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1.
Thermodynamic values for the formation of complexes of Ag +, Co 2+, Ni 2+, Cu 2+, Zn 2+, Cd 2+ ions with hydantoïn were determined at 25°C in aqueous medium 0.5 M KNO 3. Stability constants were calculated from pH metric measurements while corresponding standard enthalpies were deduced from direct calorimetric determinations. The results are interpreted and compared to those of succinimide complexes previously studied. 相似文献
2.
Complexes of ethylenediamine-N,N,N′,N′-tetraacetanilide (edtan, C 34H 36N 6O 14) with cobalt(II), nickel(II) and copper(II) in the solid state and in solution are reported for the first time. Thermodynamic data (stability constant, and derived Gibbs energy, enthalpy and entropy changes)for the 1 : 1 complexation of edtan with the metal ions at 298.15 K in water-saturated butan-1-ol gave the selectivity sequence log 10K s; Ni 2+, 4.56±0.02; Cu 2+, 4.41±0.01; Co 2+, 4.18±0.04 as found from microcalorimetric titration studies. The entropies suggested that the structure of the 1 : 1 complex with copper(II) contains fewer chelate rings than those for nickel(II) and cobalt(II) (δ cS0 : Cu-21.4, Co 5.7, Ni 3.9 J mol −1K −1). Solid complexes of the metal ions with edtan and perchlorate as the counter anion were prepared. For each, a complex with a 1 : 1 metal: edtan stoichiometry with non-coordinated perchlorate was isolated. The X-ray structure of [Cu(edtan)(H 2O)][ClO 4] 2·1.5H 2O (1) revealed a six-coordinate Cu centre with edtan acting as pentadentate ligand (2N, 3O) with the coordination sphere completed by an oxygen atom from water. In striking contrast to the Cu complex, the Co centre in [Co(edtan)(H 2O)][ClO 4] 2·H 2O·0.5C 2H 5OH (2) is seven-coordinate with hexadentate edtan (2N, 4O) and one coordinated water molecule. There is thus an excellent confirmation of the results obtained from the microcalometric study in that edtan forms four chelate rings to Cu but five to Co in the solid state. The ability of the ligand to extract metal ions from water to the water-saturated butan-1-ol phase was assessed from distribution data as a function of the aqueous phase hydrogen ion concentration and of the ligand concentration in the organic phase. The data showed that Cu 2+ is selectively extracted over a wide range of aqeous phase hydrogen ion concentrations. 相似文献
3.
Thermal decomposition taking place in solid state complex, NiC 2O 4·2H 2O, has been investigated in air by means of TG–DTG/DTA, DSC, XRD. TG–DTG/DTA curves showed that the decomposition proceeds through two well-defined steps with DTA peaks closely corresponding to the weight loss obtained. XRD showed that the final decomposition product of NiC 2O 4·2H 2O was NiO. Kinetics analysis of NiC 2O 4·2H 2O decomposition steps was performed under non-isothermal conditions. The activation energies were calculated through Friedman and Flynn–Wall–Ozawa (FWO) methods, and the most possible kinetic model function has been estimated through the multiple-linear regression method. The activation energies for the two decomposition steps of NiC 2O 4·2H 2O were 171.1 ± 4.2 and 174.4 ± 8.1 kJ/mol, respectively. 相似文献
4.
The complexation reactions between murexide and Co 2+, Ni 2+ and Cu 2+ in C 2H 5OH-H 2O mixtures have been investigated spectrophotometrically. The formation constants of the 1:1 complexes formed increase in the order Co 2+ < Ni 2+ < Cu 2+ for all solvent mixtures studied, and log Kf is a linear function of the mole fraction of ethanol. The heat of complexation was determined calorimetrically for the nickel and copper complexes. The values of Δ H° and Δ S° are solvent-dependent, and all three complexes have negative Δ H° and positive Δ S° values. 相似文献
5.
Hydrated nitrate and perchlorate salts of the transitional metal ions Co 2+, Ni 2+ and Cu 2+ have been used to investigate the coordination capability of the octaaza macrocycle L derived from 2,6-diformylpyridine and diethylenetriamine. The synthesis of the metal complexes was carried out in 1:1 and 2:1 metal:ligand molar ratios, but dinuclear complexes were obtained in all cases due to the size of the 24-membered ligand. The complexes have been characterized by elemental analysis, molar conductivity, mass spectrometry, IR spectroscopy, diffuse reflectance and magnetic measurements. The dinuclear nature of the compounds was confirmed by X-ray diffraction. The crystal structures of [Ni 2L(NO 3) 2](NO 3) 2, [Cu 2L(NO 3) 4] and [Cu 2L(ClO 4) 4], were determined. 相似文献
6.
Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA ( N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C 5H 6N 2O 2)(C 4H 5NO 4) 2−(H 2O) 2]·H 2O, [Ni(C 5H 6N 2O 2)(C 5H 7NO 4) 2−(H 2O) 2]·H 2O and [Ni(C 5H 6N 2O 2)(C 6H 8N 2O 5) 2−(H 2O) 2]·1.5H 2O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy ( E*), enthalpy (Δ H*), entropy (Δ S*) and free energy change of decomposition (Δ G*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate. 相似文献
7.
A stable chelating resin matrix was synthesized by covalently linking o-aminophenol ( o-AP) with the benzene ring of the polystyrene–divinylbenzene resin, Amberlite XAD-2, through a –N=N– group. Elemental analyses, thermogravimetric analysis (TGA) and infrared spectra have characterized the resulting chelating resin. It has been used to preconcentrate Cu 2+, Cd 2+, Co 2+, Ni 2+, Zn 2+ and Pb 2+, prior to their determination by flame atomic absorption spectrometry. The optimum pH values for quantitative sorption of Cu, Cd, Co, Ni, Zn and Pb are 6.2–7.4, 5.6–7.2, 5.6–9.0, 6.0–9.0, 5.7–7.0 and 5.0–6.0, respectively. These metals are desorbed (recovery 91–98%) with 4 mol dm −3 HNO 3. The sorption capacity of the resin is 3.37, 3.42, 3.29, 3.24, 2.94 and 3.32 mg of metal g −1 of resin, respectively, for Cu, Cd, Co, Ni, Zn and Pb. The effect of NaF, NaCl, NaNO 3, Na 2SO 4, and Na 3PO 4 on the sorption of these metal ions has been investigated. These electrolytes are tolerable up to 0.01 mol dm −3 in case of all the metal ions, except Cl − which is tolerable even up to 0.1 mol dm −3 for Zn and 1.0 mol dm −3 for Pb. The preconcentration factor for Cu, Cd, Co, Ni, Zn and Pb are 50, 50, 100, 65, 40 and 40 (concentration level 10–25 μg dm −3) respectively. Simultaneous enrichment of the six metals is possible. The method has been applied to determine Cu, Cd, Co, Ni, Zn and Pb content in well water samples (RSD≤8%). 相似文献
8.
研究了Keggin结构钼磷杂多化合物Na 5[PM(H 2O)Mo 11O 39]·nH 2O(M=Mn 2+,Co 2+,Ni 2+,Cu 2+,Zn 2+在溶液中的氧化还原性质,发现环境的改变可对杂多阴离子的极谱半波电位产生影响,其影响程度的大小决定于过渡金属离子本身的性质。取代后的钼磷杂多阴离子的半波电位顺序为Ni 2+>Co 2+>Zn 2+>Cu 2+>Mn 2+,pH值的变化影响氧化还原性质,并阐述了变价金属Cu 2+对杂多阴离子氧化还原性质的影响. 相似文献
9.
The magnetic susceptibility has been determined for CuL n(TCNQ −) 2 (L = 2,2'-bipyridine, 1,10-phenanthroline, or ethylenediamine; n = 1 or 2), having high electric conductivity. The results show that the Cu 2+L n chelates are partially reduced to Cu 2+L n in the complexes. The equilibrium Cu 2+L n(TCNQ −) 2 Cu +L n(TCNQ −)(TCNQ o) produces conduction electrons in TCNQ columns. 相似文献
10.
The infrared spectra of isotopically dilute (matrix-isolated HDO molecules) isostructural compounds M(HCOO) 2·2H 2O (M=Mn,Fe,Co,Ni,Zn,Cu) are presented and discussed in the region of the OD stretching modes. According to the structural data the compounds under study are divided into two groups: in M(HCOO) 2·2H 2O (M=Mn,Ni,Zn) the H 2O(1) molecules form stronger hydrogen bonds as compared to H 2O(2); in M(HCOO) 2·2H 2O (M=Fe,Co,Cu) the H 2O(2) molecules form stronger hydrogen bonds as compared to the H 2O(1) molecules. The influence of the metal–water interactions (synergetic effect) and the unit-cell volumes (repulsion potential of the lattice) on the hydrogen bond strength within the isostructural series is discussed. The wavenumbers of the uncoupled OD stretching modes of the HDO molecules influenced by guest ions (Cu 2+ ions matrix-isolated in M(HCOO) 2·2H 2O and M 2+ ions matrix-isolated in Cu(HCOO) 2·2H 2O) are presented and commented. For example, the analysis of the spectra reveals that when Cu 2+ ions are included in the structure of M(HCOO) 2·2H 2O the hydrogen bonds of the type M–OH 2OCHO–Cu are considerably weaker as compared to those of the same type formed when M 2+ ions are included in the structure of Cu(HCOO) 2·2H 2O if the cations remain unchanged. 相似文献
11.
