This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critica...This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.展开更多
Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was u...Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was used to pursue this goal by anchoring aromatic acids.Extending the aromatic acid was strategically deployed to design TiO_(2) complexes with violet light-induced selective aerobic oxidation of sulfide as the probe reaction.With benzoic acid(BA)as the initial molecule,horizontally extending one or two benzene rings furnishes 2-naphthoic acid(2-NA)and 2-anthracene acid(2-AA).Moreover,triethylamine(TEA),an electron transfer mediator,was introduced to maintain the integrity of the anchored aromatic acids.Notably,there was a direct correlation between theπ-conjugation of aromatic acid ligand and the selective aerobic oxidation of sulfides.Among the three aromatic acids,2-AA delivered the best result over TiO_(2) due to the most extensiveπ-conjugated system.Ultimately,violet light-induced selective aerobic oxidation of sulfides into corresponding sulfoxides was conveniently realized by cooperative photocatalysis of 2-AA-TiO_(2) with 10 mol%of TEA.This work affords an extending strategy for designing the next-generation ligands for semiconductors to expand visible light-induced selective reactions.展开更多
Metal-organic frameworks(MOFs)are well-documented for visible light photocatalysis because of their tailorable structures and tunable absorptions through organic linkers.By employing a highly conjugated linker,4,4'...Metal-organic frameworks(MOFs)are well-documented for visible light photocatalysis because of their tailorable structures and tunable absorptions through organic linkers.By employing a highly conjugated linker,4,4',4'',4'''-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid,the optical absorption of the MOF NU-1100 is effectively tuned to visible light below 600 nm region.Under green light irradiation,NU-1100 triggers charge separation and modulates electron transfer from the linkers to the Zr_(6)O_(4)(OH)_(4)^(12+)clusters,driving the oxidation of sulfides to sulfoxides.Notably,adding a redox mediator radically expedites the oxidation of sulfides by NU-1100 photocatalysis,TEMPO(2,2,6,6-tetramethylpiperidine-N-oxyl)and 4-carboxy-TEMPO.At least 2.7 and 5.2 times of conversions of phenyl methyl sulfide are achieved by NU-1100 photocatalysis with TEMPO and 4-carboxy-TEMPO,respectively.A series of characterizations illustrate that 4-carboxy-TEMPO is adsorbed onto the exterior surface of Zr_(6)O_(4)(OH)_(4)^(12+)clusters of NU-1100 to mediate hole transfer and achieve higher charge transfer efficiency.Mechanistic studies indicate that superoxide is the essential reactive oxygen species and that the oxidation of sulfides is driven by an electron transfer pathway.This study demonstrates the integration of redox mediators with MOFs can drive more efficient visible light photocatalytic reactions.展开更多
Reactive oxygen species(RoS)are essential for biological processes like cell signaling and chemical processes like organic oxidation.Moreover,the sufficient generation of RoS plays a significant role in targeted tumor...Reactive oxygen species(RoS)are essential for biological processes like cell signaling and chemical processes like organic oxidation.Moreover,the sufficient generation of RoS plays a significant role in targeted tumor treatments or oxidation of organics.Herein,a hydrazone-linked porphyrin covalent organic framework(Por-DETH-COF)is developed for red light-induced generation of ROS like singlet oxygen(^(1)O_(2))or superoxide(O_(2)·^(-))to undertake different but targeted oxidations.First,^(1)O_(2)is adopted in photodynamic therapy(PDT)for the oxidation of glioma cells.The PDT efficiency of Por-DETH-COF on the apoptosis of glioma cells is explored through flow cytometry and western blot assay.The apoptosis rate of glioma cells significantly increases over Por-DETH-COF under 660nm red light illumination,suggestive of the potency of^(1)O_(2).Second,O_(2)^(·-)is employed for the targeted oxidation of thiols.A series of thiols could be efficiently oxidized to corresponding disulfides over Por-DETH-COF under 660 nm red light illumination,indicative of the significance of O_(2)^(·-).This work highlights the potential of covalent organic frameworks in generating Ros for precise medical applications of complex chemical environments.展开更多
