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Yang CH, Wang CI, Wang YS, Hsu CP. Non-negligible Outer-Shell Reorganization Energy for Charge Transfer in Nonpolar Systems. J Chem Theory Comput 2024; 20. [PMID: 39143838 PMCID: PMC11360142 DOI: 10.1021/acs.jctc.4c00742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 07/23/2024] [Accepted: 07/30/2024] [Indexed: 08/16/2024]
Abstract
Many charge-transporting molecular systems function as ordered or disordered arrays of solid state materials composed of nonpolar (or weakly polar) molecules. Due to low dielectric constants for nonpolar systems, it is common to ignore the effects of outer-shell reorganization energy (λout). However, ignoring λout has not been properly supported and it can severely impact predictions and insights derived. Here, we estimate λout by two means: from experimental ultraviolet photoelectron spectra, in which vibronic progression in these spectra can be fitted with the widths of peaks determining the low-frequency component in reorganization energy, regarded to be closely associated with λout, and from molecular dynamic (MD) simulation of nonpolar molecules, in which disorder or fluctuation statistics for energies of charged molecules are calculated. An upper bound for λout was obtained as 505 and 549 meV for crystalline anthracene (140 K) and pentacene (50 K), respectively, by fitting of experimental data, and 212 and 170 meV, respectively, from MD simulations. These values are comparable to the inner-sphere reorganization energy (λin) arising from intramolecular vibration. With corresponding spectral density functions calculated, we found that λout is influenced both by low- and high-frequency dynamics, in which the former arises from constrained translational and rotational motions of surrounding molecules. In an amorphous state, about half of the λout's obtained are from high-frequency components, which is quite different from the conventional polar solvation. Moreover, crystalline systems exhibit super-Ohmic spectral density, whereas amorphous systems are sub-Ohmic.
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Affiliation(s)
- Chou-Hsun Yang
- Institute
of Chemistry, Academia Sinica, 128 Section 2 Academia Road, Nankang, Taipei 115, Taiwan
| | - Chun-I Wang
- Institute
of Chemistry, Academia Sinica, 128 Section 2 Academia Road, Nankang, Taipei 115, Taiwan
| | - Yi-Siang Wang
- Institute
of Chemistry, Academia Sinica, 128 Section 2 Academia Road, Nankang, Taipei 115, Taiwan
| | - Chao-Ping Hsu
- Institute
of Chemistry, Academia Sinica, 128 Section 2 Academia Road, Nankang, Taipei 115, Taiwan
- National
Center for Theoretical Sciences, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan
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2
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Abstract
The theory of electron transfer reactions establishes the conceptual foundation for redox solution chemistry, electrochemistry, and bioenergetics. Electron and proton transfer across the cellular membrane provide all energy of life gained through natural photosynthesis and mitochondrial respiration. Rates of biological charge transfer set kinetic bottlenecks for biological energy storage. The main system-specific parameter determining the activation barrier for a single electron-transfer hop is the reorganization energy of the medium. Both harvesting of light energy in natural and artificial photosynthesis and efficient electron transport in biological energy chains require reduction of the reorganization energy to allow fast transitions. This review article discusses mechanisms by which small values of the reorganization energy are achieved in protein electron transfer and how similar mechanisms can operate in other media, such as nonpolar and ionic liquids. One of the major mechanisms of reorganization energy reduction is through non-Gibbsian (nonergodic) sampling of the medium configurations on the reaction time. A number of alternative mechanisms, such as electrowetting of active sites of proteins, give rise to non-parabolic free energy surfaces of electron transfer. These mechanisms, and nonequilibrium population of donor-acceptor vibrations, lead to a universal phenomenology of separation between the Stokes shift and variance reorganization energies of electron transfer.
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Affiliation(s)
- Dmitry V Matyushov
- School of Molecular Sciences and Department of Physics, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, USA.
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Abstract
Electron transfer in nonpolar media violates the temperature scaling predicted by the fluctuation–dissipation theorem.
