A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and n...A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and neutralization. A surface tension method was employed to investigate the thermo-dynamic properties of micellization in aqueous solution for cardanol sulfonate Gemini surfactant synthesized in laboratory. As a result, the micellization of cardanol sulfonate Gemini surfactant in aqueous solutions is spontaneous and entropy-driven. The micellization process is enthalpy-entropy compensated with the compensation temperature (Tc) of 308 ± 1 K.展开更多
Enthalpy-entropy compensation was found to be a universal law in protein unfolding based on over 3 000 experimental data. Water molecular reorganization accompanying the protein unfolding was suggested as the origin-o...Enthalpy-entropy compensation was found to be a universal law in protein unfolding based on over 3 000 experimental data. Water molecular reorganization accompanying the protein unfolding was suggested as the origin-of the enthalpy-entropy compensation in protein unfolding. It is indicated that the enthalpy-entropy compensation constitutes the physical foundation that satisfies the biological need of the small free energy changes in protein unfolding, without the sacrifice of the bio-diversity of proteins. The enthalpy-entropy compensation theory proposed herein also provides valuable insights into the Privalov’s puzzle of enthalpy and entropy convergence in protein unfolding.展开更多
In this paper, the enthalpy-entropy compensation effect in the enantiomeric separation by modified cyclodextrins (CD) and diamide chiral stationary phase (GP) gas chromatography was investigated using the method of pl...In this paper, the enthalpy-entropy compensation effect in the enantiomeric separation by modified cyclodextrins (CD) and diamide chiral stationary phase (GP) gas chromatography was investigated using the method of plotting Δ( ΔH) versus Δ(ΔG) 7hm combined with t-test statistic analysis. The investigated racemates cover α-phenylethylamine and its analogs, 2-alkylamines, chiral acyclic alcohols, halogenated arylethanediol-1, 2-diperfluoropropionates, amino acid and its analogs, and two series of compounds containing chloro and bromo substituents. From the compensation analysis results, the effects of the diluent composition in the investigated chiral stationary phases, the size and the died pups on investigated cyclodextrins, the derivatization methods and the groups attached to the stereocenters on enantiomeric separation mechanisms were all discussed.展开更多
The validity of the compensation between the enthalpies and entropies obtained from the calorimetric methods was statistically examined for the first time based on computer simulations. It turned out that several clai...The validity of the compensation between the enthalpies and entropies obtained from the calorimetric methods was statistically examined for the first time based on computer simulations. It turned out that several claimed enthalpy-entropy compensations in literature based upon the calorimetric measurements were statistically correct. Interestingly, a linear relationship between the slopes and correlation coefficients of the T DeltaS-DeltaH plots of different physical origin of the compensation behavior.展开更多
文摘A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and neutralization. A surface tension method was employed to investigate the thermo-dynamic properties of micellization in aqueous solution for cardanol sulfonate Gemini surfactant synthesized in laboratory. As a result, the micellization of cardanol sulfonate Gemini surfactant in aqueous solutions is spontaneous and entropy-driven. The micellization process is enthalpy-entropy compensated with the compensation temperature (Tc) of 308 ± 1 K.
文摘Enthalpy-entropy compensation was found to be a universal law in protein unfolding based on over 3 000 experimental data. Water molecular reorganization accompanying the protein unfolding was suggested as the origin-of the enthalpy-entropy compensation in protein unfolding. It is indicated that the enthalpy-entropy compensation constitutes the physical foundation that satisfies the biological need of the small free energy changes in protein unfolding, without the sacrifice of the bio-diversity of proteins. The enthalpy-entropy compensation theory proposed herein also provides valuable insights into the Privalov’s puzzle of enthalpy and entropy convergence in protein unfolding.
基金Project (No.29775025) supported by the National Natural Science Foundation of China.
文摘In this paper, the enthalpy-entropy compensation effect in the enantiomeric separation by modified cyclodextrins (CD) and diamide chiral stationary phase (GP) gas chromatography was investigated using the method of plotting Δ( ΔH) versus Δ(ΔG) 7hm combined with t-test statistic analysis. The investigated racemates cover α-phenylethylamine and its analogs, 2-alkylamines, chiral acyclic alcohols, halogenated arylethanediol-1, 2-diperfluoropropionates, amino acid and its analogs, and two series of compounds containing chloro and bromo substituents. From the compensation analysis results, the effects of the diluent composition in the investigated chiral stationary phases, the size and the died pups on investigated cyclodextrins, the derivatization methods and the groups attached to the stereocenters on enantiomeric separation mechanisms were all discussed.
基金the NSFC. Insights from Prof. E. Grunwald of Brandeis University and from Prof. W. Linert of Technical University of Vienna are
文摘The validity of the compensation between the enthalpies and entropies obtained from the calorimetric methods was statistically examined for the first time based on computer simulations. It turned out that several claimed enthalpy-entropy compensations in literature based upon the calorimetric measurements were statistically correct. Interestingly, a linear relationship between the slopes and correlation coefficients of the T DeltaS-DeltaH plots of different physical origin of the compensation behavior.
