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1.
The complexation of Eu(III), Am(III) and Cm(III) with dicarboxylate anions with O, N or S donor groups was measured in I=6.60 mol⋅kg−1 (NaClO4) at temperatures of 0–60 °C by potentiometry and solvent extraction. The complexation thermodynamics of these complexes show
that their stability is due to highly favorable complexation entropies because the complexation enthalpies are endothermic.
Luminescence studies with Eu(III) and Cm(III) were used to measure the hydration numbers of the complexes. NMR spectra of
1H and 13C were used to determine the binding modes of La(III) with the ligands. The formation of 1:1:1 ternary complexes of M(EDTA)− with the dicarboxylate ligands was studied to determine changes in coordination of the metal cation with formation of the
ternary species. The complexation of ternary complexes changes from bidentate to monodentate as the chain length between the
binding sites of the dicarboxylates increases from 1 (malonate) to 4 (adipate). DFT computations were used to confirm the
structural aspects of the interaction of these complexes. 相似文献
2.
Vadim V. Krongauz 《Journal of Thermal Analysis and Calorimetry》2010,102(2):435-445
Kinetics of N-methyl pyrrolidone evaporation from swollen photo-crosslinked polyacrylate was monitored thermogravimetrically at temperatures
ranging from 323 to 398 K. Crosslink density dependence of evaporation kinetics was investigated in photo-crosslinked polyacrylates
with crosslinked density ranging from ≈1.2 × 102 to ≈1.7 × 104 mol m−3 and number of main chain atoms between crosslinks ranging from ≈70 atoms to ≈6 atoms, respectively. As was shown, evaporation
kinetics was controlled by the solvent diffusion in polymer. Activation energies of evaporation (diffusion) were deduced from
the rate measurements at different temperatures. Apparent activation energy of evaporation decreased from 48.7 to 31.1 kJ mol−1 with crosslink density increase. Activation energy of pure N-methyl pyrrolidone evaporation was 50.6 kJ mol−1. Decrease of the rate of solvent diffusion and unexpected decrease of diffusion activation energy with increase of crosslink
density of swollen polymer matrix was explained by decrease in polymer chain segments mobility, as indicated by Eyring’s approach
to diffusion in polymers. 相似文献
3.
Manuel A. V. Ribeiro da Silva Luísa M. P. F. Amaral 《Journal of Thermal Analysis and Calorimetry》2010,100(2):375-380
The standard (p
o = 0.1 MPa) molar enthalpies of formation
\Updelta\textf H\textm\texto ( \textl), {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} ( {\text{l),}} of the liquid 2-methylfuran, 5-methyl-2-acetylfuran and 5-methyl-2-furaldehyde were derived from the standard molar energies
of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was
used to measure the enthalpies of vaporization of the three compounds. The standard (p
o = 0.1 MPa) molar enthalpies of formation of the compounds, in the gaseous phase, at T = 298.15 K have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard
molar enthalpies of vaporization. The results obtained were −(76.4 ± 1.2), −(253.9 ± 1.9), and −(196.8 ± 1.8) kJ mol−1, for 2-methylfuran, 5-methyl-2-acetylfuran, and 5-methyl-2-furaldehyde, respectively. 相似文献
4.
A. I. Lytkin N. V. Chernyavskaya V. E. Litvinenko V. M. Nikol’skii 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(6):899-902
The enthalpies of complex formation between iminodisuccinic acid (H4L) and the Cd2+ ion were determined calorimetrically at 298.15 K and ionic strengths 0.5, 1.0, and 1.5 (KNO3). The thermodynamic characteristics of formation of CdL2− and CdHL− complexes at fixed and zero ionic strength values were calculated. 相似文献
5.
G. Rezaei Behbehani E. Tazikeh A. A. Saboury A. Divsalar M. Monajjemi 《Journal of solution chemistry》2010,39(2):153-164
A thermodynamic study on the interaction between the Cu2+ ion and human growth hormone (hGH) was studied at the temperatures 300.15 and 310.15 K in NaCl solution using isothermal
titration calorimetry. The new solvation model was used to reproduce the enthalpies of Cu2++hGH interaction over the whole range of Cu2+ concentrations. It was found that there is a set of three identical and non-interacting binding sites for Cu2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 1313.4 μmol⋅L−1 and −16.80 kJ⋅mol−1 at 300.15 K, and 1648.2 μmol⋅L−1 and −16.40 kJ⋅mol−1 and 310.15 K, respectively. The binding parameters recovered from the new equation are attributed to a structural change
of hGH and its biological activity due to metal ion interaction. 相似文献
6.
