Understanding Anomalous Cage-Escape Dynamics in Photoredox Processes Driven by a Fe(III) N-Heterocyclic Carbene Complex
Losada, Iria Bolaño LU ; Ryde, Ulf LU
and Persson, Petter
LU
(2025)
In Journal of the American Chemical Society
147(35).
p.31509-31520
- Abstract
Solvent cage-escape dynamics of bimolecular photoredox products in solution has been investigated computationally through a combination of molecular dynamics simulations and quantum chemical calculations. The present work focuses on the photoinduced oxidation of the organic electron donor dimethylaniline (DMA) by a Fe(III) N-heterocyclic carbene photosensitizer (Fe(III)NHC+) in two different solvents, serving as an example of current interest due to their relevance for the development of earth-abundant photocatalytic systems. Calculated solvent cage-escape yields of radical-cation and neutral photoproducts (DMA•+and Fe(II)NHC, respectively) by molecular dynamics simulations reveal more favorable solvation in... (More)
Solvent cage-escape dynamics of bimolecular photoredox products in solution has been investigated computationally through a combination of molecular dynamics simulations and quantum chemical calculations. The present work focuses on the photoinduced oxidation of the organic electron donor dimethylaniline (DMA) by a Fe(III) N-heterocyclic carbene photosensitizer (Fe(III)NHC+) in two different solvents, serving as an example of current interest due to their relevance for the development of earth-abundant photocatalytic systems. Calculated solvent cage-escape yields of radical-cation and neutral photoproducts (DMA•+and Fe(II)NHC, respectively) by molecular dynamics simulations reveal more favorable solvation in acetonitrile than in dichloromethane following the initial photoinduced charge-separation. These results agree with basic expectations from solvent polarity considerations but give an opposite trend compared to experimentally reported cage-escape yields. Alternative cage-escape mechanisms were therefore considered computationally to account for the anomalous experimental cage-escape yields. Both quantum chemical calculations and molecular dynamics simulations support the formation of radical-cation dimers ([(DMA)2]•+[jls-end-space/]), allowing for more efficient charge migration involving the radical-cations as the polarity of the solvent is decreased. The results further demonstrate the ability of the counterion (PF6–) to stabilize the photoproducts through radical-cation–anion pairing, suggesting that these bimolecular interactions can also play an important role to preferentially promote photoproduct formation in less polar solvents. Both radical-cation dimer formation and radical-cation–counterion interactions are therefore proposed to provide additional pathways that help to explain the experimental observations of anomalous solvation dependence of the cage-escape dynamics in the investigated system. The broader implications of the bimolecular cage-escape processes on photocatalytic reaction dynamics are also considered based on our findings about light-induced intermolecular interactions.
(Less)
- author
- Losada, Iria Bolaño
LU
; Ryde, Ulf
LU
and Persson, Petter
LU
- organization
- publishing date
- 2025-09
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of the American Chemical Society
- volume
- 147
- issue
- 35
- pages
- 12 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:40736000
- scopus:105015712403
- ISSN
- 0002-7863
- DOI
- 10.1021/jacs.5c04296
- language
- English
- LU publication?
- yes
- id
- c46d0c2d-5cbd-45c9-b190-78680a024af0
- date added to LUP
- 2025-10-15 13:02:56
- date last changed
- 2025-12-11 07:19:26
@article{c46d0c2d-5cbd-45c9-b190-78680a024af0,
abstract = {{<p>Solvent cage-escape dynamics of bimolecular photoredox products in solution has been investigated computationally through a combination of molecular dynamics simulations and quantum chemical calculations. The present work focuses on the photoinduced oxidation of the organic electron donor dimethylaniline (DMA) by a Fe(III) N-heterocyclic carbene photosensitizer (Fe(III)NHC<sup>+</sup>) in two different solvents, serving as an example of current interest due to their relevance for the development of earth-abundant photocatalytic systems. Calculated solvent cage-escape yields of radical-cation and neutral photoproducts (DMA<sup>•+</sup>and Fe(II)NHC, respectively) by molecular dynamics simulations reveal more favorable solvation in acetonitrile than in dichloromethane following the initial photoinduced charge-separation. These results agree with basic expectations from solvent polarity considerations but give an opposite trend compared to experimentally reported cage-escape yields. Alternative cage-escape mechanisms were therefore considered computationally to account for the anomalous experimental cage-escape yields. Both quantum chemical calculations and molecular dynamics simulations support the formation of radical-cation dimers ([(DMA)2]<sup>•+</sup>[jls-end-space/]), allowing for more efficient charge migration involving the radical-cations as the polarity of the solvent is decreased. The results further demonstrate the ability of the counterion (PF<sub>6</sub>–) to stabilize the photoproducts through radical-cation–anion pairing, suggesting that these bimolecular interactions can also play an important role to preferentially promote photoproduct formation in less polar solvents. Both radical-cation dimer formation and radical-cation–counterion interactions are therefore proposed to provide additional pathways that help to explain the experimental observations of anomalous solvation dependence of the cage-escape dynamics in the investigated system. The broader implications of the bimolecular cage-escape processes on photocatalytic reaction dynamics are also considered based on our findings about light-induced intermolecular interactions.</p>}},
author = {{Losada, Iria Bolaño and Ryde, Ulf and Persson, Petter}},
issn = {{0002-7863}},
language = {{eng}},
number = {{35}},
pages = {{31509--31520}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Journal of the American Chemical Society}},
title = {{Understanding Anomalous Cage-Escape Dynamics in Photoredox Processes Driven by a Fe(III) N-Heterocyclic Carbene Complex}},
url = {{http://dx.doi.org/10.1021/jacs.5c04296}},
doi = {{10.1021/jacs.5c04296}},
volume = {{147}},
year = {{2025}},
}