Polarographic behaviour of arylazo pyrazoles

The polarographic reduction of 1-phenyl-3-amino-4-arylazo-pyrazole-5-one and its arylazo substituted derivatives is studied in Britton—Robinson buffers (pH 3–10), containing 40% dimethyl formamide. The compounds exhibit a single wave in acidic solutions and two waves in alkaline solutions. A plausible mechanism has been suggested on the basis of number of protons and electrons involved in the reduction.     

Polarographic study of binary and mixed complexes of copper(II) with glycine and ethylenediaminetetraacetate

New data are presented concerning the various soluble complex species formed from copper(II) and ethylenediaminetetraacetate in the pH range 3–12. A polarographic study has been made of these species, taking into account the reversibility characteristics of the waves, and an interpretation of the electrode processes has been made on a basis of the theory developed by Matsuda and Ayabe. The study has been extended to mixed ligand complexes additionally containing glycine, and the diffusion, kinetic and ionisation constants have been determined.     

Reversible adsorption of thiophene on copper chromite

Adsorption isotherms of thiophene on copper chromite catalyst have been obtained under catalytic conditions using the gas chromatographic technique. The isotherms were found to follow the Freundlich adsorption equation. The isosteric heat of adsorption has been determined from the isotherms and found to be dependent on surface coverage.     

Polarographic investigation of Cu(II) complexes with π donor ligands

The polarographic reduction of Cu(II) complex chlorides with biguanides and N′- amidinoisoureas have been studied in aqueous 0.5 M KCl solution containing 0.01% gelatin. The complexes [except Cu(enH₂dbg)²⁺] show two well defined waves whose heights are pH dependent. The first (lower - E_1/2) and the second waves have been attributed to mono and bis(ligand)Cu(II) species respectively. Lower rate constant, higher activation energy and more negative E_1/2 values relative to those of a σ bonded Cu(II) chelates have been explained on the basis of chelate ring current and high π-basicity of the ligands. The gradual change of these values with the size of the N-substituents is due to decreased π-basicity of the respective ligands. Ratio of mono and bis biguanide with pH change has been calculated and activation energies for the complexes, calculated polarographically, have been found to be closely related to D_q values obtained from absorption band maxima.     

Chromium substituted copper ferrites via gluconate precursor route

CuFe_2−xCr_xO₄ spinel (0≤x≤2) powders were synthesized by a soft chemistry method—the gluconate multimetallic complex precursor route. The complex precursors were characterized by elemental chemical analysis, infrared (IR) and ultraviolet–visible (UV–vis) spectroscopy, thermal analysis and Mössbauer spectroscopy. The oxide powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), IR, Raman and Mössbauer spectroscopy. It was shown that the structure, morphology and magnetic properties of the obtained spinel powders depend on the concentration of Cr³⁺ ion. The XRD of the chromium substituted copper ferrite powders calcined at 700 °C/1 h indicated the formation of a cubic spinel type structure for x=0.5, 1.0 and a tetragonal structure for x=0, 0.2, 2. The crystallite size ranged from 19 nm to 39 nm. The Mössbauer spectroscopy revealed the site occupancy of iron ions, relative abundance and internal hyperfine magnetic fields in both tetrahedral and cubic CuFe_2−xCr_xO₄ spinels.     

过硫酸钾存在下的盐酸胺碘酮极谱催化波及其应用

基于K2S2O8存在下盐酸胺碘酮(ADHC)产生的极谱催化波,拟定了测定ADHC的新方法。在0.15mol/LKH2PO4Na2HPO4(pH5.6) 8.0×10-5mol/LK2S2O8底液中,ADHC于-1.32V(vs.SCE)产生的极谱催化波的二阶导数峰电流ip″与其浓度在8.0×10-8～4.0×10-7mol/L及4.0×10-7～8.0×10-5mol/L呈良好的线性关系,其线性回归方程分别为ip″/μA·s-2=-3.95 9.51×107cADHC(r=0.9939,n=7),ip″/μA·s-2=104.6 2.92×107cADHC(r=0.9958,n=7),检出限为2.70×10-8mol/L。该催化波的分析灵敏度比相应还原波提高了5倍左右,该方法用于测定ADHC的含量,结果满意。     

The adsorption site of ammonia at copper surfaces

The adsorption of ammonia at copper surfaces was studied using Hartree-Fock-Slater LCAO calculations to investigate ammonia interaction with copper clusters. Important factors influencing ammonia adsorption were established from trends in its behaviour at clusters of different size. Adsorption at different coordination sites was examined in light of these results and it was found that a strong electrostatic contribution directs the ammonia towards lower coordination sites.     

