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Bimolecular Excited-State Proton-Coupled Electron Transfer within Encounter Complexes.

ABSTRACT: Bimolecular excited-state proton-coupled electron transfer (PCET*) was observed for reaction of the triplet MLCT state of [(dpab)₂Ru(4,4'-dhbpy)]²⁺ (dpab = 4,4'-di(n-propyl)amido-2,2'-bipyridine, 4,4'-dhbpy = 4,4'-dihydroxy-2,2'-bipyridine) with N-methyl-4,4'-bipyridinium (MQ⁺) and N-benzyl-4,4'-bipyridinium (BMQ⁺) in dry acetonitrile solutions. The PCET* reaction products, the oxidized and deprotonated Ru complex, and the reduced protonated MQ⁺ can be distinguished from the excited state electron transfer (ET*) and the excited state proton transfer (PT*) products by the difference in the visible absorption spectrum of the species emerging from the encounter complex. The observed behavior differs from that of reaction of the MLCT state of [(bpy)₂Ru(4,4'-dhbpy)]²⁺ (bpy = 2,2'-bipyridine) with MQ⁺, where initial ET* is followed by diffusion-limited proton transfer from the coordinated 4,4'-dhbpy to MQ⁰. The difference in observed behavior can be rationalized based on changes in the free energies of ET* and PT*. Substitution of bpy with dpab results in the ET* process becoming significantly more endergonic and the PT* reaction becoming somewhat less endergonic.

SUBMITTER: Martinez K

PROVIDER: S-EPMC9983007 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature

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Bimolecular Excited-State Proton-Coupled Electron Transfer within Encounter Complexes.

Martinez Kristina K Koehne Sydney M SM Benson Kaitlyn K Paul Jared J JJ Schmehl Russell H RH

Journal of the American Chemical Society 20230220 8

Bimolecular excited-state proton-coupled electron transfer (PCET*) was observed for reaction of the triplet MLCT state of [(dpab)2Ru(4,4'-dhbpy)]2+ (dpab = 4,4'-di(n-propyl)amido-2,2'-bipyridine, 4,4'-dhbpy = 4,4'-dihydroxy-2,2'-bipyridine) with N-methyl-4,4'-bipyridinium (MQ+) and N-benzyl-4,4'-bipyridinium (BMQ+) in dry acetonitrile solutions. The PCET* reaction products, the oxidized and deprotonated Ru complex, and the reduced ...[more]

PMID: 36802634

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Dataset Information

Bimolecular Excited-State Proton-Coupled Electron Transfer within Encounter Complexes.

Publications

Bimolecular Excited-State Proton-Coupled Electron Transfer within Encounter Complexes.

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