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1.
The complex formation reactions between Mg2+, Ca2+, Sr2+ and Ba2+ metal cations with macrocyclic ligand, 4′-nitrobenzo-15C5, were studied in acetonitrile (AN)-methanol (MeOH) binary mixtures
at different temperatures using conductometric method. The results show that 4′-nitrobenzo-15C5 forms 1:1 [ML] complexes with
Mg2+, Ca2+ and Sr2+ metal cations in solutions. But in the case of Ba2+ cation a 1:2 [ML2] complex is formed in these solvent systems. The stability of the complexes is sensitive to the solvent composition and a
non-linear behavior was observed for variation of logK
f of the complexes versus the composition of the binary mixed solvents. The stability constants of complexes decrease suddenly
with increasing the concentration of methanol in this binary system. The values of thermodynamic parameters (ΔH
c° and ΔS
c°) for formation of (4′-nitrobenzo-15C5.Mg)2+, (4′-nitrobenzo-15C5.Ca)2+ and (4′-nitrobenzo-15C5.Sr)2+ complexes were obtained from temperature dependence of the stability constants and the results show that these parameters
are affected by the nature and composition of the mixed solvents. A non-linear behavior is observed between the ΔS
c° and the composition of the mixed solvents. 相似文献
2.
N. A. Halim Z. A. Ibrahim A. B. Ahmad 《Journal of Thermal Analysis and Calorimetry》2010,102(3):983-988
The high potential for intercalations by water and various guest molecules is induced by the exchangeable cation inside Ca2+–Montmorillonite gallery. XRD peak for Mon at 2θ = 6.04° (d
001 = 1.462 nm) shows the structural effect on the clay gallery influenced by the intercalated water layers. Further increases
in the gallery height are observed with the intercalation of octadecyl ammonium cations in OMON (d
001 = 1.840 nm) and ENR-50 matrix chains in CENR-50 (d
001 = 1.954 nm). DSC studies on the other hand reveal the thermal behaviors of intercalated molecules that are linked to the
exchangeable cations. The endothermic of Ca2+–Montmorillonite (H
Mon = 356.3 J/g) in low temperature range (30–100 °C) indicates the removal of free water and hydrogen bonded water molecules,
while the endothermic around 150 °C is related to the induced skeletal layer of water within Ca2+–Montmorillonite. The OMON endothermic (H
OMON = 47.0 J/g, T
m = 36.94 °C) tells that cation exchange had modified the water structures and content inside the renewed clay. The intercalation
of ENR-50 chains into OMON gallery reveals two endothermic with the T
m1 and T
m2 are at 86.24 and 113.80 °C, respectively. These T
ms confirm that the alkyl chain segment on octadecyl ammonium cation occupy the OMON interlayer space. 相似文献
3.
Boukraa Yamina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(13):2642-2645
A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures. 相似文献
4.
F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):763-768
Summary. The diagram of the ternary system Mg2+/Cl−, SO4
2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram,
which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4
2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.
Corresponding author. E-mail: ariguib@planet.tn
Received October 16, 2002; accepted (revised) December 3, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70th birthday 相似文献
5.
A. B. Azlarov Kh. M. Polvonov M. K. Askarova S. Tukhtaev 《Russian Journal of Inorganic Chemistry》2011,56(1):124-127
The solubility in the 2Na+,Mg2+‖2Cl−, 2ClO3−-H2O system was studied at 20 and 100°C and the solubility diagrams were plotted. New compounds were not found to form in the
title quaternary reciprocal system. The sodium chloride field was observed to expand with rising temperature. 相似文献
6.
E. M. Evstigneeva V. R. Flid E. N. Bobkova M. V. Lomonosov 《Russian Chemical Bulletin》2009,58(3):551-558
A linear correlation of chemical shifts (δ) of signals in the 13C NMR spectra of the unsubstituted terminal carbon atom of the allyl ligand in [(1-R-η3-C3H4)Pd]NO3 (R = Me, CH2OMe, CO2Me, COMe, CHO) with the substituent constants σ+ and σs- in acetone solutions was found. A considerable deviation from linearity was observed for R = Ph. The 13C nuclear magnetic screening constants were calculated by the DFT method in the GIAO approximation for equilibrium geometries
of the cations [(1-R-η3-C3H4)Pd(Me2C=0)2]+ and anions [(1-R-η3-C3H4)PdCl2]s-. In the latter case, the theoretical and experimental δ values are consistent. The influence of the substituent R on the
geometric parameters and charges on atoms in the neutral, anionic, and cationic η3-allylpalladium complexes is discussed. 相似文献
7.