TEMPO(2,2,6,6-tetramethylpipe ridine-1-oxyl)is well-established in orangocatalysis that usually work in synergy with transition-metal catalysis or semiconductor photocatalysis.Here,TEMPO was turned into a visible ligh...TEMPO(2,2,6,6-tetramethylpipe ridine-1-oxyl)is well-established in orangocatalysis that usually work in synergy with transition-metal catalysis or semiconductor photocatalysis.Here,TEMPO was turned into a visible light photocatalyst to conduct the selective aerobic oxidation of thiols into disulfides.With O2 as an oxidant,a mild and efficient protocol for the selective oxidation of thiols into disulfides including symmetrical and unsymmetrical ones with 5 mol%of TEPMO as a photocatalyst was developed at room temperature under the irradiation of 460 nm blue LEDs.It was found that a complex formed between TEMPO and thiols underpinned the visible light activity and disulfides were obtained in very high isolated yields.This work suggests that TEMPO takes diverse roles in for photocatalytic selective oxidative transformations with O2 as the oxidant.展开更多
Metal-organic frameworks(MOFs)present a multifaceted avenue for visible light photocatalysis and are candidates for environmental applications,in which electron and proton transfers are crucial.To date,the photocataly...Metal-organic frameworks(MOFs)present a multifaceted avenue for visible light photocatalysis and are candidates for environmental applications,in which electron and proton transfers are crucial.To date,the photocatalytic activity of MOFs has been attempted,but with inherent limitations against formidable redox conditions.This can be addressed by adopting an electron-proton transfer mediator to mediate the redox processes over a MOF photocatalyst.To achieve this goal,an electron-proton transfer mediator,HOOC-TEMPO(4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl),is envisioned to steer the selective oxidation of amines over a pyrene-based MOF NU-1000.There are abundant terminal hydroxyl groups of Zr-oxo cluster within the mesoporous channels of NU-1000.Supported by density functional theory calculations,the bidentate chelation of HOOC-TEMPO onto NU-1000 by reacting with the hydroxyl groups is the most feasible mode of adsorption.The optoelectronic properties of NU-1000 can be notably improved by the facile and dynamic adsorption of HOOC-TEMPO.Distinctly,1 mol%HOOCTEMPO promotes NU-1000 photocatalysis,allowing for three times of conversions in the aerobic oxidation of amines to imines.Compellingly,the hole transfer between the pyrene ligand of NU-1000 and HOOC-TEMPO is more efficient than other ligands.The merger of an electron-proton transfer mediator and MOFs creates a unique materials avenue for emerging photocatalysis.展开更多
Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembli...Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembling COFs in which the fullπ-conjugation of BTT is essential to facilitate electron transfer. Herein, a sp~2 carbon-conjugated COF, namely BTT-sp~2c-COF, is assembled from benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene-2,5,8-tricarbaldehyde and [1,1′:4′,1′′-terphenyl]-4,4′′-dicarbonitrile towards photocatalysis. More importantly, TEMPO(2,2,6,6-tetramethylpiperidin-1-yl)oxyl, 1 mol%) could considerably accelerate the selective oxidation of organic sulfides with O_(2) over BTT-sp~2c-COF. TEMPO mediates hole transfer between BTT-sp~2c-COF and organic sulfides, and O-atoms are incorporated into sulfoxides via an electron transfer pathway. Merging BTT-sp~2c-COF photocatalysis with TEMPO generally applies to transforming organic sulfides into sulfoxides. This work implies the full π-conjugation of electron-rich building blocks into COFs is a viable strategy for selective visible light photocatalysis.展开更多
The sp2 carbon-conjugated covalent organic frameworks(COFs)with fully π-conjugated lattice and high chemical stability are promising heterogeneous photocatalysts.Herein,we report the design and synthesis of a novel p...The sp2 carbon-conjugated covalent organic frameworks(COFs)with fully π-conjugated lattice and high chemical stability are promising heterogeneous photocatalysts.Herein,we report the design and synthesis of a novel palladium(Pd)porphyrin-based sp2 carbon-conjugated COF(PdPor-sp2c-COF)with an eclipsed AA stacking 2D structure.Interestingly,PdPor-sp2c-COF showed high crystallinity,good chemical stability,and a broad absorp-tion of visible light.Moreover,compared to our previously reported metal-free Por-sp2c-COF,PdPor-sp2c-COF displays an improved photocatalytic performance in the selective aerobic oxidation of sulfides under green light irradiation.The systematic mechanistic studies testified that the enhanced photocatalytic activity can be ascribed to promoting energy transfer pathway over PdPor-sp2c-COF.Our study clearly demonstrates that it is favorable to promote the energy transfer pathway in sp2 carbon-conjugated COFs by using metalloporphyrin-based molecular building blocks.This work will inspire us to design and synthesize novel photocatalysts based on COFs for the selective aerobic oxidation.展开更多
文摘This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.
