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Issue 33, 2011
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Diffusional effects on the reversible excited-state proton transfer. From experiments to Brownian dynamics simulations

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Abstract

We have studied an excited state proton transfer (ESPT) from the cationic “super” photoacid N-methyl 6-hydroxyquinolinium perfluorobutane sulfonate to non-aqueous solvents using picosecond and nanosecond time-resolved fluorescence spectroscopy. Upon the photoinduced adiabatic deprotonation from the hydroxyl moiety, a quinolinium zwitterion with a highly anisotropic charge distribution is formed. Due to the complexity of the resultant photodissociated system, the typical description of the reversible ESPT within the framework of the Spherically Symmetric Diffusion Problem (SSDP) is not possible. Additional complications are caused by the presence of a counteranion particle which affects the proton mobility. To better understand the ESPT process, we have performed extensive Brownian dynamics (BD) simulations of this three-body system as a tool to reveal the nature of the nonstationary interaction potentials and to elucidate the role of a counterion in the diffusion and reactive properties of the proton. Moreover, our results demonstrated that the anisotropy of the potential force can be taken into account after adapting this force for use in the SSDP. The results of both BD simulations and SSDP calculation with the adapted force field were used to fit the experimental kinetics of this three-body problem adequately.

Graphical abstract: Diffusional effects on the reversible excited-state proton transfer. From experiments to Brownian dynamics simulations

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Publication details

The article was received on 28 Mar 2011, accepted on 20 Jun 2011 and first published on 14 Jul 2011


Article type: Paper
DOI: 10.1039/C1CP20952C
Citation: Phys. Chem. Chem. Phys., 2011,13, 14914-14927
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    Diffusional effects on the reversible excited-state proton transfer. From experiments to Brownian dynamics simulations

    A. V. Popov, E. Gould, M. A. Salvitti, R. Hernandez and K. M. Solntsev, Phys. Chem. Chem. Phys., 2011, 13, 14914
    DOI: 10.1039/C1CP20952C

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