Baoling Wang Liuzheng Sun Haidong Ju Shilong Zhao Degang Deng Huanping Wang Shiqing Xu 《Journal of Sol-Gel Science and Technology》2009,50(3):368-371
CaAl2Si2O8: Eu2+, Mn2+ phosphors have been prepared by a sol–gel method. X-ray diffractometer, spectrofluorometer and UV–Vis spectrometer were used
to characterize structural and optical properties of the samples. The results indicate that anorthite (CaAl2Si2O8) directly crystallizes at 1000 °C in the sol–gel process. CaAl2Si2O8: Eu2+, Mn2+ phosphors show two emission bands excited by ultraviolet light. Blue (around 415 nm) and yellow (around 575 nm) emissions
originate from Eu2+ and Mn2+, respectively. With appropriate tuning of Mn2+ content, CaAl2Si2O8: Eu2+, Mn2+ phosphors exhibit different hues and relative color temperatures. 相似文献
8.
Yanluo Lu Lan Yang Min Wei Yaning Xie Tao Liu 《Journal of Solid State Electrochemistry》2007,11(9):1157-1162
Supramolecular pillared oxides were prepared through the intercalation of M2+ cations into a MnO2 host matrix by the method of ion exchange between the precursor δ-K
x
MnO2 and the corresponding guest. The materials M-MnO2 crystallize in the hexagonal system, the same structure as the precursor, with a larger interlamellar spacing. In the case
of ZrO-MnO2, extended X-ray absorption fine structure (EXAFS) determination indicates that the Zr atom locates between the MnO2 layers forming a stable structure. Compared with the precursor, the cycling property of M-MnO2 was improved distinctly, while the capacity decreased to some degree due to the strong interaction between pillars and the
host matrix. Among these pillared materials, ZrO-MnO2 has an advanced reversible capacity of 161.5 mAh·g−1 and improved cycling behavior compared with the precursor. 相似文献
9.
Tomoe Sanada Hisakazu Seto Yusuke Morimoto Kazuhiro Yamamoto Noriyuki Wada Kazuo Kojima 《Journal of Sol-Gel Science and Technology》2010,56(1):82-86
To develop new fluorescent and afterglow materials, Mn2+ and Eu3+ co-doped ZnO–GeO2 glasses and glass ceramics were prepared by a sol–gel method and their optical properties were investigated by measuring
luminescence, excitation and afterglow spectra, and luminescence quantum yield (QY). Under UV irradiation at 254 nm, some
glasses and all of the glass ceramics showed green luminescence peaking at 534 nm due to the 4T1 → 6A1 transition of tetrahedrally coordinated Mn2+ ions. The strongest luminescence was observed in a glass ceramic of 0.1MnO–0.3Eu2O3–25ZnO–75GeO2 heat treated at 900 °C, with QY of 49.8%. All of the green-luminescent glasses and glass ceramics showed green afterglow,
and the afterglow lasting for more than 60 min was obtained in a glass ceramic heat treated at 900 °C. It is considered that
the Eu3+ ions may behave as electron trapping centers to be associated with the occurrence of the green afterglow due to the Mn2+ ions in the co-doped system. 相似文献
10.
N. M. Antovic N. Svrkota I. Antovic 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):313-318
A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence
spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from
the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement
with ones obtained by the HPGe spectrometer. 相似文献
11.
Ca3Al6Si2O16: Ce3+, Tb3+ phosphors have been prepared by sol–gel method. The structure and photoluminescence properties were studied with careful.
The results indicated that the single-phased Ca3Al6Si2O16 phosphors crystallize at 1,000 °C for 2 h in conventional furnace. With appropriate concentrations of Ce3+ and Tb3+ ions into Ca3Al6Si2O16 matrix, these materials exhibit blue phosphors and white light under ultraviolet radiation. White-light emission can be achieved
because of a 400 nm emission ascribed to transitions of Ce3+ ions and three sharp peaks at 487, 543, 585 nm, respectively, resulting from transitions of Tb3+ ions. 相似文献
12.
