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1.
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
2.
To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2S2(SR)4]2− (R=—H, —CH3) are chosen for evaluation. This purpose is realized by calculating the local spin expectation values 〈S
A·S
B〉, 〈S
A
2
〉, and m
A and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry
approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory
(DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic
coupling constants J
AB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results
previously reported.
Supported by the Doctorial Initial Foundations of Hainan Normal University (Grant No. 13140252) 相似文献
3.
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
4.
The Gibbs free energies of solvation (ΔG
s) and the electronic structures of endohedral metallofullerenes M+@C60 (M+= Li+, K+) were calculated within the framework of the density functional theory and the polarizable continuum model. In water environment,
the equilibrium position of K+ is at the center of the fullerene cavity whereas that of Li+ is shifted by 0.14 nm toward the fullerene cage. The Li+ cation is stabilized by interactions with both the fullerene and solvent. The equilibrium structures of both endohedral metallofullerenes
are characterized by very close ΔG
s values. In particular, the calculated ΔG
s values for K+@C60 are in the range from −124 to −149 kJ mol−1 depending on the basis set and on the type of the density functional. Molecular dynamics simulations (TIP3P H2O, OPLS force field, water sphere of radius 1.9 nm) showed that the radial distribution functions of water density around
C60 and M+@C60 are very similar, whereas orientations of water dipoles around the endohedral metallofullerenes resemble the hydration pattern
of isolated metal ions. 相似文献
5.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献
6.
Gholam Hossein Rounaghi Mohammad Hossein Arbab Zavvar Kataneh Badiee 《Russian Journal of Inorganic Chemistry》2008,53(4):660-664
The equilibrium constants and thermodynamic parameters for complex formation of 18-Crown-6 (18C6) with Tl+, Pb2+, Hg2+, and Zn2+ metal cations have been determined by conductivity measurements in methanol (MeOH)-water (H2O) binary solutions. 18-Crown-6 forms 1:1 complexes with Hg2+ and Zn2+ cations, but in the case of Tl+ and Pb2+ cations, in addition to 1:1 stoichiometry, 1:2 (ML2) complexes are formed in some binary solvents. The thermodynamic parameters (ΔH
c0 and ΔS
c0), which were obtained from the temperature dependences of equilibrium constants, show that in most cases the complexes are
enthalpy destabilized but entropy stabilized. Non-linear behavior is observed between the equilibrium constants (log K
f
) of complexes and the composition of the mixed solvent. The selectivity of the ligand for these metal cations is sensitive
to the solvent composition, and, in some cases, the selectivity order is reversed in certain compositions of the mixed solvent.
The results also show that the mechanism of complexation reactions and the stoichiometry of complexes of some metal cations
change with the nature and even with the composition of the mixed solvent.
The article was submitted by the authors in English. 相似文献
7.
The spin Hamiltonian parameters (g factors, hyperfine structure constants and superhyperfine parameters) and local structures for Ag2+ centers in AgCl and KCl crystals are theoretically studied using the high-order perturbation formulas for a tetragonally elongated 4d 9 cluster. The impurity centers undergo relative elongations (≈0.05 Å and 0.23 Å for Ag2+ in AgCl and KCl, respectively) along the C 4 axis owing to the Jahn–Teller effect. All the calculated spin Hamiltonian parameters show good agreement with the experimental data, and the ligand contributions to the spin Hamiltonian parameters are important and should be taken into account. The unpaired spin densities in the superhyperfine parameters are determined from molecular orbital coefficients based on the cluster approach, instead of being taken as the adjustable parameters in the previous treatments. Increasing tetragonal elongation from AgCl to KCl is attributed to a decrease in chemical bonding (or lower force constant) with increasing Ag2+–Cl distance. 相似文献
8.
H. M. Ye N. Ren H. Li J. J. Zhang S. J. Sun L. Tian 《Journal of Thermal Analysis and Calorimetry》2010,101(1):205-211
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single
crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process
of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double
equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH
≠, ΔG
≠, and ΔS
≠) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated. 相似文献
9.
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
10.
Summary. The two new compounds Mn(dien)2[MoS4] (1) and Mn(dien)2[Mo2O2S6] (2) (dien = diethylenetriamine) were prepared under solvothermal conditions. Both compounds were obtained as phase-pure products. The
structures consist of new [Mn(dien)2]2+ cations and isolated tetrahedral [MoS4]2− (1) or [Mo2O2S6]2− (2) anions. Between the anions and the cations, hydrogen bonding is observed. Compound 1 crystallizes in the tetragonal space group I (a = 10.219(2), c = 9.259(2) ?, Z = 2), whereas 2 crystallizes in the monoclinic space group P21/c (a = 8.703(2), b = 18.390(4), c = 14.603(3) ?, β = 103.18(3)°, Z = 4). The thermal behaviour of the thiomolybdates was investigated using difference thermoanalysis (DTA) and thermogravimetry
(TG). Both compounds decompose under argon with a single endothermic signal in the DTA curve (peak maximum: 252 (1) and 242°C (2)).
