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1.
D. Wyrzykowski D. Zarzeczańska D. Jacewicz L. Chmurzyński 《Journal of Thermal Analysis and Calorimetry》2011,105(3):1043-1047
Isothermal titration calorimetry (ITC) and potentiometric titration methods have been used to study the process of proton
transfer in the copper(II) ion-glycylglycine reaction. The stoichiometry, conditional stability constants, and thermodynamic
parameters (ΔG, ΔH, and ΔS) for the complexation reaction were determined using the ITC method. The measurements were carried out at 298.15 K in solutions
with a pH of 6 and the ionic strength maintained with 100 mM NaClO4. Carrying out the measurements in buffer solutions of equal pH but different enthalpies of ionization of its components (Mes,
Pipes, Cacodylate) enabled determination of the enthalpy of complex formation, independent of the enthalpy of buffer ionization.
The number of protons released by glycylglycine on account of complexation of the copper(II) ions was determined from calorimetric
and potentiometric measurements. 相似文献
2.
Ninhydrin has been found to form a 1:1 complex with Cu(II) complexes of asparagine and serine. The kinetics of the complexation reaction has been studied spectrophotometrically in acetate buffer. The effect of the [ninhydrin], pH, and temperature on the reaction rate of the reaction was studied. The reaction follows fractional-order kinetics with respect to ninhydrin and first-order with respect to asparagine-Cu(II) and serine-Cu(II), respectively. The reaction proceeds through the coordination of ninhydrin with the same Cu(II) of asparagine and serine complexes. The results are best accounted by the “Template mechanism” for the inner sphere complexation. The values for the inner sphere complex formation constant were also calculated from the kinetic data. The role of Cu(II) in this reaction is to inhibit the breaking of C(SINGLEBOND)C (evolution of CO2) as well as stabilize the C(DOUBLEBOND)N of Schiff base. On the basis of observed results, probable mechanism has been proposed. © 1996 John Wiley & Sons, Inc. 相似文献
3.
The heats of reaction of zinc(II) with glycylglycine at temperatures 288.15, 298.15, and 308.15 K and ionic strengths 0.25,
0.50, and 0.75 (potassium nitrate as a supporting electrolyte) were determined by calorimetry. The thermochemical results
were processed with inclusion of stepwise equilibria. In addition to complexation reactions, “side” protolytic processes were
considered. Standard heats of complexation in the system were found by extrapolation to the zero ionic strength by an equation
with one individual parameter. The influence of the supporting electrolyte concentration and temperature on the thermodynamic
characteristics of the complexation reactions in the glycylglycine-zinc(II) system was considered. The standard enthalpies
of formation of ZnGlyGly+, Zn(GlyGly)2, and Zn(GlyGly)3− species in aqueous solution were calculated. 相似文献
4.
Y. Zhao 《Chromatographia》2000,51(3-4):231-234
Summary A new chelating reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) has been examined for high performance liquid
chromatographic (HPLC) separations of cobalt (II), copper(II) and iron (II) or cobalt (II), nickel (II), iron (II), copper
(II) and mercury (II) as metal chelates on a C18, 5μm column (250×4 mm i.d.) The chelates were eluted isocratically with methanol: acetonitrile: water containing sodium acetate
and tetrabutylammonium bromide (TBA), and detected at 254 nm. A solvent extraction procedure was developed for simultaneous
determination of the metals with detection limits within 0.02–2.5 μ g.mL−1. The method was applied to the determination of copper, cobalt and iron in natural waters. 相似文献
5.
Yunhui Dong Zhengjie Liu Lei Chen 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):435-443
Clay minerals have been widely used in wastewater disposal due to their strong sorption and complexation ability towards various
environmental pollutants. In this study, the removal of Zn(II) from aqueous solution by natural halloysite nanotubes (HNTs)
was studied as a function of various solution chemistry conditions such as contact time, pH, ionic strength, coexisting electrolyte
ions and temperature under ambient conditions. The results indicated that the removal of Zn(II) by HNTs was strongly dependent
on pH and ionic strength. Langmuir and Freundlich models were used to simulate the sorption isotherms of Zn(II) at three different
temperatures of 293, 313 and 333 K. The thermodynamic parameters (ΔH
0, ΔS
0 and ΔG
0) calculated from the temperature dependent sorption isotherms indicated that the removal process of Zn(II) by HNTs was endothermic
and spontaneous. At low pH, the removal of Zn(II) was dominated by outer-sphere surface complexation and/or cation exchange
with Na+/H+ on HNT surfaces, whereas inner-sphere surface complexation was the main removal mechanism at high pH. From the experimental
results, one can conclude that HNTs may have a good potentiality for the disposal of Zn(II)-bearing wastewaters. 相似文献
6.
