Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have ...Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel （MQ）.展开更多
The electron transfer reaction between triplet anthraquinone-2-sulfonate with poly-guanylic acid (5) (poly[G]) in acetonitrile-H2O has been investigated by 248 nm laser flash photolysis. The transient absorption spect...The electron transfer reaction between triplet anthraquinone-2-sulfonate with poly-guanylic acid (5) (poly[G]) in acetonitrile-H2O has been investigated by 248 nm laser flash photolysis. The transient absorption spectra of radical cation of poly[G] and radical anion of anthraqunione-2-sulfonate (AQS) arising from electron transfer reaction has been observed simultaneously for the first time. The formation processes of radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate as well as the decay processes of triplet anthraquinone-2-sulfonate have also been observed, the apparent rate constants for the formation and decay of transient species have been determined. The free energy changes in the process of the electron transfer was also calculated.展开更多
The microscopic moleeular theory for electron transfer in a model solvent ishahr developed. The nonlinear response of the solvent molecules is be computedquanitatively in a new way. Adopting computer simulation daa an...The microscopic moleeular theory for electron transfer in a model solvent ishahr developed. The nonlinear response of the solvent molecules is be computedquanitatively in a new way. Adopting computer simulation daa and choosingappropriate reaction coordinae, a reasonable free energy dinram is constructed and thercorganhaion energy for the product state is calculated.展开更多
After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated ...After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.展开更多
A single potential step chronoabsorptometric method for the determination of ki- netic parameters of simple quasi-reversible reactions is described.It is verified by determining the kinetic parameters for the electror...A single potential step chronoabsorptometric method for the determination of ki- netic parameters of simple quasi-reversible reactions is described.It is verified by determining the kinetic parameters for the electroreduction of ferricyanide.A long-optical-path electro- chemical cell with a plug-in electrode is used.The thickness of solution layer is 0.55 mm展开更多
The NO_2 + NO_2^- electron transfer reaction was studied with DFT-B3LYPmethod at 6-311 + G~* basis set level for the eight selected structures: four species favor thestructure of 'head to head'. The geometry o...The NO_2 + NO_2^- electron transfer reaction was studied with DFT-B3LYPmethod at 6-311 + G~* basis set level for the eight selected structures: four species favor thestructure of 'head to head'. The geometry of transition state was obtained by the linear coordinatemethod. Three parameters, non-adiabatic activation energy (E_(ad)), coupling matrix element (H_(if))and reorganization energy (λ) for electron transfer reaction can be calculated. According to thereorganization energy of the ET reaction, the values obtained from George-Griffith-Marcus (GGM)method (the contribution only from diagonal elements of force constant matrix) are larger than thoseobtained from Hessian matrix method (including the contribution from both diagonal and off-diagonalelements), which suggests that the coupling interactions between different vibrational modes areimportant to the inner-sphere reorganization energy for the ET reactions in gaseous phase. The valueof rate constant was obtained by using above three activation parameters.展开更多
Electron transfer reactions take place readily between 2, 2, 6, 6-tetramethylpiperidine oxoammonium ions (la,lb) and phenothiazines (2a—2g), giving corresponding nitroxides (3a,3b) and phenothiazine radical cations ...Electron transfer reactions take place readily between 2, 2, 6, 6-tetramethylpiperidine oxoammonium ions (la,lb) and phenothiazines (2a—2g), giving corresponding nitroxides (3a,3b) and phenothiazine radical cations (4a—4g). The rate constants for the electron self-exchange reactions between1 and3, as well as between2 and4, are determined by EPR and1HNMR line-broadening effect in acetonitrile. By application of the Marcus theory, the kinetics of the cross exchange reactions between1 and2 is studied.展开更多
DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Throug...DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Through analyzing the change of the energy and the charge densilty along hte reaction path, the bond-breaking in ET reaction for CH3X is investigated.展开更多
Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coor...Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coordinates leading to oscillations in the kinetics is examined. Different schemes of charge separation are investigated. A good fitting of experimental kinetics of native Rba. sphaeroides RCs is achieved in the five states model P*1BAHA↔P*2BAHA↔I↔P+HA↔P+BA with two excited states BAHA and BAHA and three charge separated states I, P+HA and P+BA (P is a primary electron donor, bacteriochlorophyll dimer, BA and HA are an electron acceptor, monomeric bacteriochlorophyll and bacteriopheophytin in active A-branch, respectively). In the model only the first excited state is directly populated by optical excitation. The emission of the two excited states is assumed to be at 905 and 940 nm, respectively. The intermediate state I is assumed to absorb at 1020 nm as well as the P+HA state. The model explains the deep oscillations in the kinetics of the stimulated emission and of the absorption. In the simpler schemes without the I state or with only one excited state the accordance with the experiment is achieved at unreal parameter values. A possible nature of the I and BAHA states and a possible incoherent nature of the oscillations are discussed.展开更多
Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition...Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.展开更多
光是光合作用不可或缺的底物。然而过量的光照会对光合生物造成氧化胁迫和严重的损害。为了应对持续变化的光环境,蓝藻演化形成了灵活的电子传递网络。围绕光系统I(photosystem I,PSI)的循环电子传递(cyclic electron transport,CET)将...光是光合作用不可或缺的底物。然而过量的光照会对光合生物造成氧化胁迫和严重的损害。为了应对持续变化的光环境,蓝藻演化形成了灵活的电子传递网络。围绕光系统I(photosystem I,PSI)的循环电子传递(cyclic electron transport,CET)将电子从铁氧还蛋白Fd回流到质体醌(plastoquinone,PQ)库,产生ATP且不积累NADPH。在蓝藻和高等植物中发现了2种不同的CET途径,即NDH依赖途径和PGR5依赖途径。蓝藻中黄素二铁蛋白Flv1/Flv3参与了类梅勒(Mehler-like)反应,从PSI接受电子直接将氧气还原为水,且没有活性氧的形成。以集胞藻为试验材料,通过分析不同的CET和Flv突变株在不同光照条件下的生理特征以及其P700氧化/还原动力学,进而研究CET途径和类梅勒反应在集胞藻中的功能。结果表明NDH-1复合体对CET的贡献率超过90%,维持细胞能在持续高光环境下生长,而迅速应激的类梅勒反应在缓解瞬时高光胁迫时发挥了重要作用。因此我们认为在集胞藻中NDH-1介导的循环电子途径是稳固支持其适应高光逆境的主要机制,而类梅勒反应则是在现有主要途径严重不足时的1个备用途径。响应迅速的FLV路径是野生型和NDH-1突变株的补足。展开更多
In the past decade light-induced electron transfer reactions in photosystem I have been the subject of intensive investigations that have led to the elucidation of some unique characteristics, the most striking of whi...In the past decade light-induced electron transfer reactions in photosystem I have been the subject of intensive investigations that have led to the elucidation of some unique characteristics, the most striking of which is the existence of two parallel, functional, redox active cofactors chains. This process is generally referred to as bidirectional electron transfer. Here we present a review of the principal evidences that have led to the uncovering of bidirectionality in the reaction centre of photosystem I. A special focus is dedicated to the results obtained combining time-resolved spectroscopic techniques, either difference absorption or electron paramagnetic resonance, with molecular genetics, which allows, through modification of the binding of redox active cofactors with the reaction centre subunits, an effect on their physical-chemical properties.展开更多
Alkali metal fullerides (A<sub>n</sub>C<sub>60</sub>) are versatile reagents in synthetic chemistry ofbuckminsterfullerene, for example, controlled chemical functionalizations of buckminster-fu...Alkali metal fullerides (A<sub>n</sub>C<sub>60</sub>) are versatile reagents in synthetic chemistry ofbuckminsterfullerene, for example, controlled chemical functionalizations of buckminster-fullerene might be achieved by using precursors C<sub>60</sub><sup>n-</sup>M in a desired oxidation state.Vapor-transport technique was widely used to investigate the electron-transfer reactionsbetween C<sub>60</sub> and alkali metal. This method, however, required higher temperature condi-tions （200—400℃） and a longer period of reaction time （10—15 d）. Direct reactions of C<sub>60</sub>展开更多
文摘Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel （MQ）.
