P2₁/c space group with crystallographic data: a = 9.1588(18) Å, b = 6.6238(13) Å, c = 14.602(3) Å and Z = 2. The X-ray analysis reveals a two-dimensional copper(II) polymeric coordination network constructed by bis-tridentate chelated [Cu(trans-heae)Cu]²⁺ building blocks and end-on azido ligands. The environment around the copper(II) atom can be described as a square-based pyramid. The azido bridge is very asymmetric with one Cu–N bond distance short and the other long. The Cu ··· Cu separations through μ-trans-oxamidate and μ-azido bridges are 5.2996(13) Å and 4.2464(7) Å, respectively. The copper(II) complex is a polymer in the solid state, whereas in solution it exists as discrete neutral binuclear copper(II) species. Coordination mode of the azide in solution is proved by electronic spectra. The DNA-binding properties of the binuclear copper(II) species were investigated by emission spectral and electrochemical techniques, indicating the binuclear copper(II) complex binds to HS-DNA via a groove mode.     

Electrochemical reactions of lithium with CuP2 and Li1.75Cu1.25P2 synthesized by ballmilling

Copper phosphide (CuP₂) and lithium copper phosphide (Li_1.75-Cu_1.25P₂) were synthesized by high-energy ballmilling at room temperature. The electrochemical reactions between lithium and these samples have been studied. The first lithium insertion into the CuP₂ phase till 0.0 V vs. Li leads to copper reduction and the formation of lithium phosphide (Li₃P), corresponding to a long voltage plateau. The subsequent lithium extraction until 1.3 V vs. Li presents three voltage plateaus related to the formation of new phases such as Li₂CuP, giving a reversible capacity about 810 mAh/g and faradic yield about 61%. It means that both copper and phosphorus face a change of the oxidation state for the electrochemical insertion and extraction. Lithium copper phosphide exhibits a similar reaction process. However, it provides a reversible capacity of 750 mAh/g and faradic yield of 100% at the first cycle.     

Changes of the Cu electrode real surface area during the process of electroless copper plating

The surface area (nanoscale roughness) of copper coatings deposited from electroless plating solutions containing Quadrol, L(+)- and DL(∓)-tartrate as Cu(II) ion ligands was measured using underpotential deposition thallium monolayer formation. Surface roughness of Cu coatings depends on the plating solution pH and the Cu(II) ligand, and varies over a wide range. In L(+)-tartrate and Quadrol solutions (pH 12.5–13.3) the roughness factor R _f is low and is equal to 2–3 and 4–6, respectively (substrate: electrodeposited Cu; R _f=2.2). Cu coatings of higher surface area are obtained in DL(∓)-tartrate (pH 12.3–12.7) and Quadrol (pH 12.0) solutions: R _f reaches 20–30. The correlation between R _f and Cu deposition rate was found in L(+)-tartrate solution. The Cu surface area changes are discussed in terms of partial electrochemical reactions of the autocatalytic Cu deposition process, and the decisive role of cathodic Cu(II) reduction from adsorbed Cu(II) complex species. Received: 2 November 1999 / Accepted: 22 February 2000     

Copper(II) [(4-methylphenyl)sulfonyl]-1H-imino-(2-phenyl-2-oxazoline) complexes

Neutral copper complexes of the deprotonated [(4-methylphenyl)sulfonyl]-1H-imino-(2-phenyl-2-oxazoline) proligands, [HTs-ROz], R = H, 5-Me, 4-Me, 4-Et, 4-ⁱPr, have been prepared by electrochemical oxidation of anodic copper in an MeCN solution of the corresponding proligand. The [Cu(Ts-ROz)₂] complexes were characterised by microanalysis, i.r. and electronic spectroscopies, and by e.p.r. and magnetic measurements. The crystal structures of HTs-5MeOz, [Cu(Ts-Oz)₂], [Cu(Ts-5MeOz)₂] and [Cu(Ts-4MeOz)₂] were determined by X-ray diffraction.     

Synthesis and Characterization of Bridged Bimetallic Complexes. I. Copper(II) Complexes with Conjugated Diimine Ligands

A series of binucleating Uganda with fully conjugated π-systems have been synthesized. Homobinuclear copper(II) complexes of the form [(Cu(dien)ClO₄)₂L]-(ClO₄)₂, where dien is diethylenetriamine and L is binucleating ligand, were prepared. Mononuclear complexes, with structure similar to that of the preceeding compounds, [Cu(dien)L′(ClO₄)](ClO₄) were synthesized as reference compounds. The infrared spectra, elctronic spectra and magnetic properties were studied. The inductive effect, steric effect and the effect of the length of the conjugated π-system on the magnetic exchange interaction between the two copper ions are discussed. The electrochemical properties of these complexes were investigated by cyclic voltammetry. The copper ions showed the cooperative phenomena and a quasi-reversible sequential transfer of two electrons at the same potential.     

Synthesis, characterization and crystal structure of tetranuclear copper(II) complex [Cu4(μ-Salophen)2(μ1,1-N3)2(N3)2] with alternating μ1,1-azido and phenoxo bridges

Tetranuclear copper(II) complex [Cu₄(??-Salophen)₂(??_1,1-N₃)₂(N₃)₂] (I) has been synthesized from the reaction of Cu(NO₃)₂ · 3H₂O with the Schiff-base ligand salophen condensed from salicylaldehyde and 1,2-phenylenediamine at the presence of a large excess of NaN₃, which has been characterized by elemental analyses, FT-IR spectroscopy, and single-crystal X-ray diffraction. X-ray diffraction studies show that I is a tetranuclear Cu(II) complex with a pair of end-on (EO) azido ions bridging the copper(II) ions in a central Cu(??_1,1-N₃)₂Cu core and one phenoxo bridging the copper(II) ions in a Cu(??-Salophen)Cu core. All copper(II) ions in I are four coordinated and adopt approximate square planar coordination geometry.     

Copper(I) complexes of N-(aryl)pyridine-2-aldimines: Spectral, electrochemical and catalytic properties

The reactions of N-(aryl)pyridine-2-aldimines (L-R; R = OCH₃, CH₃, H, Cl and NO₂), derived from pyridine-2-aldehyde and para-substituted anilines, with CuI in methanol under ambient conditions afford a series of brown complexes of the type [{Cu(L-R)I}₂]. The structure of the [{Cu(L-OCH₃)I}₂] complex has been determined by X-ray crystallography. In these dimeric complexes the two copper centers are linked through an iodo-bridge, and the L-R ligands are coordinated to the metal center through the pyridine-nitrogen and imine-nitrogen. All the complexes show characteristic ¹H NMR signals and intense MLCT transitions in the visible region. These complexes also show an emission near 465 nm, whilst they are excited at 340 nm, with relatively poor quantum yields (φ ∼0.002 at 298 K). Cyclic voltammetry on all the complexes shows two successive Cu(I)-Cu(II) oxidations on the positive side of SCE, and a reduction of the coordinated imine ligand on the negative side. These copper(I) complexes are found to efficiently catalyze Suzuki type C-C coupling reactions.