İbrahim Erden Ali Erdoğmuş Nebahat Demirhan Ulvi Avcıata 《Transition Metal Chemistry》2008,33(4):439-442
A new fluorene ligand, benzo[15-crown-5]-5H-pyrido[3′,2′:4,5]cylopenta[1,2-b]pyridin-5-ylidenehydrazone (bph), has been synthesized from the reaction of 4,5-diazafluoren-9-one
with 4′-formylbenzo-15-crown-5. The Co(II), Cu(II), and Ru(II) complexes of the ligand were prepared and characterized. The
metal-to-ligand ratio of the Co(II) and Cu(II) complexes was found to be 2:1 and that of the Ru(II) complex was found to be
1:1. The ligand and complexes have been characterized by FTIR, UV–visible, 1H NMR and fluorescence spectra, as well as elemental analyses and mass spectra. 相似文献
7.
Liqiang Tan Yeling Jin Jing Chen Xiaochun Cheng Jie Wu Liangdong Feng 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):601-610
The sorption of Co(II) on Na-attapulgite as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic
acid (FA) and temperature under ambient conditions was studied. The kinetic of Co(II) sorption on Na-attapulgite was described
well by pseudo-second-order model. The sorption of Co(II) on Na-attapulgite was strongly dependent on pH and ionic strength.
The sorption of Co(II) was mainly dominated by outer-sphere surface complexation and/or ion exchange at low pH, whereas inner-sphere
surface complexation or surface precipitation was the main sorption mechanism at high pH values. The presence of FA did not
affect Co(II) sorption obviously at pH <7, and a negative effect was observed at pH >7. The Langmuir and Freundlich models
were used to simulate the sorption data at different temperatures, and the results indicated that the Langmuir model simulated
the data better than the Freundlich isotherm model. The thermodynamic parameters (∆G°, ∆S°,
∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on Na-attapulgite was
an endothermic and spontaneous process. The results suggest that the attapulgite sample is a suitable material in the preconcentration
and solidification of radiocobalt from large volumes of aqueous solutions. 相似文献
8.
Radhey M. Naik Amit K. Verma Abhinav Agarwal Abhas Asthana 《Transition Metal Chemistry》2009,34(2):209-215
The kinetics of mercury(II)-catalyzed substitution of cyanide ligand in hexacyanoruthenate(II) by pyrazine (Pz) has been investigated
spectrophotometrically at 370 nm in aqueous medium. The reaction exhibits first-order dependence on [Pz] at low concentrations,
then reaches a maximum value, and finally decreases at high [Pz]. The reaction has a variable-order dependence in [Ru(CN)6
4−], unity at lower [Ru(CN)6
4−], and fractional order, not tending to zero order at higher [Ru(CN)6
4−]. The effects of pH, ionic strength, concentration of catalyst, and temperature variations have been studied. The activation
parameters for the reaction were calculated. We propose a solvent assisted interchange dissociative (I
d) mechanism for the reaction. 相似文献
9.
L. I. Budarin Z. A. Gavrilova Yu. N. Shevchenko 《Theoretical and Experimental Chemistry》1991,26(6):698-701
Thermogravimetry combined with thermal gas titrimetry were used to study the ligand substitution reactions by mono- and diethanolamine in nickel(II) hexaamminochloride and copper(II) tetraamminosulfate. It has been shown that the reactions proceed in stages and the temperature intervals of the individual stages have been determined. The kinetics of the described reactions have also been studied at isothermal conditions. The Ea values of the reactions have been calculated on the basis of the data obtained. A reaction mechanism has been proposed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 6, pp. 745–749, November–December, 1990. 相似文献
10.
D. A. Kostić G. Ž. Miletić S. S. Mitić I. D. Rašić V. V. Živanović 《Chemical Papers》2007,61(2):73-76
The complexation process of the transition metal Cu(II) with quercetin was studied. The investigation was conducted spectrophotometrically
in ethanol at the maximum absorption wavelength of 458.5 nm. Cu(II)—quercetin complex composition (1: 1) was determined using
the Job, Harvey—Manning, and mole ratio methods. Complex stability constant was calculated by the Job and mole ratio methods
and the respective logarithm values were 7.53 ± 0.25 and 7.44 ± 0.03. A new method for quantitative determination of the quercetin
content in solution was developed in this work. At the optimal conditions quercetin was determined in concentrations ranging
from 0.202 to 1.006 μg cm−3 with relative standard error of 2.5 % to 5.5 %. The lower detection limit was 0.067 μg cm−3. The method was found very accurate, reproducible, and sensitive, capable to determine microamounts of quercetin in pharmaceutical
preparations. 相似文献
11.
