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1.
A typical superparamagnetic nanoparticles-based dithiocarbamate absorbent (Fe3O4@SiO2-DTC) with core-shell structure was applied for aqueous solution heavy metal ions Ni2+, Cu2+ removal.  相似文献   

2.
A new bis-quinolylimine ligand containing an azadiene moiety, 1,4-bis(2-quinolyl)-2,3-diaza-1,3-buthadiene (1), was synthesized by one-step facile condensation. This simple ligand, when dissolved in acetonitrile, shows a Cu2+-selective fluorescence enhancement. Coordination of 1 with Cu2+ produces two kinds of complexes with 1:1 and 1:2 stoichiometries. The 1:2 complex shows a strong fluorescence (ΦF = 0.37), while the 1:1 complex does not (ΦF < 0.01). Ab initio molecular orbital calculation reveals that the 1:1 complex has a distorted structure, while the 1:2 complex has a planar structure. The planar configuration of the 1:2 complex, therefore, allows an extended π-conjugation over the entire molecule and, hence, results in fluorescence enhancement.  相似文献   

3.
Li2O–MoO3–B2O3 glasses mixed with different concentrations of CuO (ranging from 0 to 1.2 mol%) were prepared. The samples were characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Optical absorption, luminescence, ESR, IR and dielectric properties (viz., dielectric constant ?′, loss tan δ and a.c. conductivity σac, over a wide range of frequency and temperature) of these glass materials have been investigated. The results of differential scanning calorimetric studies suggest that the glass forming ability is higher for the glasses containing CuO beyond 0.6 mol%. The analysis of results of the dielectric properties has revealed that the glasses possess high insulating strength when the concentration of CuO is >0.6 mol%. The variation of a.c. conductivity with the concentration of CuO passes through a maximum at 0.6 mol%. In the high-temperature region, the a.c. conduction seems to be connected with the mixed conduction viz., electronic conduction and ionic conduction. The optical absorption spectra of these glasses exhibited bands due to Cu+ ions in the UV region in addition to the conventional band due to Cu2+ ions in the visible region. The ESR spectral studies have indicated that there is a gradual adoption of Cu2+ ions from ionic environment to covalent environment as the concentration of CuO increases beyond 0.6 mol% in the glass matrix. The luminescence spectra excited at 271 nm have exhibited an intense yellow emission band centered at about 550 nm and a relatively broad blue emission band at about 450 nm; these bands have been attributed to the 3D1  1S0 transition of isolated Cu+ ions and 3D1  1S0 transition of (Cu+)2 pairs, respectively. The quantitative analysis of the results of all these studies has indicated that as the concentration of CuO is increased beyond 0.6 mol% in the glass matrix, a part of Cu2+ ions have been reduced to Cu+ ions that have influenced the physical properties of these glasses to a substantial extent.  相似文献   

4.
Binding of copper to three peptide fragments of prion (Cu2+ binding sites: 60–91, 92–96 and 180–193 amino acid residues) was investigated by anodic stripping voltammetry to determine the stoichiometries of Cu2+-prion peptide interactions. The method relies on the synthesis of N-terminally acetylated/C-terminally amidated peptide fragments of prion by solid-phase synthesis and direct monitoring of the oxidation current of copper in the absence and presence of each prion fragment. Titration curves of Cu2+ with Ac-PHGGGWGQ-NH2, Ac-GGGTH-NH2 and Ac-VNITKQHTVTTTT-NH2 were obtained in concentrations ranging from 8.52 × 10?7 to 5.08 × 10?6, 3.95 × 10?7 to 1.94 × 10?6 and 7.82 × 10?8 to 4.51 × 10?7 M, respectively. The acquired data were used to calculate the stoichiometries (one peptide per Cu2+ ion for all the three studied systems) and apparent dissociation constants (Kd = 4.37 × 10?8–3.50 × 10?10 M) for the three complexes.  相似文献   

5.
Spectral and molecular model computations on homo-dinuclear complexes [M2L2(H2O)2Cl2] [L = 1-(salicylaldeneamino)-3-hydroxypropane, M = Cr3+, Mn3+, Fe3+, Co3+, Ni3+ or Cu3+] are consistent with a distorted hexa-coordinate geometry. X-band EPR spectral data indicated a rhombic distortion around Cu(II) ion. Magnetic moment and 57Fe Mössbauer data confirmed a high-spin state electronic configuration (t2g3eg2, S = 5/2) and asymmetric ligand environment around Fe(III) with nuclear transitions Fe(±3/2  1/2) exhibiting Kramer's double degeneracy. The neighboring Fe(III) nuclei in the homo-dinuclear species are antiferromagnetically coupled.  相似文献   

