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1.
Zhi-Heng Zhang Guo-Yin Yin Zhi-Cheng Tan Yan Yao Li-Xian Sun 《Journal of solution chemistry》2006,35(10):1347-1355
The molar heat capacities of an aqueous Li2B4O7 solution were measured with a precision automated adiabatic calorimeter in the temperature range from 80 to 356 K at a concentration of 0.3492 mol⋅kg−1. The occurrence of a phase transition was determined based on the changes in the curve of the heat capacity with temperature. A phase transition was observed at 271.72 K corresponding to the solid-liquid phase transition; the enthalpy and entropy of the phase transition were evaluated to be Δ H
m = 4.110 kJ⋅mol−1 and Δ S
m = 15.13 J⋅K−1⋅mol−1, respectively. Using polynomial equations and thermodynamic relationship, the thermodynamic functions [H
T
−H
298.15] and [S
T
−S
298.15] of the aqueous Li2B4O7 solution relative to 298.15 K were calculated in temperature range 80 to 355 K at intervals of 5 K. Values of the relative apparent molar heat capacities of the aqueous Li2B4O7 solution, C
p,φ, were calculated at every 5 K in temperature range from 80 to 355 K from the experimental heat capacities of the solution and the heat capacities of pure water. 相似文献
2.
The mean apparent molar volume of cyclohexylsulfamic acid has been determined from the density data of aqueous solutions up
to a molality of 0.540 mol⋅kg−1 and at 293.15, 298.15, 303.15, 313.15, and 323.15 K. The mean apparent molar volume of the acid was divided into contributing
ionic and molecular apparent molar volumes. The limiting apparent molar volume of the molecular acid amounts to (131.69± 0.02)
cm3⋅mol−1 and the limiting apparent molar expansibility to (0.130± 0.003) cm3⋅mol−1⋅K−1 at 298.15 K. From the limiting ionic and molecular apparent molar volumes the limiting volume change of ionization of cyclohexylsulfamic
acid was calculated. A value of −7.76 cm3⋅mol−1 was evaluated at 298.15 K. The temperature dependence of the volume change of ionization amounts to −(0.018± 0.009) cm3⋅mol−1⋅K−1. From the density data the coefficient of thermal expansion of the investigated solutions was calculated and from this the
mean apparent molar expansibility of cyclohexylsulfamic acid was derived. 相似文献
3.
4.
Daniela Ž. Popović Jelena Miladinović Milica D. Todorović Milorad M. Zrilić Joseph A. Rard 《Journal of solution chemistry》2011,40(5):907-920
The osmotic coefficients of K2HPO4(aq) have been measured at T=298.15 K by the isopiestic vapor pressure method over the range of molalities from 1.3846 mol⋅kg−1 to 13.939 mol⋅kg−1 (oversaturation) with CaCl2(aq) as the reference solution. The molalities and osmotic coefficients of saturated solutions in equilibrium with K2HPO4⋅xH2O(cr) were measured simultaneously by the same method. Available literature osmotic coefficients of K2HPO4(aq) at T=298.15 K, and our new experimental data, were combined and modeled using an extended form of Pitzer’s equation and the Clegg-Pitzer-Brimblecombe
equation based on the mole-fraction-composition scale. These equations were used to calculate the activity coefficients of
K2HPO4(aq) at T=298.15 K. 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.
Dhanpat Rai Dean A. Moore Nancy J. Hess Kevin M. Rosso Linfeng Rao Steve M. Heald 《Journal of solution chemistry》2007,36(10):1261-1285
Chromium(III)-carbonate reactions are expected to be important in managing high-level radioactive wastes. Extensive studies
on the solubility of amorphous Cr(III) hydroxide solid in a wide range of pH (3–13) at two different fixed partial pressures
of CO2(g) (0.003 or 0.03 atm.), and as functions of K2CO3 concentrations (0.01 to 5.8 mol⋅kg−1) in the presence of 0.01 mol⋅dm−3 KOH and KHCO3 concentrations (0.001 to 0.826 mol⋅kg−1) at room temperature (22±2 °C) were carried out to obtain reliable thermodynamic data for important Cr(III)-carbonate reactions.