Imre Labádi Mária Benk Kata Markó István Szilágyi 《Reaction Kinetics and Catalysis Letters》2009,96(2):327-333
Mimicking the Superoxide Dismutase Enzyme (SOD), several imidazolato-bridged copper(II)-zinc(II) complexes were prepared,
characterised by IR spectroscopy and their SOD enzyme activity was determined. 2,2′-Bipyridine, 2,2′:6′,2″-terpyridine and
tris(2-aminoethyl)amine molecules were used on both metal sides, as coordinating ligands. The complex, containing the 2,2′:6′,2″-terpyridine
ligand on copper side has the smallest SOD activity, which indicates the importance of the rigidity of the copper complex
in SOD activity. 相似文献
12.
Yan Huang Liang Chen Hualin Wang 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):777-785
Herein, hydroxyapatite (HAP) was prepared by aqueous precipitation technique and was characterized by using FT-IR and XRD
to determine its chemical functional groups and micro-structure. The removal of cobalt from aqueous solution to HAP was studied
by batch technique as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions,
fulvic acid (FA), and temperature under ambient conditions. The results indicated that the sorption of Co(II) on HAP was strongly
dependent on pH and ionic strength. The presence of FA enhanced the sorption of Co(II) on HAP at low pH, whereas reduced Co(II)
sorption on HAP at high pH. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms at three
different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Co(II) on HAP was spontaneous
and endothermic. The sorption of Co(II) was dominated by outer-sphere surface complexation and ion exchange at low pH, whereas
inner-sphere surface complexation or surface precipitation was the main sorption mechanism at high pH values. The results
suggest that the HAP is a suitable material in the preconcentration and solidification of Co(II) from large volumes of aqueous
solutions. 相似文献
13.
Cezary A. Kozlowski Tomasz Girek WladysŁaw Walkowiak Jolanta Kozlowska 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):71-77
β-Cyclodextrin (β-CD) polymers were prepared by cross-linking of β-CD with phtalic and 3-nitrophtalic anhydride in anhydrous N,N-dimethylformamide (DMF) in the presence of NaH. The weight-average molecular weight (M
W) and the chemical structure of the polymers were determined using high performance size exclusion chromatography (HPSEC) with refractive index (RI) detector, and 1H NMR spectroscopy. The molecular weight of the polymer increased with molar ratio of substrates and reaction temperature. 1H NMR spectra revealed that the β-CD polymers contained both mono- and diesters of phtalic and 3-nitrophtalic acids. In the case of phtalic moieties about four or five diester moieties groups and for 3-nitrophtalic moieties about to or three diester moieties are linkages for β-CD molecule, respectively. Results of copper(II) flotation obtained with the use of nonylphenol polyoxyethyl glycol ether as an non-anionic surfactant and β-CD polymers as complexation collector agent, show␣that the removal of Cu2+ decreases with increase of molecular mass of β-CD polymers linked by phtalic or␣3-nitrophtalic anhydrides. For both derivatives with pH increase the copper(II) removal increase. The highest flotation removal, i.e. 93%, was found for β-CD polymers synthesized at 100 °C with molar ratio CD:NaH:3-nitrophtalic anhydride equal to 1:7:7. 相似文献
14.
A. Gölcü 《Journal of Analytical Chemistry》2006,61(8):748-754
A simple, sensitive, and accurate spectrophotometric method has been developed for the assay of furosemide (FUR), which is
based on the complexation of the drug with copper(II) at pH 3.2 using Mclivaine buffer solution to produce a green adduct.
The latter has maximum absorbance at 790 nm and obeys Beer’s law within the concentration range 5–30 μg/mL. Regression analysis
of the calibration data showed a good correlation coefficient (r = 0.9997) with minimum detection limit of 0.23 μg/mL. The proposed procedure has been successfully applied to the determination
of this drug in tablets. In addition, the spectral data and stability constant for the mononuclear copper(II) complex of furosemide
(CuFUR2(MeOH)2) are reported.
The text was submitted by the author in English. 相似文献
15.
The kinetics of complexation reactions of five water-soluble heterocyclic hydrazones with nickel(II) and palladium(II) ions have been investigated by stopped-flow spectrophotometry. Rates of complexations with nickel(II) and palladium(II) in the absence of chloride ion were found to be proportional to the first order of the ligand and metal ion concentrations and to the inverse first order of the hydrogen ion concentration except for the complexation of alpha-(2-benzimidazolyl)-alpha-(5-nitro-2-pyridyl)hydrazono-3-toluenesulfonic acid with palladium(II). Rates of complexation with palladium(II) in the presence of chloride ion were best described by a two-term expression, both terms being first order in the palladium ion and ligand concentrations and inverse first order in the hydrogen ion concentration. The first term has zero dependence of the chloride ion concentration, whereas the second is first order with respect to the chloride ion concentration. The rate constant for each complexation reaction was determined. The complexation of the hydrazones with nickel(II) was estimated to go according to an Eigen mechanism and that with palladium (II) according to the associative mechanism. 相似文献
16.