6.
Release of heavy metals into water as a result of industrial activities may pose a serious threat to the environment. The objective of this study is to assess the uptake of Cu2+ from aqueous solutions onto multi-walled carbon nanotubes (MWCNT). The potential of the t-MWCNT to remove Cu2+ cations from aqueous solutions was investigated in batch reactor under different experimental conditions. The processing parameters such as initial concentration of Cu2+ ions, temperature, and adsorbent mass were also investigated. Copper uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 12.34 mg/g of Cu2+ cations on t-MWCNT. Various thermodynamic parameters, such as ΔG0, ΔH0 and ΔS0 were calculated. The thermodynamics of Cu2+ cations adsorption onto t-MWCNT system pointed at spontaneous and endothermic nature of the process. Using the second-order kinetic constants, the activation energy of adsorption (Ea) was determined as 27.187 kJ/mol according to the Arrhenius equation.  相似文献   

7.
The luminescence properties of [Ru(bpy)2MDHIP]2+ (bpy = 2,2′-bipyridine, MDHIP = 2,4-dihydrophenyl-imidazo[4,5-f][1,10]phenanthroline) in the absence and presence of DNA modulated by the introduction of Cu2+ ion and EDTA have been investigated. It is found that the ruthenium(II) complex can insert and stack between the base pairs of calf thymus DNA with MDHIP ligand, and the intramolecular hydrogen bond is located inside of the DNA. The presence of DNA can enhance the luminescence intensities of [Ru(bpy)2MDHIP]2+ both in buffer solution and on an ITO surface. Moreover, the luminescence intensities of [Ru(bpy)2MDHIP]2+ and DNA-bound [Ru(bpy)2MDHIP]2+ are quenched by Cu2+, and next recovered by the addition of EDTA. The repetitive luminescence-modulations have been achieved through the introduction of equimolar Cu2+ and EDTA, respectively. In addition, it becomes evident that the number of luminescence-modulation cycles for [Ru(bpy)2MDHIP]2+ in the absence and presence of DNA is influenced by the cumulative concentrations of CuEDTA, generated successively by the strong coordination of Cu2+ to EDTA.  相似文献   

8.
The defect structure for Cu2+ in CdSe nanocrystals is theoretically studied by analyzing the spin Hamiltonian parameters of this impurity center. This center is ascribed to Cu2+ occupying the octahedral interstitial site, rather than the tetrahedral substitutional Cd2+ site proposed by previous work. The Cu2+ center exhibits slight tetragonal elongation distortion (characterized by the elongation parameter ρ  0.03) due to the Jahn–Teller effect. The theoretical spin Hamiltonian parameters and optical transition show good agreement with the experimental data. The above unusual defect structure (occupation and symmetry) for Cu2+ in CdSe nanocrystals is discussed, as compared with the conventional trigonally distorted tetrahedral Cu2+ centers in bulk II–VI semiconductors.  相似文献   

