A complex of neodymium perchloric acid coordinated with L-glutamic acid and imidazole, [Nd(Glu)(H2O)5(Im)3](ClO4)6·2H2O was synthesized and characterized by IR and elements analysis for the first time. The thermodynamic properties of the complex
were studied with an automatic adiabatic calorimeter and differential scanning calorimetry (DSC). Glass transition and phase
transition were discovered at 221.83 and 245.45 K, respectively. The glass transition was interpreted as a freezing-in phenomenon
of the reorientational motion of ClO4− ions and the phase transition was attributed to the orientational order/disorder process of ClO4− ions. The heat capacities of the complex were measured with the automatic adiabatic calorimeter and the thermodynamic functions
[HT-H298.15] and [ST-S298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior
of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry
Authors:X. Cao, X. Yang, J. Shi, Y. Liu, and C. Wang
The effect of glucose (0–15 mass%) on the kinetics of bovine serum albumin (BSA) denatured aggregation at high concentration
in aqueous solution has been studied by differential scanning calorimetry. The observed denatured aggregation process was
irreversible and could be characterized by a denaturation temperature (Tm), apparent activation energy (Ea), the approximate order of reaction, and pre-exponential factor (A). As the glucose concentration increased from 0 to 15 mass%, Tm increased, Ea also increased from 514.59409±6.61489 to 548.48611±7.81302 kJ mol−1, and A/s−1 increased from 1.24239E79 to 5.59975E83. The stabilization increased with an increasing concentration of glucose, which was
attributed to its ability to alter protein denatured aggregation kinetics.
The kinetic analysis was carried out using a composite procedure involving the iso-conversional method and the master plots
method. The iso-conversional method indicated that denatured aggregation of BSA in the presence and absence of glucose should
conform to single reaction model. The master plots method suggested that the simple order reaction model best describe the
process. This study shows the combination of iso-conversional method and the master plots method can be used to quantitatively
model the denatured aggregation mechanism of the BSA in the presence and absence of glucose.
Authors:D. Wang, A. Bai, X. Lin, L. Fang, X. Shu, X. Shi, Q. Sun, and X. Wang
Supercritical fluid extraction (SFE) was used to extract shionone from Aster tataricus L. f. The effect of various parameters, i.e., temperature, pressure and sample particle size on yield was investigated with an analytical-scale SFE system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of temperature 40 °C, pressure 30 MPa, and a sample particle size of 40–60 mesh. Then preparative high-speed counter-current chromatography was successfully used for isolation and purification of shionone from the SFE extract with a two-phase solvent system composed of n-hexane-methanol (2:1, volume ratio). The separation produced a total of 75 mg of shionone from 500 mg of the crude extract in one step separation with the purity of 98.7%, respectively, as determined by high-performance liquid chromatography (HPLC) and 92% recovery. The structure of shionone was identified by electrospray ionization-mass spectrometry (ESI-MS), hydrogen-1 nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR).
Authors:S. Chen, X. Yang, Sh. Gao, R. Hu, and Q. Shi
The solid complexes of Cr(NO3)3 with L-α-amino acids (AA=Val, Leu, Thr, Arg, Phe and Try) have been prepared in 95% alcoholic, the compositions of which were identified as the general
formula Cr(AA)2(NO3)32H2O by elemental and chemical analyses. The bonding characteristics of the title complexes were characterized by IR, indicating
that nitrogen and oxygen atoms in the ligands coordinated to Cr3+ in a bidentate fashion. With the aid of TG-DTG and IR techniques, the complexes were subjected to thermal decomposition in
an atmosphere of oxygen, presuming that the decompositions of the complexes consist of two steps and the complexes were decomposed
into chromium hemitrioxide after undergoing dehydration and skeleton splitting of the complexes. The constant volume energies
of combustion of the complexes were determined by a RBC-P type rotating-bomb calorimeter. According to Hess's law, the standard
enthalpies of formation of the complexes were calculated as (-1831.404.40), (-2542.036.13), (-1723.813.99), (-2224.313.02),
(-2911.616.53) and (-659.327.42) kJ mol-1, respectively.
Authors:S. Chen, Sh Gao, X. Yang, R. Hu, and Q. Shi
Solid complexes of M(His)2Cl2nH2O (M=Mn, Co, Ni, Cu) of MnCl26H2O, CoCl26H2O, NiCl26H2O, CuCl22H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses,
IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter.
And the standard enthalpies of formation of the complexes have been calculated as well.
