A photocatalyst-free photoinduced radical difluoromethylation approach for the convenient synthesis of 3-CF_(2)H-coumarins from alkynoates by difluoromethyl phenoxathiinium salt(PT-CF_(2)H^(+)BF_(4)^(-))was developed....A photocatalyst-free photoinduced radical difluoromethylation approach for the convenient synthesis of 3-CF_(2)H-coumarins from alkynoates by difluoromethyl phenoxathiinium salt(PT-CF_(2)H^(+)BF_(4)^(-))was developed.This transformation in-volves radical difluoromethylation/5-exo spirocyclization/ester migration rearrangement cascade process and features mild reaction conditions,broad substrate scope and good functional groups tolerance.Using this method,a wide range of alkynoates was successfully converted to desired 3-CF_(2)H-coumarins in moderate to good yields.展开更多
Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were...Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.展开更多
Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance...Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.展开更多
Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembl...Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembly and photoinduced seeded reversible addition-fragmentation chain transfer(RAFT)polymerization to prepare a diverse set of core-shell colloidal particles with a well-defined polymer layer.Chemical compositions,structures,and thicknesses of polymer layers could be conveniently regulated by using different types of monomers and feed[monomer]/[chain transfer agent]ratios during seeded RAFT polymerization.展开更多
Photodynamic therapy(PDT)as a non-invasive anticancer modality has received increasing attention due to its advantages of noninvasiveness,high temporospatial selectivity,simple and controllable operation,etc.PDT mainl...Photodynamic therapy(PDT)as a non-invasive anticancer modality has received increasing attention due to its advantages of noninvasiveness,high temporospatial selectivity,simple and controllable operation,etc.PDT mainly relies on the generation of toxic reactive oxygen species(ROS)by photosensitizers(PSs)under the light irradiation to cause cancer cell apoptosis and death.However,solid tumors usually exhibit an inherent hypoxic microenvironment,which greatly limits the PDT efficacy of these high oxygen-dependent conventional type II PSs.Therefore,it is of great importance to design and develop efficient type I PSs that are less oxygen-dependent for the treatment of hypoxic tumors.Herein,a new strategy for the preparation of efficient type I PSs by introducing the photoinduced electron transfer(PET)mechanism is reported.DR-NO_(2) is obtained by introducing 4-nitrobenzyl to(Z)-2-(5-(4-(diethylamino)-2-hydroxybenzylidene)-4-oxo-3-phenylthiazolidin-2-ylidene)malononitrile(DR-OH)with aggregation-induced emission(AIE)feature.The AIE feature ensures their high ROS generation efficiency in aggregate,and the PET process leads to fluorescence quenching of DR-NO_(2) to promote triplet state formation,which also promotes intramolecular charge separation and electron transfer that is conducive for type I ROS particularly superoxide radicals generation.In addition,DR-NO_(2) nanoparticles are prepared by nanoprecipitation to possess nanoscaled sizes,high cancer cell uptake,and excellent type I ROS generation ability,which results in an excellent performance in PDT ablation of MCF-7 cancer cells.This PET strategy for the development of type I PSs possesses great potential for PDT applications against hypoxic tumors.展开更多
Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless...Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless,the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs,thus impeding the commercialization of perovskite-based TSCs.Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained.In this review,we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices.The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized.Beyond that,the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed.Finally,the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.展开更多
Tryptophan(Trp)carries a unique heteroaromatic indole side chain and plays a critical role in peptide or protein modification.Herein,we have reported a metal-free photoinduced N-H alkylation strategy using N-aryl glyc...Tryptophan(Trp)carries a unique heteroaromatic indole side chain and plays a critical role in peptide or protein modification.Herein,we have reported a metal-free photoinduced N-H alkylation strategy using N-aryl glycines for specific modification of tryptophan-containing peptides.The robustness of our approach is demonstrated by its wide substrate scope,excellent isolated yields,as well as almost unobservable side effects.Using this highly efficiently metal-free condition,alkylated Trp-containing peptides can be smoothly assembled.This study provides a reliable and practical tool for the chemo-selective modification of various tryptophan containing oligopeptides.展开更多