ESR spectra of copper complexes of cellulose

The ESR spectra of complexes of fibrous cotton cellulose and cupriammonia dihydroxide or cupriethylene diamine dihydroxide under various experimental conditions were determined. The spectra of both complexes with cotton cellulose were almost identical at ?100 and 25°C. The spectrum of the complex of cupriethylene diamine dihydroxide with cellulose was stable to temperatures as high as 100°C. The sum of the linewidths of the hyperfine components of the spectra for each complex was about 180 gauss. Cotton fibers were combed and aligned with their axes (lengths) parallel to the magnetic field (B_∥); after formation of either of the complexes with cellulose a minumum of hyperfine structure of components centered at H_∥ was observed. A maximum of hyperfine structure of these components was observed when the complexed fibers were aligned with their axes perpendicular to the magnetic field (B_⊥). The opposite was true of components centered at H_⊥. For a complex of cupriethylene diamine dihydroxide and cellulose at 25°C. and at high pH the g_∥ was 2.2127 and the g_∥ was 2.0476. It was suggested that the alignment of most of the complex was its axis of symmetry at a maximum angle to the axes of the cotton fiber, when the axes of the fibers were in the parallel alignment with the magnetic field. At high pH these observations were even more marked. When ramie was used with cupriethylene diamine dihydroxide at high pH, the contribution of components centered at H_∥ to the spectra was zero. Spectra for the copper compounds alone and complexed with cellobiose are also reported.     

The adsorption and catalytic transformations of chromium on Mn substituted goethite

Goethite widely occurs in the environment and its role in photoreduction of toxic Cr(VI) to less toxic Cr(III) has been previously reported in the literature. However, natural goethite is rarely stoichiometric and usually contains certain substitutional cations, such as Mn(III) or Mn(IV), which, on the other hand, is an oxidant for Cr(III). In order to provide more insight into the fate of Cr(VI) in the environment, the influence of Mn-substitution in goethite on its Cr(VI) photoreduction capability needs to be clarified. The objectives of this study were to evaluate the adsorption and photo-transformations of Cr on Mn-substituted goethite with Mn/(Mn + Fe) molar ratios ranging from 0 to 0.1. The results showed that Cr adsorption and photo-catalytic transformation on goethite were strongly influenced by the Mn content of goethite. When the system was under illumination, Cr(VI) reduction was decreased with increasing Mn-substitution in goethite. The re-oxidation of photo-reduced product, i.e., Cr(III), at the Mn sites on the surface of goethite is responsible for the lower Cr(VI) photo-reduction capacity of Mn-substituted goethite. The role of goethite in the reduction of Cr(VI) may be overestimated unless its Mn-substituted counterparts are considered. The effectiveness of Mn sites in goethite to increase toxic Cr(VI) has important implications in determining the fate and threat of Cr(VI) contamination.     

Hydrogen adsorption characteristics of activated carbon

Hydrogen adsorption on activated carbons was investigated in the present works up to 100 bars at 298 K. Coconut-shell was activated by potassium hydroxide, resulting in activated carbons with different porosities. All of prepared activated carbons are microporous and show the same adsorption properties. The complete reversibility and fast kinetics of hydrogen adsorption show that most of adsorbed quantity is due to physical adsorption. A linear relationship between hydrogen adsorption capacity and pressure is obtained for the all samples regardless of their porosities. Hydrogen adsorption capacities are linear function of porosities such as specific surface area, micropore surface area, total pore volume, and micropore volume. The maximum hydrogen adsorption capacity of 0.85 wt.% at 100 bars, 298 K is obtained in these materials.     

铜和硫酸铜选择性催化合成单取代苯基哌嗪的新方法

报道了无溶剂条件下用铜和硫酸铜作催化剂由溴苯与哌嗪选择性合成单取代苯基哌嗪的新方法，并初步研究了溶剂、反应时间、反应温度对反应产率的影响。     

A CdSO4-like 3-D framework constructed from monosodium substituted Keggin arsenotungstates and copper(II)-ethylenediamine complexes

A 6⁵·8 CdSO₄-like 3-D framework [Cu(en)₂]₃[α-AsW₁₁NaO₃₉]·2H₂O (1) constructed by monosodium-substituted Keggin arsenotungstates and copper(II)-ethylenediamine complexes (en = ethylenediamine) has been synthesized by reaction of Na₈[α-HAsW₉O₃₄]·11H₂O, CuCl₂·2H₂O and ethylenediamine under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Crystal data for 1: C₁₂H₅₂AsCu₃N₁₂NaO₄₁W₁₁, monoclinic, Cc, a = 20.409(9) Å, b = 16.737(8) Å, c = 16.561(7) Å, β = 104.607(7)°, V = 5474(4) Å³, T = 296(2) K; Z = 4, μ = 24.860 mm⁻¹, GOOF = 1.086, R₁ = 0.0284, wR₂ = 0.0759. To the best of our knowledge, 1 represents the first 6⁵·8 CdSO₄-like 3-D monovacant Keggin arsenotungstate derivative in polyoxometalate chemistry.     

