Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived 2LMCT Excited States

Prakash, Om LU ; Lindh, Linnea LU orcid ; Kaul, Nidhi ; Rosemann, Nils W. LU ; Losada, Iria Bolaño LU ; Johnson, Catherine ; Chábera, Pavel LU ; Ilic, Aleksandra LU orcid ; Schwarz, Jesper LU and Gupta, Arvind Kumar LU , et al. (2022) In Inorganic Chemistry 61(44). p.17515-17526
Abstract

Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6(brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]-, [Fe(meophtmeimb)2]PF6(meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-, and [Fe(coohphtmeimb)2]PF6(coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-. These were derived from the... (More)

Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6(brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]-, [Fe(meophtmeimb)2]PF6(meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-, and [Fe(coohphtmeimb)2]PF6(coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-. These were derived from the parent complex [Fe(phtmeimb)2]PF6(phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]-by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (2LMCT) excited states feature nanosecond lifetimes (1.6-1.7 ns) and sizable emission quantum yields (1.7-1.9%) through spin-allowed transition to the doublet ground state (2GS), completely in line with the parent complex [Fe(phtmeimb)2]PF6(2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; and (Less)
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Inorganic Chemistry
volume
61
issue
44
pages
12 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85141020127
  • pmid:36279568
ISSN
0020-1669
DOI
10.1021/acs.inorgchem.2c02410
language
English
LU publication?
yes
id
1493fee9-5f6e-4e82-b8c8-008f1253409a
date added to LUP
2022-12-21 15:14:25
date last changed
2024-06-13 22:03:59
@article{1493fee9-5f6e-4e82-b8c8-008f1253409a,
  abstract     = {{<p>Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)<sub>2</sub>]PF<sub>6</sub>(brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]<sup>-</sup>, [Fe(meophtmeimb)<sub>2</sub>]PF<sub>6</sub>(meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]<sup>-</sup>, and [Fe(coohphtmeimb)<sub>2</sub>]PF<sub>6</sub>(coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]<sup>-</sup>. These were derived from the parent complex [Fe(phtmeimb)<sub>2</sub>]PF<sub>6</sub>(phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]<sup>-</sup>by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (<sup>2</sup>LMCT) excited states feature nanosecond lifetimes (1.6-1.7 ns) and sizable emission quantum yields (1.7-1.9%) through spin-allowed transition to the doublet ground state (<sup>2</sup>GS), completely in line with the parent complex [Fe(phtmeimb)<sub>2</sub>]PF<sub>6</sub>(2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.</p>}},
  author       = {{Prakash, Om and Lindh, Linnea and Kaul, Nidhi and Rosemann, Nils W. and Losada, Iria Bolaño and Johnson, Catherine and Chábera, Pavel and Ilic, Aleksandra and Schwarz, Jesper and Gupta, Arvind Kumar and Uhlig, Jens and Ericsson, Tore and Häggström, Lennart and Huang, Ping and Bendix, Jesper and Strand, Daniel and Yartsev, Arkady and Lomoth, Reiner and Persson, Petter and Wärnmark, Kenneth}},
  issn         = {{0020-1669}},
  language     = {{eng}},
  number       = {{44}},
  pages        = {{17515--17526}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Inorganic Chemistry}},
  title        = {{Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived <sup>2</sup>LMCT Excited States}},
  url          = {{http://dx.doi.org/10.1021/acs.inorgchem.2c02410}},
  doi          = {{10.1021/acs.inorgchem.2c02410}},
  volume       = {{61}},
  year         = {{2022}},
}