Halometallates of 1-methyl-4,4-dimercapto-piperidinium. Evidence of strong hydrogen bonds with participating thiol groups

Chlorometallates of transition and B subgroup elements are readily prepared and precipitated by reaction of the corresponding metallic salts with 1-methyl-4,4-dimercaptopiperidinium chloride. These chlorometallates investigated were [ZnCl₄]^2?, [CdCl₃]^?, [CoCl₄]^2?, [CuCl₅]^3? and [FeCl₄]^2?. Strong SH … Cl interactions, but not NH … Cl, have been evidenced by IR spectroscopy in the zinc, cadmium and cobalt complexes. The SH and NH absorptions are observed at ? 2480 cm^?1 and 3060 cm^?1, respectively. Partial deuteration of the [ZnCl₄]^2? complex with d₁-methanol, shifted these IR signals to 1800 and 2260 cm^?1, clearly evidencing a X-hydrogen type of bond. The SH … Cl interaction is smaller in the [FeCl₄]^2? complex, and practically nonexistent in the [CuCl₅^3? complex.     

Study of urease inhibitory activity by medicinal plants extract based on new catalyst for Berthelot reaction and Taguchi experimental design

The Berthelot reaction is a well-established colorimetric method for determination of ammonia. In this work, the effects of different bivalent ions (Ba²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, and Pb²⁺) were studied as catalyst on the Berthelot reaction efficiency. CuCl₂ was generally found as the best catalyst that provides a rapid and stable blue indophenol color. The Taguchi experimental design methodology has been applied to find optimum conditions. Four factors including temperature, pH, reaction time, and CuCl₂ concentration at five levels were considered to achieve optimum conditions. Blue indophenol color stability for 40 min, and linearity response up to 20 mM of ammonium sulfate were achieved by further validation experiments. Limit of detection and quantification for this approach was 0.15 and 0.5 mM, respectively. Inhibitory activity of three traditional medicinal plants extract (Citrus aurantifolia, Laurus nobilis, and Zingiber officinale) was evaluated against jack bean urease activity by Berthelot reaction in the presence of CuCl₂ as catalyst, and results were compared with traditional Berthelot reaction.     

Sorption of transition metal cations on natural heulandite

The cation exchange equilibrium in the systems of natural heulandite-binary aqueous solutions of NaCl, NiCl₂, CuCl₂, ZnCl₂, and MnCl₂ was studied. The corrected coefficients of the selectivity (k ^a _M/Na) and thermodynamic constants (K _M/Na) of the cation exchange of Na⁺ cations for transition metal cations were determined. The selectivity of the cation exchange on natural heulandite increases in the following order: Ni²⁺ < Cu²⁺ < Zn²⁺ < Na²⁺ < Mn²⁺.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1101–1103, May, 1996.     

Template effects in chelating polymers

Poly(4′-methyl-4-vinyl-2,2′-bipyridine) has been prepared as have various copolymers with divinylbenzene. When polymerization is carried out in the presence of metal ions (Ni²⁺, Co²⁺, Cu²⁺) a metal-containing copolymer is obtained which, when the metal ion is removed with acid, retains some memory of the original chelating metal.     

Trace Amounts of Aqueous Copper(II) Chloride Complexes in Hypersaline Solutions: Spectrophotometric and Thermodynamic Studies

Knowledge of the thermodynamic properties of aqueous copper(II) chloride complexes is important for understanding and quantitatively modeling trace copper behavior in hydrometallurgical extraction processing. In this paper, UV–Vis spectra data of Cu(II) chloride solutions with various salinities (NaCl, 0–5.57 mol·kg^?1) are collected at 25 °C. The concentration distribution of Cu–Cl species is in good agreement with those calculated by a reaction model (RM). The simple hydrated ion, Cu²⁺, is dominant at low concentration, whereas [CuCl]⁺, [CuCl₂]⁰ and [CuCl₃]^? become increasingly important as the chloride concentration rises. Moreover, the RM calculation suggests the present of a small amount of [CuCl₄]^2?. The de-convoluted molar spectrum of each species is in excellent agreement with our previous theoretical results predicted by time-dependent density functional theory treatment of aqueous Cu-containing systems. The formation constants for these copper chloride complexes have been reported and are to be preferred, except log₁₀ K ₂ ([CuCl₂]⁰).     

Identification of dielectric effects in nanofiltration of metallic salts

Transport of four metallic salts (CuCl₂, ZnCl₂, NiCl₂ and CaCl₂) through a polyamide nanofiltration (NF) membrane has been investigated experimentally from rejection rate and tangential streaming potential measurements. Rejection rates have been further analyzed by means of the steric, electric and dielectric exclusion (SEDE) homogeneous model with the effective dielectric constant of the solution inside pores as the single adjustable parameter.     

