High-performance liquid chromatography of sugars on copper (II) modified silica gel

Summary A sensitive method of sugar analysis by HPLC is described in which a copper (II) modified silica gel as stationary phase is used. Detection is based on UV absorption of a complex formed between the sugar, copper, and ammonia.     

Dehydration of alcohols catalyzed by copper(II) sulfate adsorbed on silica gel

Copper(II) sulfate adsorbed on silica gel efficiently dehydrated secondary and tertiary alcohols under mild conditions to give olefins. The rate of dehydration of tertiary alcohols is much faster than that of secondary alcohols.     

Crystal structures of bis(ethylenediamine) copper(II) diethyldithiophosphate and di(ethylenediamine)bis (diethyldithiophosphato) copper(II) thiocyanate

Journal of Structural Chemistry -     

Cobalt(II) complexation with immobilized proteinases of Candida albicans

Complexation of cobalt(II) ion with proteolytic enzymes of Candida albicans (SAP C.alb.) of induced (ISAP C.alb.) and constitutive (CSAP C.alb.) types immobilized on the cellulose nitrate membrane surface has been studied. The maximal sorption capacity of cellulose nitrate membranes with covalently immobilized induced proteinase ISAP C.alb. with respect to Co(II) ions is 16.5 ??mol/cm², and that for CSAP C.alb. is 27.7 ??mol/cm². The model of fixed polydentate centers has been used for describing complex formation. The complexation constants (?? _n ) and the average number of immobilized ligands coordinated to one metal atom (n) have been determined. The specificity of binding of immobilized enzyme molecules to Co(II) ion has been assessed.     

Thioacetamide chemically immobilized on silica gel as a solid phase extractant for the extraction and preconcentration of copper(II), lead(II), and cadmium(II)

Thioacetamide immobilized on silica gel was prepared via the Mannich reaction. The extraction and enrichment of copper(II), lead(II), and cadmium(II) ions from aqueous solutions has been investigated. Conditions for effective extraction are optimized with respect to different experimental parameters in both batch and column processes prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH ranges for quantitative adsorption are 4.0-8.0, 2.0-7.0, and 5.0-10.0 for Pb(II), Cu(II), and Cd(II), respectively. Pb(II) and Cd(II) can be desorbed with 3 mol/L and 0.1 mol/L HCl/HNO3, and Cu(II) can be desorbed with 2.5% thiourea. The adsorption capacity of the matrix has been found to be 19.76, 16.35, and 12.50 mg/g for Pb(II), Cu(II), and Cd(II), respectively, with the preconcentration factor of approximately equal to 300 for Pb(II) and approximately equal to 200 for Cu(II) and Cd(II). Analytical utility is illustrated in real aqueous samples generated from distilled water, tap water, and river water samples.     

Potassium bis(ethylenediamine)­copper(II) ferricyanide

The title compound, potassium bis(ethylenediamine‐N,N′)copper(II) hexacyanoferrate(III), K[Cu(C₂H₈N₂)₂]‐[Fe(CN)₆], contains [Cu(en)₂]²⁺ and [Fe(CN)₆]^3? complex ions, where en is ethylenediamine. The Fe^III and K⁺ ions lie on twofold axes and the Cu^II atom lies on an inversion center. The [Cu(en)₂]²⁺ ion has square‐planar coordination with a mean Cu—N distance of 1.992 (2) Å and the [Fe(CN)₆]^3? ion has distorted octahedral coordination with a mean Fe—C distance of 1.947 (2) Å.     

Reactions of benzyldiphenylphosphine with Pd(II) sources on silica gel

Depending on the conditions used, reactions of benzyldiphenylphosphine (HL¹) with Na₂PdCl₄ on silica gel or with Pd(OAc)₂ on the same absorbent followed by treatment with LiCl provide one or more of the four compounds: the cyclopalladated binuclear complex [(μ-Cl)PdL¹]₂ (1), cis and trans isomers of the coordination complex PdCl₂(HL¹)₂ (3), the binuclear coordination complex [(μ-Cl)PdCl(HL¹)]₂ (4), and compound PdCl₂(HL¹)₃ (5). The 56% yield of complex 1 achieved using the reaction with Na₂PdCl₄ and NaOAc on SiO₂ is higher than that reported for the direct cyclopalladation of PBnPh₂ with Pd(OAc)₂ in AcOH. X-ray diffraction studies of the cyclopalladated dimer 1 and the coordination complex cis-3 are reported.     