The vaporization enthalpies and liquid vapor pressures from T = 298.15 K to T = 400 K of 1,3,5-triazine, pyrazine, pyrimidine, and pyridazine using pyridines and pyrazines as standards have been measured
by correlation-gas chromatography. The vaporization enthalpies of 1,3,5-triazine (38.8 ± 1.9 kJ mol−1) and pyrazine (40.5 ± 1.7 kJ mol−1) obtained by these correlations are in good agreement with current literature values. The value obtained for pyrimidine (41.0 ± 1.9 kJ mol−1) can be compared with a literature value of 50.0 kJ mol−1. Combined with the condensed phase enthalpy of formation in the literature, this results in a gas-phase enthalpy of formation,
Δf
H
m (g, 298.15 K), of 187.6 ± 2.2 kJ mol−1 for pyrimidine, compared to a value of 195.1 ± 2.1 calculated for pyrazine. Vapor pressures also obtained by correlation
are used to predict boiling temperatures (BT). Good agreement with experimental BT (±4.2 K) including results for pyrimidine
is observed for most compounds with the exception of the pyridazines. The results suggest that compounds containing one or
two nitrogen atoms in the ring are suitable standards for correlating various heterocyclic compounds provided the nitrogen
atoms are isolated from each other by carbon. Pyridazines do not appear to be evaluated correctly using pyridines and pyrazines
as standards. 相似文献
7.
St. Perisanu Iulia Contineanu Ana Neacsu Speranta Tanasescu 《Journal of Thermal Analysis and Calorimetry》2010,101(3):1127-1133
The energies of combustion of creatine (anhydrous and monohydrate), creatinine, and arginine were measured in a static bomb
adiabatic calorimeter, in pure oxygen at 3,040 kPa. The derived standard enthalpies of formation in solid state of the above-mentioned
compounds are, respectively, −520.4 ± 4.3, −809.7 ± 1.3, −204.2 ± 7.0, and −634.8 ± 2.3 kJ mol−1
. The data of enthalpy of formation are compared with literature values and with estimated values by means of group additivity. The dehydration of creatine monohydrate and the processes occurring in the three guanidine derivatives at temperatures exceeding
200 °C were investigated by means of DSC. 相似文献
8.
A. I. Lytkin N. V. Chernyavskaya V. E. Litvinenko 《Russian Journal of Coordination Chemistry》2011,37(12):893-896
The enthalpies of complexation between N,N-bis(carboxymethyl)aspartic acid (H4Y) and the Pb2+ ion at 298.15 K were determined from calorimetric data for a wide range of the ionic strengths (KNO3). The thermodynamic characteristics ΔH, ΔG, and ΔS, of formation of the complexes PbHY− and PbY2− were calculated for zero and fixed ionic strengths. The results obtained were interpreted. 相似文献
9.
Xiaoling Xing Fengqi Zhao Liang Xue Kangzhen Xu Jianhua Yi Rongzu Hu 《Journal of solution chemistry》2011,40(8):1427-1434
The dissolution properties of 2-(1,1-dinitromethylene)-1,3-diazepentane in N-methyl pyrrolidone(NMP) were studied with a RD496-2000
Calvet microcalorimeter at three different temperatures. The measured molar enthalpies (Δsol
H) for 2-(1,1-dinitromethylene)-1,3-diazepentane in NMP at T=(298.15,306.15,311.15) K are (5.02, 5.59, 6.67) kJ⋅mol−1, respectively. The differential molar enthalpies (Δdif
H), the specific enthalpies (Δsol
h), and the standard heat effect (Q
Θ) for 2-(1,1-dinitromethylene)-1,3-diazepentane in NMP were obtained at the same time. The kinetic parameters of activation
energy E and pre-exponential factor A are 2.26×104 J⋅mol−1 and 102.06 s−1, which indicate that NMP is a good solvent for the title compound. 相似文献
10.