基金funded by the National Natural Science Foundation of China(Nos.22072108 and 21773173)。
文摘Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was used to pursue this goal by anchoring aromatic acids.Extending the aromatic acid was strategically deployed to design TiO_(2) complexes with violet light-induced selective aerobic oxidation of sulfide as the probe reaction.With benzoic acid(BA)as the initial molecule,horizontally extending one or two benzene rings furnishes 2-naphthoic acid(2-NA)and 2-anthracene acid(2-AA).Moreover,triethylamine(TEA),an electron transfer mediator,was introduced to maintain the integrity of the anchored aromatic acids.Notably,there was a direct correlation between theπ-conjugation of aromatic acid ligand and the selective aerobic oxidation of sulfides.Among the three aromatic acids,2-AA delivered the best result over TiO_(2) due to the most extensiveπ-conjugated system.Ultimately,violet light-induced selective aerobic oxidation of sulfides into corresponding sulfoxides was conveniently realized by cooperative photocatalysis of 2-AA-TiO_(2) with 10 mol%of TEA.This work affords an extending strategy for designing the next-generation ligands for semiconductors to expand visible light-induced selective reactions.
文摘Metal-organic frameworks(MOFs)are well-documented for visible light photocatalysis because of their tailorable structures and tunable absorptions through organic linkers.By employing a highly conjugated linker,4,4',4'',4'''-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid,the optical absorption of the MOF NU-1100 is effectively tuned to visible light below 600 nm region.Under green light irradiation,NU-1100 triggers charge separation and modulates electron transfer from the linkers to the Zr_(6)O_(4)(OH)_(4)^(12+)clusters,driving the oxidation of sulfides to sulfoxides.Notably,adding a redox mediator radically expedites the oxidation of sulfides by NU-1100 photocatalysis,TEMPO(2,2,6,6-tetramethylpiperidine-N-oxyl)and 4-carboxy-TEMPO.At least 2.7 and 5.2 times of conversions of phenyl methyl sulfide are achieved by NU-1100 photocatalysis with TEMPO and 4-carboxy-TEMPO,respectively.A series of characterizations illustrate that 4-carboxy-TEMPO is adsorbed onto the exterior surface of Zr_(6)O_(4)(OH)_(4)^(12+)clusters of NU-1100 to mediate hole transfer and achieve higher charge transfer efficiency.Mechanistic studies indicate that superoxide is the essential reactive oxygen species and that the oxidation of sulfides is driven by an electron transfer pathway.This study demonstrates the integration of redox mediators with MOFs can drive more efficient visible light photocatalytic reactions.
基金supported by the National Natural Science Foundation of China(No.22072108).
文摘Reactive oxygen species(RoS)are essential for biological processes like cell signaling and chemical processes like organic oxidation.Moreover,the sufficient generation of RoS plays a significant role in targeted tumor treatments or oxidation of organics.Herein,a hydrazone-linked porphyrin covalent organic framework(Por-DETH-COF)is developed for red light-induced generation of ROS like singlet oxygen(^(1)O_(2))or superoxide(O_(2)·^(-))to undertake different but targeted oxidations.First,^(1)O_(2)is adopted in photodynamic therapy(PDT)for the oxidation of glioma cells.The PDT efficiency of Por-DETH-COF on the apoptosis of glioma cells is explored through flow cytometry and western blot assay.The apoptosis rate of glioma cells significantly increases over Por-DETH-COF under 660nm red light illumination,suggestive of the potency of^(1)O_(2).Second,O_(2)^(·-)is employed for the targeted oxidation of thiols.A series of thiols could be efficiently oxidized to corresponding disulfides over Por-DETH-COF under 660 nm red light illumination,indicative of the significance of O_(2)^(·-).This work highlights the potential of covalent organic frameworks in generating Ros for precise medical applications of complex chemical environments.
