A novel nelnatic liquid crystal compound containing a cinnamoyl moiety （PCPC） and a typically cholesteric liquid crystal cholesteryl cinnamate （CC） were synthesized to explore the mechanism ofcinnamoyl compounds, ...A novel nelnatic liquid crystal compound containing a cinnamoyl moiety （PCPC） and a typically cholesteric liquid crystal cholesteryl cinnamate （CC） were synthesized to explore the mechanism ofcinnamoyl compounds, and the chemical structures of photodimerization were confirmed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectral analysis. The photoreaction behaviors of these two cinnamoyl compounds in mesomorphic state and solution were investigated, UV-Vis spectral analysis was used to analyze the photoproduct. The results show that the photochemistry of PCPC in nematic state involves both photodimerization and photoisomerization, while CC shows a complex reaction which can be divided into three parts, and this has enabled us to present new data and interpretations regarding the [2＋2] photocycloaddition reaction. Additionally, the results of UV-Vis spectral analysis in solutions strongly suggest that UV-Vis spectral analysis can be used to study the kinetic behaviors of cinnamoyl moiety photoreaction.展开更多
The CIDNP observations indicated that photoreaction of methylfurans with chloranil resulted not only furylmethyl hydroxyphenyl ethers via radical pairs but induced furyl radical isomerization to the derivatives of cyc...The CIDNP observations indicated that photoreaction of methylfurans with chloranil resulted not only furylmethyl hydroxyphenyl ethers via radical pairs but induced furyl radical isomerization to the derivatives of cyclopropene,propadiene and pyran.展开更多
Photochemical reactions of 3-methylindole,carbazole,benzimidazole with fused polycyclic aromatic hydrocarbons in solid state were investigated,The structures of 4 new compounds were confirmed by IR,UV,\+1HNNR,MS and e...Photochemical reactions of 3-methylindole,carbazole,benzimidazole with fused polycyclic aromatic hydrocarbons in solid state were investigated,The structures of 4 new compounds were confirmed by IR,UV,\+1HNNR,MS and elemental analysis.The structure of compounds 3.6 was established by X-ray crystallography.展开更多
Photodynamic therapy(PDT)usually shows limited efficacy in solid tumors since traditional PDT is O_(2)^(-)dependent while solid tumors are inherently hypoxic.In addition,hypoxic tumor cells possess antiapoptotic pathw...Photodynamic therapy(PDT)usually shows limited efficacy in solid tumors since traditional PDT is O_(2)^(-)dependent while solid tumors are inherently hypoxic.In addition,hypoxic tumor cells possess antiapoptotic pathways that resist PDT-induced apoptosis.Therefore,developing photosensitizers(PSs)that show low O_(2)^(-)dependency and can induce nonapoptotic cell death pathways is critically needed.Herein,a series of Ru(II)polypyridine complex-based PSs,RuNMe,RuH,and RuCN,were synthesized,and their applications against hypoxic tumor cells through PDT were investigated.All three complexes showthe ability to generate the superoxide anion radical(·O_(2)^(-)),which is the type I photoreaction and less O_(2)^(-)dependent.RuNMe shows the best PDT performance against MCF-7 cells and three-dimensional multicellular spheroids,due to its higher cellular uptake and more reactive oxygen species generation.More importantly,RuNMe-incubated MCF-7 cells show photoinduced ferroptosis as evidenced by glutathione peroxidase 4 downregulation and lipid peroxide accumulation.This work not only develops a novel ferroptosis-inducing Ru(II)complex with the type I PDT process but also offers an effective strategy to solve tumor hypoxia in PDT.展开更多
Molecular design, synthesis and photochromic properties of spirooxazines and fulgides are described. In the case of fulgides, the change of the substituents may lead to different photochromic properties and different ...Molecular design, synthesis and photochromic properties of spirooxazines and fulgides are described. In the case of fulgides, the change of the substituents may lead to different photochromic properties and different photoreactions of the kind of compounds. In photochromic process of pyrryl-substituted fulgides, the excited singlet state is the mam species, but the excited triplet state is also involved. However, no excited triplet state has been observed in cyclization of aryl-substituted fulgides. In the case of spirooxazines, the substituents at 2’-position have great effect on the formation of photoproduct and on the mechanism of photoreaction. The increase of steric hindrance of the 2’-position substituent gives rise to the decrease of the quantum yield for the formation of photochromic merocyanine (PMC) and the increase of the relative quantum yield for the charge separated twist intermediate (CT).展开更多
