Pyridine-substituted Fe( iii ) complexes – on the way to one-component photo-catalytical systems
Abstract
Linked photosensitizer-catalyst dyads based on earth-abundant metal complexes are currently potential candidates for sustainable proton reduction systems. Fe(III) carbene complexes showing low-lying ligand-to-metal charge transfer (LMCT) states with lifetimes in the 0.2-0.3 ns range are promising candidates for the photosensitizer side. The latter must be linked to a proton reduction catalyst, usually of cationic character, like cobaloxime. We explore the feasibility of this approach with a model compound mimicking the inductive effect of the cobaloxime moiety on the electronic state structure of a Fe(III) photosensitizer. Thus, the homoleptic pyridine-substituted [Fe(ImPPy) 2 ] + (HImPPy = 1,1 0 -(5-(pyridin-4-yl)-1,3-phenylene)bis(3-methyl-1H-imidazol-3-ium)) complex was modified by attaching a methyl group at the pyridinyl nitrogen, to model the inductive effect of a positively charged catalytic centre on the Fe(III) photosensitizer. Reduction of ligand electron density leads to stabilization of metal-toligand ( 2 MLCT) excited states, as predicted by TD-DFT calculations. Experimental support is provided by a combination of cyclic voltammetry and ultrafast spectroscopies. [Fe(ImPPyMe) 2 ] 3+ shows a characteristic lifetime of 80 AE 10 ps for the stabilized 2 MLCT state. This constitutes a promising starting point for later use of [Fe(ImPPy) 2 ] + as a photosensitizer in bimetallic one-component dyads for photoinduced hydrogen production.
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BibTeX
@article{schmitz2026pyridinesubstituted,
title = {{Pyridine-substituted Fe( iii ) complexes – on the way to one-component photo-catalytical systems}},
author = {Lennart Schmitz and J. Luis Pérez Lustres and Ronan Viel and Jannik Löseke and Lorena Fritsch and Xiao-Hui Li and Roland Schoch and Stefan Haacke and Karsten Heyne and Matthias Bauer},
journal = {Physical Chemistry Chemical Physics},
year = {2026},
month = jul,
doi = {10.1039/d6cp00443a},
url = {https://hal.science/hal-05780390v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Pyridine-substituted Fe( iii ) complexes – on the way to one-component photo-catalytical systems
AU - Lennart Schmitz
AU - J. Luis Pérez Lustres
AU - Ronan Viel
AU - Jannik Löseke
AU - Lorena Fritsch
AU - Xiao-Hui Li
AU - Roland Schoch
AU - Stefan Haacke
AU - Karsten Heyne
AU - Matthias Bauer
PY - 2026
DA - 2026/07/27
JO - Physical Chemistry Chemical Physics
DO - 10.1039/d6cp00443a
UR - https://hal.science/hal-05780390v1
AB - Linked photosensitizer-catalyst dyads based on earth-abundant metal complexes are currently potential candidates for sustainable proton reduction systems. Fe(III) carbene complexes showing low-lying ligand-to-metal charge transfer (LMCT) states with lifetimes in the 0.2-0.3 ns range are promising candidates for the photosensitizer side. The latter must be linked to a proton reduction catalyst, usually of cationic character, like cobaloxime. We explore the feasibility of this approach with a model compound mimicking the inductive effect of the cobaloxime moiety on the electronic state structure of a Fe(III) photosensitizer. Thus, the homoleptic pyridine-substituted [Fe(ImPPy) 2 ] + (HImPPy = 1,1 0 -(5-(pyridin-4-yl)-1,3-phenylene)bis(3-methyl-1H-imidazol-3-ium)) complex was modified by attaching a methyl group at the pyridinyl nitrogen, to model the inductive effect of a positively charged catalytic centre on the Fe(III) photosensitizer. Reduction of ligand electron density leads to stabilization of metal-toligand ( 2 MLCT) excited states, as predicted by TD-DFT calculations. Experimental support is provided by a combination of cyclic voltammetry and ultrafast spectroscopies. [Fe(ImPPyMe) 2 ] 3+ shows a characteristic lifetime of 80 AE 10 ps for the stabilized 2 MLCT state. This constitutes a promising starting point for later use of [Fe(ImPPy) 2 ] + as a photosensitizer in bimetallic one-component dyads for photoinduced hydrogen production.
SN - 1463-9076
SN - 1463-9084
ER -