Photolysis of benzyl phenylacetate (ACO_2A), benzyl p-methylphenylacetate (BCO_2A) and 1-naphthyl phenylacetate (ACO_2Np) in homogeneous and micellar solutions results in products typical of radical coupling reactions...Photolysis of benzyl phenylacetate (ACO_2A), benzyl p-methylphenylacetate (BCO_2A) and 1-naphthyl phenylacetate (ACO_2Np) in homogeneous and micellar solutions results in products typical of radical coupling reactions and loss of carbon dioxide. The cage effects upon direct photolysis of these esters in acetonitrile are significantly greater than zero and those in SDS or HDTBr micellar solutions are even greater. In the triplet sensitization reaction of ACO_2 Np in micellar solutions the cage effects are smaller than those obtained upon direct irradiation. However, the application of a 0.05 or 0.2 T external magnetic field in the photolysis in micellar solutions decreases the cage effects dramatically. All these results suggest that the photoextrusions of carbon dioxide from these esters proceed via radical intermediates, and upon direct photolysis the reactive states for the cleavage re- action involve both singlet and triplet excited states.展开更多
An amphiphilic porphyrin, 5, 10, 15, 20-tetra(4-hydroxyphenyl)-porphyrin (P) was solubilized in SDS micellar solutions. By taking advantage of protonation property of pyridine groups of amphiphilic porphyrin and the U...An amphiphilic porphyrin, 5, 10, 15, 20-tetra(4-hydroxyphenyl)-porphyrin (P) was solubilized in SDS micellar solutions. By taking advantage of protonation property of pyridine groups of amphiphilic porphyrin and the UV-Vis spectral sensitivity of Soret band and Q bands to the microenvironment of the porphyrin moiety, two-step protonation was studied in detail by means of UV-Vis spectroscopy. The free base, monocation and dication were described in detail in SDS micellar solution. The possibility of microphase transition was proposed to relate to the observation of two isosbestic points.展开更多
The electroanalytical characteristies of nicotinic acid in miceilar solution,were studied by cyclic voltammetry,constant potential coulometry and chron ocoulometry.A procedure of the absorptive voltammetric determinat...The electroanalytical characteristies of nicotinic acid in miceilar solution,were studied by cyclic voltammetry,constant potential coulometry and chron ocoulometry.A procedure of the absorptive voltammetric determination of the drug was worked out.展开更多
In the present paper,a structure-based viscoelastic model is employed to characterize and predict the viscoelastic properties of a wormlike micellar solution at 20℃.Considering the effect of shear rate on linear visc...In the present paper,a structure-based viscoelastic model is employed to characterize and predict the viscoelastic properties of a wormlike micellar solution at 20℃.Considering the effect of shear rate on linear viscoelastic property,a structural parameter f is obtained.Meanwhile,another structural parameterζis determined when the effects of time and shear rate are considered simultaneously.Both structural parameters are calculated by using linear interpolation method.The startup experiment can be described well by the model.The prediction on the shear stress in the ramping-up region of the hysteresis loop experiment shows an apparent relation between the rheological behaviors in the startup experiment and those in the hysteresis loop experiment.For the hysteresis loop experiment with 30 s time interval,the defect of the calculation in 0.001-0.01 s^(−1) is due to the lack of the ramping-down history effect.In addition,the model can improve completeness of perimental data used for characterizing rheological property.展开更多
A study was made of magnetic field effects (MFEs) on the photoreduction reaction of 2-methyl-1,4-naphthoqui- none (MNQ) in Brij 35 micellar solution containing 4-lauroylamino-TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy...A study was made of magnetic field effects (MFEs) on the photoreduction reaction of 2-methyl-1,4-naphthoqui- none (MNQ) in Brij 35 micellar solution containing 4-lauroylamino-TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical (L-R) under magnetic fields below 1.75 T by a nanosecond laser flash photolysis technique. The triplet MNQ mainly underwent the hydrogen abstraction from Brij 35 molecule to give a radical pair. The escaped radical yield increased with magnetic fields from 0 to 0.62 T and then saturated from 0.62 to 1.75 T. MFEs for both sys-tems can be explained by the relaxation mechanism. However, it was supposed that additional radical, L-R affected the MFEs mainly through enhancing the spin-spin interactions of radical pairs. The effect of the micelle size on MFEs of the studying system was also discussed.展开更多
