The intensity of the signal(g=1.974)resulted from Zr+ ion on the surface or ZrO2 catalyst, increased with the calcination temperature and time, but that or the signal (g=2.003)resulted from F+s centers (surface oxygen...The intensity of the signal(g=1.974)resulted from Zr+ ion on the surface or ZrO2 catalyst, increased with the calcination temperature and time, but that or the signal (g=2.003)resulted from F+s centers (surface oxygen ion vacancies with a single trapped electron) decreased and finally disappeared at 550℃.展开更多
The kinetics for the reaction of ascorbyl palmitate and 4-hydroxy-TEMPO,4-methoxy- TEMPO or 4-hexanoyloxy-TEMPO in CTAB and SDS micelles was studied by ESR spectroscopy. It was found that the behavior of ascorbyl palm...The kinetics for the reaction of ascorbyl palmitate and 4-hydroxy-TEMPO,4-methoxy- TEMPO or 4-hexanoyloxy-TEMPO in CTAB and SDS micelles was studied by ESR spectroscopy. It was found that the behavior of ascorbyl palmitate is remarkably different from ascorbic acid in their antioxidant activity in micelles.The predominant factors governing the activity in micelles involve the lipophilicity of the antioxidant and the oxidant,the charge type of the substrates and the concentra- tion of the surfactant.As high as 2×10~4 fold rate variation was observed by changing the lipophilicity of the antioxidant and the microenvironment of the reaction medium.展开更多
Active free radicals formed by the electrooxidation of substituted anilines RC_6H_4NH_3 (R=H, p-Br, p-Cl, p-I, p-Me, p-COOH, p-MeCO, p-NO_2, m-CO_2H, and m-Cl) are trapped by spin trap 2-methyl-2-nitroso propane (MNP)...Active free radicals formed by the electrooxidation of substituted anilines RC_6H_4NH_3 (R=H, p-Br, p-Cl, p-I, p-Me, p-COOH, p-MeCO, p-NO_2, m-CO_2H, and m-Cl) are trapped by spin trap 2-methyl-2-nitroso propane (MNP). A multiple ESR signal of the solution containing electrolytic aniline and MNP is identified with the spin adduct of MNP and radical cation 1 by theore- tical simulation of observed spectrum. Furthermore, ESR spectra of para- or meta-substituted anilines give a reasonable explanation about spin adducts of MNP and the cation 2 or 3 by the same method.展开更多
ESR measurements have been carried out for some copper(Ⅱ) complexes of bis(4'-ben- zo-15-crown-5) at 77 K.The results of ESR spectrometric titration indicated that the binuclear com- plexes were prepared in the p...ESR measurements have been carried out for some copper(Ⅱ) complexes of bis(4'-ben- zo-15-crown-5) at 77 K.The results of ESR spectrometric titration indicated that the binuclear com- plexes were prepared in the present system.The binuclear complexes revealed characteristic ESR g-anisotropies (gZ<gX,gY) which are typical of the copper(Ⅱ) complexes with a 3d_Z^2 ground state doublet.However,in this case,the innermolecular copper(Ⅱ)-copper(Ⅱ) spin interaction was not observed.ESR measurements also showed that a small amount of the sandwich type copper(Ⅱ) com- plexes were formed in the presence of excess bis (4'-benzo-15-crown-5).A reasonable explanation was given for the ESR results.展开更多
Functional monomer (MP)_2PT having tertiary aromatic amino group was systhesized from the reaction of N, N-di (2-hydroxypropyl)-p-toluidine with 2-methyl acryloyl chloride. In the presence of organic peroxide, the rad...Functional monomer (MP)_2PT having tertiary aromatic amino group was systhesized from the reaction of N, N-di (2-hydroxypropyl)-p-toluidine with 2-methyl acryloyl chloride. In the presence of organic peroxide, the radical polymerization of (MP)_2PT in toluene took place. The kinetics of (MP)_2PT polymerization and the ESR spectra of LPO-(MP)2PT-MNP systems were determined respectively.展开更多
Novel polymeric Cu<sup>2+</sup> complexes derived from the reaction of cyanoacetylhydrazine (<strong>CAH</strong>;<strong>L</strong>) with CuCl<sub>2</sub>•2H<sub>...Novel polymeric Cu<sup>2+</sup> complexes derived from the reaction of cyanoacetylhydrazine (<strong>CAH</strong>;<strong>L</strong>) with CuCl<sub>2</sub>•2H<sub>2</sub>O in different solvents were synthesized and characterized. The isolated solid polymeric complexes were investigated using modern conventional physicochemical and spectral (IR, <sup>1</sup>H-NMR, UV-Vis. ESR, Raman), magnetic and thermal studies. The results revealed that <strong>CAH</strong> behaves in different ways towards the coordination of the Cu<sup>2+</sup> ion. The promotion of solvents to the cyano group was discussed on the basis of the solvent and the Cu<sup>2+</sup> ion used. Magnetic and spectral studies suggest octahedral geometry is proposed for the Cu<sup>2+</sup> complexes. EPR studies indicate the existence of polymeric complexes depending on the results of <i>g</i>-values. The results suggest that the number of copper atoms ranges from three to twelve atoms. The molecular modeling is drawn and some chemical characteristics are calculated such as chemical reactivity and energy components are investigated between the different types of the ligands.展开更多
The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of ...The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of AAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.展开更多
The fossil skull of Homo erectus hexianens was excaved in Longtan Cave, Taodian Vil-lage. Hexian County. Anhui Province in 1980. It is an important event since the fossilskulls of Peking Man. Bejing and Lantian Man. S...The fossil skull of Homo erectus hexianens was excaved in Longtan Cave, Taodian Vil-lage. Hexian County. Anhui Province in 1980. It is an important event since the fossilskulls of Peking Man. Bejing and Lantian Man. Shaanxi Province were found. The skullof Homo erectus was first discovered in South China. The age of Hexian Man has展开更多
ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the ...ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the course of the reactions.The reaction mechanism based on ESR find- ings and the products analyses is postulated to operate on radical pathways.When alkyl halides were used to react with the organometallic compound 1,the intermediate found was[Cp_2Ti(CO)X](C), and the main product was identified to be dicyclopentadienyl-acyl-halo titanium(3),an insertion of TiCO into R-X,i.e.[Cp_2Ti-C(O)R]X.When allyl or benzyl halidcs were used,the intermediate found was[Cp_2TiX](B),and the main products were identified to be the dicyclopentadienyl titanium dihalides and the coupling products of allyl or benzyl groups.展开更多
文摘The intensity of the signal(g=1.974)resulted from Zr+ ion on the surface or ZrO2 catalyst, increased with the calcination temperature and time, but that or the signal (g=2.003)resulted from F+s centers (surface oxygen ion vacancies with a single trapped electron) decreased and finally disappeared at 550℃.