A series of polymethylenediamine bis(4-methyl-7-coumarinyl)oxyacetic amides have been synthesized and their intramolecular photochemical cyclodimerizations have been investigated. It was found that only syn-HT configu...A series of polymethylenediamine bis(4-methyl-7-coumarinyl)oxyacetic amides have been synthesized and their intramolecular photochemical cyclodimerizations have been investigated. It was found that only syn-HT configuration products were obtained when these bisamides were directly irradiated in dimethyl sulfoxide solution and the yields of the products decreased with the increase of the chain length. The structures of long chain amides and their intramolecular photocyclization products were determined by IR, MS, 1H NMR and elemental analysis.展开更多
In this study,we showed that BiO Br nanoplates prepared at different pH values have substratedependent photocatalytic activities under visible-light irradiation. The BiO Br nanoplates synthesized at pH 1（BOB-1） degr...In this study,we showed that BiO Br nanoplates prepared at different pH values have substratedependent photocatalytic activities under visible-light irradiation. The BiO Br nanoplates synthesized at pH 1（BOB-1） degraded salicylic acid more effectively than did those obtained at pH 3（BOB-3）,but the order of their photocatalytic activities in rhodamine B（RhB） degradation were reversed. Electrochemical Mott–Schottky and zeta-potential measurements showed that BOB-1 had a more positive valence band and lower surface charge,leading to superior photocatalytic activity in salicylic acid degradation under visible light. However,BOB-3 was more powerful in RhB degradation because larger numbers of superoxide radicals were generated via electron injection from the excited RhB to its more negative conduction band under visible-light irradiation; this was confirmed using active oxygen species measurements and electron spin resonance analysis. This study deepens our understanding of the origins of organic-pollutant-dependent photoreactivities of semiconductors,and will help in designing highly active photocatalysts for environmental remediation.展开更多
Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.T...Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.The later color was switched back to the original color when the films were irradiated with white light.The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product 1-C at itsλ_(max) of 525 nm.The first-...展开更多
Organic matters in drinking water of Kaschin-Beck disease areas were extracted. Then analyses and characterization were performed by means of multiply chemical and physical methods. The results did not show the obviou...Organic matters in drinking water of Kaschin-Beck disease areas were extracted. Then analyses and characterization were performed by means of multiply chemical and physical methods. The results did not show the obvious difference in the frame structure of humic substances and the structure of rmcromolecular compounds in the drinking water of disease and non-disease areas, but the difference in the contents of some micromolecular compounds and radicals. The investigation also includes the preliminary research on the photoreaction of drinking water from disease and non-disease areas and the accumulation of natural organic matter in the bone of tested animals.展开更多
The synthesis of syn-photodimer from 1,4-dihydropyridine without 4-aryl was studied, and its single crystal was obtained （C22H30N2O8, Mr= 450.48）. It crystallizes in monoclinic, space group P21/c with a = 11.937（2...The synthesis of syn-photodimer from 1,4-dihydropyridine without 4-aryl was studied, and its single crystal was obtained （C22H30N2O8, Mr= 450.48）. It crystallizes in monoclinic, space group P21/c with a = 11.937（2）, b = 20.913（4）, c = 9.763（2） A,β = 108.46（3）°, V= 2311.9（8） ,A^3, Z= 4, Dc = 1.294 g/cm^3,/7（000） = 960,μ = 0.099 mm^- 1, R = 0.0640 and wR = 0.1464 for 4077 unique reflections with 1598 observed ones （I 〉 2σ（I）. It is shown that the whole molecular structure of the title compound is a twist-boat conformation, and the two double bonds have a trend of potential intramolecular reaction under high-energy irradiation.展开更多
The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation betwe...The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation between structures on the one hand and energies,on the other hand,of the reactants,transition states and products based on both singlet ground（S0） and triplet excited（T1） potential energy surfaces.The feasible mechanism indicates that an intramolecular Norrish/Yang cyclization reaction takes place via H-abstraction to obtain the sole chiral cyclobutanol photoproduct.The located crossing point plays an important role in the cyclization process,which permits intersystem crossing（ISC） from T1 to S0 state.The rate-determining step may be to experience ISC between two different potential energy surfaces,requiring sufficient time for electron spin reversion,i.e.,spin multiplicity alteration.These conclusions are further confirmed by the second-order M ller-Plesset perturbation theory（MP2） calculations.展开更多