Two distinctive rearranged 19-nor-7,8-seco-labdane diterpenoids(1 and 2)with a novel tetracyclo[5.2.1.0^(2,5.)0^(4,10)]decane skeleton,a derivative of the open tetrahydrofuran ring(7),three dimeric compounds(8-10),and...Two distinctive rearranged 19-nor-7,8-seco-labdane diterpenoids(1 and 2)with a novel tetracyclo[5.2.1.0^(2,5.)0^(4,10)]decane skeleton,a derivative of the open tetrahydrofuran ring(7),three dimeric compounds(8-10),and four revised homologs(3-6)were obtained from Chinese liverwort Pallavicinia ambigua.Their structures were identified via combined analysis of their spectroscopic data,single-crystal X-ray diffraction patterns,and ECD calculations.The light-driven conversion of compound 5 to compounds 1-4 demonstrated that photochemically induced postmodification involved in biosynthesis is an important way to diversify natural structures.A preliminary cytotoxicity assay revealed that compound 5 showed significant inhibition in the human prostate cancer(PC-3)cell line via an apoptotic pathway.展开更多
An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-st...An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-stage functionalization of medicine derivatives.Mechanism studies suggest a plausible visible light triggered ligand-to-metal charge transfer(LMCT)/1,4-hydrogen atom transfer(HAT)cascade.展开更多
AIM:To investigate the relationship between autophagy and apoptosis in photoinduced injuries in retinal pigment epithelium(RPE)cells and how Lycium barbarum polysaccharide(LBP)contributes to the increased of RPE cells...AIM:To investigate the relationship between autophagy and apoptosis in photoinduced injuries in retinal pigment epithelium(RPE)cells and how Lycium barbarum polysaccharide(LBP)contributes to the increased of RPE cells to photoinduced autophagy.METHODS:In vitro cultures of human RPE strains(ARPE-19)were prepared and randomly divided into the blank control,model,low-dose LBP,middle-dose LBP,high-dose LBP,and 3-methyladenine(3MA)groups.The viability of the RPE cells and apoptosis levels in each group were tested through cell counting kit-8(CCK8)method with a flow cytometer(Annexin V/PI double staining technique).The expression levels of LC3II,LC3I,and P62 proteins were detected with the immunofluorescence method.The expression levels of beclin1,LC3,P62,PI3K,P-mTOR,mTOR,P-Akt,and Akt proteins were tested through Western blot.RESULTS:LBP considerably strengthens cell viability and inhibits the apoptosis of RPE cells after photoinduction.The PI3K/Akt/mTOR signal pathway is activated because of the upregulation of the phosphorylation levels of Akt and mTOR proteins,and thus autophagy is inhibited.CONCLUSION:LBP can inhibit the excessive autophagy in RPE cells by activating the PI3K/Akt/mTOR signaling pathways and thereby protect RPE cells from photoinduced injuries.展开更多
Photoinduced birefringence is investigated in a new amorphous copolymer containing azobenzene groups. The levels of birefringence signal are found to depend an the polarization angle between the pump beam and the prob...Photoinduced birefringence is investigated in a new amorphous copolymer containing azobenzene groups. The levels of birefringence signal are found to depend an the polarization angle between the pump beam and the probe beam, and on the ellipticity of the pump beam. Both the growth and decay processes of the birefringence signal can be described by known biexponential equations. The rate constants and the amplitudes associated with the growth process of the photoinduced birefringence are observed to display a linear dependence with the pump beam intensity. A new dynamic model of the photoinduced birefringence is presented taking into account the contributions of both the bans and cis isomers of azobenzene groups and the local polymer segments. The numerical treatment of this model shows good agreement with the experimental data in the whole writing-erasing processes of the photoinduced birefringence conducted in our polymer samples.展开更多
Photoinduoed reaction of chloranil (TCBQ) with 2-methylfuran la and 2,5-dimethylfuran 1b in benzene gave addition products 2a and 2b respecvely together with tetrachlorohydroquinone 3. A mechanism of sequential electr...Photoinduoed reaction of chloranil (TCBQ) with 2-methylfuran la and 2,5-dimethylfuran 1b in benzene gave addition products 2a and 2b respecvely together with tetrachlorohydroquinone 3. A mechanism of sequential electron and proton transfer from la or 1b to ~3TCBQ followed by coupling of the furfuryl and semiquinone radical pairs was proposed and is evidenced by the photo-CIDNP studies of the TCBQ-1a and TCBQ-1b systems.展开更多
Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 mum and frequency d...Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 mum and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model.展开更多