A combination of techniques (XRD, XANES, EXAFS, UV-Vis-NIR spectroscopy, thermodynamic analyses of solubility data, and quantum
mechanical calculations) was used to characterize the solid and aqueous species. The Pitzer ion-interaction approach was used
to interpret the solubility data. Only two aqueous species [Cr(OH)(CO3)22− and Cr(OH)4CO33−] are required to explain Cr(III)-carbonate reactions in a wide range of pH, CO2(g) partial pressures, and bicarbonate and carbonate concentrations. Calculations based on density functional theory support
the existence of these species. The log 10
K° values of reactions involving these species [{Cr(OH)3(am) + 2CO2(g)⇌Cr(OH)(CO3)22−+2H+} and {Cr(OH)3(am) + OH−+CO32−
⇌Cr(OH)4CO33−}] were found to be −(19.07±0.41) and −(4.19±0.19), respectively. No other data on any Cr(III)-carbonato complexes are available
for comparisons. 相似文献
8.
Rabindra N. Roy Lakshmi N. Roy Shahaf Ashkenazi Joshua T. Wollen Craig D. Dunseth Michael S. Fuge Jared L. Durden Chandra N. Roy Hannah M. Hughes Brett T. Morris Kevin L. Cline 《Journal of solution chemistry》2009,38(4):449-458
The values of the second dissociation constant, pK
2, of N-(2-hydroxyethyl) piperazine-N′-2-ethanesulfonic acid (HEPES) have been reported at twelve temperatures over the temperature range 5 to 55 °C, including
37 °C. This paper reports the results for the pa
H of eight isotonic saline buffer solutions with an I=0.16 mol⋅kg−1 including compositions: (a) HEPES (0.01 mol⋅kg−1) + NaHEPES (0.01 mol⋅kg−1) + NaCl (0.15 mol⋅kg−1); (b) HEPES (0.02 mol⋅kg−1) + NaHEPES (0.02 mol⋅kg−1) + NaCl (0.14 mol⋅kg−1); (c) HEPES (0.03 mol⋅kg−1) + NaHEPES (0.03 mol⋅kg−1) + NaCl (0.13 mol⋅kg−1); (d) HEPES (0.04 mol⋅kg−1) + NaHEPES (0.04 mol⋅kg−1) + NaCl (0.12 mol⋅kg−1); (e) HEPES (0.05 mol⋅kg−1) + NaHEPES (0.05 mol⋅kg−1) + NaCl (0.11 mol⋅kg−1); (f) HEPES (0.06 mol⋅kg−1) + NaHEPES (0.06 mol⋅kg−1) + NaCl (0.10 mol⋅kg−1); (g) HEPES (0.07 mol⋅kg−1) + NaHEPES (0.07 mol⋅kg−1) + NaCl (0.09 mol⋅kg−1); and (h) HEPES (0.08 mol⋅kg−1) + NaHEPES (0.08 mol⋅kg−1) + NaCl (0.08 mol⋅kg−1). Conventional pa
H values, for all eight buffer solutions from 5 to 55 °C, have been calculated. The operational pH values with liquid junction
corrections, at 25 and 37 °C have been determined based on the NBS/NIST standard between the physiological phosphate standard
and four buffer solutions. These are recommended as pH standards for physiological fluids in the range of pH = 7.3 to 7.5
at I=0.16 mol⋅kg−1. 相似文献
9.