The complexes of Mn 2+, Cd 2+, Fe 3+, Pb 2+, Ni 2+, Co 2+, Zn 2+ and Cu 2+ with EDTA and cyclohexane-1,2-diaminetetraacetic acid (CDTA) were separated and detected in column and ion electrokinetic chromatography with suppressed conductivity and direct UV detection, respectively. In column ion chromatography (IC) these complexes were separated on an IonPac AS4A anion-exchange column (Dionex, USA). Parameters of carrier electrolyte, which were examined in the ion electrokinetic chromatography (IEKC) mode, include polymer and sulfate concentrations. In IEKC separation selectivity of complexes with poly(diallyldimethylammonium) cation as modifier is similar as for an IonPac AS4A column both for EDTA and CDTA chelates. It was shown that the ion-exchange capacity of the electrokinetic system is more than 100-times lower than the capacity of the IC column for the same peak resolution. In comparison with column main advantages of electrokinetic version are high separation efficiency (220 000–390 000 theoretical plates) and the absence of the analyte interaction with the sorbent matrix. 相似文献
12.
Wool fibres were modified by treatment with tannic acid (TA) solution or by acylation with ethylenediaminetetraacetic (EDTA) dianhydride. The unmodified and modified fibres were subsequently treated with Cu 2+ and Co 2+ solutions, at alkaline pH, and analysed by Attenuated Total Reflectance, ATR/IR spectroscopy to evaluate the changes induced in the structure of the fibre by metal binding. The spectral changes were correlated to metal adsorption results obtained by Inductive Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The IR results were discussed in relation to our previous findings on the metal binding mode of Bombyx mori and Tussah silk fibres; the changes observed in the spectra were explained by considering the different affinity of the fibres for the modifying reagent and the amount of the metal absorbed. More relevant spectral changes were observed upon Cu2+ complexation rather than Co2+ complexation, according to the metal absorption results. The most relevant changes were observed for the EDTA-modified wool sample treated with Cu2+, according to the higher affinity of wool for EDTA. The IR spectra were quantitatively evaluated by the intensity ratio between the Amide I and Amide II bands (IAmideI/IAmideII) and its trend as a function of metal absorption was reported. The present investigation demonstrated that the interaction between fibre and metal and the subsequent fibre modification depend on the chemical nature of the fibre, the metal cation and the modifying reagent. 相似文献
13.
Heteropoly molybdophosphates with general formula M(?)P2Mo18O62 ·xH2O, where M = H+, K+, NH4+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+ and Ag+, were prepared and characterlzed by elemental analysis, IR and UV spectrometry and thermal analysis. The solubilities of the compounds were examined. The IR spectra show that the countercations and the crystallization water have an influence upon the vibration frequencies of vMo-Oc and vMo-Oc-Mo·In the UV spectra, the charge-transfer bands are assigned to e→e and e→b2 transition. All the compounds decompose at 328-534℃. 相似文献
14.
Cobalt(II) and copper(II) complexes with 1-allyl-2-methylimidazole (L), of general formula [ML 2(NO 3) 2], have been prepared in the solid state. The compounds were characterised by structural, spectroscopic and magnetic measurements. The metal ions in both six coordinate complexes are surrounded by two nitrogen atoms of the imidazole rings and four oxygen atoms of the chelating nitrato group (the CoN 2O 4 and CuN 2O 4 chromophores). The structure of both chromophores is described by a very distorted tetragonal bipyramid. The formation of successive complexes of the azole with Co 2+, Ni 2+, Cu 2+, Zn 2+ and Cd 2+ in aqueous solution was followed potentiometrically. An irregularity in the Kn constants of successive Co 2+ and Zn 2+ complexes suggests a change in the coordination sphere of the central ions from octahedral to tetrahedral. With the Co 2+–1-allyl-2-methylimidazole system, the change has been proven by inspection of the visible absorption spectra. 相似文献
15.