9.
A systematic investigation of the reactions of Cu(ClO4)2 · 6H2O with maleamic acid (H2L) in the presence of 2,2′-bipyridine (bpy) has been carried out. The chemical and structural identity of the products depends on the solvent, the absence or presence of external hydroxides in the reaction mixture and the molar ratio of the reactants. Various reaction schemes have led to the isolation of the complexes [Cu2(HL)2(bpy)2(H2O)2](ClO4)2 (1), [Cu2(HL)2(bpy)2(H2O)2](ClO4)2 · 2H2O (1 · 2H2O), [Cu(L′′)(bpy)]n · 2nH2O (2 · 2nH2O), [Cu2(L′′)(bpy)2(H2O)2]n(ClO4)2n · 0.5nH2O (3 · 0.5nH2O), [Cu2(L′′)2(bpy)2] · 2MeOH (5 · 2MeOH), [Cu2(L′)2(bpy)2(ClO4)2] (6) and [Cu(ClO4)2(bpy)(MeCN)2] (7b), where L′′2? and L′? are the maleate(?2) and monomethyl maleate(?1) ligands, respectively. The HL? ion has been transformed to L′′2? and L′? in the known compounds 2 · 2nH2O and 6, respectively, via metal ion-assisted processes involving hydrolysis (2 · 2nH2O) and methanolysis (6) of the primary amide group. The reaction that leads to 6 takes place through the formation of the mononuclear complex [Cu(ClO4)2(bpy)(MeOH)2] (7a), whose structure was assigned on the basis of its spectral similarity with the structurally characterized complex 7b. The structures of the cations in 1 and 1 · 2H2O consists of two CuII atoms bridged by the carboxylate groups of the two HL? ligands, each exhibiting the less common η2 coordination mode; a chelating bpy molecule and a H2O ligand complete square pyramidal coordination at each metal centre. The structure of the dinuclear repeating unit in the 1D coordination polymer 3 · 0.5nH2O consists of two CuII atoms bridged by two syn,syn η1:η1:μ2 carboxylate groups belonging to two L′′2? ions; each ligand bridged two neighboring [CuII,II2] units thus promoting the formation of a helical chain. The structure of the dinuclear molecule of complex 5 · 2MeOH consists of two CuII atoms bridged by two η2 carboxylate groups from two L′′2? ligands; the second carboxylate group of each maleate(?2) ligand is monodentately coordinated to CuII, creating a remarkable seven-membered chelating ring. The L′? ion behaves as a carboxylate-type ligand in 6, with the carboxylate group being in the familiar syn,syn η1:η1:μ2 coordination mode; a chelating bpy molecule and a coordinated ClO4? complete five-coordination at each CuII centre. The crystal structures of the complexes are stabilized by various H-bonding patterns. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands.  相似文献   

10.
Isomorphously substituted (MeDM) and impregnated metal-containing MCM-41 (MeOx/IM) catalysts, in which Me = Co, Cu, Cr, Fe or Ni, have been prepared. Structural and textural characterizations of the catalysts were performed by means of X-ray diffraction (XRD), chemical analysis, Raman spectroscopy, electron paramagnetic resonance (EPR), N2 adsorption isotherms and temperature programmed reduction (TPR). Cu2+, Co2+, and Cr4+/Cr3+ species were found over the catalysts as cations incorporated in the MCM-41 structure (MeDM) or highly dispersed oxides on the surface (MeOx/IM). The MeDM catalysts exhibited a good performance in the dehydrogenation of ethylbenzene with CO2. However, MeOx/IM catalysts had a low performance in styrene production (activity less than 15 × 10?3 mmol h?1 and selectivity for styrene less than 80%) due to the high reducibility of the metals species. However, Ni2+ or Fe3+ coordinated with the MCM-41 framework, as well as NiOx and Fe2O3 extra-framework species, is continuously oxidized by the CO2 to maintain the active sites for dehydrogenating ethylbenzene. Deactivation studies on the FeDM sample showed that Fe3+ species produced active sp2 carbon compounds, which are removed by CO2; the referred sample is catalytically selective for styrene and stable over 24 h of reaction. In contrast, highly active Ni2+ and Ni0 species produced a large amount of polyaromatic carbonaceous deposits from styrene, as identified by TPO, TG and Raman spectroscopy. An acid–base mechanism is proposed to operate to adsorb ethylbenzene and abstract the β-hydrogen. CO2 plays a role in furnishing the lattice oxygen to maintain the Fe3+ active sites in the dehydrogenation of ethylbenzene to form styrene.  相似文献   

11.
《Solid State Sciences》2007,9(10):961-963
Electron paramagnetic resonance (EPR) and optical studies have been carried out on Cu2+ doped bis(thiourea)cadmium chloride single crystal, which belongs to a potential semi-organic non-linear material, at room temperature. The spin Hamiltonian parameters were determined as gxx = 2.04331, gyy = 2.04373, gzz = 2.05750 and Axx = 91G, Ayy = 115G, Azz = 136G. These parameters suggest that the spectroscopic splitting parameter g and hyperfine splitting parameter A exhibit rhombic symmetry. The optical study reveals that the non-linear optical property of the host lattice has been enhanced due to Cu2+ doping.  相似文献   