Donald A. Palmer Pascale Bénézeth Caibin Xiao David J. Wesolowski Lawrence M. Anovitz 《Journal of solution chemistry》2011,40(4):680-702
Results of solubility experiments involving crystalline nickel oxide (bunsenite) in aqueous solutions are reported as functions
of temperature (0 to 350 °C) and pH at pressures slightly exceeding (with one exception) saturation vapor pressure. These
experiments were carried out in either flow-through reactors or a hydrogen-electrode concentration cell for mildly acidic
to near neutral pH solutions. The results were treated successfully with a thermodynamic model incorporating only the unhydrolyzed
aqueous nickel species (viz., Ni2+) and the neutrally charged hydrolyzed species (viz., Ni(OH)20)\mathrm{Ni(OH)}_{2}^{0}). The thermodynamic quantities obtained at 25 °C and infinite dilution are, with 2σ uncertainties:
log10Ks0o = (12.40 ±0.29),\varDeltarGmo = -(70. 8 ±1.7)\log_{10}K_{\mathrm{s0}}^{\mathrm{o}} = (12.40 \pm 0.29),\varDelta_{\mathrm{r}}G_{m}^{\mathrm{o}} = -(70. 8 \pm 1.7) kJ⋅mol−1;
\varDeltarHmo = -(105.6 ±1.3)\varDelta_{\mathrm{r}}H_{m}^{\mathrm{o}} = -(105.6 \pm 1.3) kJ⋅mol−1;
\varDeltarSmo = -(116.6 ±3.2)\varDelta_{\mathrm{r}}S_{m}^{\mathrm{o}} =-(116.6 \pm 3.2) J⋅K−1⋅mol−1;
\varDeltarCp,mo = (0 ±13)\varDelta_{\mathrm{r}}C_{p,m}^{\mathrm{o}} = (0 \pm 13) J⋅K−1⋅mol−1; and log10Ks2o = -(8.76 ±0.15)\log_{10}K_{\mathrm{s2}}^{\mathrm{o}} = -(8.76 \pm 0.15);
\varDeltarGmo = (50.0 ±1.7)\varDelta_{\mathrm{r}}G_{m}^{\mathrm{o}} = (50.0 \pm 1.7) kJ⋅mol−1;
\varDeltarHmo = (17.7 ±1.7)\varDelta_{\mathrm{r}}H_{m}^{\mathrm{o}} = (17.7 \pm 1.7) kJ⋅mol−1;
\varDeltarSmo = -(108±7)\varDelta_{\mathrm{r}}S_{m}^{\mathrm{o}} = -(108\pm 7) J⋅K−1⋅mol−1;
\varDeltarCp,mo = -(108 ±3)\varDelta_{\mathrm{r}}C_{p,m}^{\mathrm{o}} = -(108 \pm 3) J⋅K−1⋅mol−1. These results are internally consistent, but the latter set differs from those gleaned from previous studies recorded in
the literature. The corresponding thermodynamic quantities for the formation of Ni2+ and Ni(OH)20\mathrm{Ni(OH)}_{2}^{0} are also estimated. Moreover, the Ni(OH)3 -\mathrm{Ni(OH)}_{3}^{ -} anion was never observed, even in relatively strong basic solutions (mOH - = 0.1m_{\mathrm{OH}^{ -}} = 0.1 mol⋅kg−1), contrary to the conclusions drawn from all but one previous study. 相似文献
10.