The photoinduced reactions of aryl halides with carbazolyl nitrogen anion,in dimethyl sulfoxide,yield the corresponding N-arylated products.These reactions are suggested in terms of the S;Nl mechaism of nucleophilic s...The photoinduced reactions of aryl halides with carbazolyl nitrogen anion,in dimethyl sulfoxide,yield the corresponding N-arylated products.These reactions are suggested in terms of the S;Nl mechaism of nucleophilic substitution.展开更多
Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showe...Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption（NLA） coefficient and the value of nonlinear refraction（NLR） index of the products increased from 0 to 3.167 cm/GW and from 0.64×10^ 4 to 6.83×10 ^4 cm 2 /GW,respectively.展开更多
A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelec...A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelectrode was prepared by further annealing treatment to explore the photoinduced cathodic protection(CP)performance.Compared with WO_(3)and ZnO,the photoinduced CP and electron storage capacity performance of WO_(3)/ZnWO_(4)/ZnO is significantly improved in 3.5%NaCl solution without adding any hole scavenger.The electron storage capacity of the WO_(3)/ZnWO_(4)/ZnO heterojunction makes it possible to continuously protect metallic materials in the dark after switching off the light,which can realize long-term and effective photoinduced CP.展开更多
Hydrogen titanate nanotubes were synthesized by hydrothermal process using 10 M NaOH and TiO2 anatase powder. The material synthesized was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) a...Hydrogen titanate nanotubes were synthesized by hydrothermal process using 10 M NaOH and TiO2 anatase powder. The material synthesized was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to ensure the structural and morphological characteristics. The interaction of calf thymus DNA (CT-DNA) and bovine serum albumin protein with suspended aqueous solution of titanate nanotubes was investigated using UV absorption spectroscopy and the apparent association constant was found to be, Kb= 1.68 × 104 M-1 and Kap=5.41 × 103 M-1 for DNA and BSA respectively. Addition of the titanate nano material resulted quenching of fluorescence spectra of ethidium bromide-DNA in tris HCl buffer solution and that of aqueous protein solution. The apparent binding constant (Ksv= 5.46 × 104M-1 for DNA binding and Ksv = 6.063 × 103M-1 for protein binding) was deduced from relevant fluorescence quenching data using Stern-Volmer equation.展开更多
Hydrogen-atom-transfer(HAT)is an efficient way for direct C-H functionalization of inert C-H bonds,therefore it has attracted great interests in recent years.So far,various HAT catalysts have been developed.Among them...Hydrogen-atom-transfer(HAT)is an efficient way for direct C-H functionalization of inert C-H bonds,therefore it has attracted great interests in recent years.So far,various HAT catalysts have been developed.Among them,quinuclidine and its derivatives show different characters toward other HAT catalysts as they tend to abstract electron-rich and hydridic hydrogens in the presence of weak and neutral C-H bonds.These features enable direct C-H functionalization of compounds with various groups which are unable or difficult by other methods.This review summarizes recent advance of photoinduced reactions with quinuclidine and its derivatives as HAT catalysts and exhibits powerful synthetic potential by using quinuclidine and its derivatives as HAT catalysts.展开更多
Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- ...Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- triphenyl porphyrinate （NiPCnA, n=4,5,6）, were synthesized, in which the porphyrin moiety was connected to l-adamantanamine via a flexible hydrocarbon chain. The fluorescence quenching between these donor substrates and mono-6-p-nitrobenzoyl-β-cyclodextrin （NBCD） was studied in detail. Distinct fluorescence quenching occured in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer （PET） inside the supramolecular assembly between the porphyrin donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern- Volmer quenching constants and static binding constants. It was demonstrated that the PET interaction between the porphyrin subunits and NBCD is indeed effective.展开更多
文摘A photocatalyst-free photoinduced radical difluoromethylation approach for the convenient synthesis of 3-CF_(2)H-coumarins from alkynoates by difluoromethyl phenoxathiinium salt(PT-CF_(2)H^(+)BF_(4)^(-))was developed.This transformation in-volves radical difluoromethylation/5-exo spirocyclization/ester migration rearrangement cascade process and features mild reaction conditions,broad substrate scope and good functional groups tolerance.Using this method,a wide range of alkynoates was successfully converted to desired 3-CF_(2)H-coumarins in moderate to good yields.