Drug-induced phototoxicity is elicited by exposure of skin and/or eyes to topical or systemic administration of chemicals,followed by exposure to sunlight.For photosafety testing,a new screening strategy,employing in ...Drug-induced phototoxicity is elicited by exposure of skin and/or eyes to topical or systemic administration of chemicals,followed by exposure to sunlight.For photosafety testing,a new screening strategy,employing in vitro photochemical/photobiological and in vivo cassette-dosing pharmacokinetic(PK)studies,was proposed[1,2].The screening system provided reliable phototoxic predictions of tested chemicals at least within the same chemical series;however,the applicability of the proposed strategy is not fully understood.展开更多
The ability to selectively introduce diverse functionality onto hydrocarbons is of substantial value in the synthesis of both small molecules and pharmaceuticals.In this endeavour,as a photocatalyst-and metalfree proc...The ability to selectively introduce diverse functionality onto hydrocarbons is of substantial value in the synthesis of both small molecules and pharmaceuticals.In this endeavour,as a photocatalyst-and metalfree process,the electron donor–acceptor(EDA)strategy has not been well explored.Here we report an approach to aliphatic carbon-hydrogen bond diversification through an EDA complex constituted by HCl and S^(IV)=O groups.As an efficient hydrogen atom transfer(HAT)reagent,chlorine radical can be produced via a proton-coupled electron transfer process in this system.Based on this unusual path,a photopromoted versatile aliphatic C–H functionalization is developed without photo-and metal-catalysts,including thiolation,arylation,alkynylation,and allylation.This conversion has concise and ambient reaction conditions,good functional group tolerance,and substrate diversity,and provides an alternative solution for the high value-added utilization of bulk light alkanes.展开更多
Bifunctional reagents that serve as dual coupling partners with an activating species have emerged as valuable synthetic tools in organic chemistry.They allow for the development of diverse reaction modes with enhance...Bifunctional reagents that serve as dual coupling partners with an activating species have emerged as valuable synthetic tools in organic chemistry.They allow for the development of diverse reaction modes with enhanced efficiency and structural variability,which is in high demand for atom-economic and sustainable synthesis.Among them,bifunctional reagents containing Nheteroaryl groups have received much attention due to their ability to introduce privileged N-heteroaryl moieties into complex molecules that are otherwise challenging to access.Furthermore,these reagents have been employed under visible-light conditions to achieve various synthetic applications,enabling difunctionalization of alkenes,alkynes,and[1.1.1]propellanes under mild reaction conditions,providing access to highly functionalized N-heteroarenes.In this review,we provide an overview of the recent achievements and applications of photoinduced difunctionalization using bifunctional reagents containing N-heteroaryl groups.We systematically categorize the representative contributions in the field based on bifunctional reagents and their reactivity patterns.This review aims to highlight the potential of these reagents as powerful synthetic tools for sustainable and diverse synthesis.展开更多
Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electro...Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights(405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism.展开更多
The first example of the p-orbital overlap controlled enantioselectivity of Norrish type II photocyclization reaction was described. Irradiation of 5-methyl bicyclo[l. 1.1 ]pentanyl ketone with UV in the solid state a...The first example of the p-orbital overlap controlled enantioselectivity of Norrish type II photocyclization reaction was described. Irradiation of 5-methyl bicyclo[l. 1.1 ]pentanyl ketone with UV in the solid state as well as in the acetonitrile solution afforded the Norrish/Yang photocyclization compound as the sole product. Solid-state asymmetric photochemical studies using ionic chiral auxiliary technique led to the enantioselectivity as high as 60%. The results were rationalized by Xray single crystal structure.展开更多
Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic...Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in June, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in June（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DOM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both Fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on MeHg.The DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.展开更多
