Solvation Dynamics of a Radical Ion Pair in Micro-Heterogeneous Binary Solvents: A Semi-Quantitative Study Utilizing MARY Line-Broadening Experiments

Authors

  • Dr. Kunal Pal,

    Corresponding author
    1. Institute of Physical and Theoretical Chemistry, Graz University of Technolgy, Stremayrgasse 9/Z2, A-8010 Graz (Austria)
    • Institute of Physical and Theoretical Chemistry, Graz University of Technolgy, Stremayrgasse 9/Z2, A-8010 Graz (Austria)
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  • Dr. Günter Grampp,

    1. Institute of Physical and Theoretical Chemistry, Graz University of Technolgy, Stremayrgasse 9/Z2, A-8010 Graz (Austria)
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  • Dr. Daniel R. Kattnig

    1. Institute of Physical and Theoretical Chemistry, Graz University of Technolgy, Stremayrgasse 9/Z2, A-8010 Graz (Austria)
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  • MARY=magnetically affected reaction yield

Abstract

This work aims at elucidating the mechanism of solvation of a radical ion pair (RIP) in a micro-heterogeneous binary solvent mixture using magnetically affected reaction yield (MARY) spectroscopy. For the exciplex-forming 9,10-dimethylanthracene/N,N-dimethylaniline system a comparative, composition-dependent MARY line-broadening study is undertaken in a heterogeneous (toluene/dimethylsulfoxide) and a quasi-homogenous (propyl acetate/butyronitrile) solvent mixture. The half-saturation field extrapolated to zero-quencher concentration, B1/2, and the self-exchange rate constants are analyzed in the light of solvent dynamical properties of the mixtures and a dielectric continuum solvation model. The dependence of B1/2 on the solvent composition is explained by cluster formation giving rise to shortened RIP lifetimes. The results are in qualitative agreement with the continuum solvation model suggesting that it could serve as a theoretical basis for quantitative modeling.

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