N. V. Pashchevskaya M. A. Nazarenko S. N. Bolotin A. I. Oflidi V. T. Panyushkin 《Russian Journal of Inorganic Chemistry》2010,55(9):1425-1432
The composition and structure of copper(II) benzimidazole complexes obtained by the reaction of CuCl2 with benzimidazole (BIm) were determined. At pH 4.5–5.5, depending on the reactant ratio, dimeric compounds with the composition
Cu(BIm)4Cl2 · 2H2O and Cu(BIm)2Cl2 · H2O are formed. They are converted to monomers at about 200°C. At pH > 8, irrespective of the reactant ratio, the polymer (Cu(OH)L)n is formed. The complexation of copper(II) with benzimidazole in water and aqueous dioxane was studied by potentiometry, and
the stability constants of the complex compounds and their dependence on the solvent composition were determined. 相似文献
17.
Brij Bhushan Tewari 《Russian Journal of Inorganic Chemistry》2008,53(3):490-493
A mixed complexation reaction of methionine and cysteine with copper(II) and cobalt(II) has been studied in solution phase
using the paper electrophoretic technique at ionic strength 0.1 M and a temperature of 35°C. The binary equilibria copper(II)-methionine
and cobalt(II)-methionine have also been studied, since this is prerequisite for the investigation of mixed complexes. The
stability constants of copper(II)-methionine-cysteine and cobalt(II)-methionine-cysteine mixed complexes were found to be
2.80 ± 0.07 and 2.44 ± 0.11 (logarithm of stability constant values), respectively.
This article was submitted by the authors in English. 相似文献
18.
Alaa Eldin M. Abdel-Hady 《Transition Metal Chemistry》2008,33(7):873-878
A kinetic study of the oxidation of [Co(H2L)(H2O)2]2+ (H2L = N,N-bis (salicylaldehyde-1,2-diaminoethane) Schiff base) by periodate in aqueous solution was performed over pH (2.3–3.4) range,
(0.1–0.5) mol dm−3 ionic strength and temperatures 20–35 °C for a range of periodate and complex concentrations. The reaction rate showed a
first-order dependence on both reactants and increased with pH over the range studied. The effects of Cu(II) and Fe(II) on
the reaction rate were investigated over the (1.0–9.0) × 10−5 mol dm−3 range. The reaction was inhibited as the concentration of Cu(II) increased, and it was independent on Fe(II) concentrations
over the ranges studied. An inner-sphere mechanism is proposed for the oxidation pathways of both the protonated and deprotonated
CoII complex species. 相似文献
19.
Ibrahim M. EI-Mehasseb Abd El-Motaleb M. Ramadan Raafat M. Issa 《Transition Metal Chemistry》2006,31(6):730-739
The oxidation of catechol by molecular oxygen in the presence of a catalytic amount of copper(II) complex with 2-methyl-3-amino-(3H)quinazoline-4-one (MAQ) and various anions (Cl−, Br−, ClO
4
−
, SCN−, NO
3
−
and SO
4
–
) was studied. The catecholase biomimetic catalytic activity of the copper(II) complexes has been determined spectrophotometrically
by monitoring the oxidative transformation of catechol to the corresponding light absorbing o-quinone (Q). The rate of the catalytic oxidation reaction was investigated and correlated with the catalyst structure, time,
concentration of catalyst and substrate and finally solvent effects. Addition of pyridine or Et3N showed a dramatic effect on the rate of oxidation reaction. Kinetic investigations demonstrate that the rate of oxidation
reaction has a first order dependence with respect to the catalyst and catechol concentration and obeying Michaelis–Menten
Kinetics. It was shown that the catalytic activity depends on the coordination environment of the catalyst created by the
nature of counter anions bound to copper(II) ion in the complex molecule and follows the order: Cl− > NO
3
−
> Br− > SO
4
–
> SCN− > ClO
4
−
. To further elucidate the catalytic activity of the complexes, their electrochemical properties were investigated and the
catecholase mimetic activity has been correlated with the redox potential of the Cu2+/Cu+ couple in the complexes. 相似文献
20.
The thermal dehydration of copper(II) acetate hydrate has been studied between 353 and 406 K, over a range of humidities.
The dehydration is controlled by nucleation-and-growth kinetics at low temperatures, with an activation energy of 154 kJ·mol−1, which changes to contracting-disc kinetics at higher temperatures with a lower activation energy of 76 kJ·mol−1. Frequency factors have also been derived; the value for the high temperature process is low (107s−1) and that for the low temperature step is high (1017s−1). Optical microscopy has been used to clarify the bulk kinetics; there is evidence for a reactive layer at the surface of
the decomposing solid.
In celebration of the 60th birthday of Dr Andrew K. Galwey 相似文献