The use of copper(I) halides as a preparative tool

The use of copper(I) halides as a preparative tool is discussed with respect to the synthesis of adduct compounds with new polymeric and oligomeric main group molecules. By using this approach new polymers of main group elements--some of which have been predicted by theoretical investigations--can be obtained in a crystalline state and are therefore accessible for a basic structural characterization. Thus, it becomes possible to compare the structural data, experimental data, and theoretical results. Mixed copper halide chalcogenides are accessible when complex copper thiometalates and copper halides are combined. These solid-state compounds are of special interest since they provide experimental access to new main group molecules. In addition, they exhibit a high copper ion conductivity when certain structural features are present in the compounds. A survey is given of basic synthetic and general structural aspects.     

EPR study of copper(II) complexes of hydroxysalen derivatives in order to be used in the DNA cleavage

Two series of functionalized hydroxy-salen-copper(II) complexes with various side chain lengths have been synthesized. The first one is characterised by amino side chain protected by the tert-butyloxycarbonyl group (Boc) whereas, the second series is obtained by removal of the Boc-protecting group under acidic conditions and formation instead of it an ammonium salt. EPR studies were carried out on the copper(II) complexes. EPR signals attributed to monomers and dimers of Cu2+ species were evidenced. Determination of the copper(II) environment in each complex was attempted using all the experimental results. Square planar and tetrahedral symmetries were found for the copper(II) monomers. From the fine structure observed for the pair signal, the distance between the Cu2+ ions in the pair has been calculated (3.9-4.3A). From these values, it seems that the formation of pairs is obtained by a face-to-face bimolecular association.     

Carbonates in zeolites: Formation,properties, reactivity

Two possible schemes of carbonate formation (with and without water participation) in cationic form zeolites are considered. Activation energy for the formation of hydrogen carbonate in NaX zeolite from water and carbon dioxide is calculated at the DFT level with periodic boundary conditions, while the problems of modeling the formation of symmetric carbonate in the same zeolite are discussed. The formation of copper carbonate is studied using binuclear CuOCu clusters from CO₂ where the influence of water on the barrier is discussed. The questions related to DFT application to binuclear copper clusters are also considered by comparison with the data obtained at the MP2 level. The reactivity of copper carbonate is tested in the reaction with methanol. © 2015 Wiley Periodicals, Inc.     

联合处理电位法和极谱法得到的实验数据确定金属配合物稳定常数(英)

The cadmium(Ⅱ)-glycinamide system was modeled and its stability constants were calculated by a unified mathematical treatment for experimental data obtained from ion selective electrode (ISE) and differential pulse polarography (DPP). It has been shown that very much the same experimental complex formation curve (ECFC) and theoretical complex formation curve (TCFC) could be given from both experimental techniques for the same experimental conditions, such as the same total ligand c(L_T) and metal ion c(M_T) concentrations. The combination of the two techniques is of many advantages as ISE can be performed at low a c(L_T)∶c(M_T) ratio and significantly higher c(M_T), whereas DPP could be used well at larger the c(L_T)∶c(M_T) ratio and very low c(M_T). This makes it possible to study a metal-ligand system in much broader range of experimental conditions that, in turn, provides us more data and information about the metal-ligand system of interest. Application of the unified mathematical treatment to the cadmium-glycinamide system in this paper, three new complexes MHL, ML₃ and ML₃(OH) as well as two complexes ML and ML₂, reported in literatures, could be modeled and all their stability constants have been refined.     

Stabilization at high temperatures

A general detailed model of polymer oxidative degradation in the presence of a stabilizer-oxygen acceptor was considered. The motion of the degradation zone boundary and the sample lifetime were obtained for various conditions of the process. In particular, it is shown that within the given concentration immobile oxygen acceptor has the best stabilizing properties. The theoretical results are compared with the experimental data obtained by using two independent methods: polymer sample cracking and a change in the ESR signal. Good agreement between theory and experiment was obtained.     