文摘Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.
基金supported by the Fundamental Re-search Funds for the Central Universities(Ganglong Cui)and National Key Research and Development Pro-gram of China(No.2021YFA1500703 to Ganglong Cui)National Natural Science Foundation of China(No.22103067 to Xiao-Ying Xie)and Natural Science Foundation of Shandong Province(No.ZR2021QB105 to Xiao-Ying Xie).
文摘Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.
基金support from the Science and Technology Program of Guangzhou(No.2024A04J2821)the National Natural Science Foundation of China(Nos.52222301,22171055)the Guangdong Natural Science Foundation for Distinguished Young Scholar(No.2022B1515020078)。
文摘Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembly and photoinduced seeded reversible addition-fragmentation chain transfer(RAFT)polymerization to prepare a diverse set of core-shell colloidal particles with a well-defined polymer layer.Chemical compositions,structures,and thicknesses of polymer layers could be conveniently regulated by using different types of monomers and feed[monomer]/[chain transfer agent]ratios during seeded RAFT polymerization.
文摘Photodynamic therapy(PDT)as a non-invasive anticancer modality has received increasing attention due to its advantages of noninvasiveness,high temporospatial selectivity,simple and controllable operation,etc.PDT mainly relies on the generation of toxic reactive oxygen species(ROS)by photosensitizers(PSs)under the light irradiation to cause cancer cell apoptosis and death.However,solid tumors usually exhibit an inherent hypoxic microenvironment,which greatly limits the PDT efficacy of these high oxygen-dependent conventional type II PSs.Therefore,it is of great importance to design and develop efficient type I PSs that are less oxygen-dependent for the treatment of hypoxic tumors.Herein,a new strategy for the preparation of efficient type I PSs by introducing the photoinduced electron transfer(PET)mechanism is reported.DR-NO_(2) is obtained by introducing 4-nitrobenzyl to(Z)-2-(5-(4-(diethylamino)-2-hydroxybenzylidene)-4-oxo-3-phenylthiazolidin-2-ylidene)malononitrile(DR-OH)with aggregation-induced emission(AIE)feature.The AIE feature ensures their high ROS generation efficiency in aggregate,and the PET process leads to fluorescence quenching of DR-NO_(2) to promote triplet state formation,which also promotes intramolecular charge separation and electron transfer that is conducive for type I ROS particularly superoxide radicals generation.In addition,DR-NO_(2) nanoparticles are prepared by nanoprecipitation to possess nanoscaled sizes,high cancer cell uptake,and excellent type I ROS generation ability,which results in an excellent performance in PDT ablation of MCF-7 cancer cells.This PET strategy for the development of type I PSs possesses great potential for PDT applications against hypoxic tumors.
基金the National Natural Science Foundation of China(Grant No.62274018)the Xinjiang Construction Corps Key Areas of Science and Technology Research Project(Grant No.2023AB029)the Key Project of Chongqing Overseas Students Returning to China Entrepreneurship and Innovation Support Plan(Grant No.cx2023006).
文摘Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless,the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs,thus impeding the commercialization of perovskite-based TSCs.Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained.In this review,we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices.The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized.Beyond that,the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed.Finally,the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.
