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Exceptional Excited-State Lifetime of an Iron(II)-N-Heterocyclic Carbene Complex Explained

Fredin, Lisa LU ; Papai, Matyas; Rozsalyi, Emese; Vanko, Gyoergy; Wärnmark, Kenneth LU ; Sundström, Villy LU and Persson, Petter (2014) In The Journal of Physical Chemistry Letters 5(12). p.2066-2071
Abstract
Earth-abundant transition-metal complexes are desirable for sensitizers in dye-sensitized solar cells or photocatalysts. Iron is an obvious choice, but the energy level structure of its typical polypyridyl complexes, featuring low-lying metal-centered states, has made such complexes useless as energy converters. Recently, we synthesized a novel iron-N-heterocyclic carbene complex exhibiting a remarkable 100-fold increase of the lifetime compared to previously known iron(II) complexes. Here, we rationalize the measured excited-state dynamics with DFT and TD-DFT calculations. The calculations show that the exceptionally long excited-state lifetime (similar to 9 ps) is achieved for this Fe complex through a significant destabilization of both... (More)
Earth-abundant transition-metal complexes are desirable for sensitizers in dye-sensitized solar cells or photocatalysts. Iron is an obvious choice, but the energy level structure of its typical polypyridyl complexes, featuring low-lying metal-centered states, has made such complexes useless as energy converters. Recently, we synthesized a novel iron-N-heterocyclic carbene complex exhibiting a remarkable 100-fold increase of the lifetime compared to previously known iron(II) complexes. Here, we rationalize the measured excited-state dynamics with DFT and TD-DFT calculations. The calculations show that the exceptionally long excited-state lifetime (similar to 9 ps) is achieved for this Fe complex through a significant destabilization of both triplet and quintet metal-centered scavenger states compared to other Feu complexes. In addition, a shallow (MLCT)-M-3 potential energy surface with a low-energy transition path from the (MLCT)-M-3 to (MC)-M-3 and facile crossing from the (MC)-M-3 state to the ground state are identified as key features for the excited-state deactivation. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Letters
volume
5
issue
12
pages
2066 - 2071
publisher
The American Chemical Society
external identifiers
  • wos:000337870100003
  • scopus:84903216322
ISSN
1948-7185
DOI
10.1021/jz500829w
language
English
LU publication?
yes
id
6091db5e-c4ff-4757-b452-e28dbe1b5d8e (old id 4609128)
date added to LUP
2014-08-28 15:55:56
date last changed
2017-09-10 04:06:47
@article{6091db5e-c4ff-4757-b452-e28dbe1b5d8e,
  abstract     = {Earth-abundant transition-metal complexes are desirable for sensitizers in dye-sensitized solar cells or photocatalysts. Iron is an obvious choice, but the energy level structure of its typical polypyridyl complexes, featuring low-lying metal-centered states, has made such complexes useless as energy converters. Recently, we synthesized a novel iron-N-heterocyclic carbene complex exhibiting a remarkable 100-fold increase of the lifetime compared to previously known iron(II) complexes. Here, we rationalize the measured excited-state dynamics with DFT and TD-DFT calculations. The calculations show that the exceptionally long excited-state lifetime (similar to 9 ps) is achieved for this Fe complex through a significant destabilization of both triplet and quintet metal-centered scavenger states compared to other Feu complexes. In addition, a shallow (MLCT)-M-3 potential energy surface with a low-energy transition path from the (MLCT)-M-3 to (MC)-M-3 and facile crossing from the (MC)-M-3 state to the ground state are identified as key features for the excited-state deactivation.},
  author       = {Fredin, Lisa and Papai, Matyas and Rozsalyi, Emese and Vanko, Gyoergy and Wärnmark, Kenneth and Sundström, Villy and Persson, Petter},
  issn         = {1948-7185},
  language     = {eng},
  number       = {12},
  pages        = {2066--2071},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Letters},
  title        = {Exceptional Excited-State Lifetime of an Iron(II)-N-Heterocyclic Carbene Complex Explained},
  url          = {http://dx.doi.org/10.1021/jz500829w},
  volume       = {5},
  year         = {2014},
}