Lebedev B. V. Bykova T. A. Lobach A. S. 《Journal of Thermal Analysis and Calorimetry》2000,62(1):257-265
The temperature dependence of the molar heat capacity (C0
p) of hydrofullerene C60H36 between 5 and 340 K was determined by adiabatic vacuum calorimetry with an error of about 0.2%. The experimental data were
used for the calculation of the thermodynamic functions of the compound in the range 0 to340 K. It was found that at T=298.15 K and p=101.325 kPa C0
p (298.15)=690.0 J K−1 mol−1,Ho(298.15)−Ho(0)= 84.94 kJ mol−1,So(298.15)=506.8 J K−1 mol−1, Go(298.15)−Ho(0)= −66.17 kJ mol−1. The standard entropy of formation of hydrofullerene C60H36 and the entropy of reaction of its formation by hydrogenation of fullerene C60 with hydrogen were estimated and at T=298.15 K they were ΔfSo= −2188.4 J K−1 mol−1 and ΔrSo= −2270.5 J K−1mol−1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Fursemide is the chemical compound 4-chloro-2-(furan-2-ylmethylamino)-5-(aminosulfonyl) benzoic acid. It was oxidized by diperiodatocuprate(III)
in alkali solutions, and the oxidation products were identified as furfuraldehyde and 2-amino-4-chloro-5-(aminosulfonyl) benzoic
acid. The reaction kinetics were studied spectrophotometrically. The reaction was observed to be first order in [oxidant]
and fractional order each in [fursemide] and [periodate], whereas added alkali retarded the rate of reaction. The reactive
form of the oxidant was inferred to be [Cu(H3IO6)2]−. A mechanism consistent with the experimental results was proposed, in which oxidant interacts with the substrate to give
a complex as a pre-equilibrium state. This complex decomposed in a slow step to give a free radical that was further oxidized
by reaction with another molecule of DPC to yield 2-amino-4-chloro-5-(aminosulfonyl) benzoic acid and furfuraldehyde in a
fast step. This reaction was studied at 25, 30, 35, 40 and 45 °C, and the activation parameters E
a,ΔH
#,ΔS
# and ΔG
# were determined to be 51 kJ⋅mol−1,48.5 kJ⋅mol−1,−63.5 J⋅K−1⋅mol−1 and 67 kJ⋅mol−1, respectively. The value of log 10
A was calculated to be 6.8. 相似文献
12.
Mahmoud M. Al Omari Mohammad B. Zughul J. Eric D. Davies Adnan A. Badwan 《Journal of solution chemistry》2008,37(6):875-893
Guest–host interaction of astemizole (Astm) with cyclodextrins (CDs) has been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), proton nuclear magnetic resonance (1H-NMR) and molecular mechanical modeling (MM+). Estimates of the complex formation constant, K
11, show that the tendency of Astm to complex with CDs follows the order: β-CD>HP-β-CD>γ-CD, α-CD. 1:1 Astm/β-CD complex formation at pH=5.0 was largely driven by the hydrophobic effect (desolvation), which was quantitatively estimated
at −16.5 kJ⋅mol−1, whereas specific interactions contribute only −5.3 kJ⋅mol−1 to 1:1 complex stability (ΔG
11o=−22.7 kJ⋅mol−1). The percentage contributions of the hydrophobic effect and specific interactions were therefore 73 and 27%, respectively.
Both enthalpic and entropic factors contribute equally well (−11 kJ⋅mol−1 each) to 1:1 Astm/β-CD complex stability. 1H-NMR and MM+ molecular modeling studies indicate the formation of different isomeric 1:1 and 1:2 complexes. The dominant driving force
for complexation is evidently van der Waals with very little electrostatic contribution. PSD, 1H-NMR, DSC, XRPD and MM+ studies proved the formation of inclusion complexes in solution and the solid state. 相似文献
13.
Liang Xue Feng-Qi Zhao Xiao-Ling Xing Zhi-Ming Zhou Kai Wang Hong-Xu Gao Jian-Hua Yi Rong-Zu Hu 《Journal of Thermal Analysis and Calorimetry》2010,102(3):989-992
The thermal decomposition behavior of 3,4,5-triamino-1,2,4-triazole dinitramide was measured using a C-500 type Calvet microcalorimeter
at four different temperatures under atmospheric pressure. The apparent activation energy and pre-exponential factor of the
exothermic decomposition reaction are 165.57 kJ mol−1 and 1018.04 s−1, respectively. The critical temperature of thermal explosion is 431.71 K. The entropy of activation (ΔS
≠), enthalpy of activation (ΔH
≠), and free energy of activation (ΔG
≠) are 97.19 J mol−1 K−1, 161.90 kJ mol−1, and 118.98 kJ mol−1, respectively. The self-accelerating decomposition temperature (T
SADT) is 422.28 K. The specific heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide was determined with a micro-DSC method
and a theoretical calculation method. Specific heat capacity (J g−1 K−1) equation is C
p = 0.252 + 3.131 × 10−3
T (283.1 K < T < 353.2 K). The molar heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide is 264.52 J mol−1 K−1 at 298.15 K. The adiabatic time-to-explosion of 3,4,5-triamino-1,2,4-triazole dinitramide is calculated to be a certain value
between 123.36 and 128.56 s. 相似文献
14.
Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at 298.15 K with an estimated uncertainty of ±3 kJ · mol−1. A comprehensive set of thermodynamic data for otavite (CdCO3), smithsonite (ZnCO3), hydrozincite (Zn5(OH)6(CO3)2), malachite (Cu2(OH)2CO3), azurite (Cu3(OH)2(CO3)2), and siderite (FeCO3) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given by various data bases deviate from each other by more than 10 kJ · mol−1 which can be attributed to a discrepancy in the auxiliary data for the Fe2+ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic properties valid at infinite dilution, T = 298.15 K, and p = 105 Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous solution is reviewed. 相似文献
15.
Qing-Fen Meng Zhi-Cheng Tan Ya-Ping Dong Hai-Tao Feng Xiao-Huan Wang Quan Shi Wu Li 《Journal of solution chemistry》2010,39(7):1087-1098
The molar heat capacities of three different concentrations of aqueous SrCl2 solutions, 0.1212, 0.4615 and 1.878 mol⋅kg−1, were measured, using a precision automated adiabatic calorimeter in the temperature range from 80 to 320 K. Solid–liquid
phase transitions were observed at 272.83, 270.18 and 255.15 K, respectively, for these three solutions. The molar enthalpies
and entropies of the phase transitions were evaluated. The experimental heat capacity data were fitted to polynomial equations,
and based on the polynomial equations and thermodynamic relationship, the thermodynamic functions relative to 298.15 K, [H
T
−H
298.15 K] and [S
T
−S
298.15 K], of the three solutions were derived in the range of 80 to 320 K with an interval of 5 K. 相似文献
16.
The disaccharide isomaltose is produced via an enzymatic reaction and is adsorbed to BEA zeolite. This reaction integrated
adsorption can be achieved as fluidized bed as well as fixed bed. We investigated isotherms, adsorption enthalpies and sorption
kinetics of BEA zeolite and extrudates with a novel aluminum phosphate sintermatrix. These extrudates contain 50% (w/w) of
BEA 150 zeolites (Si/Al = 75) as primary crystals. BET-surface for extrudates is 245 m2⋅g−1 and 487 m2⋅g−1 for zeolite. Extrudates show a monomodal macropore structure with a maximum at 90 nm. All isotherms show a type I shape.
For lower equilibrium concentrations, which occur during the enzymatic reaction, Henry’s law is applied and compared to a
Langmuir model. Adsorption equilibrium constant K
i,L
calculated from Langmuir for extrudates at 4 °C is 64.7 mL⋅g−1 and more than twice as high as obtained from Henry’s law with K
i
is 26.8 mL⋅g−1. Adsorption on extrudates at 4 °C is much stronger than on zeolite crystals where the Henry coefficient K
i
is 17.1 mL⋅g−1. Adsorption enthalpy Δh
Ad calculated from van’t Hoff plot with the Henry equation is −44.3 kJ⋅mol−1 for extrudates and −29.6 kJ⋅mol−1 for zeolite crystals. Finally, the kinetics for ad- and desorption were calculated from the initial slope. The diffusion
rate for ad- and desorption on extrudates were in the same range while adsorption on zeolites is three orders of magnitudes
faster than desorption. 相似文献
17.