Remote in situ analytical spectroscopy and its applications in the nuclear industry

Heavy metals exist in natural waters in different species. Mobility and bioavailability of bound metals can be influenced by some complex factors in the aquatic environment. Therefore, it is useful to determine the complexation properties of various ligands influenced by different metals. The copper and zinc complexation capacity was determined for a natural ligand (fulvic acid) and anthropogenic pollutants (e.g. nitrilotriacetic acid and ethylenediaminetetraacetic acid). The interactions between several ligands and metal ions and their effects on the complexation capacity were analyzed in particular. Applying methods of experimental design, such as multifactorial plans, it is possible to determine influence and interaction of various parameters (e.g. concentration of zinc or copper) by a minimum number of experiments. Differential pulse polarography was used for the determination of the complexation capacity. Methods of parametric and robust multiple linear regressions were applied for the interpretation of the measured values.     

Complexes of copper(II) with adenosine or guanosine nucleosides, nucleotides 5'-monophosphate, 2'-deoxynucleosides or 2'-deoxynucleotides 5'-monophosphate in aqueous solution

In this paper copper(II) complex formation in aqueous solution with a series of nucleosides (adenosine or guanosine) or nucleotides 5'-monophosphate is studied by means of potentiometry, visible spectrophotometry and ultraviolet circular dichroism. A chemical model has been formulated for each binary system (at T= 25 degrees C and I = 0.1 M), with particular attention to the interaction in the basic field. A spectrum (both visible absorption and ultraviolet circular dichroism) for each complex with a significant percentage of formation (in the adopted experimental conditions) has been calculated, allowing structural details to be hypothesised. The interaction with deprotonated alcoholic group(s) of the ribose moiety has been found to be fundamental in determining the co-ordination chemistry of each ligand considered while cases of co-operation between the purine and ribose donor(s) were also considered. Confirmations were also obtained by an investigation on the corresponding 2'-deoxy compounds as ligands.     

Relationship between the Structure of Cement Stone and the Parameters of Ice Formation during Stone Freezing

The specific features of ice formation during freezing of hardening binders are considered as dependent on the structural characteristics. The theoretical grounds for the relationship between the crystallization point of the pore-confined liquid and the pore size are discussed. The possible mechanisms of frost-caused cement stone destruction and the conditions of their development are considered. A model is proposed for estimating the danger of ice formation. The results of experimental studies are given for ice formation during freezing of tricalcium silicate and tricalcium aluminate. The parameters of ice formation are shown to be interrelated with the properties of the porous structure formed during hardening of these binders. The laws characterizing the degree of danger due to ice formation during freezing of cement stone are established.     

The wettability of electrodes made of natural metal sulfides

Experimental methods for the evaluation of the wettability of electrodes made from natural mineral sulfides are discussed for the case of potentiostatic polarization. The wettability, induced by xanthates with different lengths of the alkyl chain, was studied for the case of pyrite, chalcopyrite, galena, arsenopyrite and chalcocite. Therefore measurements of the detachment force of an air bubble (ABDF) and of the induction time (ABIT) were performed. The first of these allows us to estimate the conditions for the destruction of the bubble-mineral complex, and the second allows us to estimate the conditions of aggregate formation under collision. The study was carried out at various polarization potentials in a borate buffer solution. The results of the measurements are compared with thermodynamic data and with experimental results obtained for representative cases such as xanthate sorption and flotation recovery. A correlation of the flotation experiments with the ABDF results can be demonstrated. Received: 28 February 1997 / Accepted: 12 August 1997     

Fabrication of copper hydroxyphosphate with complex architectures

Copper hydroxyphosphate [Cu(2)(OH)PO(4)] with complex architectures has been synthesized through a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. Powder X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectrometry are used to characterize various properties of the obtained samples. Single-crystals, twinned-crystals, and various novel architectures of copper hydroxyphosphate can be constructed through a careful control of synthetic parameters, such as the molar ratio of initial reagents, reagent concentration, reaction time, and temperature. On the basis of structure and chemical bond analysis, copper hydroxyphosphate crystals tend to grow along the c-axis and have a rotation twinned-crystal growth habit, which is essential for the formation of various complex architectures. The current approach provides a facile strategy to synthesize copper hydroxyphosphate crystals with unique morphologies and complex architectures, which may be applicable to the synthesis of other inorganic materials.     

