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Volumn 110, Issue 38, 2006, Pages 18853-18858

Electron transfer driven by proton fluctuations in a hydrogen-bonded donor - Acceptor assembly

Author keywords

[No Author keywords available]

Indexed keywords

HYDROGEN BONDS; ISOTOPES; MOLECULAR DYNAMICS; NAPHTHALENE; PROTONS; THERMAL EFFECTS;

EID: 33749639818     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp056703q     Document Type: Article
Times cited : (54)

References (58)
  • 5
    • 84955366908 scopus 로고    scopus 로고
    • V. Balzani, Ed.; Wiley-VCH: Weinheim, Germany; Vol. 1.1.5
    • Hammes-Schiffer, S. In Electron Transfer in Chemistry; V. Balzani, Ed.; Wiley-VCH: Weinheim, Germany, 2001; Vol. 1.1.5; pp 189-214.
    • (2001) Electron Transfer in Chemistry , pp. 189-214
    • Hammes-Schiffer, S.1
  • 28
    • 84906358074 scopus 로고    scopus 로고
    • note
    • The Zn(II) porphyrin amidinium was prepared as a chloride salt, and the naphthalene diimide carboxylate was prepared as a tetramethylamonium salt.
  • 29
    • 84906372617 scopus 로고    scopus 로고
    • note
    • 1 excited state of the Zn porphyrin. Yet the reverse reaction ultimately recovers the porphyrin ground state, possibly via intermediates involving triplet excited states of the Zn porphyrin or the naphthalene diimide.
  • 37
    • 84906372618 scopus 로고    scopus 로고
    • note
    • In the benzoate experiments, both bound and unbound porphyrins are expected to exist in reasonable concentrations at the spectroscopic concentrations employed. Yet the apparent similarity between bound and unbound lifetimes means that the 1-H(D):benzoate data cannot be reliably fit to a biexponential decay function, despite there being a good physical basis for doing so. Consequently, the empirically fit monoexponential decay functions are biased to some extent by the fraction of unbound porphyrin that also contributes to the signal, and this fraction is subject to experimental error.
  • 40
    • 84906401294 scopus 로고    scopus 로고
    • note
    • The published driving force for this system (ΔG° = -0.46 eV, ref 27) neglected the solvent-dependent Coulombic term (ΔG(ε)). Using the Born equation, we estimate an additional 0.12 eV towards the driving force for ET in this system in 2-MeTHF, based on a donor-acceptor distance of 13 Å, and radii of 5 and 4 Å for the donor and acceptor, respectively. Additionally, a small T-dependence in the Coulombic term should arise due to the T-dependence of the solvent dielectric constant, however we neglected this minor effect in the fitting of reorganization energies. This issue is addressed at another point in the text.
  • 41
    • 84906358075 scopus 로고    scopus 로고
    • note
    • Calculated using the Marcus dielectric continuum model for 2-MeTHF, based on a donor-acceptor distance of 13 Å, and radii of 5 and 4 Å for the donor and acceptor, respectively.
  • 57
    • 84906386683 scopus 로고    scopus 로고
    • note
    • While we have focused on the dynamic variation of electronic coupling through proton motion, the driving force and reorganization energy for ET could potentially dominate the T-dependence of ET. However, in this case, we are able to learn about the nature of the proton-mediated electronic coupling because the magnitude of the driving force and reorganization energy are similar enough that the resulting activation energy is low. This is analogous to studies on the distance-dependence of ET rates in modified proteins. There, electron donors and acceptors are selected to minimize the activation energy for ET, highlighting the variation of the electronic coupling term with donor-acceptor distance (e.g., see ref 58).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.