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Affiliation(s)
- Dmitry V. Matyushov
- Department of Physics and School of Molecular Sciences
- Arizona State University
- Tempe
- USA
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Feskov SV, Mikhailova VA, Ivanov AI. Non-equilibrium effects in ultrafast photoinduced charge transfer kinetics. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2016. [DOI: 10.1016/j.jphotochemrev.2016.11.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ghosh S, Horvath S, Soudackov AV, Hammes-Schiffer S. Electrochemical Solvent Reorganization Energies in the Framework of the Polarizable Continuum Model. J Chem Theory Comput 2014; 10:2091-102. [DOI: 10.1021/ct500051e] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Soumya Ghosh
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Samantha Horvath
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Alexander V. Soudackov
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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Kao YT, Guo X, Yang Y, Liu Z, Hassanali A, Song QH, Wang L, Zhong D. Ultrafast dynamics of nonequilibrium electron transfer in photoinduced redox cycle: solvent mediation and conformation flexibility. J Phys Chem B 2012; 116:9130-40. [PMID: 22735101 DOI: 10.1021/jp304518f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We report here our systematic characterization of a photoinduced electron-transfer (ET) redox cycle in a covalently linked donor-spacer-acceptor flexible system, consisting of N-acetyl-tryptophan methylester as an electron donor and thymine as an electron acceptor in three distinct solvents of water, acetonitrile, and dioxane. With femtosecond resolution, we determined all the ET time scales, forward and backward, by following the complete reaction evolution from reactants to intermediates and finally to products. Surprisingly, we observed two distinct ET dynamics in water, corresponding to a stacked configuration with ultrafast ET in 0.7 ps and back ET in 4.5 ps and a partially folded C-clamp conformation with ET in 322 ps but back ET in 17 ps. In acetonitrile and dioxane, only the C-clamp conformations were observed with ET in 470 and 1068 ps and back ET in 110 and 94 ps, respectively. These relatively slow ET dynamics in hundreds of picoseconds all showed significant conformation heterogeneity and followed a stretched decay behavior. With both forward and back ET rates determined, we derived solvent reorganization energies and coupling constants. Significantly, we found that solvent molecules intercalated in the cleft of the C-clamp structure mediate electron transfer with a tunneling parameter (β) of 1.0-1.4 Å(-1) and the high-frequency vibration modes in the product(s) couple with the back ET process, leading to the ultrafast back ET dynamics in tens of picoseconds. These findings provide mechanistic insights of nonequilibrium ET dynamics modulated by conformation flexibility, mediated by unique solvent configuration, and accelerated by vibrational coupling.
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Affiliation(s)
- Ya-Ting Kao
- Department of Physics, and Programs of Biophysics, Chemical Physics, and Biochemistry, 191 West Woodruff Avenue, The Ohio State University, Columbus, Ohio 43210, USA
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Ivanishko IS, Beregovaya IV, Hartmann S, Köhler W, Borovkov VI. Intrinsic Reaction Parameters for Electron Transfer from Aromatic Radical Anions to Vicinal Dibromoalkanes in Alkane Solutions. J Phys Chem A 2011; 115:9861-75. [DOI: 10.1021/jp2040828] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I. S. Ivanishko
- Institute of Chemical Kinetics and Combustion of SB RAS, 3, Institutskaya Street, 630090 Novosibirsk, Russia
| | - I. V. Beregovaya
- N. N. Vorozhtsov Institute of Organic Chemistry, 9, Prospect Akademika Lavrentyeva, 630090 Novosibirsk, Russia
| | - S. Hartmann
- Physics Department, University of Bayreuth, 95440 Bayreuth, Germany
| | - W. Köhler
- Physics Department, University of Bayreuth, 95440 Bayreuth, Germany
| | - V. I. Borovkov
- Institute of Chemical Kinetics and Combustion of SB RAS, 3, Institutskaya Street, 630090 Novosibirsk, Russia
- Novosibirsk State University, 2, Pirogova Street, 630090 Novosibirsk, Russia
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Borovkov VI. Excess electrons scavenging in n-dodecane solution: The role of tunneling of electron from its localized state to acceptor. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2008.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ayala R, Sprik M. A Classical Point Charge Model Study of System Size Dependence of Oxidation and Reorganization Free Energies in Aqueous Solution. J Phys Chem B 2007; 112:257-69. [DOI: 10.1021/jp0748516] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Regla Ayala
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Michiel Sprik
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
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Abstract
We investigate the energy gap law of electron transfer in nonpolar solvents for charge separation and charge recombination reactions. In polar solvents, the reaction coordinate is given in terms of the electrostatic potentials from solvent permanent dipoles at solutes. In nonpolar solvents, the energy fluctuation due to solvent polarization is absent, but the energy of the ion pair state changes significantly with the distance between the ions as a result of the unscreened strong Coulomb potential. The electron transfer occurs when the final state energy coincides with the initial state energy. For charge separation reactions, the initial state is a neutral pair state, and its energy changes little with the distance between the reactants, whereas the final state is an ion pair state and its energy changes significantly with the mutual distance; for charge recombination reactions, vice versa. We show that the energy gap law of electron-transfer rates in nonpolar solvents significantly depends on the type of electron transfer.