多元醇法制备Cu2O/CNTs复合材料的研究

以Cu(CH₃COO)₂•H₂O和经硝酸处理的CNTs作为原料, 采用多元醇法成功合成了纳米氧化亚铜均布于碳纳米管表面的复合光催化剂. 用透射电镜(TEM), 高分辨透射电镜(HRTEM), X射线粉末衍射(XRD)对样品进行了表征, 测试结果表明大小为2～5 nm的氧化亚铜纳米颗粒均匀分散于碳纳米管的表面. 讨论了反应条件对Cu₂O在CNTs上负载效果的影响并就多元醇法合成Cu₂O/CNTs复合材料的反应机理作了初步探讨.     

Formation of copper nanoparticles during the reduction of Cu2+ ions in solutions and dispersions of polycation-poly(acrylic acid) interpolymer complexes in acidic media

The phase behavior of mixed acidic solutions of the high-molecular-mass cationic polyelectrolyte poly(1,2-dimethyl-5-vinylpyridinium methyl sulfate) and PAA at a PAA-to-polycation ratio of <1 base-mol/base-mol in narrow pH ranges at 6–30°C is studied. The reduction of Cu²⁺ ions in solutions and dispersions of interpolyelectrolyte complexes yields copper nanoparticles. It is shown that the mean-square diameters of nanoparticles formed in solutions of nonstoichiometric polyelectrolyte complexes are much smaller than those obtained in solutions of each component of the polyelectrolyte complex under the same conditions. These values decrease as the thermodynamic quality of the solvent with respect to the polymer of the pseudomatrix nonstoichiometric polyelectrolyte complex worsens. The experimental data may be explained in terms of the theoretical concept of pseudomatrix formation of a new phase in polymer solutions.     

Copper uptake by silica and iron oxide under high surface coverage conditions: surface charge and sorption equilibrium modeling

A sorption modeling approach based on surface complexation concepts was applied to predict copper uptake and its effects on the surface electrostatic potential of ferric oxide and silica colloids. Equilibrium modeling of copper uptake by ferric oxide using the traditional surface complexation model (SCM) was reasonably successful with some discrepancies especially in the acidic pH ranges and high colloid concentration cases. Good predictions of the ferric oxide charge reversals during uptake were obtained from the modeling. Based on the SCM predictions, copper removal from solution is due to the outer-sphere complexation of the first hydrolysis product, resulting in the surface-metal complex SO(-)CuOH(+). The SCM was found to be insufficient to describe copper uptake by silica particles. To address discrepancies between experimental data and SCM predictions, the SCM was modified to include attributes of the surface polymer model (SPM), which incorporates sorption of the dimeric copper species Cu(2)(OH)(2)(2+). The continuum model (CM) was also studied as a second modification to the SCM to include formation of surface precipitates. Both the SPM and the CM were successful in modeling copper uptake and zeta potential variations as a function of pH at various solution conditions and colloid concentrations. From the SPM and CM predictions, it was concluded that for systems with high surface loadings, copper removal from solution occurs due to the formation of both monomeric and dimeric surface complexes, as well as through precipitation mechanisms.     

Interfacial rheological properties of adsorbed protein layers and surfactants: a review

Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants. Therefore these properties have been studied extensively. In this review an overview is given of interfacial properties of proteins at a mesoscopic scale and the effect of LMW surfactants (emulsifiers) on them. Properties addressed are the adsorbed amount, surface tension (reduction), network formation at interfaces and possible conformational changes during and after adsorption. Special attention is given to interfacial rheological behaviour of proteins at expanding and compressing interfaces, which simulate the behaviour in real emulsions and foams. It will be illustrated that information on interfacial rheological properties, protein conformation and interactions between adsorbed molecules can be obtained by changing experimental conditions. The relation between interfacial rheology and emulsion and foam stabilisation is subsequently addressed. It is concluded that there is a need for new measuring devices that monitor several interfacial properties on a mesoscopic and microscopic scale at the same time, and for physical models describing the various processes of importance for proteins. Real progress will only be possible if both are combined in an innovative way.     