12.
In contrast to well established experimental results of vibronic coupling effects in octahedral dn complexes with Eg ground states (Cu2+, Ag2+; Cr2+, Mn3+ etc.), not much useful material is available for the Jahn–Teller (JT) effect in orbital triplet ground states. The present study is concerned with this deficiency, providing data for octahedral halide model complexes with 3dn cations – in particular for TiIII, VIII and high-spin CoIII, NiIII with T2g and T1g ground states, which involve, to first-order, solely splitting of the π-antibonding t2g MOs. Besides experimental results – structural and spectroscopic, mainly from d–d spectra – data from computations are needed for a quantitative treatment of the Tg ? (?g + τ2g) vibronic interaction as well as in the Eg ? ?g coupling case (MnIII, low-spin NiIII); DFT was the method of choice, if only critically selected outcomes are utilised. The theoretical bases of the treatment are the dn ligand field matrices in Oh, extended by the inclusion of lower-symmetry distortion parameters, and the conventional theory of vibronic coupling. Caution is needed when classifying the effects of interelectronic repulsion; DFT does not reproduce the magnitudes of the Racah parameters B, C, as deduced from the d–d spectra, properly – the presumed reasons are analysed. DFT even allows one to deduce reliable vibronic coupling constants via the analysis of orbitally degenerate excited states (CrIII, 4A2g ground state). The group-theoretical analysis of the interaction with the JT-active ?g and τ2g modes yields D4h, D3d and D2h as the possible distortion symmetries in the case of a Tg ground state. The DFT-calculations give clear evidence, that the D4h stationary points represent the absolute minima in the Tg ? (?g + τ2g) potential surface – in agreement with experiment, where available. For the first time, vibronic coupling constants, characterising JT splitting of ground and excited Tg states, can be presented for trivalent 3dn cations in octahedral halide ligand fields. They turn out to be smaller by a factor of almost 3 in comparison to those, which determine the coupling in σ-antibonding eg MOs.The tetragonal splitting of Tg states is typically only small, around 0.1 eV, and suggests that strain influences from a specific ligand arrangement and/or the presence of different ligands may modify the potential surface considerably. We have studied such effects via compounds AIMIIIF4, where an elastic strain induced by the host structure, and a binding strain, due to the simultaneous existence of (largely) terminal and of bridging ligands, are active. A novel strain model, in its interplay with JT coupling, is proposed and applied – using energies from the d–d spectra, structural results and data from DFT.Chloride complexes are only known for TiIII to FeIII; the rather small electronegativity already of CoIII suggests a reducing ligand-to-metal (3dn) electron transfer for n  6. Similarly, the low-lying ligand-to-metal charge transfer bands in the d–d spectra of the CuIIIF63? complex and the reduced Tg ? ?g coupling strength suggest a pronounced covalency of the CuIII–F, and, even more distinctly, of the CuIII–O bond, which is of interest for superconductivity. The NiIIIF63? polyhedron possesses a low-spin configuration in the elpasolite structure. The spectroscopic evidence and the DFT data indicate, that the minimum positions of the alternative a2A1g(a2Eg) and a4A2g (a4T1g) potential curves are only ≤0.02 eV apart, giving rise to interesting high-spin/low-spin phenomena. It is the strong Eg ? ?g as compared to the T1g ? ?g coupling, which finally stabilises a spin-doublet ground state in D4h.We think, that the selected class of solids is unique particularly for the study of Jahn–Teller coupling in T ground states, with model character for other systems. In our overview a procedure is sketched, which uses reliable computational results (here from DFT) for supplementing incomplete experimental data, and presents – on a semiquantitative scale – convincing statements, consistent with chemical intuition. It is also a pleading for ligand field theory, which rationalises d-d spectra in terms of chemical bonding; though the latter spectra provide frequently only rather coarse information, their assistance in the energy analysis is crucial.  相似文献   

13.
Single crystals of the Y5Cu5Mg8, Y5Cu5Mg13, Y5Cu5Mg16 and YCuMg4 compounds were synthesized by heating in a resistance furnace evacuated quartz vials containing Ta-crucibles with element pieces. SEM-EDXS analyses were performed to check phases composition. The structures were refined from X-ray single crystal diffraction data. Y5Cu5Mg8, Y5Cu5Mg13 and Y5Cu5Mg16 represent new structure types: Y5Cu5Mg8 – orthorhombic, Pmma, oP36, a = 2.63723(15), b = 0.40066(2), c = 0.74115(6) nm, Z = 2, wR2 = 0.0597, 939 F2 values, 60 variables; Y5Cu5Mg13 – orthorhombic, Cmcm, oS92, a = 0.40973(2), b = 1.92794(8), c = 2.57907(11) nm, Z = 4, wR2 = 0.1134, 1208 F2 values, 75 variables; Y5Cu5Mg16 – orthorhombic, Cmcm, oS104, a = 0.41360(8), b = 1.9239(4), c = 2.9086(6) nm, Z = 4, wR2 = 0.0760, 1383 F2 values, 84 variables. YCuMg4 crystallizes in the TbCuMg4 structure type (Cmmm, oS48, a = 1.35754(4), b = 2.03153(6), c = 0.39060(1) nm, Z = 8, wR2 = 0.0401, 661 F2 values, 45 variables). The crystal chemistry of these two-layer structures is comparatively discussed. Majority of novel compounds were characterized as members of inhomogeneous 2D intergrowth structure series of R5M5X5, X4 (Mg4) and empty Mg octahedra building blocks of general formula R5kM5kX5k + 4l + m. The common pentagonal prism derivative structural fragments around the most electropositive yttrium atoms were outlined in all these intermetallics.  相似文献   