Effect of metals on anaerobic digestion of water hyacinth-cattle dung

The effect of several salts, FeCl₃, NiCl₂, CoCl₂, CuCl₂, and ZnCl₂, on anaerobic digestion of water hyacinth-cattle dung was examined. Among the salts studied, FeCl₃ caused a more than 60% increase in gas production with a high methane content.     

Photoconductivity of poly(vinyl alcohol) films containing Cu2+ complexes

Photoconductivity has been measured in well-dried poly(vinyl alcohol) (PVAl) films containing Cu²⁺ complexes prepared by treatment with Cu(NO₃)₂, CuSO₄, CuCl₂, and CuBr₂. When the ratio [Cu²⁺]/[MU] ([MU] denoting the concentration of PVAl monomer residues) is greater than 0.015, illumination at the charge-transfer (UV) band produces a strong photocurrent in PVAl-CuCl₂ and PVAl-CuBr₂, but not in PVAl-Cu(NO₃)₂ or PVAl-CuSO₄. Optical absorption spectra suggest that two halide ions enter the first coordination sphere in the cis configuration. The temperature dependence of ESR indicates the existence of antiferromagnetic superexchange interaction via intervening halide ions. Hence, there exists a network structure of the PVAl-CuCl₂ or PVAl-CuBr₂ complex. The dependence of the photocurrent on the polarity of the illuminated electrode shows that the majority of carriers are holes. Holes in the network structure produced by charge transfer from halogen to Cu²⁺ ions are concluded to be responsible for the photoconduction.     

Stability and nature of complexes of the type MCl+ in aqueous solution (M=Mn,Co, Ni,and Zn)

Equilibrium constants have been determined both potentiometrically and spectrophotometrically for reactions of the type M²⁺+Cl^??MCl⁺ using aqueous solutions of the corresponding metal perchlorates as the reaction media (M=Mn, Co, Ni, and Zn). The variation in the quotient of the activity coefficients of these reactions with increasing molality of the reaction medium has been found to be approximately the same for the CuCl⁺ (previously studied), MnCl⁺, and ZnCl⁺ complexes, while a different dependence is observed for the CoCl⁺ and NiCl⁺ complexes. The results are interpreted as indicating equilibrium coexistence of the [MCl(OH₂)₅]⁺ and {[M(OH₂)₆]Cl}⁺ species in the latter two cases. Approximate values of the corresponding equilibrium constants are estimated in addition to the derived overall thermodynamic stability constants of the MCl⁺ formal complexes. The latter are found to follow a partly inverted Irving-Williams series, the fact being accountable in terms of the ligand field stabilization energy.     

Low Temperature Synthesis of Zeolite Films on Glassy Carbon: Towards Designing Molecularly Selective Electrochemical Devices

Faujasite‐type zeolite films have been grown on glassy carbon electrode surfaces embedded in an epoxy resin matrix by a quasi ambient temperature hydrothermal synthesis. The resulting zeolite modified electrodes are mechanically stable and provide an advantageous combination of electrochemical detection with charge and size selectivities at the molecular level, as demonstrated with the aid of some model electroactive probes or analytes (Ru(NH₃)₆³⁺, Fe(CN)₆^3?, Ru(bpy)₃²⁺, dopamine, ascorbic acid). To act efficiently as a physical molecular sieve barrier between the electrode surface and the external solution, these films must have a thickness of about 0.7 μm. These results open the door for further development of molecular sieving electrochemistry.     

Thermosensitivity of poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone): Effect of transition-metal halides

The effect of the halides of a series of transition metals on the properties of aqueous solutions of poly(N-vinylpyrrolidone) is studied. It is shown that the introduction of ZnCl₂ into solutions of poly(N-vinylpyrrolidone) causes phase separation with an increase in temperature. In the presence of halides of other transition metals (CdCl₂, CuCl₂), this phenomenon is not observed. However, the addition of HCl and/or alkali-metal halides to these systems likewise gives rise to phase separation, and in the ZnCl₂-based systems, the cloud point of solution substantially decreases with the introduction of alkali-metal salts. The same situation is observed in the case of polyvinylcaprolactam. Thus, it is concluded that the observed phenomena are associated with the formation of MtCl₄²⁻ complex anions in solutions that promote the globulization of polymer chains with participation of water molecules surrounding polymer chains and cations of transition-metal salts bound to complexes with C=O groups of lactam rings of the polymers.     

