Influence of a nearby substrate on the reorganization energy of hole exchange between dye molecules

Manke, F.; Frost, Jarvist M.; Vaissier, Valérie; Nelson, Jenny; Barnes, Piers R. F.

doi:10.1039/c4cp06078d

“…More detailed consideration can be found in our earlier work. 25,26 Furthermore, we calculated λ i for a specific configuration of the dye molecules.…”

Section: Calculation Of the Reorganization Energy Of Hole Exchange Bementioning

confidence: 99%

Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules

Vaissier

¹

,

Frost

²

,

Barnes

³

et al. 2015

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The parameters controlling the kinetics of intermolecular charge transfer are traditionally estimated from electronic structure calculations on the charge donor and charge acceptor in isolation. Here, we show that this procedure results in inaccuracies for hole transfer between a pair of organic dye molecules by comparing charge-constrained density functional theory (DFT) calculations on a dye cation/neutral dye pair to the conventional DFT calculations on the isolated molecules. We quantify the error made in the reorganization energy of hole exchange between dye molecules (λ i ). We choose three indolene-based organic dyes with application to dye-sensitized solar cells, namely, D149, D102, and D131, for which experimental values of λ are available. We find that, although highly system dependent, the intermolecular interaction between the charge donor and acceptor can lead to a 0.25 eV change in λ i , illustrating the limitations of the widely used original method in predicting the rate of charge transfer.

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“…Secondly, to account better knowledge about the height barrier of SEO, free energy of activation for the SEO was calculated using four-point method proposed by Nelsen (see SI). [52][53][54] We are convinced that this method result in a reasonable estimation of the electron transfer (ET) activation barrier. Thirdly, it has been reported that HFIP plays a critical role with oxidizing agent rather than with the radical cation formed.…”

Section: Mechanism Of Dimerizationmentioning

confidence: 99%

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hussein¹,

Ma²,

Al-Yasari³

2020

Preprint

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<a>A mechanistic insight into </a>the hetero- and homodimerizations (HETD and HOMD) of styrenes promoted by hypervalent iodine reagents (HVIRs; DMP and PIDA) and facilitated by HFIP to yield all trans cyclobutanes is reported using density functional theory (DFT) calculations. The initialization involving direct bimolecular one-electron transfer is found to be highly unfavored, especially for the PIDA system. At this point, we suggest that the reaction is initiated with an overall two-electron reductive cleavage of two I─O bond cleavages, affording I(III) (iodinane) and I(I) (iodobenzene) product with DMP and PIDA as oxidant, respectively. The resulting acetate groups are stabilized by the solvent HFIP through strong hydrogen bonding interaction, which promotes the electron transfer process. The nature of the electron transfer is studied in detail and found that the overall two-electron transfer occurs within tri-molecular complex organized by π-stacking interactions and as a stepwise and concerted mechanism for I(III) and I(V) oxidants, respectively. The reaction rate is determined by the initialization step: for I(III), the initiation is thermodynamically endergonic, whereas the endergonicity for I(V) is modest. Upon initialization, the reaction proceeds through a stepwise [2+2] pathway, involving a radical-cationic π-π stacked intermediate, either hetero- or homodimerized. DFT results supported by quasiclassical molecular dynamics simulations show that HOMD is dynamically competing pathway to HETD although the latter is relatively faster, in accordance with experimental observations.

show abstract

“…Secondly, to account better knowledge about the height barrier of SEO, free energy of activation for the SEO was calculated using four-point method proposed by Nelsen (see SI). [53][54][55] We are convinced that this method result in a reasonable estimation of the electron transfer (ET) activation barrier. Thirdly, it has been reported that HFIP plays a critical role with oxidizing agent rather than with the radical cation formed.…”

Section: Mechanism Of Dimerizationmentioning

confidence: 99%

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hussein

¹

,

Ma²,

Al-Yasari³

2020

Preprint

0

View full text Add to dashboard Cite

<a>A mechanistic insight into </a>the hetero- and homodimerizations (HETD and HOMD) of styrenes promoted by hypervalent iodine reagents (HVIRs; DMP and PIDA) and facilitated by HFIP to yield all trans cyclobutanes is reported using density functional theory (DFT) calculations. The initialization involving direct bimolecular one-electron transfer is found to be highly unfavored, especially for the PIDA system. At this point, we suggest that the reaction is initiated with an overall two-electron reductive cleavage of two I─O bond cleavages, affording I(III) (iodinane) and I(I) (iodobenzene) product with DMP and PIDA as oxidant, respectively. The resulting acetate groups are stabilized by the solvent HFIP through strong hydrogen bonding interaction, which promotes the electron transfer process. The nature of the electron transfer is studied in detail and found that the overall two-electron transfer occurs within tri-molecular complex organized by π-stacking interactions and as a stepwise and concerted mechanism for I(III) and I(V) oxidants, respectively. The reaction rate is determined by the initialization step: for I(III), the initiation is thermodynamically endergonic, whereas the endergonicity for I(V) is modest. Upon initialization, the reaction proceeds through a stepwise [2+2] pathway, involving a radical-cationic π-π stacked intermediate, either hetero- or homodimerized. DFT results supported by quasiclassical molecular dynamics simulations show that HOMD is dynamically competing pathway to HETD although the latter is relatively faster, in accordance with experimental observations.

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Influence of a nearby substrate on the reorganization energy of hole exchange between dye molecules

Cited by 17 publications

References 34 publications

Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules

Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

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