The behaviour of photoreaction occurring on the superfine duster interface of semiconductor CdS has been studied. The results indicated that the size quantization effect of semiconductor nanoparticles was obviously re...The behaviour of photoreaction occurring on the superfine duster interface of semiconductor CdS has been studied. The results indicated that the size quantization effect of semiconductor nanoparticles was obviously reflected not only in their physical properties, but also in the interfacial photocatalysis reactions initiated by superfine nanopartides. This means that the direction and mechanisms in photoreactions of the compounds adsorbed on the surface of nanopartides could vary with the alteration of particle size because the redox potential values of semiconductor particles could be changed with the variation of particle size. Doubtlessly, this effect could play an important role in controlling the interfacial reaction mechanisms and raising the selectivity to photoreaction paths.展开更多
An X-band EPR study on a Na_3(CrMo_6O_(24)H_6)·8H_2O single crystal diluted by its isomor-phic compound Na_3(AlMo_6O_(24)H_6)·8H_2O at room temperature is reported. Using the least squares-fitting method to ...An X-band EPR study on a Na_3(CrMo_6O_(24)H_6)·8H_2O single crystal diluted by its isomor-phic compound Na_3(AlMo_6O_(24)H_6)·8H_2O at room temperature is reported. Using the least squares-fitting method to simulate the EPR data for principal planes, the Hamiltonian parameterswere obtained. The principal values of the g tensors are g_(ZZ) = 1.904, g_(XX)= 1.973, g_(YY)=1.933. The zero field splitting tensor parameters are D = 0.275 cm^(-1), E = 0.05 cm^(-1). The fielddependence of Cr^(3+) energy levels with field at different angles from the principal axes whenthe field is along the principal planes is calculated based on these experimental parameters.The isofrequency plots of calculated field vs. angle are also shown. They agree well with theexperimental results.展开更多
The photochemical behavior of bicyclo[2.1.1]hexyl derivatives was investigated by irradiation with a 450 W medium-pressure mercury lamp in acetonitrile solution.The irradiation of methyl bicyclo[2.1.1]hexane-5-carbony...The photochemical behavior of bicyclo[2.1.1]hexyl derivatives was investigated by irradiation with a 450 W medium-pressure mercury lamp in acetonitrile solution.The irradiation of methyl bicyclo[2.1.1]hexane-5-carbonylbenzoate(1a)led to both Norrish type II cyclization and cleavage products with a molar ratio of 1∶2.2,whereas the irradiation of methyl 5-methylbicyclo[2.1.1]hexane-5-carbonylbenzoate(1b)afforded the only Norrish/Yang photocyclization compound as the sole product.Such results were illustrated by several geometric parameters for Norrish/Yang photoreaction asφ_(1),φ_(4) andβobtained from the crystal structures.Furthermore,asymmetric pho-tochemical studies using ionic chiral auxiliary technique were also conducted in the solid state.展开更多
文摘A novel nelnatic liquid crystal compound containing a cinnamoyl moiety （PCPC） and a typically cholesteric liquid crystal cholesteryl cinnamate （CC） were synthesized to explore the mechanism ofcinnamoyl compounds, and the chemical structures of photodimerization were confirmed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectral analysis. The photoreaction behaviors of these two cinnamoyl compounds in mesomorphic state and solution were investigated, UV-Vis spectral analysis was used to analyze the photoproduct. The results show that the photochemistry of PCPC in nematic state involves both photodimerization and photoisomerization, while CC shows a complex reaction which can be divided into three parts, and this has enabled us to present new data and interpretations regarding the [2＋2] photocycloaddition reaction. Additionally, the results of UV-Vis spectral analysis in solutions strongly suggest that UV-Vis spectral analysis can be used to study the kinetic behaviors of cinnamoyl moiety photoreaction.
文摘The CIDNP observations indicated that photoreaction of methylfurans with chloranil resulted not only furylmethyl hydroxyphenyl ethers via radical pairs but induced furyl radical isomerization to the derivatives of cyclopropene,propadiene and pyran.
文摘Photochemical reactions of 3-methylindole,carbazole,benzimidazole with fused polycyclic aromatic hydrocarbons in solid state were investigated,The structures of 4 new compounds were confirmed by IR,UV,\+1HNNR,MS and elemental analysis.The structure of compounds 3.6 was established by X-ray crystallography.
基金This work was financially supported by the National Natural Science Foundation of China(grant nos.22122701,21731004,91953201,92153303,21977044,and 21907050)the Natural Science Foundation of Jiangsu Province(grant nos.BK20202004 and BK20190282)the Excellent Research Program of Nanjing University(grant no.ZYJH004).