The complexes, M[M(C 2O 4) 3]· xH 2 O, where x=4 for M=Cr(III), x=2 for M=Sb(III) and x=9 for M=La(III) have been synthesized and their thermal stability was investigated. The complexes were characterized by elemental analysis, IR and electronic spectral data, conductivity measurement and powder X-ray diffraction (XRD) studies. The chromium(III)tris(oxalato)chromate(III)tetrahydrate (COT), Cr[Cr(C 2 O 4) 3]·4H 2O, released water in a stepwise fashion. Removal of the last trace of water was accompanied by a partial decomposition of the oxalate group. Thermal investigation using TG, DTG and DTA techniques in air produced Cr 2O 3 at 858°C through the intermediate formation of Cr 2O 3 and CrC 2O 4 at around 460°C. While DSC study in nitrogen up to 670°C produced a mixture of Cr 2O 3 and CrC 2O 4. In antimony(III)tris(oxalato)antimonate(III)dihydrate (AOD), Sb[Sb(C 2O 4) 3]·3H 2O the dehydration took place during the decomposition of precursor at 170–290°C and finally at ca. 610°C Sb 2 O 5 along with trace amounts of Sb 2O 4 were produced. Trace amount of Sb 2O 3 and Sb along with Sb 2O is proposed as the end product at 670°C of AOD in nitrogen. The oxide La 2O 3 is formed at 838°C from the study with TG, DTG and DTA in air of lanthanum(III)tris(oxalato)lanthanum(III)nonahydrate (LON), La[La(C 2O 4) 3]·9H 2O. Intermediate dioxycarbonate, La 2O 2CO 3 was generated at 526°C prior to its decomposition to lanthanum oxide in air; whereas in N 2 the formation of La 2(CO 3) 3 at 651°C was proposed. The thermal parameters have been evaluated for each step of the dehydration and decomposition of COT, AOD and LON using five non-mechanistic equations i.e. Flynn and Wall, Freeman and Carroll, Modified Freeman and Carroll, Coats–Redfern and MacCallum–Tanner equations. Kinetic parameters, such as, E*, ko, Δ H*, Δ S* etc. were also supplemented by DSC studies in nitrogen for all the three complexes. Some of the intermediate species have been identified by analytical and powder XRD studies. Tentative schemes has been proposed for the decomposition of all three compounds in air and nitrogen. 相似文献
16.
Studies of the non-isothermal decomposition of M (mnt) (5-NO 2-phen) (M=Co II, Cu II, Zn II) were carried out by thermogravimetry. The thermal decomposition mechanisms and associated kinetics have been investigated. The kinetic parameters were obtained from an analysis of the TG–DTG curves by integral and differential methods. The most probable kinetic model functions were suggested by comparison of the kinetic parameters. Mathematical expressions for the kinetic compensation effect were derived. 相似文献
17.
We reported four fluorescent chemosensors containing tryptophan units. The fluorescence spectrum titration experiments suggest that chemosensors 1, 2, 3 and 4 are highly selective for Cu 2+ and Fe 3+ over Li +, Na +, K +, Co 2+, Zn 2+, Ni 2+, Hg 2+ and Cr 3+ via forming complexes with Cu 2+ or Fe 3+, which is confirmed by dramatical quench of fluoreseence in aqueous solution at pH 7.4, thus making all the chemosensors suitable for Cu 2+ and Fe 3+ fluorescent sensors. 相似文献
18.
Metal complexes were prepared by the reaction of Cu(II) chloride with sodium salt of random copolymers of 2-acrylamido-2-methylpropane sulphonic acid, AMPS, and isodecyl methacrylate, i-DMA. Composition was varied in the feed to obtain copolymers and their corresponding metal chelates with different content of i-DMA hydrophobic monomer. The copolymers and their metal chelates were characterized by Fourier transformed IR spectroscopy (FTIR) and scanning electron microscopy (SEM) as well as energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction studies revealed that the polymers and their chelates were amorphous. Also, the stabilities of the copolymers and their metal chelates were investigated using thermal methods such as TGA and DSC analysis. Lower thermal stability was found for the polymer–metal complexes compared to that of the copolymers. Fluorescence spectroscopy was used to further confirm the copolymers and their Cu(II) metal complexes self-aggregate in water. Critical micellar concentrations become lower by metal complexation. A synergistic effect in self-assembly behaviour in water solutions of Cu(II) polycomplexes is attributed to the interplay between hydrophilic–hydrophobic interactions and electrostatic forces with Cu2+ ions. Physical crosslinking of polymeric micelles obtained by metal complexation led to more stable micelles. Sodium salt copolymers led to secondary aggregation while ionic crosslinking provided lonely micelles distributed through the substrate as seen by SEM. These results point to a mechanism in which cation-assisted-polymer-modified water structure plays a central role in the phase separation behaviour. 相似文献
19.
Thermodynamic values for the formation of Ag +, Cd 2+, Ni 2+ and Cu 2+ complexes with succinimide were determined at 25°C in aqueous medium 0.5 M KNO 3. The stability constants were calculated from pH metric measurements and the related enthalpies from direct calorimetric determinations. An interpretation of the results is given, based on the character of the established bonds. 相似文献
20.
本文在不同温度和离子强度为0.1的条件下,以pH电位法分别测定了Co 2+、Ni 2+、Cu 2+、Zn 2+、Cd 2+与天门冬酰胺形成1:2络合物时的平衡常数。在所有测定的温度范围内,吉氏自由能变化的递变顺序为Cu 2+2+2+2+2+。以温度系数法计算了有关络合反应的焓和墙的变化,并据此对反应的动力问题进行了讨论。 相似文献
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