Switching Between ILCT and 3MLCT Excited States by Complex Formation in Ruthenium–Polypyridine Complex Containing Thiacrown-Ether Unit
Abstract
In this work, we report an example of tuning the photophysical properties of a polypyridine ruthenium(II) complex via the coordination of a second cation. A new ruthenium(II) complex contains a thiacrown-ether fragment that allows selective binding of additional metal cations (Ba2+, Cd2+, Pb2+), leading to pronounced changes in the optical and electronic properties of the bimetallic system. Spectroscopic and electrochemical studies reveal that the monoruthenium precursor displays dual excitation pathways involving either intraligand charge transfer (ILCT) or triplet metal-to-ligand charge transfer (3MLCT) excited states. Upon coordination of a second metal ion, the ILCT channel is suppressed, and only the 3MLCT state remains emissive, resulting in a significant increase in phosphorescence quantum yields (up to 22.6% in degassed solutions) for the bimetallic derivative. Time-resolved emission studies confirm the conversion from biexponential to monoexponential luminescence decay upon complexation. Electrochemical analysis and density functional theory (DFT) calculations support the hypothesis that cation binding alters the electron density distribution within the chromophore, stabilizing the MLCT pathway. These results demonstrate that incorporation of a second cation provides an effective strategy to control excited-state dynamics in ruthenium complexes, offering opportunities for the rational design of photosensitizers and photofunctional materials.
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BibTeX
@article{tokarev2026switching,
title = {{Switching Between ILCT and 3MLCT Excited States by Complex Formation in Ruthenium–Polypyridine Complex Containing Thiacrown-Ether Unit}},
author = {Sergey Tokarev and Anatoly Botezatu and Daria Kharkovskaya and Gediminas Jonusauskas and Yuri Fedorov and Olga Fedorova},
journal = {Molecules},
year = {2026},
month = jun,
doi = {10.3390/molecules31132213},
url = {https://hal.science/hal-05788202v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Switching Between ILCT and 3MLCT Excited States by Complex Formation in Ruthenium–Polypyridine Complex Containing Thiacrown-Ether Unit
AU - Sergey Tokarev
AU - Anatoly Botezatu
AU - Daria Kharkovskaya
AU - Gediminas Jonusauskas
AU - Yuri Fedorov
AU - Olga Fedorova
PY - 2026
DA - 2026/06/24
JO - Molecules
DO - 10.3390/molecules31132213
UR - https://hal.science/hal-05788202v1
AB - In this work, we report an example of tuning the photophysical properties of a polypyridine ruthenium(II) complex via the coordination of a second cation. A new ruthenium(II) complex contains a thiacrown-ether fragment that allows selective binding of additional metal cations (Ba2+, Cd2+, Pb2+), leading to pronounced changes in the optical and electronic properties of the bimetallic system. Spectroscopic and electrochemical studies reveal that the monoruthenium precursor displays dual excitation pathways involving either intraligand charge transfer (ILCT) or triplet metal-to-ligand charge transfer (3MLCT) excited states. Upon coordination of a second metal ion, the ILCT channel is suppressed, and only the 3MLCT state remains emissive, resulting in a significant increase in phosphorescence quantum yields (up to 22.6% in degassed solutions) for the bimetallic derivative. Time-resolved emission studies confirm the conversion from biexponential to monoexponential luminescence decay upon complexation. Electrochemical analysis and density functional theory (DFT) calculations support the hypothesis that cation binding alters the electron density distribution within the chromophore, stabilizing the MLCT pathway. These results demonstrate that incorporation of a second cation provides an effective strategy to control excited-state dynamics in ruthenium complexes, offering opportunities for the rational design of photosensitizers and photofunctional materials.
SN - 1420-3049
ER -