Structural parameters of Cu<Superscript>2+</Superscript> aqua complexes in aqueous solutions of its salts

Published data of various research techniques and own experimental results obtained by the X-ray structural analysis concerning structural characteristics of copper(II) aqua complexes in aqueous solutions of its salts under standard conditions have been generalized. Structural parameters of the nearest environment of this ion, such as coordination number, interparticle distances, and ionic association types, were considered. The possibility of the Jahn-Teller effect realization in aqueous solutions of Cu²⁺ salts was examined.     

The determination of glycerol : Absorptiometric determination as the copper complex

Spectrophotometric studies of the copper-glycerol complex are reported. A single 1 : l complex is formed under the experimental conditions employed. The interference of precipitated or colloidal copper(II) hydroxide can be overcome by filtration through glass-fibre discs or by application of a correction factor. Filtered solutions of the complex in 90% ethanol obey Beer's law over a wide range of concentration. The stability of the complex and the effects of variation in alcohol and alkali concentration have been studied.An absorptiometric method for the determination of 0.5–40 mg of glycerol is proposed and the effect of possible interferences is considered.     

Determination of Configuration and Conformation of a Reserpine Derivative with Seven Stereogenic Centers Using Molecular Dynamics with RDC-Derived Tensorial Constraints**

NMR-based determination of the configuration of complex molecules containing many stereocenters is often not possible using traditional NOE data and coupling patterns. Making use of residual dipolar couplings (RDCs), we were able to determine the relative configuration of a natural product containing seven stereocenters, including a chiral amine lacking direct RDC data. To identify the correct relative configuration out of 32 possible ones, experimental RDCs were used in three different approaches for data interpretation: by fitting experimental data based singular value decomposition (SVD) using a single alignment tensor and either (i) a single conformer or (ii) multiple conformers, or alternatively (iii) using molecular dynamics simulations with tensorial orientational constraints (MDOC). Even though in all three approaches one and the same configuration could be selected and clear discrimination between possible configurations was achieved, the experimental data was not fully satisfied by the methods based on single tensor approaches. While these two approaches are faster, only MDOC is able to fully reproduce experimental results, as the obtained conformational ensemble adequately covers the conformational space necessary to describe the molecule with inherent flexibility.     

Experimental and thermodynamic modelling of systems containing water and ethylene glycol: Application to flow assurance and gas processing

Accurate knowledge of hydrate phase equilibrium in the presence of inhibitors is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. In this communication, we report new experimental dissociation data for various systems consisting of methane/water/ethylene glycol and natural gas/water/ethylene glycol. A statistical thermodynamic approach, with the Cubic-Plus-Association equation of state, is employed to model the phase equilibria. The hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The thermodynamic model was used to predict the hydrate dissociation conditions of methane and natural gases in the presence of distilled water or ethylene glycol aqueous solutions. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.     

Progress in the study on the composition and formation mechanism of gallstone

Our serial studies from 1970s on chemical composition, structure determination and formation mechanism of gallstones were reviewed. The chemical component investigation of brown-pigment gallstone demonstrated that it consists of macromolecules such as proteins, glyco-proteins, polysaccharides, bilirubin polymers and pigment polymers, and biomolecules such as cholesterol, bile salts, calcium salts of carbonate, phosphate, fatty acids and bilirubinate as well as various metal ions. The binding of metal ions with bile salts and bilirubin plays important roles in gallstone formation, i.e., calcium bilirubinate complex is the major constitute of brown-pigment gallstones, and copper bilirubinate complex is critical in the black color appearance of black-pigment gallstone. The cross section of many gallstones exhibits a concentric ring structure composed of various small particles with a fractal character. This is nonlinear phenomenon in gallstone formation. A typical model system of metal ions-deoxycholate (or cho