文摘Photodynamic therapy(PDT)usually shows limited efficacy in solid tumors since traditional PDT is O_(2)^(-)dependent while solid tumors are inherently hypoxic.In addition,hypoxic tumor cells possess antiapoptotic pathways that resist PDT-induced apoptosis.Therefore,developing photosensitizers(PSs)that show low O_(2)^(-)dependency and can induce nonapoptotic cell death pathways is critically needed.Herein,a series of Ru(II)polypyridine complex-based PSs,RuNMe,RuH,and RuCN,were synthesized,and their applications against hypoxic tumor cells through PDT were investigated.All three complexes showthe ability to generate the superoxide anion radical(·O_(2)^(-)),which is the type I photoreaction and less O_(2)^(-)dependent.RuNMe shows the best PDT performance against MCF-7 cells and three-dimensional multicellular spheroids,due to its higher cellular uptake and more reactive oxygen species generation.More importantly,RuNMe-incubated MCF-7 cells show photoinduced ferroptosis as evidenced by glutathione peroxidase 4 downregulation and lipid peroxide accumulation.This work not only develops a novel ferroptosis-inducing Ru(II)complex with the type I PDT process but also offers an effective strategy to solve tumor hypoxia in PDT.
基金Project supported by the National Natural Science Foundation of China
文摘Molecular design, synthesis and photochromic properties of spirooxazines and fulgides are described. In the case of fulgides, the change of the substituents may lead to different photochromic properties and different photoreactions of the kind of compounds. In photochromic process of pyrryl-substituted fulgides, the excited singlet state is the mam species, but the excited triplet state is also involved. However, no excited triplet state has been observed in cyclization of aryl-substituted fulgides. In the case of spirooxazines, the substituents at 2’-position have great effect on the formation of photoproduct and on the mechanism of photoreaction. The increase of steric hindrance of the 2’-position substituent gives rise to the decrease of the quantum yield for the formation of photochromic merocyanine (PMC) and the increase of the relative quantum yield for the charge separated twist intermediate (CT).
文摘A series of polymethylenediamine bis(4-methyl-7-coumarinyl)oxyacetic amides have been synthesized and their intramolecular photochemical cyclodimerizations have been investigated. It was found that only syn-HT configuration products were obtained when these bisamides were directly irradiated in dimethyl sulfoxide solution and the yields of the products decreased with the increase of the chain length. The structures of long chain amides and their intramolecular photocyclization products were determined by IR, MS, 1H NMR and elemental analysis.
基金supported by the National Natural Science Funds for Distinguished Young Scholars(21425728)the National Natural Science Foundation of China(21173093+4 种基金211770482127308821477044)the Key Project of Natural Science Foundation of Hubei Province(2013CFA114)the the Fundamental Research Funds for the Central Universities(CCNU14Z01001 CCNU14KFY002)~~
文摘In this study,we showed that BiO Br nanoplates prepared at different pH values have substratedependent photocatalytic activities under visible-light irradiation. The BiO Br nanoplates synthesized at pH 1（BOB-1） degraded salicylic acid more effectively than did those obtained at pH 3（BOB-3）,but the order of their photocatalytic activities in rhodamine B（RhB） degradation were reversed. Electrochemical Mott–Schottky and zeta-potential measurements showed that BOB-1 had a more positive valence band and lower surface charge,leading to superior photocatalytic activity in salicylic acid degradation under visible light. However,BOB-3 was more powerful in RhB degradation because larger numbers of superoxide radicals were generated via electron injection from the excited RhB to its more negative conduction band under visible-light irradiation; this was confirmed using active oxygen species measurements and electron spin resonance analysis. This study deepens our understanding of the origins of organic-pollutant-dependent photoreactivities of semiconductors,and will help in designing highly active photocatalysts for environmental remediation.
文摘Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.The later color was switched back to the original color when the films were irradiated with white light.The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product 1-C at itsλ_(max) of 525 nm.The first-...
文摘Organic matters in drinking water of Kaschin-Beck disease areas were extracted. Then analyses and characterization were performed by means of multiply chemical and physical methods. The results did not show the obvious difference in the frame structure of humic substances and the structure of rmcromolecular compounds in the drinking water of disease and non-disease areas, but the difference in the contents of some micromolecular compounds and radicals. The investigation also includes the preliminary research on the photoreaction of drinking water from disease and non-disease areas and the accumulation of natural organic matter in the bone of tested animals.