14.
Synthesis, molecular and supramolecular structures, electrochemistry and magnetic properties of two diphenoxo-bridged dicopper(II) compounds [CuII2L(H2O)(ClO4)]·ClO4·2H2O (1) and [CuII2L(N3)2]·2H2O (2) derived from a tetraimino diphenolate macrocyclic ligand H2L, obtained on [2+2] condensation of 4-methyl-2,6-diformylphenol and 2,2′-dimethyl-1,3-diaminopropane, are presented. Supramolecular structure of both 1 and 2 are three-dimensional resulting from hydrogen bonding interactions. Interestingly, the 3-D self-assembly of 2 contains micropores having the dimension of 0.35 nm. Electrochemical analyses reveal that both of these compounds exhibit two-step couples in the reduction window. Variable-temperature (2–300 K) magnetic susceptibilities measurements of the two compounds reveal that the metal centers in both of the complexes are coupled by strong antiferromagnetic interactions with J values (H = ?JS1·S2) ?776 and ?836 cm?1 for 1 and 2, respectively.  相似文献   

15.
The anisotropic and isotropic spin-Hamiltonian parameters (g factors and hyperfine structure constants) of tetragonal Cu(H2O)62+ clusters due, respectively, to the static and dynamic Jahn–Teller effects for Cu2+ in trigonal A2Mg3(NO3)12·24H2O (A = La, Bi) crystals are calculated from the high-order perturbation formulas based on the cluster approach. In the approach, the admixture between the d orbitals of 3dn ion and the p orbitals of ligand ion via covalence effect is considered. All of the calculated results are in agreement with the experimental values. The tetragonal elongations (characterized by ΔR = R// ? R) of Cu(H2O)62+ cluster due to the Jahn–Teller effect in A2Mg3(NO3)12·24H2O crystals are acquired from the calculations. The results are discussed.  相似文献   

16.
Phosphate glasses have several technological interests due to their specific physical properties such as high thermal expansion coefficient, high refractive indice and low melting temperature, that make them suitable for use as conductors, ionic conductors, semiconductors and biomedical materials. The phosphate glasses, in particular the pyrophosphate forms, are not widely studied. In this work we have elaborated the Na2Pb1−xCuxP2O7 glasses, with a large range of composition (0  x  1), by conventional melting method. Thermal parameters of the glasses were determined using the differential scanning calorimetry. The structure of the glasses was investigated by IR spectroscopy. The local environment of paramagnetic ions Cu2+ was analyzed by EPR and magnetic measurements. It was showed that the network structure of the glasses was drastically influenced by the copper content.  相似文献   

17.
Core-shell Cu2O/Cu composites were successfully prepared by over-reduction of aqueous CuSO4 with hydrazine hydrate as reductant. Field emission scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) clearly illuminate that the core is Cu2O with 400 nm in diameter, and the shell is Cu with about 50 nm in thickness. The core-shell Cu2O/Cu exhibited weaker polarization and higher coulombic efficiency than pure octahedral Cu2O, especially in the initial stage of cycles. After 50 cycles, the reversible capacity of Cu2O/Cu (360 mAh g?1) was much higher than that of pure Cu2O (160 mAh g?1). The improvement of electrochemical properties is attributed to the core-shell structure of Cu2O/Cu and the catalytic effect of Cu on the decomposition of Li2O during the charging process.  相似文献   

