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PCET-Based Ligand Limits Charge Recombination with an Ir(III) Photoredox Catalyst.
- Source :
-
Journal of the American Chemical Society [J Am Chem Soc] 2021 Aug 25; Vol. 143 (33), pp. 13034-13043. Date of Electronic Publication: 2021 Aug 11. - Publication Year :
- 2021
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Abstract
- Upon photoinitiated electron transfer, charge recombination limits the quantum yield of photoredox reactions for which the rates for the forward reaction and back electron transfer are competitive. Taking inspiration from a proton-coupled electron transfer (PCET) process in Photosystem II, a benzimidazole-phenol (BIP) has been covalently attached to the 2,2'-bipyridyl ligand of [Ir(dF(CF <subscript>3</subscript> )ppy) <subscript>2</subscript> (bpy)][PF <subscript>6</subscript> ] (dF(CF <subscript>3</subscript> )ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine; bpy = 2,2'-bipyridyl). Excitation of the [Ir(dF(CF <subscript>3</subscript> )ppy) <subscript>2</subscript> (BIP-bpy)][PF <subscript>6</subscript> ] photocatalyst results in intramolecular PCET to form a charge-separated state with oxidized BIP. Subsequent reduction of methyl viologen dication (MV <superscript>2+</superscript> ), a substrate surrogate, by the reducing moiety of the charge separated species demonstrates that the inclusion of BIP significantly slows the charge recombination rate. The effect of ∼24-fold slower charge recombination in a photocatalytic phthalimide ester reduction resulted in a greater than 2-fold increase in reaction quantum efficiency.
Details
- Language :
- English
- ISSN :
- 1520-5126
- Volume :
- 143
- Issue :
- 33
- Database :
- MEDLINE
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 34378919
- Full Text :
- https://doi.org/10.1021/jacs.1c01701