基金The project was supported by the Science and Technology Department of Henan Province (0624270041)
文摘The synthesis of syn-photodimer from 1,4-dihydropyridine without 4-aryl was studied, and its single crystal was obtained （C22H30N2O8, Mr= 450.48）. It crystallizes in monoclinic, space group P21/c with a = 11.937（2）, b = 20.913（4）, c = 9.763（2） A,β = 108.46（3）°, V= 2311.9（8） ,A^3, Z= 4, Dc = 1.294 g/cm^3,/7（000） = 960,μ = 0.099 mm^- 1, R = 0.0640 and wR = 0.1464 for 4077 unique reflections with 1598 observed ones （I 〉 2σ（I）. It is shown that the whole molecular structure of the title compound is a twist-boat conformation, and the two double bonds have a trend of potential intramolecular reaction under high-energy irradiation.
基金Supported by the National Natural Science Foundation of China(No.20904007)
文摘The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation between structures on the one hand and energies,on the other hand,of the reactants,transition states and products based on both singlet ground（S0） and triplet excited（T1） potential energy surfaces.The feasible mechanism indicates that an intramolecular Norrish/Yang cyclization reaction takes place via H-abstraction to obtain the sole chiral cyclobutanol photoproduct.The located crossing point plays an important role in the cyclization process,which permits intersystem crossing（ISC） from T1 to S0 state.The rate-determining step may be to experience ISC between two different potential energy surfaces,requiring sufficient time for electron spin reversion,i.e.,spin multiplicity alteration.These conclusions are further confirmed by the second-order M ller-Plesset perturbation theory（MP2） calculations.
文摘Drug-induced phototoxicity is elicited by exposure of skin and/or eyes to topical or systemic administration of chemicals,followed by exposure to sunlight.For photosafety testing,a new screening strategy,employing in vitro photochemical/photobiological and in vivo cassette-dosing pharmacokinetic(PK)studies,was proposed[1,2].The screening system provided reliable phototoxic predictions of tested chemicals at least within the same chemical series;however,the applicability of the proposed strategy is not fully understood.
基金supported by the National Key Research and Development Program of China(2022YFC2804105)the Joint Fund of Shandong Natural Science Foundation(ZR2021LSW013)+5 种基金Natural Science Foundation of Shandong Province(ZR2020QB044,ZR2020QH364,ZR2023MH245,and ZR2022QB090)Postdoctoral Science Foundation of China(2020M682157)Qingdao Emerging Industry Cultivation Project in 2023(23-1-4-xxgg-19-nsh)Shandong Provincial Science and Technology SME Innovation Capacity Improvement Project(2022TSGC2204)the National Natural Science Foundation of China(82003787)Postdoctoral Innovation Project of Shandong Province。
文摘The ability to selectively introduce diverse functionality onto hydrocarbons is of substantial value in the synthesis of both small molecules and pharmaceuticals.In this endeavour,as a photocatalyst-and metalfree process,the electron donor–acceptor(EDA)strategy has not been well explored.Here we report an approach to aliphatic carbon-hydrogen bond diversification through an EDA complex constituted by HCl and S^(IV)=O groups.As an efficient hydrogen atom transfer(HAT)reagent,chlorine radical can be produced via a proton-coupled electron transfer process in this system.Based on this unusual path,a photopromoted versatile aliphatic C–H functionalization is developed without photo-and metal-catalysts,including thiolation,arylation,alkynylation,and allylation.This conversion has concise and ambient reaction conditions,good functional group tolerance,and substrate diversity,and provides an alternative solution for the high value-added utilization of bulk light alkanes.
基金supported by the Institute for Basic Science(IBS-R010-A2)。
文摘Bifunctional reagents that serve as dual coupling partners with an activating species have emerged as valuable synthetic tools in organic chemistry.They allow for the development of diverse reaction modes with enhanced efficiency and structural variability,which is in high demand for atom-economic and sustainable synthesis.Among them,bifunctional reagents containing Nheteroaryl groups have received much attention due to their ability to introduce privileged N-heteroaryl moieties into complex molecules that are otherwise challenging to access.Furthermore,these reagents have been employed under visible-light conditions to achieve various synthetic applications,enabling difunctionalization of alkenes,alkynes,and[1.1.1]propellanes under mild reaction conditions,providing access to highly functionalized N-heteroarenes.In this review,we provide an overview of the recent achievements and applications of photoinduced difunctionalization using bifunctional reagents containing N-heteroaryl groups.We systematically categorize the representative contributions in the field based on bifunctional reagents and their reactivity patterns.This review aims to highlight the potential of these reagents as powerful synthetic tools for sustainable and diverse synthesis.
