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1.
Allopurinol (ALP), an inhibitor of the xanthine oxidase enzime, is reported to provide protection against free-radical mediated damage by various mechanisms, including free-radical scavenging and metal chelation (i.e. Cu(II)). To obtain a wider insight into the molecular aspects of the beneficial action of ALP, free ALP and the Cu(II)- ALP system were investigated by radiation chemical and spectroscopic studies. Pulse radiolysis experiments show that ALP is a good · OH scavenger (1.8 × 109 and 5.4 × 109 M-1 s-1 at pH 6.0 and 11.0, respectively), leading to · OH-adducts and transient semi-oxidized species, such as phenoxyl radicals. The latter are also formed by the reaction of ALP with some specific one-electron oxidizing radicals (i.e. N3 and SO4
-). The semi-oxidized species are stabilized by their resonance properties and scarcely react with oxygen. In addition, the chelation of Cu(II) by ALP does not significantly affect the reactivity of the drug towards ·OH (2.5×09 M-1 s-1). Raman and the IR spectra support the good chelating ability of ALP, indicating the formation of two Cu(II)- ALP complexes with a slightly different structure. Depending on the metal/ligand ratio, pyrimidine nitrogens may take part to the Cu(II) co-ordination in addition to the N pyrazolic atoms and the C O groups of some ALP molecules. These results suggest that ALP may inhibit oxidative damage both through the direct radical scavenging and the copper-chelation mechanism. In fact, both the conversion of a harmful radical, such as ·OH, into a less reactive transient species, and the capture of copper ions, which play a relevant role in metal-catalysed generation of reactive oxygen species, will prove beneficial for the cell protection. 相似文献
2.
The efficiency of calcium and magnesium phosphates of different compositions in the extraction of Cu2+, Zn2, and Co2+ ions from aqueous solutions was studied. 相似文献
3.
Nizam M. El-Ashgar Issa M. El-Nahhal Mohamed M. Chehimi Michel Delamar Florence Babonneau Jacques Livage 《Journal of Sol-Gel Science and Technology》2007,41(1):3-10
A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH2)3-N[CH2CONH(C6H4)NH2]2, where P represents [Si–O]
n
polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH2)3N(CH2CO2Et)2 with 1,2-diaminobenzene in toluene. 13C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O).
The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1
metal to ligand complexes. 相似文献
4.
Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters
(ΔG
o, ΔH, ΔS) for the formation of the citrate complexes with the Mn2+, Co2+, Ni2+ and Zn2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic
strength of 100 mM was maintained with NaClO4. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes
have been discussed. 相似文献
5.
The volta potential difference method at 298.15 K was used to determine the real primary medium effect for magnesium, calcium,
cadmium, and copper ions, and also the real Gibbs transfer energy of these ions from water into a mixed water ethanol (EtOH)
solution. The surface potential value at the nonaqueous solution/gas phase interface $
\Delta \chi _{H_2 O}^{EtOH}
$
\Delta \chi _{H_2 O}^{EtOH}
was obtained. With account for this value, chemical thermodynamic characteristics of the studied ions in the water-ethanol
solvent were calculated and the effect of composition and nature of the mixed solvent on the values obtained was analyzed.
The dependence of variation in the thermodynamic characteristics of cation resolvation was established on their crystallographic
radius that corresponds to the following sequence: Ca2+ < Cd2+ < Cu2+ < Mg2+. 相似文献
6.
G. G. Gorboletova S. N. Gridchin A. A. Lutsenko 《Russian Journal of Coordination Chemistry》2010,36(9):693-696
Heat effects of mixing of aqueous solutions of Cu(NO3)2 and L-valine were measured by the calorimetric method at 298.15 K and a ionic strength of 0.5–1.5 (KNO3). The standard heat effects of formation of the Cu(II) complexes with L-valine in an aqueous solution were obtained by the
extrapolation to the zero ionic strength using the equation with one individual parameter. The standard thermodynamic characteristics
of complex formation in the Cu2+-L-valine system were calculated. 相似文献
7.
S. A. Bychkova A. V. Katrovtseva E. V. Kozlovskii 《Russian Journal of Coordination Chemistry》2008,34(2):93-96
The process of complex formation of maleic acid (H2L) with the ions Zn2+, Ni2+, Co2+, Cu2+ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO3). The moieties ZnL, CoL, NiL, NiL 2 2? , CuL, and CuL 2 2? were detected and their stability constants were determined. 相似文献
8.
Feather fibers were modified by treatment with 5% tannic acid (TA) solution. Kinetics of the modification was investigated
as a function of the reaction time. The maximum loading of TA on feather reached 8.3% after being treated by TA for 9 h. The
adsorption of metal cations (Cu2+, Zn2+) by unmodified and TA-modified feather fibers was investigated as a function of fiber weight gain, temperature, and pH of
the metal solution. The adsorption was enhanced at alkaline pH and ambient temperature and increased with the weight gain
of TA. The maximum uptake of metal cations (Cu2+, 0.77 mmol/g; Zn2+, 0.95 mmol/g) was obtained by TA-modified feather at weight gain: 8.3%, pH 11, while at the acidic pH, the adsorption of
metal cations by either unmodified or TA-modified feather was negligible. The influence of anions on the adsorption of metal
cations was also studied. The uptake of Cu2+ from chloride was higher and faster than that from nitrate. Desorption of the metals was performed at acidic pH 2.5 for 48 h.