文摘The electron transfer reaction between triplet anthraquinone-2-sulfonate with poly-guanylic acid (5) (poly[G]) in acetonitrile-H2O has been investigated by 248 nm laser flash photolysis. The transient absorption spectra of radical cation of poly[G] and radical anion of anthraqunione-2-sulfonate (AQS) arising from electron transfer reaction has been observed simultaneously for the first time. The formation processes of radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate as well as the decay processes of triplet anthraquinone-2-sulfonate have also been observed, the apparent rate constants for the formation and decay of transient species have been determined. The free energy changes in the process of the electron transfer was also calculated.
文摘The microscopic moleeular theory for electron transfer in a model solvent ishahr developed. The nonlinear response of the solvent molecules is be computedquanitatively in a new way. Adopting computer simulation daa and choosingappropriate reaction coordinae, a reasonable free energy dinram is constructed and thercorganhaion energy for the product state is calculated.
文摘After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.
文摘A single potential step chronoabsorptometric method for the determination of ki- netic parameters of simple quasi-reversible reactions is described.It is verified by determining the kinetic parameters for the electroreduction of ferricyanide.A long-optical-path electro- chemical cell with a plug-in electrode is used.The thickness of solution layer is 0.55 mm
基金ProjectsupportedbytheNaturalScienceFoundationofShandongProvince (No .Y99B0 1) theNationalKeyLaboratoryFoundationofCrystalMaterial(No.S0 1A0 2 )andtheNationalNaturalScienceFoundationofChina (No .2 96 730 5 ) .
文摘The NO_2 + NO_2^- electron transfer reaction was studied with DFT-B3LYPmethod at 6-311 + G~* basis set level for the eight selected structures: four species favor thestructure of 'head to head'. The geometry of transition state was obtained by the linear coordinatemethod. Three parameters, non-adiabatic activation energy (E_(ad)), coupling matrix element (H_(if))and reorganization energy (λ) for electron transfer reaction can be calculated. According to thereorganization energy of the ET reaction, the values obtained from George-Griffith-Marcus (GGM)method (the contribution only from diagonal elements of force constant matrix) are larger than thoseobtained from Hessian matrix method (including the contribution from both diagonal and off-diagonalelements), which suggests that the coupling interactions between different vibrational modes areimportant to the inner-sphere reorganization energy for the ET reactions in gaseous phase. The valueof rate constant was obtained by using above three activation parameters.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29572047)
文摘Electron transfer reactions take place readily between 2, 2, 6, 6-tetramethylpiperidine oxoammonium ions (la,lb) and phenothiazines (2a—2g), giving corresponding nitroxides (3a,3b) and phenothiazine radical cations (4a—4g). The rate constants for the electron self-exchange reactions between1 and3, as well as between2 and4, are determined by EPR and1HNMR line-broadening effect in acetonitrile. By application of the Marcus theory, the kinetics of the cross exchange reactions between1 and2 is studied.
文摘DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Through analyzing the change of the energy and the charge densilty along hte reaction path, the bond-breaking in ET reaction for CH3X is investigated.