基金the financial support from the National Natural Science Foundation of China(No.22107062)the National Natural Science Foundation of Shanghai(No.21ZR1422600)。
文摘Tryptophan(Trp)carries a unique heteroaromatic indole side chain and plays a critical role in peptide or protein modification.Herein,we have reported a metal-free photoinduced N-H alkylation strategy using N-aryl glycines for specific modification of tryptophan-containing peptides.The robustness of our approach is demonstrated by its wide substrate scope,excellent isolated yields,as well as almost unobservable side effects.Using this highly efficiently metal-free condition,alkylated Trp-containing peptides can be smoothly assembled.This study provides a reliable and practical tool for the chemo-selective modification of various tryptophan containing oligopeptides.
基金national financial support from the National Key R&D Program of China(No.2019YFA0905700)the National Natural Science Foundation of China(Nos.82173703 and 81874293)the Major Basic Research Program of Shandong Provincial Natural Science Foundation(No.ZR2019ZD26)。
文摘Two distinctive rearranged 19-nor-7,8-seco-labdane diterpenoids(1 and 2)with a novel tetracyclo[5.2.1.0^(2,5.)0^(4,10)]decane skeleton,a derivative of the open tetrahydrofuran ring(7),three dimeric compounds(8-10),and four revised homologs(3-6)were obtained from Chinese liverwort Pallavicinia ambigua.Their structures were identified via combined analysis of their spectroscopic data,single-crystal X-ray diffraction patterns,and ECD calculations.The light-driven conversion of compound 5 to compounds 1-4 demonstrated that photochemically induced postmodification involved in biosynthesis is an important way to diversify natural structures.A preliminary cytotoxicity assay revealed that compound 5 showed significant inhibition in the human prostate cancer(PC-3)cell line via an apoptotic pathway.
基金support from the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017124).
文摘An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-stage functionalization of medicine derivatives.Mechanism studies suggest a plausible visible light triggered ligand-to-metal charge transfer(LMCT)/1,4-hydrogen atom transfer(HAT)cascade.
基金Supported by National Natural Science Foundation of China(No.82060885)Ningxia Scientific Research Program for Institution of Higher Education(No.NGY2018-99)Ningxia Natural Science Foundation(No.2020AAC03172)。
文摘AIM:To investigate the relationship between autophagy and apoptosis in photoinduced injuries in retinal pigment epithelium(RPE)cells and how Lycium barbarum polysaccharide(LBP)contributes to the increased of RPE cells to photoinduced autophagy.METHODS:In vitro cultures of human RPE strains(ARPE-19)were prepared and randomly divided into the blank control,model,low-dose LBP,middle-dose LBP,high-dose LBP,and 3-methyladenine(3MA)groups.The viability of the RPE cells and apoptosis levels in each group were tested through cell counting kit-8(CCK8)method with a flow cytometer(Annexin V/PI double staining technique).The expression levels of LC3II,LC3I,and P62 proteins were detected with the immunofluorescence method.The expression levels of beclin1,LC3,P62,PI3K,P-mTOR,mTOR,P-Akt,and Akt proteins were tested through Western blot.RESULTS:LBP considerably strengthens cell viability and inhibits the apoptosis of RPE cells after photoinduction.The PI3K/Akt/mTOR signal pathway is activated because of the upregulation of the phosphorylation levels of Akt and mTOR proteins,and thus autophagy is inhibited.CONCLUSION:LBP can inhibit the excessive autophagy in RPE cells by activating the PI3K/Akt/mTOR signaling pathways and thereby protect RPE cells from photoinduced injuries.
基金This work was supported by the National Natural Science Foundation of China (No. 19604015) and Guangdong Provincial Natural Science Foundation (No. 980279 and 980346).
文摘Photoinduced birefringence is investigated in a new amorphous copolymer containing azobenzene groups. The levels of birefringence signal are found to depend an the polarization angle between the pump beam and the probe beam, and on the ellipticity of the pump beam. Both the growth and decay processes of the birefringence signal can be described by known biexponential equations. The rate constants and the amplitudes associated with the growth process of the photoinduced birefringence are observed to display a linear dependence with the pump beam intensity. A new dynamic model of the photoinduced birefringence is presented taking into account the contributions of both the bans and cis isomers of azobenzene groups and the local polymer segments. The numerical treatment of this model shows good agreement with the experimental data in the whole writing-erasing processes of the photoinduced birefringence conducted in our polymer samples.