SPECTROSCOPIC INVESTIGATION ON THE TRICHLORO-, TETRAHALO- AND MIXED-TETRAHALO-CUPRATES OF THE PIPERIDINIUM AND MORPHOLINIUM CATIONS

Abstract

Some halo- and mixed-halo-cuprates of the type CuCl₃ · L, CuCl₄ · L₂, CuCl₃Br · L₂, CuCl₂Br₂ · L₂ and CuBr₄ · L₂, were prepared and characterized by means of far-i.r., i.r. and n.i.r. spectroscopy, magnetic moments and conductivity measurements. A band at 19000 cm^?1, which appears only in the CuCl₃ · L complexes, is characteristic of Cu₂Cl^2- ₆ dimer or polymer species. For these complexes and for CuCl₄(Morph)₂ and CuCl₃Br(Morph)₂ (Morph = morpholinium cation) an approaching square-planar geometry, while for all the other complexes a distorted-tetrahedral geometry, may be suggested from their spectroscopic properties, compared to those of other tri- and tetra-halo-cuprates of known structure. An intermediate structure between these geometries may be proposed for the CuCl₃ · Pipd complex. The planar geometry is probably stabilized by extensive NH … Cl hydrogen bonding interactions greater with the morpholinium cation than with the piperidinium cation. No thermochromic behaviour in the solid state in the 290–370° K temperature range is observed. The room-temperature magnetic moments agree with the proposed configurations.     

Raman spectral changes of alcoholic zinc chloride solutions from liquid state to glassy state

Raman spectral changes associated with vitrification were measured for ZnCl₂·4OROH solutions (ROH=methanol, ethanol and 1-propanol). Solvated ZnCl₂ is the only major Zn-species in these solutions at room temperature while the dominant Zn-species stabilized in the glassy alcoholic solutions are ZnCl ₃ ^– , ZnCl ₄ ^2– and [Zn(MeOH)₆]²⁺ for the methanol solution, ZnCl₂ and ZnCl ₃ ^– for the ethanol solution and ZnCl₂ for the 1-propanol solution. Together with Raman data for aqueous ZnCl₂ solutions, the differences in the dominant Zn-species in the glassy alcoholic solutions are discussed in terms of the dielectric constants of solvents (water and alcohols).     

Osmotic and Activity Coefficients of the {<Emphasis Type="Italic">x</Emphasis>ZnCl<Subscript>2</Subscript>+(1−<Emphasis Type="Italic">x</Emphasis>)ZnSO<Subscript>4</Subscript>}(aq) System at 298.15 K

Isopiestic vapor pressure measurements were made for {xZnCl₂+(1−x)ZnSO₄}(aq) solutions with ZnCl₂ molality fractions of x=(0,0.3062,0.5730,0.7969, and 1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements cover the water activity range 0.901–0.919≤a _w≤0.978. The experimental osmotic coefficients were used to evaluate the parameters of an extended ion-interaction (Pitzer) model for these mixed electrolyte solutions. A similar analysis was made of the available activity data for ZnCl₂(aq) at 298.15 K, while assuming the presence of equilibrium amounts of ZnCl⁺(aq) ion-pairs, to derive the ion-interaction parameters for the hypothetical pure binary electrolytes (Zn²⁺,2Cl⁻) and (ZnCl⁺,Cl⁻). These parameters are required for the analysis of the mixture results. Although significant concentrations of higher-order zinc chloride complexes may also be present in these solutions, it was possible to represent the osmotic coefficients accurately by explicitly including only the predominant complex ZnCl⁺(aq) and the completely dissociated ions. The ionic activity coefficients and osmotic coefficients were calculated over the investigated molality range using the evaluated extended Pitzer model parameters.     

A Simple Coulometric Method for Determining Cu[II] and Cu[I] Contents in Various Solid Samples

Abstract

Determination of copper individual oxidation states (Cu[II] and Cu[I] in various solid samples is a rather difficult problem. Results are here presented to demonstrate that constant current coulametric techniques are useful to realize these determinations with good analytical characteristics. The analytical equivalence points obtained are based on the reversible electron transfer mechanisms: Cu[II] + 3 HC1 + 2 e CuCl^2? ₃ + 2H⁺ and : CuCl^2? ₃ +e = Cu(O) + 3 Cl^?, respectively, after quantitative dissolution in aqueous HC1 6 M. Cyclic voltammetric measurements with a carbon paste electrode are made to characterize the electron transfers involved and to investigate the analytical utility of the technique in various media. Analytical determinations are given, e.g., in the analysis of the CuO/Cu₂ O content of various samples.     