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Affiliation(s)
- M Tachiya
- National Institute of Advanced Industrial Science and Technology (AIST)AIST Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan.
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Vener MV, Tovmash AV, Rostov IV, Basilevsky MV. Molecular simulations of outersphere reorganization energies in polar and quadrupolar solvents. The case of intramolecular electron and hole transfer. J Phys Chem B 2007; 110:14950-5. [PMID: 16869609 DOI: 10.1021/jp061069h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Outersphere reorganization energies (lambda) for intramolecular electron and hole transfer are studied in anion- and cation-radical forms of complex organic substrates (p-phenylphenyl-spacer-naphthyl) in polar (water, 1,2-dichloroethane, tetrahydrofuran) and quadrupolar (supercritical CO2) solvents. Structure and charge distributions of solute molecules are obtained at the HF/6-31G(d,p) level. Standard Lennard-Jones parameters for solutes and the nonpolarizable simple site-based models of solvents are used in molecular dynamics (MD) simulations. Calculation of lambda is done by means of the original procedure, which treats electrostatic polarization of a solvent in terms of a usual nonpolarizable MD scheme supplemented by scaling of reorganization energies at the final stage. This approach provides a physically relevant background for separating inertial and inertialless polarization responses by means of a single parameter epsilon(infinity), optical dielectric permittivity of the solvent. Absolute lambda values for hole transfer in 1,2-dichloroethane agree with results of previous computations in terms of the different technique (MD/FRCM, Leontyev, I. V.; et al. Chem. Phys. 2005, 319, 4). Computed lambda values for electron transfer in tetrahydrofuran are larger than the experimental values by ca. 2.5 kcal/mol; for the case of hole transfer in 1,2-dichloroethane the discrepancy is of similar magnitude provided the experimental data are properly corrected. The MD approach gives nonzero lambda values for charge-transfer reaction in supercritical CO2, being able to provide a uniform treatment of nonequilibrium solvation phenomena in both quadrupolar and polar solvents.
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Affiliation(s)
- M V Vener
- Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow 105064, Russia
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Leontyev IV, Tachiya M. Molecular level approaches for investigation of electron transfer in nonpolar solvents. J Chem Phys 2007; 126:064501. [PMID: 17313223 DOI: 10.1063/1.2423026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors extend their previous work published in Leontyev and TachiyaJ. Chem. Phys. 123, 224502 (2005) and study not only forward but also reverse electron transfer between pyrene and dimethylaniline in a nonpolar solvent, n-hexane. The distribution function methodology and molecular dynamics technique adopted in their previous work are used. Two algorithms (I and II) are formulated for obtaining the reorganization energy and the solvation free energy difference in the linear response approximation. The two algorithms are combined with different cutoff schemes and tested for polarizable and nonpolarizable solvent models. Agreement between the results obtained by the two algorithms was achieved only for simulations employing the particle mesh Ewald treatment. It is concluded that algorithm I provides a reliable scheme for evaluation of the reorganization energy and the solvation free energy difference. Moreover, a new algorithm referred to as the G-function algorithm is formulated which does not assume the linear response approximation, and is tested on evaluation of the solvation free energy difference. Agreement between the results from the G-function algorithm and those from algorithms I and II is fairly good, although it depends on the degree of statistical consistency of the simulations. In the case of nonpolar solvents the G-function method has practical importance because, unlike the conventional thermodynamic integration approach, it requires equilibrium molecular configuration ensembles only for the initial and final states of the system.
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Affiliation(s)
- I V Leontyev
- National Institute of Advanced Industrial Science and Technology, AIST Central 5, Tsukuba, Ibaraki 305-8565, Japan
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