Theoretical study of electron transfer in uranyl(VI)–uranyl(V) complexes in solution

The rates of the electron self‐exchange between uranyl(VI) and uranyl(V) complexes in solution have been investigated in detail with quantum chemical methods. The calculations have shown that the bond length of U? Oyl is elongated by 0.1 Å when the extra electron is localized on the sites. The diabatic potential surfaces are obtained. The inner reorganization energies are 212.6 and 226.8 kJ mol^?1 for hydroxide and fluoride bridge systems, respectively. The solvent reorganization energies are 28.12 and 31.60 kJ mol^?1 for hydroxide and fluoride bridge systems, respectively. The nuclear frequency factors are 3.17 × 10¹³ and 3.12 × 10¹³ s^?1 for hydroxide and fluoride bridge systems, respectively. The electronic coupling matrix elements are 1.89 and 4.06 kJ mol^?1 for hydroxide and fluoride bridge systems, respectively. The electron‐transfer rates of our calculations are 12.95 and 0.819 M^?1 s^?1 for hydroxide and fluoride bridge systems, respectively. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

生物体系中电子转移机理的研究Ⅱ: 分子间电子转移及 电子供、受体间不同基 团的影响

利用自编程序MOPAC-ET中AM1方法,及KT(Koopman'sTheorem)法,研究了二苯负离子体系的分子间电子转移现象,计算了其电子供、受体在不同距离下的V~A~B及它们之间的相关性,另外,还对两苯环间不同介入基团对电子转移的影响做了初步研究,发现不同的介入基团存在着较大的差异。     

Kinetic Study of the Ru(II) Catalyzed Oxidation of Pentacyanoferrate(ll) Complexes by Peroxydisulfate

The oxidation reactions of Fe(CN)₅L^3? (L = 4-ampy, py, dpa) complexes by S₂O₈^2? were catalyzed upon the addition of a trace amount of Ru(NH₃)₅L′²⁺ (L′ = pz, py or dcb) complex, and the reaction becomes zero-order in Fe(II). The reaction time is ～10² fold faster than the simple Fe(CN)₅L^3?-S₂O₈^2? system. The mechanism of this Ru(II) catalyzed redox reaction is proposed as Ru(NH₃)₅L′²⁺ + 1/2 S₂O₈^2? → Ru(NH₃)₅L′³⁺ + SO₄^2? Ru(NH₃)₅L′³⁺ + Fe(CN)₅L^3? ? Ru(NH₃)₅L′²⁺ + Fe(CN)₅L^2?     

从表面电化学实验参数理解活性基团的微观结构

从分子水平上理解电子传递中电活性基团的结构变化能够直接促进我们对电化学、分子/纳米电子学、生命过程中电子传递的认识。表面电化学是经典的宏观实验方法,从宏观的实验数据中也可以了解分子结构和电活性基团所处的微环境的信息。对此,本文从表面电化学的转移系数、表观转移电子数和重组能三个方面进行了介绍。表面电化学的转移系数的变化规律可以用来指示分子间的相互作用,表观转移电子数能够给出生物大分子基团间的连接信息,重组能可以反应出电活性中心溶剂化环境的变化。本文旨在充分发挥宏观实验方法在分子电化学方面的研究价值。     

卟啉－苝酰亚胺分子阵列的合成及应用进展

由于卟啉与苝酰亚胺基元之间存在高效的能量转移或电子转移过程, 卟啉-苝酰亚胺分子阵列表现出优良的光电性能, 在有机分子器件、有机太阳能电池和光收集材料等高新技术领域展示出广阔的应用前景. 综述了近十几年来卟啉-苝酰亚胺分子阵列的合成及应用研究进展, 并展望了其发展前景.     

C~6~0环加成衍生物光诱导电子转移过程中自由基 复合反应动力学的时间分辨 ESR研究

运用时间分辨电子自旋共振(ESR)方法,分别对比研究了一种不同分子结构的富勒烯环加成衍生物中分子内以及它们与电子给体三乙胺之间的分子间光诱导电子转移(PET)反应历程,并通过探索其自由基复合反应过程的动力学参数差异,分析了给体产物自由基的结构稳定性对复合反应动力学参数的调控作用。     

Motion of redox molecules in solution monitored by the highly-sensitive EQCM technique