Fatemeh Hesami Gholam Hossein Rounaghi Massoumeh Mohajeri Somayeh Tarahomi 《Journal of solution chemistry》2011,40(8):1408-1417
The complexation reactions of 4′-nitrobenzo-15-crown-5 (4′NB15C5) with Zn2+, Mn2+, Cr3+ and Sn4+ cations were studied in acetonitrile–ethanol (AN–EtOH) binary solvent mixtures at different temperatures by the electrical
conductometry method. The stability constants of the resulting 1:1 complexes were determined from computer fitting of the
conductance versus mole ratio data. The results show that the selectivity order of 4′NB15C5 for the metal cations in the AN–EtOH
(mol-%AN=76) binary solvent at 298.15 K is: Cr3+>Mn2+≈Zn2+>Sn4+, but the selectivity order changes with the composition of the mixed solvents. A nonlinear relationship was observed between
the stability constants (log 10
K
f) of these complexes and the composition of the AN–EtOH binary solvents. The corresponding thermodynamic parameters (DHco, DSco)(\Delta H_{\mathrm{c}}^{\mathrm{o}}, \Delta S_{\mathrm{c}}^{\mathrm{o}}) were obtained from the temperature dependence of the stability constants using van’t Hoff plots. The results show that the
values and also the sign of these parameters are influenced by the nature and composition of the mixed solvents. 相似文献
13.
Anjing Wang Junmei He Lingna Kong Naidong Zhang Tong Zheng 《Research on Chemical Intermediates》2017,43(4):2175-2186
This paper investigated the photodegradation characteristics of benzoquinones and benzoquinoneimines. The photosensitivity of benzoquinones and benzoquinoneimines were analyzed by measuring the yield of SO 4 ?· in a light/Fe2+/S2O8 2? system and the degradation mechanism of benzoquinones, then discussed benzoquinoneimines in light/Fe2+/S2O8 2? and light/S2O8 2? system. The results revealed that a more aggressive oxidation of benzoquinones and benzoquinoneimines by the sunlight/Fe2+/S2O8 2? method showed a more rapid and more complete removal of chromaticity than that of the UV/Fe2+/S2O8 2? method. It was showed that they were photosensitizers, and they could generate 1O2 and O 2 ?· which could promote the formation of SO 4 ?· and ·OH in the sunlight system. Nevertheless, for benzoquinones, the sunlight/S2O8 2? method was superior to the UV/S2O8 2? method. For benzoquinoneimines, the sunlight/S2O8 2? method was inferior to the UV/S2O8 2? method. In addition, the yield of SO 4 ?· in the sunlight/Fe2+/S2O8 2? system was more than that of the UV/Fe2+/S2O8 2? system. Therefore, the photosensitivity of benzoquinones is superior to benzoquinoneimines in water treatment. 相似文献
14.
Kan Zhu Zhengwen Yang Dong Yan Zhiguo Song Dacheng Zhou Rongfei Wang Jianbei Qiu 《Journal of Sol-Gel Science and Technology》2012,62(2):149-152
Tb3+–Yb3+ co-doped Ca5(PO4)3F inverse opal photonic crystals were prepared by a self-assembly technique in combination with a sol–gel method. Upconversion
luminescence characteristics of the inverse opals were investigated. The results indicate that photonic band gap has a significant
effect on upconversion luminescence of Tb3+–Yb3+ co-doped Ca5(PO4)3F inverse opal. Significant inhibition of the green or blue upconversion luminescence was inspected if the photonic band gap
overlapped with the emission band of Tb3+ ions. 相似文献
15.
A. C. Yanes J. J. Velázquez J. del-Castillo J. Méndez-Ramos V. D. Rodríguez 《Journal of Sol-Gel Science and Technology》2009,51(1):4-9
Nanostructured transparent glass-ceramics with composition of 95SiO2–5LaF3 co-doped with 0.3Yb3+, 0.1Ho3+ and 0.1Tm3+ (mol%) were synthesized by thermal treatment of precursor sol–gel derived glasses. X-ray diffraction and transmission electron
microscopy analysis point out the precipitation of hexagonal LaF3 nanocrystals with diameter ranging from 11 to 20 nm in these nano-glass-ceramics. White light generation by means of efficient
blue, green and red up-conversion luminescence under infrared excitation at 980 nm was observed and involved mechanisms were
analyzed. Colour tuneability is achieved by varying the up-conversion emission ratios as a function of pump power. 相似文献
16.
