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Analysis of Hydroge...
Analysis of Hydrogen-Bonding Effects on Excited-State Proton-Coupled Electron Transfer from a Series of Phenols to a Re(I) Polypyridyl Complex
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- Dongare, Prateek (författare)
- Uppsala universitet,Fysikalisk kemi,Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC 27599 USA.
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- Bonn, Annabell G. (författare)
- Uppsala universitet,Fysikalisk kemi,Univ North Carolina Chapel Hill, Dept Chem, Chapel Hill, NC 27599 USA.
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- Maji, Somnath (författare)
- Uppsala universitet,Fysikalisk kemi,Indian Inst Technol, Dept Chem, Hyderabad 502285, Telangana, India.
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- Hammarström, Leif, 1964- (författare)
- Uppsala universitet,Fysikalisk kemi
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(creator_code:org_t)
- 2017-06-01
- 2017
- Engelska.
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 121:23, s. 12569-12576
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- In the present study of proton-coupled electron transfer (PCET) reactions, the excited-state of a fac-[(CO)(3)Re-I(bpy)(4,4'-bpy)](+) (bpy = 2,2'-bipyridine and 4,4'-bpy = 4,4'-bipyridine) complex was reductively quenched by a series of phenols. A variation of substituents on the phenols substantially alters their pK(a) and E degrees values and provides an opportunity to study photoinduced PCET as a function of their redox properties. Analyses of absorption spectral changes indicate that the phenols form a weak hydrogen bond with the pyridinic nitrogen of the 4,4'-bpy ligand in the ground-state, and ground-state association, constant (K-A) values were determined. This H-bonded adduct quenches the excited Re complex by PCET from the phenol, to form the reduced and,protonated Re complex. The KA values-obtained aid quantitative evaluation of the rate constant for the PCET reaction in the H-bonded, adduct. Thus, photophysical studies and Mechanistic analysis indicate that the reaction occurs via a concerted mechanistic pathway, for the unsubstituted phenol and phenols with electron-withdrawing subtituents. Furthermore; the magnitude of the quenching varies systematically with the proton-coupled potentials of the phenols and not their hydrogen-bonding strength (as reflected in K-A). This study is one of the first detailed analyses of intermolecular H-bonding between a self-assembling metal complex and a series of substituted phenols in an effort to study their relationship with the kinetic parameters in a photoinduced CPET reaction.
Ämnesord
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
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