Excited-state behavior and photoinduced electron transfer of pH-sensitive Ir(III) complexes with cyclometallation (C/N–) ratios between 0/6 and 3/3

Lentz, Cédric; Marcélis, Lionel; Troian‐Gautier, Ludovic; Robeyns, Koen; Cauët, Émilie; Elias, Benjamin

doi:10.1016/j.jphotochem.2020.112957

Cited by 11 publications

(15 citation statements)

References 81 publications

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“…Such versatility is particularly striking in the series [Ir(ppy) x (bpy) 3‐x ] (3–x)+ (ppy=2‐phenylpyridine, bpy=2,2′‐bipyridine), where x varies between 0 and 3 (Table 1). [4] The number of Ir−C bonds has drastic effects on the frontier orbitals of the resulting complex due to the difference in σ‐donation ability between Ir−C and Ir−N bonds [5] . One effect is the delocalization of the HOMO level onto the cyclometalated ligand framework.…”

Section: Introductionmentioning

confidence: 99%

“…Complexes with both bidentate and tridentate ligands will be thoroughly examined. Complexes with one cyclometalated bond (IrC 1 N 5 , IrC 1 N 4 Cl) will not be discussed here, as these are by so far scarce in the literature [4,17] . First, the basic photochemistry of iridium complexes will be described, highlighting the main differences between the different families of complexes.…”

Section: Introductionmentioning

confidence: 99%

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A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

et al. 2021

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Photo‐induced electron transfer chemistry between molecules is a central theme in several fields including biology, physics and chemistry. Specifically, in photoredox catalysis, greater use has been made of iridium(III) complexes as they exhibit ground‐ and excited‐state redox potentials that span a very large range. Unfortunately, most of these complexes suffer from limited visible light absorption properties. This concept article highlights recent developments in the synthesis of iridium(III) complexes with increased visible light absorption properties and their use as candidates for visible light driven redox catalysis. Fundamental tools are provided to enable the independent tuning of the HOMO and LUMO energy levels. Recent examples are given with the hope that this concept article will foster further developments of iridium(III)‐based sensitizers for visible light driven reactivity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

et al. 2021

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“…Recall from the electrochemical and photophysical data that the reduced state of Ir is thermodynamically capable of reducing BrAPN, while the excited Ir* is not, further supporting the cycle in Figure 5. 26 , which is then reduced by TEOA to form the reduced iridium state.…”

Section: Preparation Of Heterogenized Nanopowdermentioning

confidence: 99%

“…Example reaction of photoredox catalyst [Ir III (bpy)(ppy)2] + with light, where ppy=2phenylpyridine, and bpy=2,2′-bipyridine. 26 The catalyst undergoes a metal to ligand charge transfer (MLCT) and intersystem crossing (ISC) to form the charge separated excited state species. Excited state potentials displayed in the scheme are based on literature data collected in acetonitrile under argon.…”

Section: Introductionmentioning

confidence: 99%

“…Excited state potentials displayed in the scheme are based on literature data collected in acetonitrile under argon. 26 Furthermore, homogeneous molecular photoredox catalysts have the advantage of being highly tunable due to their molecular nature, allowing a variety of organic transformations to be studied. However, as they are usually in the same phase as the organic substrate and product, a purification step is needed to separate them from the reaction mixture.…”

Section: Introductionmentioning

confidence: 99%

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Photoredox Catalysis Using Heterogenized Iridium Complexes

Materna

Hammarström²

2021

Preprint

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Heterogenized photoredox catalysts provide a path to generating chemicals in an environmentally friendly way, with facile reuse of catalysts in batch or continuous processes. In this study, heterogenized iridium complexes as photoredox catalysts were assembled via covalent attachment to three metal oxide surfaces (ITO, ZrO2, Al2O3) either in the form of thin films or nanopowders and tested as photoredox catalysts for reductive dehalogenation of bromoacetophenone to acetophenone. All catalysts produced acetophenone with high conversions and yields. The fastest reactions were complete in fifteen minutes under mild conditions using Al2O3 surfaces, which provided the most robust and reusable supports. The catalytic performance was compared on both nanopowder and thin film supports, showing that both constructs could be used for photoredox catalysis. The nanopowder-based catalysts resulted in faster and more efficient catalysis, while the thin film-immobilized catalysts were more robust and easily reused. Importantly, the thin film constructs show promise for future photoelectrochemical and electrochemical photoredox setups. Finally, all catalysts could be reused 2-3 times, performing at least 1000 turnovers with Al2O3 supports, highlighting that heterogenized catalysts can perform photoredox catalysis in an environmentally friendly fashion.

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Luminescent and Photoredox‐Active Molybdenum(0) Complexes Competitive with Isoelectronic Ruthenium(II) Polypyridines

Jin,

Wagner,

Wenger

2023

Angewandte Chemie

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Ruthenium(II) complexes with chelating polypyridine ligands are among the most frequently investigated compounds in photophysics and photochemistry, owing to their favorable luminescence and photoredox properties. Equally good photoluminescence performance and attractive photocatalytic behavior is now achievable with isoelectronic molybdenum(0) complexes. The zero‐valent oxidation state of molybdenum is stabilized by carbonyl or isocyanide ligands, and metal‐to‐ligand charge transfer (MLCT) excited states analogous to those in ruthenium(II) complexes can be established. Microsecond MLCT excited‐state lifetimes and photoluminescence quantum yields up to 0.2 have been achieved in solution at room temperature, and the emission wavelength has become tunable over a large range. The molybdenum(0) complexes are stronger photoreductants than ruthenium(II) polypyridines and can therefore perform more challenging chemical reductions. The triplet nature of their luminescent MLCT states allows sensitization of photon upconversion via triplet‐triplet annihilation, to convert low‐energy input radiation into higher‐energy output fluorescence. This review summarizes the current state of the art concerning luminescent molybdenum(0) complexes and highlights their application potential. Molybdenum is roughly 140 times more abundant and far cheaper than ruthenium, hence this research is relevant in the greater context of finding more sustainable alternatives to using precious and rare transition metals in photophysics and photochemistry.

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Excited-state behavior and photoinduced electron transfer of pH-sensitive Ir(III) complexes with cyclometallation (C/N–) ratios between 0/6 and 3/3

Cited by 11 publications

References 81 publications

A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

Photoredox Catalysis Using Heterogenized Iridium Complexes

Luminescent and Photoredox‐Active Molybdenum(0) Complexes Competitive with Isoelectronic Ruthenium(II) Polypyridines

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