Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimeriz...Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole.The photoreaction proceeds via an electron transfer mechanism,where magnesium perchlorate accelerated formation of the photo-oxygenated product.展开更多
The photooxygenation of caffeine sensitized by Hypocrellin B in alcohol solvents hasbeen investigated in this paper. The products have been isolated and identified. The mainproduct is 8--alkoxyl substituted caffeine d...The photooxygenation of caffeine sensitized by Hypocrellin B in alcohol solvents hasbeen investigated in this paper. The products have been isolated and identified. The mainproduct is 8--alkoxyl substituted caffeine derivatives. Deuterium. oxygen partial pressure andNaN_3-quenching experiments indicate that the reaction proceeds on singlet oxygen mechanism.展开更多
The photooxidation and its electron transfer (ET) mechanism of acenaphthenone (ANO) sensitized by 9,10-dicyanoanthracence (DCA) are investigated. It has been found that the reaction with a stepwise manner led to the f...The photooxidation and its electron transfer (ET) mechanism of acenaphthenone (ANO) sensitized by 9,10-dicyanoanthracence (DCA) are investigated. It has been found that the reaction with a stepwise manner led to the formation of 1,8- (3’-hydroxy)-β-naphthalene lactone and 1,8-naphthalenedicarboxylic anhydride. By cyclic voltammetry, fluorescence quenching, exciplex emission, co-sensitbation of biphenyl/DCA as well as CIDNP studies, it is verified that ANO can behave as an electron donor to undergo ET reaction with singlet DCA which is a thermodynamically-favored process.展开更多
Syntheses of 2,3-dimethyl-4H-furo[3,2-c]coumarin and 3-phenyl-4H-furo[3,2-c]coumarin as angular furocou- marins were carried out through Williamson reaction of 4-hydroxycoumarin with a-haloketones followed by cycli- z...Syntheses of 2,3-dimethyl-4H-furo[3,2-c]coumarin and 3-phenyl-4H-furo[3,2-c]coumarin as angular furocou- marins were carried out through Williamson reaction of 4-hydroxycoumarin with a-haloketones followed by cycli- zation. Photooxygenation of the synthesized furocoumarin derivatives was performed and the photoproducts were isolated and characterized. The affinity of 2,3-dimethyl-4H-furo[3,2-c]coumarin towards DNA and the antibacterial activity were evaluated and compared with 8-methoxypsoralen （8-MOP）.展开更多
Kinetic studies of the singlet oxygenation of the title compounds were performed accord- ing to Monroe's method. The reaction rate increases with temperature decreasing, leading to a ne- gative activation enthalpy...Kinetic studies of the singlet oxygenation of the title compounds were performed accord- ing to Monroe's method. The reaction rate increases with temperature decreasing, leading to a ne- gative activation enthalpy and a large negative activation entropy. These data are interpreted as the evidence for the intermediacy of an exciplex. The solvent effect on the reaction rate suggests that the “dioxetane” path involves a transition state or an intermediate with significant zwitterionic character. The electronic effect of the substituent is obvious, with electron-withdrawing substituent retarding the reaction and electron-donating substituent increasing the reaction rate. However, steric bulkiness at the 6-position does not play an important role in the reaction rate.展开更多
Benzoic acid and substituted benzoic acids are produced in photooxygenation of 1-aryl- 1-trimethylsilyloxy-1-propene(1)sensitized by 9,10-dicyanoanthracene(DCA)in acetonitrile.An electron transfer mechanism is propose...Benzoic acid and substituted benzoic acids are produced in photooxygenation of 1-aryl- 1-trimethylsilyloxy-1-propene(1)sensitized by 9,10-dicyanoanthracene(DCA)in acetonitrile.An electron transfer mechanism is proposed in which superoxide ion(O)combines with cation radical of 1 to form a dioxetane(2)which cleaves to form trimethylsilylbenzoate(3)and then 3 is converted to benzoic acids by hydrolysis.展开更多
Amyloid β-peptide （Aβ） aggregation is a critical step in the pathogenesis of Alzheimer＇s disease （AD）. Inhibition of A[3 production, dissolution of existing aggregates and clearance of Aβ represent valid thera...Amyloid β-peptide （Aβ） aggregation is a critical step in the pathogenesis of Alzheimer＇s disease （AD）. Inhibition of A[3 production, dissolution of existing aggregates and clearance of Aβ represent valid therapeutic strategies against AD. Herein, a novel platinum（II）-coordinated graphitic carbon nitride （g-C3N4） nanosheet （g-C3N4@Pt） has been designed to covalently bind to Aβ and modulate the peptide＇s aggregation and toxicity. Furthermore, g-CBN4@Pt nanosheets possess high photocatalytic activity and can oxygenate Aβ upon visible light irradiation, remarkably attenuating both the aggregation potency and neurotoxicity of Aβ Due to its ability to cross the blood-brain barrier （BBB） and its good biocompatibility, g-C3N4@Pt nanosheet is a promising inhibitor of Aβ aggregation. This study may serve as a model for the engineering of novel multifunctional nanomaterials used for the treatment of AD.展开更多
基金supported by a Grant-in-Aid for Scientific Research on Priority Areas"Fundamental Science and Technology of Photofunctional Interfaces(417)"(Nos.14050085,15033264,17029058)the Cooperation for Innovative Technology and Advanced Research in Evolutional Area(CITY AREA) program from the Ministry of Education,Culture,Sports,Science and Technology of Japan
文摘Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole.The photoreaction proceeds via an electron transfer mechanism,where magnesium perchlorate accelerated formation of the photo-oxygenated product.
