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Living Long and Prosperous: Productive Intraligand Charge-Transfer States from a Rhenium(I) Terpyridine Photosensitizer with Enhanced Light Absorption


Fernandez-Teran, Ricardo; Sévery, Laurent (2021). Living Long and Prosperous: Productive Intraligand Charge-Transfer States from a Rhenium(I) Terpyridine Photosensitizer with Enhanced Light Absorption. Inorganic Chemistry, 60(3):1334-1343.

Abstract

The ground- and excited-state properties of six rhenium(I) κ2N-tricarbonyl complexes with 4′-(4-substituted-phenyl)terpyridine ligands bearing substituents of different electron-donating abilities were evaluated. Significant modulation of the electrochemical potentials and a nearly 4-fold variation of the triplet metal-to-ligand charge-transfer (3MLCT) lifetimes were observed upon going from CN to OMe. With the more electron-donating NMe2 group, we observed in the κ2N complex the appearance of a very strong absorption band, red-shifted by ca. 100 nm with respect to the other complexes. This was accompanied by a dramatic enhancement of the excited-state lifetime (380 vs 1.5 ns), and a character change from 3MLCT to intraligand charge transfer (3ILCT), despite the remote location of the substituent. The dynamics and character of the excited states of all complexes were assigned by combining transient IR spectroscopy, IR spectroelectrochemistry, and (time-dependent) density functional theory calculations. Selected complexes were evaluated as photosensitizers for hydrogen production, with the κ2N-NMe2 complex resulting in a stable and efficient photocatalytic system reaching TONRe values of over 2100, representing the first application of the 3ILCT state of a rhenium(I) carbonyl complex in a stable photocatalytic system.

Abstract

The ground- and excited-state properties of six rhenium(I) κ2N-tricarbonyl complexes with 4′-(4-substituted-phenyl)terpyridine ligands bearing substituents of different electron-donating abilities were evaluated. Significant modulation of the electrochemical potentials and a nearly 4-fold variation of the triplet metal-to-ligand charge-transfer (3MLCT) lifetimes were observed upon going from CN to OMe. With the more electron-donating NMe2 group, we observed in the κ2N complex the appearance of a very strong absorption band, red-shifted by ca. 100 nm with respect to the other complexes. This was accompanied by a dramatic enhancement of the excited-state lifetime (380 vs 1.5 ns), and a character change from 3MLCT to intraligand charge transfer (3ILCT), despite the remote location of the substituent. The dynamics and character of the excited states of all complexes were assigned by combining transient IR spectroscopy, IR spectroelectrochemistry, and (time-dependent) density functional theory calculations. Selected complexes were evaluated as photosensitizers for hydrogen production, with the κ2N-NMe2 complex resulting in a stable and efficient photocatalytic system reaching TONRe values of over 2100, representing the first application of the 3ILCT state of a rhenium(I) carbonyl complex in a stable photocatalytic system.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > Physical and Theoretical Chemistry
Physical Sciences > Inorganic Chemistry
Uncontrolled Keywords:Physical and Theoretical Chemistry, Inorganic Chemistry
Language:English
Date:1 February 2021
Deposited On:02 Feb 2021 13:03
Last Modified:03 Feb 2021 21:02
Publisher:American Chemical Society (ACS)
ISSN:0020-1669
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/acs.inorgchem.0c01939
PubMed ID:32909754

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