Magneto-optic and luminescent properties of tellurite glass TeO<Subscript>2</Subscript>-ZnCl<Subscript>2</Subscript> doped with rare-earth elements

Tellurite glasses were synthesized on the basis of the binary system composed of 70 mol % TeO₂ and 30 mol % ZnCl₂ and doped with Nd³⁺, Pr³⁺, Tb³⁺, Er³⁺, Yb³⁺, Ho³⁺. The physicochemical, luminescent, and magneto-optic properties of these glasses were studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1262–1265.Original Russian Text Copyright © 2004 by Grishin, Gurev, Intyushin, Elliev, Pavlova, Savikin.     

Latest developments of bulk crystals and thin films of rare-earth doped CaF2 for laser applications

Several CaF₂ single crystals doped with trivalent rare-earth ions have been grown in the recent years in the form of bulk crystals by using the Bridgman method and in the form of thin films by using the MBE and LPE techniques. The spectroscopic, gain and laser properties of these crystals doped with Pr³⁺, on the one hand, and with Yb³⁺, Tm³⁺ or Er³⁺ ions, on the other hand, have been studied and are reviewed here for their laser potentials in the red and in the infrared spectral domains, respectively.     

Luminescent PMMA Films and PMMA@SiO2 Nanoparticles with Embedded Ln3+ Complexes for Highly Sensitive Optical Thermometers in the Physiological Temperature Range**

In recent years, luminescent materials doped with Ln³⁺ ions have attracted much attention for their application as optical thermometers based on both downshifting and upconversion processes. This study presents research done on the development of highly sensitive optical thermometers in the physiological temperature range based on poly(methyl methacrylate) (PMMA) films doped with two series of visible Ln³⁺ complexes (Ln³⁺=Tb³⁺, Eu³⁺, and Sm³⁺) and SiO₂ nanoparticles (NPs) coated with these PMMA films. The best performing PMMA film doped with Tb³⁺ and Eu³⁺ complexes was the PMMA[TbEuL₁tppo]1 film (L₁=4,4,4-trifluoro-1-phenyl-1,3-butadionate; tppo=triphenylphosphine oxide), which showed good temperature sensing of S_r=4.21 % K⁻¹ at 313 K, whereas for the PMMA films doped with Tb³⁺ and Sm³⁺ complexes the best performing was the PMMA[TbSmL₂tppo]3 film (L₂=4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadionate), with S_r=3.64 % K⁻¹ at 313 K. Additionally, SiO₂ NPs coated with the best performing films from each of the series of PMMA films (Tb–Eu and Tb–Sm) and their temperature-sensing properties were studied in water, showing excellent performance in the physiological temperature range (PMMA[TbEuL₁tppo]1@SiO₂: S_r=3.84 % °C at 20 °C; PMMA[TbSmL₂tppo]3@SiO₂: S_r=3.27 % °C at 20 °C) and the toxicity of these nanoparticles on human cells was studied, showing that they were nontoxic.     

Bildung und Verhalten von Chlorozinksäuren in äthanolischer Lösung

Formation and Behaviour of Chlorozinc Acids in Ethanolic Solution The reaction between ZnCl₂ and HCl in ethanol leads to H₂ZnCl₄ only. The behaviour of H₂ZnCl₄ · 3 (C₂H₅)₂O, (NH₄)₂[ZnCl₄] and HCl in ethanolic solutions has been investigated by means of conductivity measurements at ?10 and ?20°C. The equivalent conductivities have been determined. The Stokes radii of [ZnCl₄]^2?, H⁺, and [(C₂H₅)₂OH]⁺ are calculated.     

Phase transitions in the A2BX4-compound: Tetramethylammonium tetrachlorozincate tetrachlorocuprate, [(CH3)4N]2Zn0.5Cu0.5Cl4, and room temperature crystal structure determination

Preparation, crystal structure, and infra-red absorption spectra are reported for the first material in an A₂BX₄ compound with metal transition substitution in tetrahedral anion, tetramethylammonium tetrachlorozincate tetrachlorocuprate: [(CH₃)₄N]₂Zn_0.5Cu_0.5Cl₄. The calorimetric study shows five endothermic peaks at 248.75, 271.75, 278.6, 286.7, and 293.7 K. The determination of unit cell in the 240–298 K temperature range confirms those observed by the DSC technique. At room temperature, the compound crystallizes in an orthorhombic system (P2₁ cn space group) with Z = 4 and the following unit cell dimensions: a = 8.988 (3), b = 15.527 (2) and c = 12.269 (4) ?. The structure was solved by using 1986 independent reflections down to an R value of 0.048. The crystal structure consists of alternating organic-inorganic [(TMA)⁺/(Cu)ZnCl₄²⁻] layers and organic sheets (TMA)²⁺. All Organic groups and (Cu)ZnCl₄²⁻ are not disordered. Their main geometrical features are those commonly observed in the atomic arrangements of (TMA)₂ZnCl₄ and (TMA)₂CuCl₄. The text was submitted by the authors in English.