Preparation of platinum(II) sulfide complexes immobilized on silica

We report on preparation of silica-immobilized platinum(II) complexes of the [{SiO₂}O₂Si(CH₃)· (CH₂)₃SR]₂PtCl₂ type (R = Bu, Hex, or Bn; {SiO₂} = silica surface).     

Sorption of Cu(II) onto silica gel immobilized calix[4]arene derivative with tripodal structure

This study contains the synthesis of silica gel-immobilized calix[4]arene derivative (TR-CL[4]P) as a new sorbent and its sorption studies towards Cu (II) ion in aqueous solution. The aldehyde pointed calix[4]arene derivative 5 was synthesized and then it was immobilized onto 3-aminopropilsilica gel (APS). In batch sorption experiments, the experimental results showed that TR-CL[4]P is effective sorbent towards Cu (II) ion. Therefore, the effect of solution pH, sorption time, temperature and initial metal ion concentration onto Cu (II) sorption was investigated. Maximum Cu(II) removal was obtained at 30?°C, 30?min and pH 6.0 for TR-CL[4]P and the batch sorption capacity was found as 17.8?mg/g. The characteristics of the sorption process for Cu (II) ion were evaluated by using the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption isotherms. Also, thermodynamic parameters, i.e., ΔG, ΔS, and ΔH were calculated for the system.     

On the complexation of copper (II) ion with 2-hydroxybenzamide

The complexation of the Cu2+ ion with 2-Hydroxybenzamide (salicylamide, HL) has been studied, at 25 degrees C, by potentiometric measurements with a glass electrode in NaCIO4 media for ionic strength ranging from 0.5 to 3 mol/dm3. The data are consistent with the formation of the complexes CuH(-1)(HL)+, CuH(-2)(HL)2, Cu2H(-2)(HL)2(2+) and CuH(-2)(HL). The minor species, Cu2H(-2)(HL)2(2+) and CuH(-2)(HL), amount to at least 20% of the total copper. Elaboration of the data according to the Specific Interaction Theory yields the constants valid in the infinite dilution reference state: [formulas: see text] and the interaction coefficients (kg/mol) of complex species with medium ions: b(L-,Na+) = 0.11 +/- 0.03; b(CuH(-1)(HL)+,NaClO4) = 0.17 +/- 0.05; b(CuH(-2)(HL)2,NaClO4) = 0.11 +/- 0.05; b(Cu2H(-2)(HL)2(2+),NaClO4) = 0.2(7) +/- 0.1; b(CuH(-2)(HL),NaClO4) = -0.0(3) +/- 0.1.     

Kinetic study of copper(II) complexation with 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone and kinetic-spectrophotometric determination of copper(II)

The kinetics of complexation reaction of Cu(II) with 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) has been examined spectrophotometrically. The ligand was synthesized for the first time. The complexation reaction was carried out in a DMF-water medium at 35°C. The complex has maximum absorbance at 393 nm. Kinetic and activation parameters of the complexation reaction were calculated by the Arrhenius and Eyring equations using the data obtained from investigating the effect of temperature on reaction rates under the specified conditions. We also proposed reaction rate equations. Based on the studied complexation reaction, a simple kinetic method for the spectrophotometric determination of copper(II) has been developed. The calibration graphs are linear in the concentration range 0.2–1.9 μg/mL. The species that caused interference were investigated. The text was submitted by the authors in English.     

The determination of anionic detergents with the bis (ethylenediamine)copper(II) ion

A method is described for the determination of anionic detergents. The detergent anions are extracted into chloroform as an ion-association compound with the bis(ethylenediamine)copper(II) cation. Determinations are completed by colorimetry or atomic absorption spectrometry. With a 150-ml water sample, the limit or detection is 0.03 μg ml^-1 (as LAS) for colorimetry or 0.06 μg ml^-1 for a.a.s. The method requires only one phase separation step and is highly selective. It is directly applicable to brine and sea-water samples.     