Authors:G. Xie, S. Chen, S. Gao, X. Meng, and Q. Shi
A novel solid complex, formulated as Ho(PDC)3
(o-phen), has been obtained from the reaction
of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and
in absolute ethanol, which was characterized by elemental analysis, TG-DTG
and IR spectrum. The enthalpy change of the reaction of complex formation
from a solution of the reagents, ΔrHmθ (sol), and the molar heat capacity of the complex, cm,
were determined as being –19.1610.051 kJ mol–1
and 79.2641.218 J mol–1 K–1
at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy
change of complex formation from the reaction of the reagents in the solid
phase, ΔrHmθ(s), was calculated as
being (23.9810.339) kJ mol–1 on the
basis of an appropriate thermochemical cycle and other auxiliary thermodynamic
data. The thermodynamics of reaction of formation of the complex was investigated
by the reaction in solution at the temperature range of 292.15–301.15
K. The constant-volume combustion energy of the complex, ΔcU, was determined as being –16788.467.74
kJ mol–1 by an RBC-II type rotating-bomb
calorimeter at 298.15 K. Its standard enthalpy of combustion, ΔcHmθ, and standard enthalpy of formation,
ΔfHmθ, were calculated to be –16803.957.74 and –1115.428.94
kJ mol–1, respectively.
Authors:S. Dong, X. Shi, Q. Liu, Z. Zhang, and L. Zhao
A simple hydrolysis method has been developed for determination of phenylethanoid glycosides in Lamiophlomis rotata (L.R.). Different kinds of phenylethanoid glycosides were hydrolyzed in hydrochloric acid solution to produce corresponding phenethyl alcohols and cinnamic acids, mainly containing hydroxytyrosol, homovanillyl alcohol, 3,4-dimethoxyphenethyl alcohol, caffeic acid, fumalic acid and 3,4-dimethoxycinnamic acid. The six analytes could be determined simultaneously by high-performance liquid chromatography (HPLC). The effects of mobile phase, pH and concentration of running buffer, detection wavelength, flow rate and injection volume were also investigated. Under the optimum conditions, the six hydrolyzates could be perfectly separated within 45 min. The response was linear over four orders of magnitude with detection limits (S/N = 3) ranging from 1 × 10−8 to 1.5 × 10−4 mol L−1 for the analytes. The method has been successfully applied to the analysis of real sample Du-Yi-Wei capsule and Qi-Zheng-Yan-Tong patch, with satisfactory results.
Authors:X.-C. Lv, Z.-C. Tan, Z.-A. Li, Y.-S. Li, J. Xing, Q. Shi, and L.-X. Sun
The (R)-BINOL-menthyl dicarbonates,
one of the most important compounds in catalytic asymmetric synthesis, was
synthesized by a convenient method. The molar heat capacities Cp,m
of the compound were measured over the temperature range from 80 to 378 K
with a small sample automated adiabatic calorimeter. Thermodynamic functions
[HT–H298.15] and [ST–S298.15] were derived in the
above temperature range with a temperature interval of 5 K. The thermal stability
of the substance was investigated by differential scanning calorimeter (DSC)
and a thermogravimetric (TG) technique.
Authors:S. Chen, X. Meng, Q. Shuai, B. Jiao, S. Gao, and Q. Shi
solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of
hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC)
and 1,10-phenanthroline (o-phen⋅H2O)
in absolute ethanol. IR spectrum of the complex indicated that Eu3+
in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms
from the o-phen. TG-DTG investigation provided
the evidence that the title complex was decomposed into EuS.
enthalpy change of the reaction of formation of the complex in ethanol, ΔrHmθ(l), as –22.2140.081 kJ mol–1,
and the molar heat capacity of the complex, cm,
as 61.6760.651 J mol–1 K–1,
at 298.15 K were determined by an RD-496 III type microcalorimeter. The enthalpy
change of the reaction of formation of the complex in solid, ΔrHmθ(s), was calculated as 54.5270.314 kJ mol–1
through a thermochemistry cycle. Based on the thermodynamics and kinetics
on the reaction of formation of the complex in ethanol at different temperatures,
fundamental parameters, including the activation enthalpy (ΔH≠θ),
the activation entropy (ΔS≠θ),
the activation free energy (ΔG≠θ),
the apparent reaction rate constant (k),
the apparent activation energy (E), the
pre-exponential constant (A) and the reaction
order (n), were obtained. The constant-volume
combustion energy of the complex, ΔcU,
was determined as –16937.889.79 kJ mol–1
by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy
of combustion, ΔcHmθ,
and standard enthalpy of formation, ΔfHmθ,
were calculated to be –16953.379.79 and –1708.2310.69
kJ mol–1, respectively.
Authors:L. Fu, Y. Chen, H. Du, J. Mao, X. Shi, and S. Li
A novel double -diketone 1,6-bis(1-phenyl-3-methyl-5-oxo-pyrazol-4-yl) hexanedione-[1,6] (BPMOPH) was further studied on its coordination compounds with uranium and thorium, respectively. The IR, UV, and1H-NMR spectra were examined, and the proposed structure is discussed.