Received November 5, 2001. Accepted December 27, 2001 相似文献
11.
E. Vessally M. Nikoorazm A. Esmaili H. Ghoudarzi Afshar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(4):631-635
Thermal internal energy gaps, ΔE
s−t; enthalpy gaps, ΔH
s−t; Gibbs free energy gaps, ΔD
s−t, between singlet (s) and triplet (t) states of R2C4H2M (M = C, Si, and Ge) were calculated at B3LYP/6-311++G** level of theory. The ΔG
s−t of R2C4H2C was increased in the order (in kcal/mol): R = −CH3 (−10.51) > −H (−9.59) > i-Pr (−9.51) > t-Bu (−8.98). While, the ΔG
s−t of R2C4H2Si and R2C4H2Ge were increased in the order (in kcal/mol): −CH3 (17.01) > i-Pr (15.30) > −H (15.26) > t-Bu (14.35) and -H (22.79) > −CH3 (22.69) > i-Pr (21.66) > t-Bu (21.01), respectively. 相似文献
12.
L. S. Nikolaeva A. N. Semenov L. I. Burova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2039-2046
Chemical equilibria in the high-molecular-weight heparin (Na4hep)-arginine (HArg)-H2O-NaCl and MCl2-Na4hep-HArg-H2O-NaCl systems of electrolytes (M = Ca2+, Mg2+) were calculated by the method of mathematical simulation of chemical equilibria from representative planned pH-metric titration
experiment at 2.30 ≤ pH ≤ 10.50 in a physiological solution medium in the presence of 0.154 M NaCl as a background electrolyte
at 37°C. The initial concentrations of the basic components were n × 10−3 M (n ≤ 4). 相似文献
13.
Zhen-Qian Zhang Hong Li Juan Xu Su Yao Zheng-He Xu Jin-Gang Liu Liang-Nian Ji 《Transition Metal Chemistry》2007,32(6):776-780
The effects of copper ion on the interaction of [Ru(bpy)2HPIP]2+(bpy = 2,2′-bipyridine, HPIP = 2-(2-hydroxyphenyl) imidazo [4,5-f] [1, 10] phenanthroline) with DNA have been investigated
by electronic absorption spectroscopy and fluorescence spectroscopy. HPIP ligand of the complex with an intramolecular hydrogen
bond can bind Cu2+ in the absence of DNA, as revealed by the absorbance and fluorescence decrease for [Ru(bpy)2HPIP]2+. The resultant heterometallic complex binds to DNA via intercalation of HPIP into the DNA base pairs and its DNA-binding ability is stronger than [Ru(bpy)2HPIP]2+ itself. The DNA bound [Ru(bpy)2HPIP]2+ cannot bind Cu2+ at low Cu2+ concentration and the intramolecular hydrogen bond in HPIP is located inside the DNA helix. While the Cu2+ concentration is relative high, Cu2+ can quench the fluorescence of DNA bound [Ru(bpy)2HPIP]2+. The quenching reason is proposed. 相似文献
14.
L. G. Bulusheva A. V. Okotrub V. V. Bashilov V. I. Sokolov 《Russian Chemical Bulletin》2005,54(12):2730-2734
The electronic structure of the (η2-C60)Pd[P(Ph2)C5H4]2Fe complex was calculated by the “hybrid” B3LYP method. Comparison of the experimental X-ray emission C-Kα spectrum and theoretical
spectrum of the compound demonstrated that the electron interactions between the C60 core, palladium atom, and organometallic fragment are described correctly in the framework of the quantum chemical method
used. The electronic structure of the organometallic fullerene complex can be presented as a set of blocks of orbitals corresponding
to different types of chemical bond.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2640–2644, December, 2005. 相似文献
15.