Summary. Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic
properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry
or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at
298.15 K with an estimated uncertainty of ±3 kJ · mol−1. A comprehensive set of thermodynamic data for otavite (CdCO3), smithsonite (ZnCO3), hydrozincite (Zn5(OH)6(CO3)2), malachite (Cu2(OH)2CO3), azurite (Cu3(OH)2(CO3)2), and siderite (FeCO3) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility
experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given
by various data bases deviate from each other by more than 10 kJ · mol−1 which can be attributed to a discrepancy in the auxiliary data for the Fe2+ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard
enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic
properties valid at infinite dilution, T = 298.15 K, and p = 105 Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous
solution is reviewed.
Received June 26, 2001. Accepted July 2, 2001 相似文献
18.
E. Tazikeh Lemeski G. Rezaei Behbehani A. A. Saboury M. Monajjemi R. Zafar Mehrabian M. Ahmadi Golsefidi H. Rajabzadeh M. T. Baei S. Hasanzadeh 《Journal of solution chemistry》2011,40(4):575-586
The interaction of human growth hormone (hGH) with the divalent mercury ion was studied by isothermal titration calorimetry
at two temperatures of 27 °C and 37 °C in aqueous solutions. We found that there is a set of two identical and non-interacting
binding sites for Hg2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 4.2 mmol⋅L−1 and −14.8 kJ⋅mol−1 at 27 °C and 5.1 mmol⋅L−1 and −14.2 kJ⋅mol−1 at 37 °C, respectively. The results obtained indicate that the stability of the protein increases due to the binding of mercury
ions using the extended solvation theory. 相似文献
19.
Ameer Ghuzlaan Mahmoud M. Al Omari Khaldoun A. Al-Sou’od 《Journal of solution chemistry》2009,38(1):83-94
Guest–host interaction of prednisone (PN) with cyclodextrins (CDs) have been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM). Estimates of the complex formation constant (K
11) show that the tendency of PN to complex with CDs follows the order: β-CD>γ-CD>HP-β-CD>α-CD. At the same pH of 7.0, β-CD forms soluble 1:1 and insoluble 1:2 PN/CD complexes (BS-type PSDs). The thermodynamic functions for 1:1 PN/β-CD estimated at pH = 7.0 (ΔG
11o=−20.8 kJ⋅mol−1) show that complexation is driven by enthalpy (−30.7 kJ⋅mol−1) but retarded by entropy (ΔS
11o=−33.1 J⋅mol−1⋅K−1) changes. The MM modeling study indicates the formation of different isomeric 1:1 complexes with CDs. PSD, DSC, XRPD, SEM
and MM studies established the formation of inclusion complexes in solution and the solid state. 相似文献
20.
Mahmoud M. Al Omari Mohammad B. Zughul J. Eric D. Davies Adnan A. Badwan 《Journal of solution chemistry》2009,38(6):669-683
Guest-host interactions of haloperidol (Halo) with β-cyclodextrin (β-CD) have been investigated using several techniques including phase solubility diagrams (PSD), proton nuclear magnetic resonance
(1H-NMR), X-ray powder diffractometry (XRPD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM+).
From an analysis of the PSDs, both protonated and neutral Halo (pK
a=8.5) form soluble 1:1 and 1:2 Halo/β-CD complexes, while the insoluble complex has 1:2 (Halo:β-CD) stoichiometry (BS-type PSD). Ionization of Halo reduces its tendency to complex with β-CD, where the protonated species at pH=4.6 and 6.0 have K
11 values of 100 L⋅mol−1 and 298 L⋅mol−1, respectively, compared with 2000 L⋅mol−1 for neutral species at pH=10.6. The hydrophobic character of Halo was found to provide 32% of the driving force for complex
stability, whereas other factors including specific interactions contribute −15 kJ⋅mol−1.
1H-NMR and MM+ studies indicate the formation of isomeric 1:1 and 1:2 complexes, where the chlorophenyl, flurophenyl, piperidine and butanone
moieties become included into separate β-CD cavities. The dominant driving force for complexation is evidently van der Waals with very little electrostatic contribution.
PSD, 1H-NMR, XRPD, DSC and SEM studies indicate the formation of inclusion complexes in solution and in the solid state. 相似文献