Adrian Topolski Monika Lipiska Przemysaw Kita Joanna Winiewska 《Transition Metal Chemistry》2008,33(7):843-847
The formation of CuII–Br–FeIII-type heterobimetallic complexes was observed spectrophotometrically, given the non-additivity of the spectra from the copper(II)
and iron(III) complexes. The kinetics of the oxidation of promazine radical (ptz+•) to promazine 5-oxide, by iron(III) bromides, copper(II) bromides, and a mixture of these complexes in acidic aqueous solutions,
have been studied using UV–Vis spectroscopy at I = 1.0 M (H+, Cu2+, Fe3+, Br−) and T = 318 K. Copper(II) inhibits the oxidation of the promazine radical to promazine sulfoxide using iron(III) complexes. A rate
retardation effect, characterized by the dependence of the pseudo second-order rate constant (k
II) on the copper(II) concentration k
II = a/(1 + b[CuII]), can be rationalized as a result of CuII–Br–FeIII-type heterobimetallic complex formation. 相似文献
11.
Stefan Perişanu Iulia Contineanu Mircea D. Banciu Hui Zhao Nigam Rath James Chickos 《Structural chemistry》2006,17(6):639-648
Condensed and gas phase enthalpies of formation of 3:4,5:6-dibenzo-2-hydroxymethylene-cyclohepta-3,5-dienenone (1, (−199.1 ± 16.4), (−70.5 ± 20.5) kJ mol−1, respectively) and 3,4,6,7-dibenzobicyclo[3.2.1]nona-3,6-dien-2-one (2, (−79.7 ± 22.9), (20.1 ± 23.1) kJ mol−1) are reported. Sublimation enthalpies at T=298.15 K for these compounds were evaluated by combining the fusion enthalpies at T = 298.15 K (1, (12.5 ± 1.8); 2, (5.3 ± 1.7) kJ mol−1) adjusted from DSC measurements at the melting temperature (1, (T
fus, 357.7 K, 16.9 ± 1.3 kJ mol−1)); 2, (T
fus, 383.3 K, 10.9 ± 0.1) kJ mol−1) with the vaporization enthalpies at T = 298.15 K (1, (116.1 ± 12.1); 2, (94.5 ± 2.2) kJ mol−1) measured by correlation-gas chromatography. The vaporization enthalpies of benzoin ((98.5 ± 12.5) kJ mol−1) and 7-heptadecanone ((94.5 ± 1.8) kJ mol−1) at T = 298.15 K and the fusion enthalpy of phenyl salicylate (T
fus, 312.7 K, 18.4 ± 0.5) kJ mol−1) were also determined for the correlations. The crystal structure of 1 was determined by X-ray crystallography. Compound
1 exists entirely in the enol form and resembles the crystal structure found for benzoylacetone. 相似文献
12.
V. H. Whitley D. E. Hooks K. J. Ramos J. F. O’Hara A. K. Azad A. J. Taylor J. Barber R. D. Averitt 《Analytical and bioanalytical chemistry》2009,395(2):315-322
The far infrared spectra of (100), (010), and (001)-oriented RDX single crystals were measured as the crystal was rotated
about the axis perpendicular to the polarization plane of the incident radiation. Absorption measurements were taken at temperatures
of both 20 K and 295 K for all rotations using terahertz time–domain spectroscopy. A number of discrete absorptions were found
ranging from 10–100 cm−1 (0.3–3 THz). The absorptions are highly dependent on the orientation of the terahertz polarization with respect to crystallographic
axes. 相似文献
13.
14.
J. E. Vargas L. Giraldo J. C. Moreno-Piraján 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1105-1109
Immersion enthalpies of activated carbon samples obtained by activation with steam at temperatures between 600 and 900 °C
and activation times between 1 and 10 h were determined. The calorimetric liquids of immersion are CCl4, water, NaOH, and HCl 2 M solutions, and the values of the immersion enthalpies are related to other properties of the activated
carbons such as the surface area B.E.T., the micropore volume, the content of acid, and basic surface groups. The highest
values for the immersion enthalpies take place for the polar solvent CCl4 and for HCl solution, with values between 4.0 and 75.2 J g−1 and 9.15 and 48.3 J g−1, respectively. 相似文献
15.