文摘Photoinduoed reaction of chloranil (TCBQ) with 2-methylfuran la and 2,5-dimethylfuran 1b in benzene gave addition products 2a and 2b respecvely together with tetrachlorohydroquinone 3. A mechanism of sequential electron and proton transfer from la or 1b to ~3TCBQ followed by coupling of the furfuryl and semiquinone radical pairs was proposed and is evidenced by the photo-CIDNP studies of the TCBQ-1a and TCBQ-1b systems.
文摘Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 mum and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model.
文摘The photoinduced reactions of aryl halides with carbazolyl nitrogen anion,in dimethyl sulfoxide,yield the corresponding N-arylated products.These reactions are suggested in terms of the S;Nl mechaism of nucleophilic substitution.
基金Supported by the National Natural Science Foundation of China(11174229)
文摘Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption（NLA） coefficient and the value of nonlinear refraction（NLR） index of the products increased from 0 to 3.167 cm/GW and from 0.64×10^ 4 to 6.83×10 ^4 cm 2 /GW,respectively.
基金financially supported by the National Natural Science Foundation of China(No.41976036)the State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute(LSMRI)(Nos.KF190408 and KF190404)。
文摘A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelectrode was prepared by further annealing treatment to explore the photoinduced cathodic protection(CP)performance.Compared with WO_(3)and ZnO,the photoinduced CP and electron storage capacity performance of WO_(3)/ZnWO_(4)/ZnO is significantly improved in 3.5%NaCl solution without adding any hole scavenger.The electron storage capacity of the WO_(3)/ZnWO_(4)/ZnO heterojunction makes it possible to continuously protect metallic materials in the dark after switching off the light,which can realize long-term and effective photoinduced CP.
文摘Hydrogen titanate nanotubes were synthesized by hydrothermal process using 10 M NaOH and TiO2 anatase powder. The material synthesized was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to ensure the structural and morphological characteristics. The interaction of calf thymus DNA (CT-DNA) and bovine serum albumin protein with suspended aqueous solution of titanate nanotubes was investigated using UV absorption spectroscopy and the apparent association constant was found to be, Kb= 1.68 × 104 M-1 and Kap=5.41 × 103 M-1 for DNA and BSA respectively. Addition of the titanate nano material resulted quenching of fluorescence spectra of ethidium bromide-DNA in tris HCl buffer solution and that of aqueous protein solution. The apparent binding constant (Ksv= 5.46 × 104M-1 for DNA binding and Ksv = 6.063 × 103M-1 for protein binding) was deduced from relevant fluorescence quenching data using Stern-Volmer equation.
基金Financial support from National Natural Science Foundation of China(Nos.21871053 and 21532001)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2019R01005)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2020ZD04)。
文摘Hydrogen-atom-transfer(HAT)is an efficient way for direct C-H functionalization of inert C-H bonds,therefore it has attracted great interests in recent years.So far,various HAT catalysts have been developed.Among them,quinuclidine and its derivatives show different characters toward other HAT catalysts as they tend to abstract electron-rich and hydridic hydrogens in the presence of weak and neutral C-H bonds.These features enable direct C-H functionalization of compounds with various groups which are unable or difficult by other methods.This review summarizes recent advance of photoinduced reactions with quinuclidine and its derivatives as HAT catalysts and exhibits powerful synthetic potential by using quinuclidine and its derivatives as HAT catalysts.
基金V. ACKN0WLEDGMENT This work was supported Science Foundation of China by the National Natural （No.20472079）.
文摘Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- triphenyl porphyrinate （NiPCnA, n=4,5,6）, were synthesized, in which the porphyrin moiety was connected to l-adamantanamine via a flexible hydrocarbon chain. The fluorescence quenching between these donor substrates and mono-6-p-nitrobenzoyl-β-cyclodextrin （NBCD） was studied in detail. Distinct fluorescence quenching occured in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer （PET） inside the supramolecular assembly between the porphyrin donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern- Volmer quenching constants and static binding constants. It was demonstrated that the PET interaction between the porphyrin subunits and NBCD is indeed effective.