The behavior of redox molecules in solution that was not detected by electrochemical techniques was measured by a highly-sensitive electrochemical quartz crystal microbalance (EQCM) technique that has been improved in this study to obtain a high sensitivity of EQCM measurement in solution. The improved EQCM technique allowed to monitor the motion of a redox molecule, that is an access of the molecule to an electrode surface and repulsion from the surface during redox. An EQCM technique currently in use has measured adsorption of redox molecules on an electrode surface or polymerization on the surface caused by a chemical reaction following redox, which exhibits an enough large mass change response to detect with an EQCM measurement. However, access and repulsion of redox molecule, which is a slight motion of the molecule near on electrode surface, has not been detected and investigated by an EQCM technique, because the mass change response seems to be very small. In this study, the redox behavior of methyl viologen on a bare gold surface, pyridinethiol surface and methylpyridinethiol surface was investigated. Although the three electrodes give the same cyclic voltammogram of methyl viologen, the three are different in QCM response recorded at the same time as the voltammetry. Access/repulsion of methyl viologen within an electrical double layer was monitored by the highly-sensitive EQCM technique.     

Dynamic electron transfers in B2H6 and Cu(PH3)2(BH4)

In order to investigate the coupling of molecular vibrations and electron distribution, dynamic electron transfers in B₂H₆ and Cu(PH₃)₂(BH₄) are lated by using a new variational method. In both molecules, the dynamic electron density near bridging hydrogen atoms decreases to form the density valley by exciting specific vibrational modes. On the other hand, in both sides of the valley density hills grow up. For these molecules, similar contour maps are given by the modes with different symmetry which have large contribution of the bridging ligands. While the dynamic electron transfer of B₂H₆ arises in symmetric form, the vibrational modes of the Cu complex gives the asymmetric redistribution of the dynamic electron density. This is attributed to the difference of the symmetry between the two molecules.     

Semiconductor photoinduced cycloreversion of the dimer of methyl 2-naphthoate

The dimer of methyl 2-naphthoate (1) has been found to undergo efficient cyclorever-sion to its monomer, methyl naphtha)ene-2-carboxylate (2) on illuminated ZnO and TiO2 but not on CdS. An electron transfer and cation radical chain mechanism is proposed. Quantum yields, solvent effect, the role of oxygen, and the quenching of the reaction were investigated, and were consistent with the proposed mechanism.     

Unexpected formation of the novel fluorinated diazenes

Fluoroalkanesulfonyl azides reacted with morpholine giving unexpectedly N-fluoroalkanesulfonyl-N-morpholino diazenes, which were fully characterized by using spectral methods and X-ray diffraction analysis.     

Surface effects of monolayer-protected gold nanoparticles on the redox reactions between ferricyanide and thiosulfate

The intense research interest in nanosized particle materials is mainly fueled by their unique physical, chemical, electronic, and magnetic properties[1]. Among these, they have shown great application po-tentialities in the catalytic regulation of elec-t…     

微生物电化学系统电子中介体

电化学活性微生物与电极之间的胞外电子传递在微生物电化学系统(microbial electrochemical systems,MESs)产能、生物修复等功能的实现中起着关键作用.目前,研究者对微生物胞外电子传递机理了解有限,限制了MESs的应用.相比于需要微生物功能蛋白与电极接触才能发生的直接电子传递,间接电子传递可通过具有可逆氧化还原活性的电子中介体(electron transfer mediators,ETMs)实现电子的传递,从而有效提高微生物胞外电子传递效率.在间接电子转移过程中,ETMs起着中间电子受体和中间电子供体的作用,即被还原后可将电子传递给最终电子受体并被重新还原;理论上每个ETMs分子可以循环数千次,因此ETMs对特定环境下终端氧化物(如铁离子)的循环有着极其显著的作用.本文系统总结了MESs中ETMs及间接电子传递机制近年来的研究进展,并且在此基础上探讨了ETMs在MESs中的研究趋势,以期推动MESs在生物修复、能源生产方面的实际应用.     

Electron transfer and structural change: distinguishing concerted and two-step processes

In electron-transfer reactions accompanied by structural changes, the structural change can be concerted with electron transfer or can occur in a separate reaction either preceding or following the electron-transfer step. In this paper we discuss ways of distinguishing concerted reactions from the latter two-step type. Included are recent examples in which no intermediates have been detected in the reactions, thus precluding the direct assignment to the two-step category. In these cases, other means are used to build support for the two-step mechanism with respect to the concerted process. These include an example of structural change preceding electron transfer, a demonstration that the current models of concerted reactions cannot fit the voltammetric data, and a case in which an independent measure of the inner reorganization energy was used to show that the reaction could not be a concerted electron transfer and structural change.     

Electron attachment to a hydrated DNA duplex: the dinucleoside phosphate deoxyguanylyl-3',5'-deoxycytidine

The minimal essential section of DNA helices, the dinucleoside phosphate deoxyguanylyl-3',5'-deoxycytidine dimer octahydrate, [dGpdC](2), has been constructed, fully optimized, and analyzed by using quantum chemical methods at the B3LYP/6-31+G(d,p) level of theory. Study of the electrons attached to [dGpdC](2) reveals that DNA double strands are capable of capturing low-energy electrons and forming electronically stable radical anions. The relatively large vertical electron affinity (VEA) predicted for [dGpdC](2) (0.38 eV) indicates that the cytosine bases are good electron captors in DNA double strands. The structure, charge distribution, and molecular orbital analysis for the fully optimized radical anion [dGpdC](2)(·-) suggest that the extra electron tends to be redistributed to one of the cytosine base moieties, in an electronically stable structure (with adiabatic electron affinity (AEA) 1.14 eV and vertical detachment energy (VDE) 2.20 eV). The structural features of the optimized radical anion [dGpdC](2)(·-) also suggest the probability of interstrand proton transfer. The interstrand proton transfer leads to a distonic radical anion [d(G-H)pdC:d(C+H)pdG](·-), which contains one deprotonated guanine anion and one protonated cytosine radical. This distonic radical anion is predicted to be more stable than [dGpdC](2)(·-). Therefore, experimental evidence for electron attachment to the DNA double helices should be related to [d(G-H)pdC:d(C+H)pdG](·-) complexes, for which the VDE might be as high as 2.7 eV (in dry conditions) to 3.3 eV (in fully hydrated conditions). Effects of the polarizable medium have been found to be important for increasing the electron capture ability of the dGpdC dimer. The ultimate AEA value for cytosine in DNA duplexes is predicted to be 2.03 eV in aqueous solution.     

The Effect of Auxiliary Nitrogenated Linkers on the Design of New Cadmium-Based Coordination Polymers as Sensors for the Detection of Explosive Materials

Three new cadmium-based coordination polymers, denoted [Cd(hfipbb)(4,4’-bipy)] ( CdPF-1 ), [Cd(hfipbb)(2,2’-bipy)] ( CdPF-2 ), and [Cd(hfipbb)(1,10-phen)] ( CdPF-3 ), have been hydrothermally synthesized by using the well-known V-shaped organic linker 4,4’-(hexafluoroisopropylidene)bis(benzoic acid) (H₂hfipbb), together with different nitrogenated auxiliary linkers. Considering the d¹⁰ configuration of the transition metal selected, the luminescent properties for these CdPF-n materials were explored, finding that materials CdPF-2 and CdPF-3 act as excellent sensors in the detection of explosive nitro aromatic compounds. The photoluminescence properties of CdPF-2 and CdPF-3 revealed that significant and sensitive fluorescence quenching was observed toward NP (nitrophenol) for CdPF-2 and PA (picric acid) for CdPF-3 in MeOH suspensions.     

Role of the electronic properties of azurin active site in the electron‐transfer process

Electron transfer proteins, such as azurin (a blue copper protein), are promising candidates for the implementation of biomolecular nanoelectronic devices. To understand the details of electron transfer in redox active azurin molecules, we performed plane‐wave pseudo‐potential density functional theory (DFT) calculations of the protein active site in the two possible oxidation states Cu(I) and Cu(II). The ab initio results are used to discuss how the electronic spectrum and wavefunctions may mediate the shuttling of electrons through the copper ion. We find that the Cu‐ligand hybridization is very similar in the two charge states of the metal center, but the energy spectrum changes substantially. This result might indicate important effects of electronic correlations in the redox activity and consequent electron transfer through the Cu site. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

ω-甲亚砜基苯乙酮阴离子与对硝基苄基衍生物的反应

Russell 等于六十年代曾用 ESR 的方法和化学方法证实某些脂肪族和芳香族硝基化合物与各种阴离子之间发生单电子转移,时-硝基苄基衍生物也可以与许多阴离子反应。我们则进一步研究对-硝基苄基衍生物(1～4)与ω-