G. V. Girichev V. V. Rybkin V. V. Tyunina A. V. Krasnov N. V. Tverdova N. P. Kuz’mina I. G. Zaitseva 《Russian Journal of Inorganic Chemistry》2011,56(1):99-103
A mass spectrometric study of the saturated vapor over ytterbium tris(hexafluoroacetylacetonate) Yb(hfa)3 (hfa = CF3-C(O)-CH-C(O)-CF3) and of the vapor overheated up to the thermal decomposition temperature of the complex is presented. The vapor composition
changes markedly with increasing temperature. At T ≈ 370 K, the mass spectrum of the vapor over Yb(hfa)3 indicates the presence of ions containing one to three metal atoms. As the temperature is raised, the ion currents due to
oligomer ions decrease. The oligomers are not detected at T > 440 K. The total decomposition temperature of Yb(hfa)3 is 663(9) K. The second-law enthalpy of sublimation (ΔH
so (380 K)) is 134 ± 7 kJ/mol for the monomer and 138 ± 10 kJ/mol for the dimer. The enthalpy of dissociation of the dimer into
monomer molecules is nearly equal to the enthalpy of sublimation of the monomer and dimer: ΔH
dis(380 K) = 130 ± 15 kJ/mol. 相似文献
16.
D. A. Loginov M. M. Vinogradov Z. A. Starikova P. V. Petrovskii A. R. Kudinov 《Russian Chemical Bulletin》2007,56(11):2162-2165
The visible light irradiation of the [(η5-C6H7)Fe(η-C6H6)]+ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η5-C6H7)Fe(MeCN)3]+ (2). The reaction of 1 with ButNC in MeCN produced the stable isonitrile complex [(η5-C6H7)Fe(ButNC)3]+ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P5) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η5-C6H7)Fe(μ-η:η-cyclo-P5)FeCp*]+ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P5). The structure of the complex [3]PF6 was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007. 相似文献
17.
Lipeng Zhang Hui Zhang Zhiwei Ge Xianjin Yu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):537-546
The fate and transport of toxic metal ions and radionuclides in the environment is generally controlled by sorption reactions.
The removal of 60Co(II) from wastewaters by MnO2 was studied as a function of various environmental parameters such as shaking time, pH, ionic strength, foreign ions, and
humic substances under ambient conditions. The results indicated that the sorption of 60Co(II) on MnO2 was strongly dependent on pH and ionic strength. At low pH, the sorption of 60Co(II) was dominated by outer-sphere surface complexation and ion exchange with Na+/H+ on MnO2 surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The presence of HA/FA enhances
60Co(II) sorption at low pH values, whereas reduces 60Co(II) sorption at high pH values. The Langmuir and Freundlich models were used to simulate the sorption isotherms of 60Co(II) at three different temperatures of 298.15, 318.15 and 338.15 K. The thermodynamic parameters (ΔH
0, ΔS
0 and ΔG
0) calculated from the temperature dependent sorption isotherms indicated that the sorption process of 60Co(II) on MnO2 was endothermic and spontaneous. 相似文献
18.
The mechanism of the spin-forbidden reaction Ti+(4F, 3d24s1) + C2H4→TiC2H2
+ (2A2) + H2 on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points
between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling
(SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm−1 in the intermediate complex IM1-4B2. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-2A1, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct
reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the
lowest energy path on the doublet PES to exothermic TiC2H2
+(2A2) + H2 products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti++C2H4→4IC→IM1-4B2→4,2ISC→IM1-2A1→[2TSins]→IM2→[2TSMCTS]→IM5→TiC2H2
+(2A2)+H2.
Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University. 相似文献
19.
Nopsiri Chaiyo Rangson Muanghlua Surasak Niemcharoen Banjong Boonchom Panpailin Seeharaj Naratip Vittayakorn 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1023-1029
The thermal transformation of Na2C2O4 was studied in N2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique
(XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger–Akahira–Sunose (KAS)
methods. The activation energies (E
α) of Na2C2O4 decomposition were found to be consistent. Decreasing E
α at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated
through the Liqing–Donghua method was ‘cylindrical symmetry (R2 or F1/2)’ of the phase boundary mechanism. Thermodynamic functions (ΔH*, ΔG* and ΔS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy
pathway and revealed a very hard mechanism. 相似文献
20.
Ashmi T. Patel Heena R. Shevde Arun Pratap 《Journal of Thermal Analysis and Calorimetry》2012,107(1):167-170
Recently, multicomponent glass forming alloys have been found which exhibit extraordinary glass forming ability and cooling
rates of less than 100 K/s are sufficient to suppress nucleation of crystalline phases and consequently bulk metallic glass
(BMG) is formed. The undercooled melts of BMG systems have high thermal stability in the undercooled region. Therefore, it
is interesting to study the thermodynamics of such materials. This article investigates the thermodynamic behavior of a BMG
system namely Zr52.5Cu17.9Ni14.6Al10Ti5 by estimating the Gibbs free energy difference ΔG, entropy difference ΔS, enthalpy difference ΔH between the undercooled liquid and corresponding equilibrium crystalline solid phase, in the entire temperature range from
T
m to T
K. Glass forming ability (GFA) of this system has been investigated through various GFA parameters indicating the degree of
ease of glass formation. 相似文献