基金supported by the National Natural Science Foundation of China (21877011, 21576038, 21421005)the Fundamental Research Funds for the Central Universities of China (DUT16TD21)+1 种基金Science Program of Dalian City (2014J11JH133, 2015J12JH207)the Supercomputing Center of Dalian University of Technology
文摘Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights(405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism.
基金We are grateful to the financial supports from the National Natural Science Foundation of China （Nos. 20802013, 21002018, 21072038）, the Natural Scientific Research Innovation Foundation in Harbin institute of Technology （Nos. 01107866, 01107986） and the Wenzhou Science and Technology Program （No. G20100056）.
文摘The first example of the p-orbital overlap controlled enantioselectivity of Norrish type II photocyclization reaction was described. Irradiation of 5-methyl bicyclo[l. 1.1 ]pentanyl ketone with UV in the solid state as well as in the acetonitrile solution afforded the Norrish/Yang photocyclization compound as the sole product. Solid-state asymmetric photochemical studies using ionic chiral auxiliary technique led to the enantioselectivity as high as 60%. The results were rationalized by Xray single crystal structure.
基金provided from the National Science and Engineering Council (NSERC) of Canada in the form of a discovery grant (#341960-2013)Canada Research Chair (#950-203477)an NSERC CREATE (#371177-2010)scholarship to S.J.K
文摘Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in June, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in June（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DOM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both Fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on MeHg.The DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.
文摘The behaviour of photoreaction occurring on the superfine duster interface of semiconductor CdS has been studied. The results indicated that the size quantization effect of semiconductor nanoparticles was obviously reflected not only in their physical properties, but also in the interfacial photocatalysis reactions initiated by superfine nanopartides. This means that the direction and mechanisms in photoreactions of the compounds adsorbed on the surface of nanopartides could vary with the alteration of particle size because the redox potential values of semiconductor particles could be changed with the variation of particle size. Doubtlessly, this effect could play an important role in controlling the interfacial reaction mechanisms and raising the selectivity to photoreaction paths.
文摘An X-band EPR study on a Na_3(CrMo_6O_(24)H_6)·8H_2O single crystal diluted by its isomor-phic compound Na_3(AlMo_6O_(24)H_6)·8H_2O at room temperature is reported. Using the least squares-fitting method to simulate the EPR data for principal planes, the Hamiltonian parameterswere obtained. The principal values of the g tensors are g_(ZZ) = 1.904, g_(XX)= 1.973, g_(YY)=1.933. The zero field splitting tensor parameters are D = 0.275 cm^(-1), E = 0.05 cm^(-1). The fielddependence of Cr^(3+) energy levels with field at different angles from the principal axes whenthe field is along the principal planes is calculated based on these experimental parameters.The isofrequency plots of calculated field vs. angle are also shown. They agree well with theexperimental results.
基金We are grateful for the financial supports from the National Natural Science Foundation of China(Nos.21372055 and 21272047)the State Key Laboratory of Urban Water Resource and Environment(SKLUWRE)(No.2012DX10)+1 种基金the Fundamental Research Funds for the Central Universities(No.HIT.BRETIV.201310)the Zhejiang Natural Science Foundation(No.LY12B02009).
文摘The photochemical behavior of bicyclo[2.1.1]hexyl derivatives was investigated by irradiation with a 450 W medium-pressure mercury lamp in acetonitrile solution.The irradiation of methyl bicyclo[2.1.1]hexane-5-carbonylbenzoate(1a)led to both Norrish type II cyclization and cleavage products with a molar ratio of 1∶2.2,whereas the irradiation of methyl 5-methylbicyclo[2.1.1]hexane-5-carbonylbenzoate(1b)afforded the only Norrish/Yang photocyclization compound as the sole product.Such results were illustrated by several geometric parameters for Norrish/Yang photoreaction asφ_(1),φ_(4) andβobtained from the crystal structures.Furthermore,asymmetric pho-tochemical studies using ionic chiral auxiliary technique were also conducted in the solid state.
