Abstract
Proton-coupled electron transfer (PCET) from amino acids with water as the primary proton acceptor is a fundamental model reaction of wide relevance. We have investigated the kinetics and mechanism of PCET from tryptophan derivatives to laser flash-generated [Ru(bpy)3]3+ oxidants in aqueous solutions. The PCET reaction followed either a concerted electron-proton transfer (CEP) mechanism or a step-wise electron transfer-proton transfer (ETPT) mechanism, depending on pH and the identity of the RuIII oxidant. The CEP reaction showed a pH-dependent rate constant, with an increase in log kCEP of 0.3-0.5 per pH unit, and a significant kinetic isotope effect (KIE = 2-4), both in intramolecular and bimolecular model systems. Our results suggest that CEP with water as the proton acceptor is a general feature of amino acid oxidation, and provide further experimental observations towards a detailed understanding of the PCET process in water.
| Original language | English |
|---|---|
| Pages (from-to) | 7732-7736 |
| Number of pages | 5 |
| Journal | Energy and Environmental Science |
| Volume | 5 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Jul 2012 |
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ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Environmental Chemistry
- Pollution
- Nuclear Energy and Engineering
Cite this
Bimolecular proton-coupled electron transfer from tryptophan with water as the proton acceptor. / Zhang, Ming Tian; Nilsson, Johan; Hammarström, Leif.
In: Energy and Environmental Science, Vol. 5, No. 7, 07.2012, p. 7732-7736.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Bimolecular proton-coupled electron transfer from tryptophan with water as the proton acceptor
AU - Zhang, Ming Tian
AU - Nilsson, Johan
AU - Hammarström, Leif
PY - 2012/7
Y1 - 2012/7
N2 - Proton-coupled electron transfer (PCET) from amino acids with water as the primary proton acceptor is a fundamental model reaction of wide relevance. We have investigated the kinetics and mechanism of PCET from tryptophan derivatives to laser flash-generated [Ru(bpy)3]3+ oxidants in aqueous solutions. The PCET reaction followed either a concerted electron-proton transfer (CEP) mechanism or a step-wise electron transfer-proton transfer (ETPT) mechanism, depending on pH and the identity of the RuIII oxidant. The CEP reaction showed a pH-dependent rate constant, with an increase in log kCEP of 0.3-0.5 per pH unit, and a significant kinetic isotope effect (KIE = 2-4), both in intramolecular and bimolecular model systems. Our results suggest that CEP with water as the proton acceptor is a general feature of amino acid oxidation, and provide further experimental observations towards a detailed understanding of the PCET process in water.
AB - Proton-coupled electron transfer (PCET) from amino acids with water as the primary proton acceptor is a fundamental model reaction of wide relevance. We have investigated the kinetics and mechanism of PCET from tryptophan derivatives to laser flash-generated [Ru(bpy)3]3+ oxidants in aqueous solutions. The PCET reaction followed either a concerted electron-proton transfer (CEP) mechanism or a step-wise electron transfer-proton transfer (ETPT) mechanism, depending on pH and the identity of the RuIII oxidant. The CEP reaction showed a pH-dependent rate constant, with an increase in log kCEP of 0.3-0.5 per pH unit, and a significant kinetic isotope effect (KIE = 2-4), both in intramolecular and bimolecular model systems. Our results suggest that CEP with water as the proton acceptor is a general feature of amino acid oxidation, and provide further experimental observations towards a detailed understanding of the PCET process in water.
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U2 - 10.1039/c2ee03137j
DO - 10.1039/c2ee03137j
M3 - Article
VL - 5
SP - 7732
EP - 7736
JO - Energy and Environmental Science
JF - Energy and Environmental Science
SN - 1754-5692
IS - 7
ER -