基金This work was supported by the National Science Foundation of China and the National Laboratory for Structure Chemistry of Unstable and Stable Species
文摘Photolysis of benzyl phenylacetate (ACO_2A), benzyl p-methylphenylacetate (BCO_2A) and 1-naphthyl phenylacetate (ACO_2Np) in homogeneous and micellar solutions results in products typical of radical coupling reactions and loss of carbon dioxide. The cage effects upon direct photolysis of these esters in acetonitrile are significantly greater than zero and those in SDS or HDTBr micellar solutions are even greater. In the triplet sensitization reaction of ACO_2 Np in micellar solutions the cage effects are smaller than those obtained upon direct irradiation. However, the application of a 0.05 or 0.2 T external magnetic field in the photolysis in micellar solutions decreases the cage effects dramatically. All these results suggest that the photoextrusions of carbon dioxide from these esters proceed via radical intermediates, and upon direct photolysis the reactive states for the cleavage re- action involve both singlet and triplet excited states.
文摘An amphiphilic porphyrin, 5, 10, 15, 20-tetra(4-hydroxyphenyl)-porphyrin (P) was solubilized in SDS micellar solutions. By taking advantage of protonation property of pyridine groups of amphiphilic porphyrin and the UV-Vis spectral sensitivity of Soret band and Q bands to the microenvironment of the porphyrin moiety, two-step protonation was studied in detail by means of UV-Vis spectroscopy. The free base, monocation and dication were described in detail in SDS micellar solution. The possibility of microphase transition was proposed to relate to the observation of two isosbestic points.
文摘The electroanalytical characteristies of nicotinic acid in miceilar solution,were studied by cyclic voltammetry,constant potential coulometry and chron ocoulometry.A procedure of the absorptive voltammetric determination of the drug was worked out.
文摘In the present paper,a structure-based viscoelastic model is employed to characterize and predict the viscoelastic properties of a wormlike micellar solution at 20℃.Considering the effect of shear rate on linear viscoelastic property,a structural parameter f is obtained.Meanwhile,another structural parameterζis determined when the effects of time and shear rate are considered simultaneously.Both structural parameters are calculated by using linear interpolation method.The startup experiment can be described well by the model.The prediction on the shear stress in the ramping-up region of the hysteresis loop experiment shows an apparent relation between the rheological behaviors in the startup experiment and those in the hysteresis loop experiment.For the hysteresis loop experiment with 30 s time interval,the defect of the calculation in 0.001-0.01 s^(−1) is due to the lack of the ramping-down history effect.In addition,the model can improve completeness of perimental data used for characterizing rheological property.
基金Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars State Education Ministry+1 种基金 and the Scientific Research Foundation for the Returned Overseas University of Science and Technology of China (No. 2047308
文摘A study was made of magnetic field effects (MFEs) on the photoreduction reaction of 2-methyl-1,4-naphthoqui- none (MNQ) in Brij 35 micellar solution containing 4-lauroylamino-TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical (L-R) under magnetic fields below 1.75 T by a nanosecond laser flash photolysis technique. The triplet MNQ mainly underwent the hydrogen abstraction from Brij 35 molecule to give a radical pair. The escaped radical yield increased with magnetic fields from 0 to 0.62 T and then saturated from 0.62 to 1.75 T. MFEs for both sys-tems can be explained by the relaxation mechanism. However, it was supposed that additional radical, L-R affected the MFEs mainly through enhancing the spin-spin interactions of radical pairs. The effect of the micelle size on MFEs of the studying system was also discussed.