High-performance ligand-exchange liquid chromatography (HPLEC) of aromatic amines with copper(II), nickel(II) and zinc(II) loaded chelating silica gel columns

Summary An 8-hydroxyquinoline, 8-hydroxy-5-sulphonic-acid-quinoline and a 2-amino-1-cyclopentene-1-dithiocarboxylic acid silica gel, loaded with copper(II), nickel(II) or zinc(II) were examined for the separation of some aromatic amines in the normal phase mode. All phases studied interact strongly with the sample compounds, but the presence of cations increases the selectivity of the columns drastically in some cases. Nickel(II) or zinc(II) loading proved to be better than copper(II) loading, because with these ions strong peak broadening and disturbances of the baseline are avoided. Endcapping of the chelating silica gels was indispensable in order to obtain reasonable efficiencies.     

Twinned low‐temperature structures of tris(ethylenediamine)zinc(II) sulfate and tris(ethylenediamine)copper(II) sulfate

Tris(ethylenediamine)zinc(II) sulfate, [Zn(C₂H₈N₂)₃]SO₄, (I), undergoes a reversible solid–solid phase transition during cooling, accompanied by a lowering of the symmetry from high‐trigonal P1c to low‐trigonal P and by merohedral twinning. The molecular symmetries of the cation and anion change from 32 (D₃) to 3 (C₃). This lower symmetry allows an ordered sulfate anion and generates in the complex cation two independent N atoms with significantly different geometries. The twinning is the same as in the corresponding Ni complex [Jameson et al. (1982). Acta Cryst. B 38 , 3016–3020]. The low‐temperature phase of tris(ethylenediamine)copper(II) sulfate, [Cu(C₂H₈N₂)₃]SO₄, (II), has only triclinic symmetry and the unit‐cell volume is doubled with respect to the room‐temperature structure in P1c. (II) was refined as a nonmerohedral twin with five twin domains. The asymmetric unit contains two independent formula units, and all cations and anions are located on general positions with 1 (C₁) symmetry. Both molecules of the Cu complex are in elongated octahedral geometries because of the Jahn–Teller effect. This is in contrast to an earlier publication, which describes the complex as a compressed octahedron [Bertini et al. (1979). J. Chem. Soc. Dalton Trans. pp. 1409–1414].     

Synethesis and Crystal Structure of Bi(ethylenediamine)copper Tetracyanonickelate(II)

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｒｅｐａｒａｔｉｏｎａｎｄｓｔｕｄｙｏｆｐｏｌｙｎｕｃｌｅａｒ,ｃｙａｎｉｄｅｂｒｉｄｇｅｄｍｅｔａｌｃｏｍｐｌｅｘｅｓｈａｖｅａｔｔｒａｃｔｅｄｃｏｎｓｉｄｅｒａｂｌｅｉｎｔｅｒｅｓｔｏｖｅｒｔｈｅｐａｓｔｄｅｃａｄｅ〔1～ 10〕.Ｉｎｔｅｒｍｅｔａｌｌｉｃｅｌｅｃｔｒｏｎｉｃｃｏｕ ｐｌｉｎｇｐｒｏｖｉｄｅｄｂｙｔｈｅｃｙａｎｉｄｅｂｒｉｄｇｅｓｈａｓｌｅｄｔｏｎｏｖｅｌｍｉｘｅｄ ｖａｌｅｎｃｅｐｒｏｐｅｒｔｉｅｓ,ａｎｄｐｈｏｔｏｉｎｄｕｃｅｄｅｌｅｃｔｒｏｎ…     

Quantitative photoacoustic spectrometry : Determination of copper(II) and iron(III) complexed on modified silica gel samples

Calibration curves for copper(II) and iron(III) complexed with N-2-aminoethyl-3-aminoprophyltrimethoxysilane (AEAPS) immobilized on silica gel were prepared separately by photoacoustic spectroscopy (p.a.s.) based on a response function that combines the amplitude and phase values. The concentration of copper and iron in two-component samples are determined by obtaining the response at 600 and 400 nm, respectively, and referring to the calibration graphs. The relative errors in the concentrations determined by p.a.s. compared to atomic absorption spectrometry for copper range from ?9.3 to 3.2%, while for iron the range is ?52.7 to 4.5%. The large error for iron was due to its low concentration and absorptivity. With suitable chromophores and matrix, the response function extends the linear range of the calibration graph and can be used for nondestructive determination of two components.