Reinterpreting the Fate of Iridium(III) PhotocatalystsâScreening a Combinatorial Library to Explore Light-Driven Side-Reactions.
J Am Chem Soc
; 144(25): 11189-11202, 2022 06 29.
Article
em En
| MEDLINE
| ID: mdl-35704840
ABSTRACT
Photoredox catalysts are primarily selected based on ground and excited state properties, but their activity is also intrinsically tied to the nature of their reduced (or oxidized) intermediates. Catalyst reactivity often necessitates an inherent instability, thus these intermediates represent a mechanistic turning point that affords either product formation or side-reactions. In this work, we explore the scope of a previously demonstrated side-reaction that partially saturates one pyridine ring of the ancillary ligand in heteroleptic iridium(III) complexes. Using high-throughput synthesis and screening under photochemical conditions, we identified different chemical pathways, ultimately governed by ligand composition. The ancillary ligand was the key factor that determined photochemical stability. Following photoinitiated electron transfer from a sacrificial tertiary amine, the reduced intermediate of complexes containing 1,10-phenanthroline derivatives exhibited long-term stability. In contrast, complexes containing 2,2'-bipyridines were highly susceptible to hydrogen atom transfer and ancillary ligand modification. Detailed characterization of selected complexes before and after transformation showed differing effects on the ground and excited state reduction potentials dependent on the nature of the cyclometalating ligands and excited states. The implications of catalyst stability and reactivity in chemical synthesis was demonstrated in a model photoredox reaction.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fenantrolinas
/
Irídio
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
/
Screening_studies
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Austrália
País de publicação:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
/
UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA