Evolution of the Reaction Mechanism during Ultrafast Photoinduced Electron Transfer

Kuz’min, M. G.; Соболева, И. В.; Dolotova, E. V.

doi:10.1021/jp8004794

Cited by 12 publications

(18 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, subsequent computational studies ,− ,− of quenching in neat conventional liquids point to a fundamental shortcoming of such a model for treating neat-solvent quenching. Instead of a single nearby partner, in neat redox-active liquids, the fluorophore is surrounded by multiple reactive partners.…”

Section: Resultsmentioning

confidence: 99%

Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes

Saladin

Maroncelli

2020

J. Phys. Chem. B

View full text Add to dashboard Cite

Study of electron transfer in ionic liquids is of interest for what it may reveal about the effects of solvent dynamics on electron transfer as well as for helping to inform current efforts to employ ionic liquids as electrolytes in energy-related applications. The present report describes time-resolved fluorescence quenching measurements of electron transfer between electronically excited 7-aminocoumarin dyes and a redox-active pyridinium ionic liquid, 1-butylpyridinium bis(trifluoromethylsulfonyl)imide ([Py 4 ][Tf 2 N]). Comparable measurements of fluorescence quenching in conventional dipolar solvents were made over 20 years ago, primarily in aromatic amine liquids. Like these prior experiments, use of commercially available coumarin dyes allowed the driving force for electron transfer (−ΔG ET ) to be varied over a 0.7 V range, leading to electron transfer rates that increase with driving force over the range 10 10 −10 12 s −1 . These rates are similar to rates previously measured in aromatic amine solvents, despite the much greater polarity of the ionic liquid, which increases the driving force by more than 0.5 eV. Fluorescence decays of most of the fluorophores in [Py 4 ][Tf 2 N] were found to be highly non-exponential functions of time, including both subpicosecond components and components in the 10 2 −10 3 ps range. Such broadly distributed emission dynamics were not observed in prior studies. Emission decays in [Py 4 ][Tf 2 N] resemble the broadly distributed solvation response characteristic of ionic liquids, suggesting that solvent motions may control the rate of electron transfer, at least in the more slowly reacting dyes. This similarity could be interpreted either in terms of solvent motions being responsible for varying the energy gap or the electronic coupling between the reactant and product states.

show abstract

Section: Resultsmentioning

confidence: 99%

Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes

Saladin

Maroncelli

2020

J. Phys. Chem. B

View full text Add to dashboard Cite

show abstract

“…For this reason the experimental kinetics cannot be used for the determination of the parameters of electron tunneling and of the electronic coupling decay parameter a as previously reported. 5,6,[20][21][22][23] In these works the contribution of the reaction inside the interior of the solvent shell in a low viscous solvent (MeCN) was 7) and ( 10)).…”

Section: Competition Of Various Mechanisms Of Etmentioning

confidence: 99%

“…The kinetics was discussed earlier in terms of the interplay of non-stationary diffusion and distant ET (electron tunneling). [19][20][21][22][23] In several cases, including non-stationary diffusion, P(ln k) cannot be described by the hyperbolic function (3) or by the Gaussian function. The time dependent rate constant for non- stationary diffusion is known to be expressed by the Smoluchowski equation 5,6 k Diff ðtÞ ¼ 4πr…”

Section: Kinetics Of Et In Diluted Solutions Diffusion Control Of Etmentioning

confidence: 99%

“…Here we shall consider the kinetics of the ET reaction of excited perylene with tetracyanoethylene in MeCN as an example. Various mechanisms were discussed for this reaction, which try to explain the deviations of the experimental kinetics from the Smoluchowski equation for ordinary non-stationary diffusion: the electron tunneling (distant or remote ET) 5,6,[20][21][22][23] and the so called two-channel reaction, 5,6,[19][20][21]23 which assumes the formation of both ground-state and electronically excited radical ions of perylene. A consideration of the rate distribution provides a possibility to check these hypotheses simply by comparison of the experimental P(ln k) with that expected for electron tunneling and two-channel mechanisms.…”

Section: Competition Of Various Mechanisms Of Etmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of transformations of the ultrafast electron transfer photoreaction mechanism in liquid solutions by the rate distribution approach

Kuz’min

Соболева

2014

Photochem Photobiol Sci

Self Cite

View full text Add to dashboard Cite

Representation of the experimental reaction kinetics in the form of rate distribution is shown to be an effective method for the analysis of the mechanisms of these reactions and for comparisons of the kinetics with QC calculations, as well as with the experimental data on the medium mobility. The rate constant distribution function P(k) can be obtained directly from the experimental kinetics N(t) by an inverse Laplace transform. The application of this approach to kinetic data for several excited-state electron transfer reactions reveals the transformations of their rate control factors in the time domain of 1-1000 ps. In neat electron donating solvents two components are observed. The fastest component (k > 1 ps(-1)) was found to be controlled by the fluctuations of the overall electronic coupling matrix element, involving all the reactant molecules, located inside the interior of the solvent shell, rather than for specific pairs of reactant molecules. The slower component (1 > k > 0.1 ps(-1)) is controlled by the medium reorganization (longitudinal relaxation times, τL). A substantial contribution from the non-stationary diffusion controlled reaction is observed in diluted solutions ([Q] < 1 M). No contribution from the long-distance electron transfer (electron tunneling) proposed earlier for the excited-state electron transfer between perylene and tetracyanoethylene in acetonitrile is observed. The rate distribution approach provides a simple and efficient method for the quantitative analysis of the reaction mechanism and transformation of the rate control factors in the course of the reactions.

show abstract

“…Experimental apparent activation free energy (blue ) and activation enthalpy (red ) for quenching of aromatic compounds by various quenchers[66][67][68][69][70][71]. Free energies of transient exciplex formation (magenta ) are calculated according to (10) (for τ 0 = 1 ns); the entropy of transient exciplex formation (green ) TΔS Ex* = ΔH Ex * − ΔG Ex * (assuming ΔH Ex * ≈ ΔH ‡ App ).Simulated curves are: (1)ΔG ‡ for Marcus mechanism ((2), λ = 0.6 eV) and (2)ΔG Ex * for transient exciplex mechanism ((15), a = 0.13, b = 0.07, c = 0.14 eV); (3) ΔH ‡ App = 0.12 − ΔG ET * /Dependences of pyrene fluorescence and triplet state quantum yields on the concentration of dibutyl phthalate in acetonitrile at room temperature [69].…”

mentioning

confidence: 99%

Transient Exciplex Formation Electron Transfer Mechanism

Kuz’min

Соболева

Dolotova

2011

Advances in Physical Chemistry

Self Cite

View full text Add to dashboard Cite

Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated) mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

show abstract

Evolution of the Reaction Mechanism during Ultrafast Photoinduced Electron Transfer

Cited by 12 publications

References 15 publications

Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes

Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes

Analysis of transformations of the ultrafast electron transfer photoreaction mechanism in liquid solutions by the rate distribution approach

Transient Exciplex Formation Electron Transfer Mechanism

Contact Info

Product

Resources

About