基金supported by the National Natural Science Foundation of China(Nos.21773173,21503086)the Fundamental Research Funds for the Central Universities(No.2042018kf0212)the start-up fund of Wuhan University。
文摘TEMPO(2,2,6,6-tetramethylpipe ridine-1-oxyl)is well-established in orangocatalysis that usually work in synergy with transition-metal catalysis or semiconductor photocatalysis.Here,TEMPO was turned into a visible light photocatalyst to conduct the selective aerobic oxidation of thiols into disulfides.With O2 as an oxidant,a mild and efficient protocol for the selective oxidation of thiols into disulfides including symmetrical and unsymmetrical ones with 5 mol%of TEPMO as a photocatalyst was developed at room temperature under the irradiation of 460 nm blue LEDs.It was found that a complex formed between TEMPO and thiols underpinned the visible light activity and disulfides were obtained in very high isolated yields.This work suggests that TEMPO takes diverse roles in for photocatalytic selective oxidative transformations with O2 as the oxidant.
基金supported by the National Natural Science Foundation of China(22072108 and 22372124).
文摘Metal-organic frameworks(MOFs)present a multifaceted avenue for visible light photocatalysis and are candidates for environmental applications,in which electron and proton transfers are crucial.To date,the photocatalytic activity of MOFs has been attempted,but with inherent limitations against formidable redox conditions.This can be addressed by adopting an electron-proton transfer mediator to mediate the redox processes over a MOF photocatalyst.To achieve this goal,an electron-proton transfer mediator,HOOC-TEMPO(4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl),is envisioned to steer the selective oxidation of amines over a pyrene-based MOF NU-1000.There are abundant terminal hydroxyl groups of Zr-oxo cluster within the mesoporous channels of NU-1000.Supported by density functional theory calculations,the bidentate chelation of HOOC-TEMPO onto NU-1000 by reacting with the hydroxyl groups is the most feasible mode of adsorption.The optoelectronic properties of NU-1000 can be notably improved by the facile and dynamic adsorption of HOOC-TEMPO.Distinctly,1 mol%HOOCTEMPO promotes NU-1000 photocatalysis,allowing for three times of conversions in the aerobic oxidation of amines to imines.Compellingly,the hole transfer between the pyrene ligand of NU-1000 and HOOC-TEMPO is more efficient than other ligands.The merger of an electron-proton transfer mediator and MOFs creates a unique materials avenue for emerging photocatalysis.
基金supported by the National Natural Science Foundation of China (22072108)。
文摘Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembling COFs in which the fullπ-conjugation of BTT is essential to facilitate electron transfer. Herein, a sp~2 carbon-conjugated COF, namely BTT-sp~2c-COF, is assembled from benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene-2,5,8-tricarbaldehyde and [1,1′:4′,1′′-terphenyl]-4,4′′-dicarbonitrile towards photocatalysis. More importantly, TEMPO(2,2,6,6-tetramethylpiperidin-1-yl)oxyl, 1 mol%) could considerably accelerate the selective oxidation of organic sulfides with O_(2) over BTT-sp~2c-COF. TEMPO mediates hole transfer between BTT-sp~2c-COF and organic sulfides, and O-atoms are incorporated into sulfoxides via an electron transfer pathway. Merging BTT-sp~2c-COF photocatalysis with TEMPO generally applies to transforming organic sulfides into sulfoxides. This work implies the full π-conjugation of electron-rich building blocks into COFs is a viable strategy for selective visible light photocatalysis.
基金supported by the National Natural Science Foundation of China(22225503,U21A20285,and 22375153)the Hubei Provincial Natural Science Foundation of China(2023AFA011)the Funda-mental Research Funds for Central Universities(2042023kf0127).
文摘The sp2 carbon-conjugated covalent organic frameworks(COFs)with fully π-conjugated lattice and high chemical stability are promising heterogeneous photocatalysts.Herein,we report the design and synthesis of a novel palladium(Pd)porphyrin-based sp2 carbon-conjugated COF(PdPor-sp2c-COF)with an eclipsed AA stacking 2D structure.Interestingly,PdPor-sp2c-COF showed high crystallinity,good chemical stability,and a broad absorp-tion of visible light.Moreover,compared to our previously reported metal-free Por-sp2c-COF,PdPor-sp2c-COF displays an improved photocatalytic performance in the selective aerobic oxidation of sulfides under green light irradiation.The systematic mechanistic studies testified that the enhanced photocatalytic activity can be ascribed to promoting energy transfer pathway over PdPor-sp2c-COF.Our study clearly demonstrates that it is favorable to promote the energy transfer pathway in sp2 carbon-conjugated COFs by using metalloporphyrin-based molecular building blocks.This work will inspire us to design and synthesize novel photocatalysts based on COFs for the selective aerobic oxidation.