Isomerization of olefins and substituted olefins catalyzed by nickel complexes

The catalytic activity of several Ni (diphosphine)₂/acid homogeneous systems (acid = HCN, CF₃COOH, CCl₃COOH, and H₂SO₄) in the double bond and cistrans isomerizations of olefins has been tested with the following compounds: pentene-1, cis-pentene-2, trans-pentene-2, allyl benzene, allyl cyanide, allyl alcohol. The catalytic efficiency of the Ni(diphosphine)₂/acid systems depends markedly on the nature both of the diphosphine and of the acid employed. When the diphosphine is 1,4-bis(diphenylphosphino)butane and acid = HCN a particularly efficient catalytic system is formed in situ and only in the case of the allyl cyanide is the isomerization limited. During the isomerization of pentene-1, the stereoselectivity in the formation of the cis-2 and trans-2 isomers is quite dependent on the nature of the cocatalyst. It is proposed that a σ-alkyl mechanism is operating in the $\text{Ni(O)}\text{CF}{}_3\text{COOH}$ system and a π-allyl one in the case of $\text{Ni(O)}\text{HCN}$.     

土壤对重金属Cu(Ⅱ)、Cd(Ⅱ)的吸附研究

采用等温吸附平衡法研究了土壤对重金属Cu2+和Cd2+的吸附,研究了浓度、搅拌时间、静置时间以及pH对土壤吸附铜和镉影响。结果表明,土壤对铜的吸附量大于镉,土壤对重金属吸附的最佳条件是搅拌15 min,静置20 min,pH为7.0,初步确定土壤对铜和隔的吸附属于Freundlich吸附。     

在TritonX－100存在下用2－QADN2，7示波极谱法测定痕量铜

合成了１－（２－喹啉偶氮）－２，７－二羟萘，研究了本试剂与铜络合物的极谱特性。在ｐＨ９．６０的缓冲溶液中，当有０．００２５％ＴｒｉｔｏｎＸ－１００存在时，Ｃｕ（Ⅱ）－２－ＱＡＤＮ２，７络合物在－０．４１Ｖ产生一灵敏示波极谱波，用此波检测痕量铜的下限为１．０×１０－１０ｍｏｌ／Ｌ。     

Electron transfer reactions of some ferrous complexes of substituted 1,10-phenanthroline

The cyclic voltammograms of ferrous complexes of 5-substituted 1,10-phenanthroline were obtained. The anodic and the cathodic peak potentials shifted toward positive side by substituting electron-withdrawing group for 5-hydrogen in 1,10-phenanthroline. This result was interpreted by that the probability of the transition of electron from d orbital to the empty MO of the ligand was increased by the introduction of electron-withdrawing group, and hence the oxidation of the ferrous complex became more difficult. The oxidized substances of ferrous complex containing this functional group were labile and decomposed chemically.     

Arsenic adsorption using copper (II) oxide nanoparticles

Arsenic poisoning is a major problem in today's life. To reduce its concentration in drinking water, different metal based compounds were explored as arsenic adsorbents. In the present study, copper (II) oxide nanoparticles were prepared by thermal refluxing technique and used as an adsorbent for arsenic removal from water. Characterization of the adsorbent using TEM, BET, XRD and FTIR implied that the prepared adsorbent was in nano size and had excellent adsorption behavior with surface area of 52.11 m²/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed and found that copper (II) oxide had very good efficiency towards arsenic adsorption. Thermodynamic parameters and adsorption kinetics were studied in detailed to know the nature and mechanism of adsorption. Results showed that the adsorption process followed pseudo second order kinetic and endothermic behavior. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 1086.2 μg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation is reported to know the amount of adsorbent required for efficient removal of arsenic from aqueous medium.     

Inspired dual functional adsorption films of armed molecules on copper

In this study, double norfloxacin skeletons including the target armed molecules (DNs) displaying antibacterial and anticorrosion properties for copper in aqueous solutions were presented. The molecular modelling and material simulation calculations suggest that the target molecules could be adsorbed to copper surface, which was further demonstrated by attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The experimental results show that the copper surface which adsorbed the target armed molecules exhibited an excellent inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The potentiodynamic polarization plots and electrochemical impedance spectroscopy demonstrate that the DNs of 0.100 mM achieved over 95% corrosion inhibition efficiency for copper in 0.5 M H₂SO₄ solution at 298 K. The results given in this study may guide us to achieve bacterial and corrosion resistances for copper based on the drug-included armed molecules.