Characterizing the Behavior and Properties of an Excited Electronic State: Electron-Transfer Mediated Quenching of Fluorescence

Lars Poulsen , Arantza Zabala Ruiz , Steen Uttrup Pedersen and Peter R. Ogilby
Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
J. Chem. Educ., 2003, 80 (7), p 819
DOI: 10.1021/ed080p819
Publication Date (Web): July 1, 2003

Abstract

We have designed a series of laboratory exercises to illustrate a range of key concepts traditionally encountered in a general course on physical chemistry. In these exercises, optical spectroscopic measurements, electrochemical measurements, kinetic measurements, and computer modeling are used to characterize the properties and behavior of an electronic excited state. Specifically, students are asked to use these tools to answer a question posed at the outset: "Upon interaction with a series of molecules, Q, are the fluorescent states of 9-cyano- and 9,10-dicyanoanthracene quenched via an electron transfer process?" In the laboratory, students experimentally quantify rate constants, kq (exp), for cyanoanthracene excited state removal by the molecules Q in a Stern–Volmer study of fluorescence quenching. In other experiments, students collect information that allows them to independently calculate the rate constants, kq (calc), for these same molecules Q that would be expected if quenching proceeds via an electron transfer process. Upon comparison of these respective kq values in a Rehm–Weller plot of both kq (exp) and kq (calc) against the Gibbs energy of electron transfer, the students ascertain that the quenching reaction studied indeed proceeds via electron transfer.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Physical Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Transport Properties

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    Steady-State Fluorescence Anisotropy To Investigate Flavonoids Binding to Proteins

    Christine M. Ingersoll and Christen M. Strollo
    Journal of Chemical Education2007 84 (8), 1313
    • Steady-State Fluorescence Anisotropy To Investigate Flavonoids Binding to Proteins

      Christine M. Ingersoll and Christen M. Strollo
      Journal of Chemical Education2007 84 (8), 1313

      A laboratory experiment using steady-state fluorescence polarization or anisotropy to determine the binding constant for a flavonoid–protein interaction is described. Using the intrinsic fluorescence of quercetin (a model flavonoid), the fluorescence ...

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  • Received: August 03, 2009

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