Guillaume Maurin Youssef Belmabkhout Gerhard Pirngruber Lucia Gaberova Philip Llewellyn 《Adsorption》2007,13(5-6):453-460
Grand Canonical Monte Carlo simulations combined with adsorption measurements have been carried out to gain further insight
into the CO2 adsorption process at the microscopic scale in both LiY and NaY faujasites at various temperatures. A new Li+−CO2 force field derived by ab initio calculations was validated by a reasonable agreement between the simulated isotherms and those obtained by experiments in
a wide range of temperature (from 323 K to 473 K). In addition, the microscopic mechanisms of CO2 adsorption in both systems, consistent with the trends observed for the simulated differential enthalpies of adsorption as
a function of the loading, were proposed. It was observed that two different types of adsorption behaviour exist for NaY and
LiY at 323 K and 373 K, mainly caused by the significant more exposed position of the SII Na+ from the six-ring plane of the supercage compared to those occupied by the SII Li+, whereas at higher temperature, both faujasites exhibit the same flat profile for the differential enthalpy of adsorption
as a function of loading. 相似文献
16.
Linfeng Rao Guoxin Tian Thandankorai G. Srinivasan PierLuigi Zanonato Plinio Di Bernardo 《Journal of solution chemistry》2010,39(12):1888-1897
Spectrophotometric titrations were performed to identify the Np(V)/acetate complex and determine the equilibrium constants
at various temperatures (T=283 to 343 K) and at the ionic strength 1.05 mol⋅kg−1. The enthalpies of complexation at the corresponding temperatures were determined by microcalorimetric titrations. Results
show that the complexation of Np(V) with acetate is weak but strengthens as the temperature increases. The complexation reaction
is endothermic and entropy driven. The enhancement of complexation at higher temperatures is primarily due to the increasingly
larger entropy gain when the solvent molecules are released from the highly-ordered solvation spheres of NpO2+\mathrm{NpO}_{2}^{+} and acetate to the bulk solvent where the degree of disorder is higher at higher temperatures. 相似文献
17.
Zofia Rzączyńska Anna Danczowska-Burdon Justyna Sienkiewicz-Gromiuk 《Journal of Thermal Analysis and Calorimetry》2010,101(2):671-677
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light
lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas
Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate
lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO− groups appear thus indicating that complexation process took place. 相似文献
18.
Abstract
Cholesterol complexes with tri-n-butyl phosphate, tri-n-octylamine, N,N-dimethylacetamide, and cyclohexanone in benzene and toluene solutions were studied using conventional IR spectroscopy. The spectra were recorded in the region of fundamental OH stretching (3,700–3,100 cm−1) at 298 K. The experimental spectra were resolved into bands corresponding to the cholesterol monomer and particular oligomeric and complex species. The formation constants of complexes were determined from the-least squares plots of the linearized expressions of Bjerrum’s formation function. The stoichiometry of complexes was also identified in this way. The identification of the particular resolved bands was performed from their location, and from the dependence of their intensity on the cholesterol monomer and free base concentration. 相似文献19.
Makoto Takezaki Hiroyuki Aoki Michiko Kodama Toshihiro Tominaga 《Journal of Thermal Analysis and Calorimetry》2010,101(3):1149-1153
The solubility of hexadecyltrimethylammonium tetrachloroaurate (CTA·AuCl4) in water was measured at different temperatures of 288.2, 293.2, 298.2, 303.2, and 308.2 K. The enthalpy change associated
with the formation of the CTA·AuCl4 precipitate was estimated on the basis of the van’t Hoff equation and was found to be −42.5 ± 2.8 kJ mol−1 at 298.2 K. The calorimetric enthalpy change for the CTA·AuCl4 precipitate formation was directly determined by isothermal titration calorimetry performed at 298.2 K and was found to agree
well with that estimated from the van’t Hoff equation. 相似文献
20.
V. S. Sudavtsova M. I. Ivanov V. V. Berezutskii V. G. Kudin M. A. Shevchenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(12):2237-2240
Partial and integral mixing enthalpies of melts of the Eu-Sn system were determined by calorimetry at 1300 (1250) K in the
concentration intervals 0 < x
Sn < 0.16 and 0.7 < x
Sn < 1. It was found that the first partial mixing enthalpies of Sn and Eu were −215.6 ± 10.6 and −161.2 ± 7.6 kJ/mol, respectively.
The thermodynamic properties of the Eu-Sn alloys were modeled using the theory of ideal associated solutions over a wide interval
of concentrations and temperatures. In was found that the activities of components exhibit strong negative deviations from
Raoult’s law. At minimum, the calculated integral Gibbs energies of mixing reach −43.4 kJ/mol at x
Sn = 0.48; ΔG
ex = −36 kJ/mol, ΔS
ex = −22 J/(mol K). 相似文献