18.
Transition-metal doped double-perovskite structure oxides GdBaCo2/3Fe2/3Ni2/3O5+δ (FN-GBCO), GdBaCo2/3Fe2/3Cu2/3O5+δ (FC-GBCO), GdBaCoCuO5+δ (C-GBCO) and pristine GdBaCo2O5+δ (GBCO) were synthesized via a citrate combustion method. The thermal-expansion coefficient (TEC) and electrochemical performance of the oxides were investigated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The TEC exhibited by the FC-GBCO cathode up to 900 °C is 14.6 × 10?6 °C?1, which is lower than the value of GBCO (19.9 × 10?6 °C?1). Area specific resistances (ASR) of 0.165 Ω cm2 at 700 °C and 0.048 Ω cm2 at 750 °C were achieved for the FC-GBCO cathode on a Ce0.9Gd0.1O1.95 (CGO) electrolyte. An electrolyte supported (300 μm thick) single-cell configuration of FC-GBCO/CGO/Ni-CGO attained a maximum power density of 435 mW cm?2 at 700 °C. The unique composition of GBCO co-doped with Fe and Cu ions in the Co sites exhibited reduced TEC and enhancement of electrochemical performance and good chemical compatibility with CGO, and this composition is proving to be a potential cathode for IT-SOFCs.  相似文献   

19.
《Solid State Sciences》2007,9(7):644-652
Na2Cu(PO2NH)4·7H2O and KxNa2−xCu(PO2NH)4·7H2O (x  0.5) were synthesized by gel crystallization in sodium silicate gels. The crystal structures were solved by single-crystal X-ray methods and found to be isotypic (Pnma, Z = 4; Na2Cu(PO2NH)4·7H2O: a = 627.5(2) pm, b = 1456.0(3) pm, c = 1900.5(4) pm, R1 = 0.0352; K0.47Na1.53Cu(PO2NH)4·7H2O: a = 632.2(2) pm, b = 1460.0(3) pm, c = 1936.4(4) pm, R1 = 0.0345). The P4N4 rings of the tetrametaphosphimate anion exhibit a distorted chair-2 conformation with admixtures of saddle and crown conformation. The M+ ions are six- and sevenfold coordinated by oxygen atoms, the Cu2+ ions are fivefold coordinated, respectively. The MO7 and the CuO5 units form pairs of face-sharing polyhedra, which are connected by common corners forming chains and are further interconnected by tetrametaphosphimate anions, forming a three-dimensional network structure with channels along [100] and [010]. The MO6 units form chains of face-sharing polyhedra, which are situated in the channels along [100]. Extended hydrogen bonding reinforces the three-dimensional framework structure of the compounds. 23Na-MAS NMR experiments were conducted to verify the K/Na distribution on the M sites derived from the X-ray crystal structure refinement.  相似文献   

20.
Infrared spectroscopy in the far (FIR), mid (MIR), and near (NIR) regions was used to study the structural changes of a thermally treated clay mineral montmorillonite saturated with Li+ or Cu2+ cations (Li-JP and Cu-JP samples). Cation exchange capacity (CEC) values decreased by 89 and 64% in Li- and Cu-samples, respectively, heated at 300 °C. The IR spectra confirm that the charge of exchangeable cations significantly affect their final position after fixation upon heating. No absorption bands related to the vibrations of interlayer cations were observed in the FIR spectra of unheated or heated samples; however, different modification of the complex vibrational mode involving motion of octahedral aluminium relative to the tetrahedral sheet was observed near 197 cm−1. The vibrations of OH groups in both MIR (νOH, 3630–3670 cm−1) and NIR (2νOH, 7070–7170 cm−1) regions proved that the Li+ migrated into the octahedral vacancies, thus creating local trioctahedral domains, such as AlMgLiOH. Though Cu2+ has similar ionic radius as Li+, no spectral features indicating its presence in the octahedral positions have been found even in the sample heated at 300 °C. Fixed Cu(II) is supposed to be located deep in the ditrigonal cavities of the tetrahedral sheets of Cu-JP. The NIR spectra of heated Cu-JP samples show new components near 7045 and 5170 cm−1. These modes are believed to correspond to overtone bands associated with hydrated Cu2+ ions tightly bound in close proximity to the ditrigonal cavities of the basal surface (ObasalCu2+H2O). The NIR spectra confirm that in Cu-JP heated at 200 °C, then saturated with Li+ and Cu2+ and heated again at 300 °C small Li+ ions migrate into the vacant octahedral sites even though Cu(II) have been trapped in the hexagonal cavities of the tetrahedral sheets in the course of previous heat treatment.  相似文献   

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