基金国家重点研发计划(2021YFA1502400)国家自然科学基金(22272176,22002166,22125205,22072146,22002158)+2 种基金中国科学院洁净能源创新研究院合作基金(DNL202007)榆林学院-中国科学院洁净能源创新研究院联合基金(YLU-DNL Fund 2022008)中国科学院青年创新促进计划(Y201938)资助项目。
文摘Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coordinates leading to oscillations in the kinetics is examined. Different schemes of charge separation are investigated. A good fitting of experimental kinetics of native Rba. sphaeroides RCs is achieved in the five states model P*1BAHA↔P*2BAHA↔I↔P+HA↔P+BA with two excited states BAHA and BAHA and three charge separated states I, P+HA and P+BA (P is a primary electron donor, bacteriochlorophyll dimer, BA and HA are an electron acceptor, monomeric bacteriochlorophyll and bacteriopheophytin in active A-branch, respectively). In the model only the first excited state is directly populated by optical excitation. The emission of the two excited states is assumed to be at 905 and 940 nm, respectively. The intermediate state I is assumed to absorb at 1020 nm as well as the P+HA state. The model explains the deep oscillations in the kinetics of the stimulated emission and of the absorption. In the simpler schemes without the I state or with only one excited state the accordance with the experiment is achieved at unreal parameter values. A possible nature of the I and BAHA states and a possible incoherent nature of the oscillations are discussed.
基金supported by the National Natural Science Foundation of China(No.20472079)
文摘Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.
基金Elite Youth Program of Chinese Academy of Agricultural Sciences and the Agricultural Science and Technology Innovation Program。
文摘光是光合作用不可或缺的底物。然而过量的光照会对光合生物造成氧化胁迫和严重的损害。为了应对持续变化的光环境,蓝藻演化形成了灵活的电子传递网络。围绕光系统I(photosystem I,PSI)的循环电子传递(cyclic electron transport,CET)将电子从铁氧还蛋白Fd回流到质体醌(plastoquinone,PQ)库,产生ATP且不积累NADPH。在蓝藻和高等植物中发现了2种不同的CET途径,即NDH依赖途径和PGR5依赖途径。蓝藻中黄素二铁蛋白Flv1/Flv3参与了类梅勒(Mehler-like)反应,从PSI接受电子直接将氧气还原为水,且没有活性氧的形成。以集胞藻为试验材料,通过分析不同的CET和Flv突变株在不同光照条件下的生理特征以及其P700氧化/还原动力学,进而研究CET途径和类梅勒反应在集胞藻中的功能。结果表明NDH-1复合体对CET的贡献率超过90%,维持细胞能在持续高光环境下生长,而迅速应激的类梅勒反应在缓解瞬时高光胁迫时发挥了重要作用。因此我们认为在集胞藻中NDH-1介导的循环电子途径是稳固支持其适应高光逆境的主要机制,而类梅勒反应则是在现有主要途径严重不足时的1个备用途径。响应迅速的FLV路径是野生型和NDH-1突变株的补足。
文摘In the past decade light-induced electron transfer reactions in photosystem I have been the subject of intensive investigations that have led to the elucidation of some unique characteristics, the most striking of which is the existence of two parallel, functional, redox active cofactors chains. This process is generally referred to as bidirectional electron transfer. Here we present a review of the principal evidences that have led to the uncovering of bidirectionality in the reaction centre of photosystem I. A special focus is dedicated to the results obtained combining time-resolved spectroscopic techniques, either difference absorption or electron paramagnetic resonance, with molecular genetics, which allows, through modification of the binding of redox active cofactors with the reaction centre subunits, an effect on their physical-chemical properties.
基金Project supported by the National Natural Science Foundation of China and Science Foundation of Shanghai Committee of Science and Technology.
文摘Alkali metal fullerides (A<sub>n</sub>C<sub>60</sub>) are versatile reagents in synthetic chemistry ofbuckminsterfullerene, for example, controlled chemical functionalizations of buckminster-fullerene might be achieved by using precursors C<sub>60</sub><sup>n-</sup>M in a desired oxidation state.Vapor-transport technique was widely used to investigate the electron-transfer reactionsbetween C<sub>60</sub> and alkali metal. This method, however, required higher temperature condi-tions （200—400℃） and a longer period of reaction time （10—15 d）. Direct reactions of C<sub>60</sub>