基金This work was supported by the National Natural Science Foundation of China and the State Education Commission.
文摘The kinetics for the reaction of ascorbyl palmitate and 4-hydroxy-TEMPO,4-methoxy- TEMPO or 4-hexanoyloxy-TEMPO in CTAB and SDS micelles was studied by ESR spectroscopy. It was found that the behavior of ascorbyl palmitate is remarkably different from ascorbic acid in their antioxidant activity in micelles.The predominant factors governing the activity in micelles involve the lipophilicity of the antioxidant and the oxidant,the charge type of the substrates and the concentra- tion of the surfactant.As high as 2×10~4 fold rate variation was observed by changing the lipophilicity of the antioxidant and the microenvironment of the reaction medium.
文摘Active free radicals formed by the electrooxidation of substituted anilines RC_6H_4NH_3 (R=H, p-Br, p-Cl, p-I, p-Me, p-COOH, p-MeCO, p-NO_2, m-CO_2H, and m-Cl) are trapped by spin trap 2-methyl-2-nitroso propane (MNP). A multiple ESR signal of the solution containing electrolytic aniline and MNP is identified with the spin adduct of MNP and radical cation 1 by theore- tical simulation of observed spectrum. Furthermore, ESR spectra of para- or meta-substituted anilines give a reasonable explanation about spin adducts of MNP and the cation 2 or 3 by the same method.
文摘ESR measurements have been carried out for some copper(Ⅱ) complexes of bis(4'-ben- zo-15-crown-5) at 77 K.The results of ESR spectrometric titration indicated that the binuclear com- plexes were prepared in the present system.The binuclear complexes revealed characteristic ESR g-anisotropies (gZ<gX,gY) which are typical of the copper(Ⅱ) complexes with a 3d_Z^2 ground state doublet.However,in this case,the innermolecular copper(Ⅱ)-copper(Ⅱ) spin interaction was not observed.ESR measurements also showed that a small amount of the sandwich type copper(Ⅱ) com- plexes were formed in the presence of excess bis (4'-benzo-15-crown-5).A reasonable explanation was given for the ESR results.
文摘Functional monomer (MP)_2PT having tertiary aromatic amino group was systhesized from the reaction of N, N-di (2-hydroxypropyl)-p-toluidine with 2-methyl acryloyl chloride. In the presence of organic peroxide, the radical polymerization of (MP)_2PT in toluene took place. The kinetics of (MP)_2PT polymerization and the ESR spectra of LPO-(MP)2PT-MNP systems were determined respectively.
文摘Novel polymeric Cu<sup>2+</sup> complexes derived from the reaction of cyanoacetylhydrazine (<strong>CAH</strong>;<strong>L</strong>) with CuCl<sub>2</sub>•2H<sub>2</sub>O in different solvents were synthesized and characterized. The isolated solid polymeric complexes were investigated using modern conventional physicochemical and spectral (IR, <sup>1</sup>H-NMR, UV-Vis. ESR, Raman), magnetic and thermal studies. The results revealed that <strong>CAH</strong> behaves in different ways towards the coordination of the Cu<sup>2+</sup> ion. The promotion of solvents to the cyano group was discussed on the basis of the solvent and the Cu<sup>2+</sup> ion used. Magnetic and spectral studies suggest octahedral geometry is proposed for the Cu<sup>2+</sup> complexes. EPR studies indicate the existence of polymeric complexes depending on the results of <i>g</i>-values. The results suggest that the number of copper atoms ranges from three to twelve atoms. The molecular modeling is drawn and some chemical characteristics are calculated such as chemical reactivity and energy components are investigated between the different types of the ligands.
基金The project was supported by the National Natural Science Foundation of China
文摘The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of AAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.
文摘The fossil skull of Homo erectus hexianens was excaved in Longtan Cave, Taodian Vil-lage. Hexian County. Anhui Province in 1980. It is an important event since the fossilskulls of Peking Man. Bejing and Lantian Man. Shaanxi Province were found. The skullof Homo erectus was first discovered in South China. The age of Hexian Man has
基金Supported by the National Natural Science Foundation of China.
文摘ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the course of the reactions.The reaction mechanism based on ESR find- ings and the products analyses is postulated to operate on radical pathways.When alkyl halides were used to react with the organometallic compound 1,the intermediate found was[Cp_2Ti(CO)X](C), and the main product was identified to be dicyclopentadienyl-acyl-halo titanium(3),an insertion of TiCO into R-X,i.e.[Cp_2Ti-C(O)R]X.When allyl or benzyl halidcs were used,the intermediate found was[Cp_2TiX](B),and the main products were identified to be the dicyclopentadienyl titanium dihalides and the coupling products of allyl or benzyl groups.