A new bimetallic cyano-bridged complex, based on copper(II) macrocycle and hexacyanoiron(III) as building blocks, [CuL(H2O)2]{[CuL][Fe(CN)6] · 2H2O} (1) (L = 1,3,6,8,11,14-hexaazatricyclo[12.2.1.18,11]-octadecane) has been synthesized and magnetically characterized. Make
a study of magnetic using a chain model which takes into account of monomeric impurity confirm showing an antiferromagnetic
coupling in paramagnetic ions with J = −0.170 cm−1 and 3.56 % impurity. 相似文献
17.
The complex [Ni(En)2][Ni(CN)4] · 3.5H2O (I) (En = ethylenediamine) was synthesized by the reaction of [Ni(En)2](ClO4)2 and K2[Ni(CN)4] in an H-shaped tube. The crystal structure of I has been determined by single-crystal X-ray analysis. The crystal of complex I is orthorhombic, space group Pnna with a = 28.151(3), b = 8.3946(8), c = 14.5441(13)Å, M =404.76, Z = 8, V = 3437.0(5)Å3. The structure of complex I reveals infinite zigzag chains shaped structure are formed by cis-Ni(En)2-μ-(NC)2, cis-μ-(NC)2Ni(CN)2, and trans-μ-(CN)2Ni(En)2. 相似文献
18.
Kaolinite clay obtained from Ubulu-Ukwu, Delta state in Nigeria was modified with polyvinyl alcohol (PVA) reagent to obtain
PVA-modified Kaolinite clay adsorbent. Scanning Electron Microscopy (SEM) of the PVA-modified adsorbent suggests that Kaolinite
clay particles were made more compact in nature with no definite structure. Modification of Kaolinite clay with PVA increased
its adsorption capacity for 300 mg/L Pb2+ and Cd2+ by a factor of at least 6, i.e., from 4.5 mg/g to 36.23 mg/g and from 4.38 mg/g to 29.85 mg/g, respectively, at 298 K. Binary
mixtures of Pb2+ and Cd2+ decreased the adsorption capacity of Unmodified Kaolinite clay for Pb2+ by 26.3% and for Cd2+ by 0.07%, respectively. In contrast, for PVA-modified Kaolinite clay, the reductions were up to 50.9% and 58.5% for Pb2+ and Cd2+, respectively.
The adsorption data of Pb2+ and Cd2+ onto both Unmodified and PVA-modified Kaolinite clay adsorbents were found to fit the Pseudo-Second Order Kinetic model (PSOM),
indicating that adsorption on both surfaces was mainly by chemisorption and is concentration dependent. However, kinetic adsorption
data from both adsorbent generally failed the Pseudo-First order Kinetic model (PFOM) test.
Extents of desorption of 91% Pb2+ and 94% Cd2+ were obtained, using 0.1 M HCl, for the Unmodified Kaolinite clay adsorbent. It was found that 99% Pb2+ and 97% Cd2+, were desorbed, for PVA-modified Kaolinite clay adsorbents within 3 min for 60 mg/L of the metal ions adsorbed by the adsorbents. 相似文献
19.
N. V. Aksenov H. Bruchertseifer G. Ya. Starodub G. K. Vostokin E. E. Tereshatov G. A. Bozhikov S. V. Shishkin S. N. Dmitriev 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):341-343
A rapid method for the preparation of 87Y/87mSr radionuclide generator from a rubidium chloride target irradiated with 35 MeV α-particles is described. A simple two-step
procedure is used to obtain a carrier-free 87mSr isotope with a high enough radiochemical yield and high purity in the final aqueous fraction. 相似文献
20.
V. N. Belyaev N. L. Lebedeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1841-1850
Using the third law of thermodynamics, we found the enthalpy Δr
H
o(0) = 71 ± 7 of the reaction Eu+ + H2O ↔ EuOH+ + H and the binding energies D
0(Eu+-OH) = 423 ± 7 and D
0(Eu-OH) = 389 ± 11 (kJ/mol). To determine the latter, we additionally used the ionization potential I
0(EuOH) = 5.32 ± 0.08 eV found using the Stark intramolecular effect. 相似文献