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

Justin M. Hodgkiss, Niels H. Damrauer, Steve Pressé, Joel Rosenthal, Daniel G. Nocera

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

The temperature-isotope dependence of proton-coupled electron transfer (PCET) for a noncovalent molecular dyad is reported. The system consists of an excited-state Zn(II) porphyrin that transfers an electron to a naphthalene diimide acceptor through an amidinium-carboxylate interface. Two different isotope effects are observed for variant temperature regimes. A reverse isotope effect (i.e., kH/kD < 1) is observed as T approaches 120 K (kH/kD = 0.9, 120 K), whereas a normal isotope effect (i.e., kH/kD > 1) is recovered as the temperature is increased (kH/kD = 1.2, 300 K). The transition between these limits is smooth, with a crossover temperature of T ∼ 160 K. These observations are in accordance with charge-transfer dynamics that are susceptible to bath-induced fluctuations in the proton coordinate.

Original languageEnglish (US)
Pages (from-to)18853-18858
Number of pages6
JournalJournal of Physical Chemistry B
Volume110
Issue number38
DOIs
StatePublished - Sep 28 2006
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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