The feather–TA–metal complexes exhibited higher stability for metal cations than the feather–metal complexes. All these experiments
reveal that TA-modified feather fibers have good adsorption to metal cations and can be used as metal adsorbent in wastewater
treatment. 相似文献
9.
N. V. Shul’ga I. L. Shashkova N. V. Mil’vit A. I. Rat’ko 《Russian Journal of Applied Chemistry》2007,80(8):1304-1308
Kinetic characteristics of the interaction of trisubstituted calcium phosphate Ca3(PO4)2 · xH2O with Cu2+, Zn2+, Co2+, and Pb2+ ions in aqueous solutions were studied. 相似文献
10.
Two novel coordination polymers, namely {[Co(Ttac)0.5(1,4-Bib)(H2O)] · H2O}n (I) and {[La(HTtac)2(2H2O)] · H2O}n (II) (H4Ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, 1,4-Bib = 1,4-bis(1-imidazoly) benzene), have been designed and successfully prepared via hydrothermal process, and characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 1039298 (I), 1039300 (II)). Structural analysis reveals that the H4Ttac ligands adopt different coordination modes in the as-synthesized I and II, and thus give rise to the targeted coordination polymers with different configurations. It is worth mentioning that, coordination polymer I is assembled from low-dimensional structures into three-dimensional (3D) via π···π stacking interactions, while three-dimensional coordination polymer II is formed by covalent bonds. Luminescent properties of coordination polymer II have been studied at ambient temperature. Significantly, luminescent measurement indicates that coordination polymer II may be acted as potential luminescent recognition sensors towards Cu2+ and Mn2+ ions. 相似文献
11.
G. G. Gorboletova S. N. Gridchin A. A. Lutsenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1856-1861
Heats of the interaction of Cu(NO3)2 solutions with L-glutamine solutions were measured directly by calorimetry at a temperature of 298.15 K and ionic strength
values of 0.5, 1.0, and 1.5 (KNO3). Using RRSU universal software, the experimental data were subjected to rigorous mathematical treatment with allowances
made for several concurrent processes in the system. The heats of formation of the CuL+ and CuL2 complexes were calculated from the calorimetric measurements. The standard heats of the complex formation of Cu2+ with L-glutamine were obtained by extrapolation to zero ionic strength. The complete thermodynamic characteristic (Δr
H
o, Δr
G
o, Δr
S
o) of the complex formation processes in a Cu2+—L-glutamine system was obtained. 相似文献
12.
Veronika Janíková Eugen Jóna Róbert Janík Viliam Pavlík Darina Ondrušová Michaela Ďurčeková 《Chemical Papers》2016,70(1):131-134
The influence of Ca2+-, Cu2+- and Fe3+-exchanged montmorillonite (MMT) on the type of interaction with aniline in the interlayer space of MMT has been studied by means of X-ray powder diffraction and infrared spectra. Results of X-ray diffraction showed that aniline was successfully intercalated into the interlayer space of MMT. Based on IR spectra evaluation, aniline was indirectly coordinated through a water-bridge in Ca2+- and Fe3+-MMT and it was indirectly coordinated through a water-bridge as well as protonated in Cu2+-MMT (the spectrum of protonated aniline showed deformation and changes in the NH 3 + absorption at approximately 1521 cm?1). It is important to point out that Cu2+-MMT indirect coordination and protonation occur simultaneously. 相似文献
13.
Yufen Chen Tengxuan Tang Yuhua Chen Dongmei Xu 《Research on Chemical Intermediates》2018,44(4):2379-2393
A novel 1,8-naphthalimide dye with simple structure has been produced by a facile synthetic method for colorimetric and fluorescent sensing of H+ and Cu2+. In CH3CN/H2O (1/1, v/v), the dye could monitor H+ using dual channels (ratiometric absorbance and fluorescence intensity change) from pH 6.2 to 12.0. Meanwhile, in the pH range of 1.9–5.2, the dye could also be used to detect Cu2+ using triple channels [ultraviolet–visible (UV–Vis) absorption, fluorescence intensity reduction, as well as fluorescence blueshift]. The detection limits for Cu2+ evaluated by colorimetric and fluorescent titration were 6.10 × 10?7 and 2.62 × 10?7 M, respectively. The dye exhibited specific selectivity and sensitivity for H+ and Cu2+ over various coexisting metal ions. Moreover, the sensing mechanism of the dye for H+ and Cu2+ was carefully examined. 相似文献
14.
