Electron Transfer Reaction Between Desoxyadenosine and Triplet 2-Methyl-1,4-naphthaquinone:A Laser Photolysis Study

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）.

Photoinduced Electron Transfer Reaction between Poly-guanylic Acid(5') with Anthraquinone-2-sulfonate

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.

Nonequilibrium Solvent Free Energy Curve from Molecular Theory in Electron Transfer Reaction

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.

THE CALCULATION OF RATE CONSTANT OF ELECTRON TRANSFER REACTION AT ELECTRODES

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.

CHRONOABSORPTOMETRY FOR THE DETERMINATION OF KINETIC PARAMETERS OF ELECTRON TRANSFER REACTIONS USING LONG-OPTICAL-PATH ELECTROCHEMICAL CELL

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

Theoretical Study on the NO_2+NO_2^- Electron Transfer Reaction

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.

Bidirectional Electron Transfer in the Reaction Centre of Photosystem I

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.

The Inner-sphere Reorganization Energy of M-H/M^+-H System in Gaseous Phase

A new ab-initio method of computing reorganization energy (RE) for the electron transfer (ET) reaction between M-H and M+-H system is presented. Values of RE from precise RE definition and the George-Griffith-Marcus (GGM) model were obtained and compared with the RE obtained from the experimental spectroscopic data. Results show that in the gaseous phase, ET reactions by the new method can give better values than classical GGM model.

Novel clicked tetrathiafulvalene-calix[4]arene assemblies:Synthesis and intermolecular electron transfer toward p-chloranil

Two tetrathiafulvalene-calix[4]arene assemblies （TTF-calix-1 and TFF-calix-2） have been synthesized by the click reaction. Both their cyclic voltammograms show, as expected, two one-electron quasi- reversible redox behavior. The UV-vis absorption spectra studies show that these two assemblies undergo progressive oxidation at the TFF moiety in presence of increasing amounts of Cu2＋ or Hg2＋. Moreover, the absorption studies show intermolecular electron transfer between compounds TrF-calix- I or TI＇F-calix-2 and p-chloranil may be promoted by specific metal ions such as Pb2＋, Sc3＋ etc.

Coupling matrix element of electron self-exchange reactions in solution

On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron trader reaction, a new accurate hydration potential function scheme for the determination of electron transfer coupling matrix element is presented. The coupling matrix element between two hydrated ions of the reacting system in solution is calculated. The results and the applicability of this scheme are discussed.