文摘The photooxygenation of caffeine sensitized by Hypocrellin B in alcohol solvents hasbeen investigated in this paper. The products have been isolated and identified. The mainproduct is 8--alkoxyl substituted caffeine derivatives. Deuterium. oxygen partial pressure andNaN_3-quenching experiments indicate that the reaction proceeds on singlet oxygen mechanism.
基金Project supported by the National Natural Science Foundation of China
文摘The photooxidation and its electron transfer (ET) mechanism of acenaphthenone (ANO) sensitized by 9,10-dicyanoanthracence (DCA) are investigated. It has been found that the reaction with a stepwise manner led to the formation of 1,8- (3’-hydroxy)-β-naphthalene lactone and 1,8-naphthalenedicarboxylic anhydride. By cyclic voltammetry, fluorescence quenching, exciplex emission, co-sensitbation of biphenyl/DCA as well as CIDNP studies, it is verified that ANO can behave as an electron donor to undergo ET reaction with singlet DCA which is a thermodynamically-favored process.
文摘Syntheses of 2,3-dimethyl-4H-furo[3,2-c]coumarin and 3-phenyl-4H-furo[3,2-c]coumarin as angular furocou- marins were carried out through Williamson reaction of 4-hydroxycoumarin with a-haloketones followed by cycli- zation. Photooxygenation of the synthesized furocoumarin derivatives was performed and the photoproducts were isolated and characterized. The affinity of 2,3-dimethyl-4H-furo[3,2-c]coumarin towards DNA and the antibacterial activity were evaluated and compared with 8-methoxypsoralen （8-MOP）.
基金This report was partially supported by the National Natural Science Foundation of China
文摘Kinetic studies of the singlet oxygenation of the title compounds were performed accord- ing to Monroe's method. The reaction rate increases with temperature decreasing, leading to a ne- gative activation enthalpy and a large negative activation entropy. These data are interpreted as the evidence for the intermediacy of an exciplex. The solvent effect on the reaction rate suggests that the “dioxetane” path involves a transition state or an intermediate with significant zwitterionic character. The electronic effect of the substituent is obvious, with electron-withdrawing substituent retarding the reaction and electron-donating substituent increasing the reaction rate. However, steric bulkiness at the 6-position does not play an important role in the reaction rate.
基金This work was supported by the National Natural Science Foundation of China.
文摘Benzoic acid and substituted benzoic acids are produced in photooxygenation of 1-aryl- 1-trimethylsilyloxy-1-propene(1)sensitized by 9,10-dicyanoanthracene(DCA)in acetonitrile.An electron transfer mechanism is proposed in which superoxide ion(O)combines with cation radical of 1 to form a dioxetane(2)which cleaves to form trimethylsilylbenzoate(3)and then 3 is converted to benzoic acids by hydrolysis.
基金This work was supported by the National Basic Research Program of China （Nos. 2012CB720602 and 2011CB936004）, and the National Natural Science Foundation of China （Nos. 21210002, 21431007, and 21533008）.
文摘Amyloid β-peptide （Aβ） aggregation is a critical step in the pathogenesis of Alzheimer＇s disease （AD）. Inhibition of A[3 production, dissolution of existing aggregates and clearance of Aβ represent valid therapeutic strategies against AD. Herein, a novel platinum（II）-coordinated graphitic carbon nitride （g-C3N4） nanosheet （g-C3N4@Pt） has been designed to covalently bind to Aβ and modulate the peptide＇s aggregation and toxicity. Furthermore, g-CBN4@Pt nanosheets possess high photocatalytic activity and can oxygenate Aβ upon visible light irradiation, remarkably attenuating both the aggregation potency and neurotoxicity of Aβ Due to its ability to cross the blood-brain barrier （BBB） and its good biocompatibility, g-C3N4@Pt nanosheet is a promising inhibitor of Aβ aggregation. This study may serve as a model for the engineering of novel multifunctional nanomaterials used for the treatment of AD.