We have investigated the presence of foreign ions into the bulk structure and the external surfaces of aragonite using periodic
ab-initio methods. Four cations isovalent to Ca2+ were studied: Mg2+, Sr2+, Ba2+ and Zn2+. The calculations were performed at structures (bulk, surface) that contain four and eight CaCO3 units. Our results, at the Hartree-Fock level, show that the incorporation of those ions into aragonite depends strongly
on their size. Mg2+ and Zn2+, due to their smaller size, can substitute Ca2+ ions in the crystal lattice while the incorporation of Sr2+ and Ba2+ into aragonite is energetically less favoured. Examination of the [011], [110] and [001] surfaces of aragonite revealed that
the surface incorporation reduces the energetic cost for the larger ions. These systems provide challenging examples for most
shape analysis methods applied in Mathematical Chemistry. 相似文献
15.
The absorption of Fe3+ ions from Fe3+-Zn2+ mixture with zinc and calcium phosphates was studied. 相似文献
16.
A new malonamide fluoroionophore possessing two pyrene moieties was synthesized. This bispyrene exhibited the fluorescence
of the pyrene monomer (λem = 395 nm) and intramolecular excimer (λem = 467 nm) emissions. The designed derivative showed the excellent ion sensing ability to Cu2+. The "on-off-off" and "off-on-off" fluorescence responses were demonstrated by the addition of the variable Cu2+ concentration. The utilization of the dual off/on responses could apply to the estimation of the rough Cu2+ concentration. 相似文献
17.
A. V. Budruev L. N. Karyakina O. P. Levina A. V. Oleinik 《Russian Journal of Coordination Chemistry》2005,31(3):181-184
An aqua complex of copper(II) o-azidobenzoate, [Cu(OH)ABA2H2O]2 (ABA is o-azidobenzoic acid), was synthesized in an aqueous solution and identified by IR and electronic absorption spectroscopy. In the complex, the azido group is not coordinated by Cu2+. When dissolved in dry organic solvents (DMF, DMSO, dioxane, and methanol), the complex undergoes dehydration to give a chelate complex (CC) containing the Cu2+-coordinated azido group as a result of the electron density redistribution at its N atoms. The IR spectrum of the chelate complex contains no absorption band at 2135 cm–1 corresponding to the stretching vibrations of the azido group. The resulting CC is unstable in solutions and spontaneously decomposes with a release of molecular nitrogen. The interaction of a Cu2+ ion with o-azidobenzoic acid in dry organic solvents affords a CC similar to the complex obtained on the dissolution of [Cu(OH)ABA2H2O]2 in dry solvents.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 195–198.Original Russian Text Copyright © 2005 by Budruev, Karyakina, Levina, Oleinik.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date. 相似文献
18.
Markus Andersson Örjan Hansson Lars Öhrström Alexander Idström Magnus Nydén 《Colloid and polymer science》2011,289(12):1361-1372
P(1-VIm-co-MMA) copolymers with 4 or 44 wt.% 1-VIm (abbreviated PVM-4 and PVM-44) where polymerized from 1-VIm (1-vinylimidazole)
and methylmethacrylate with azobisisobutyronitrile as initiator and reacted with either Cu2+ or Zn2+. The resulting coordinated polymer complexes were studied using ICP-AES, CP/MAS 13C NMR, conductivity measurements, vibrational spectroscopy (mid-FTIR and far-FTIR), DSC, and EPR. It was established by ICP-AES,
CP/MAS 13C NMR, conductivity, mid-FTIR and EPR measurements that the transition metal ions in the complexes were exclusively coordinated
by the imidazole ligand. The coordination geometry is square planar with regard to Cu(II) complexes. The strong interaction
between the polymeric imidazole ligand and the transition metal ion cross-links the system, resulting in augmentation of T
g (the glass transition temperature), especially for copolymers with high relative amount of 1-VIm. The effect of changing
metal ion is more complicated and depends on both the strength of the coordinate interaction as well as the coordination number.
The solubility of the coordinate polymer complex in conventional solvents is low due to the coordinate cross-links. However,
the coordinate polymer complexes are soluble in strongly coordinating solvents such as acetonitrile and dimethylsulfoxide. 相似文献
19.
20.
Xiaoju Liu Guoyu Ren Xiangrong Ma Yulin Xiang Liguo Gao Xiaoyan Ma 《Russian Journal of Applied Chemistry》2017,90(12):2016-2018
An efficient highly diluted synthetic approach to the synthesis of 1,9-dicarbonyl-2,8-dioxo-butyne ester ferrocenophane (L) has been developed. The title compound was characterized by IR, UV, FL, 1H NMR, spectroscopies, elemental analysis and so on. Further complex L shows fluorescence responses to Co2+ and Cu2+ in CH3OH, The results indicate that the complex could be applied in multianayte detection. The binding ability of receptor L CH3OH was tested for various cations (Co2+, Cu2+, Zn2+, and Ni2+ in water) and the binding constants for Co2+ and Cu2+ were the computed, having a distinct absorbance shift. The receptor is a very attractive array because its distinct absorbance shift profile in a semi-aqueous phase, making it applicable in the area of biology, environmental sciences and material chemistry. 相似文献